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FAO/SF: 53/KEN-3

SURVEY OF THE IRRIGATION POTENTIAL OF THE LOWER TANA RIVER BASIN

KENYA

FINAL REPORT ^ Volume I GENERAL

V

ISHIC LIBRAE? UNITED NATIONS DEVELOPMENT PROGRAMME KE - 1968.06 )OD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS Wageningen The Netherlands *•• [ "=»

VOLUMES OF THE FINAL REPORT

Volume I --.. •' "--.',, ^

The General Report-ThéSGeneral Report is issued by the Food and. Agriculture Orga­ nization of the United Nations acting^ as executing agency for the -project on' behalf of

the' United Nations Development Programme. The volume contains the essential story of ; *• the studies, carried out during the survey and the agency's conclusions and recom­ mendations based thereon., '"''*.--''

Volumes II to VII <- -,

The Technical Volumes. The technical volumes as listed hereunder are-issued by the executing agency as technical annexes to the Generar'Report, "~as prepared by the cooperating consultants, the Consortium of International Land Development- Consultants, N.V., of the Netherlands, and Acres International Limited, of Canada.

• 4 r' ' - \ Volume II Appendix A - Hydrology and Meteorology Appendix B - Engineering Surveys"

^ Volume-Ill Appendix C - Soils (.' ' ' . •

AppendbTD - Vegetation " ; v v ^. - - ) .V;- , :. x , - -

, Volume IIIA Maps'accompanying Appendixes C and D

Volume IV Appendix^ E - Chemical Analyses

Volume V Appendix F - Agronomic Studies Appendix G - Agroeconorhic Studies Appendix H - Agricultural Development X"

*A Volume VI. Appendix^ I - Water Resources Planning

AppendixvJ - Power Development" r Appendix K - Irrigation; Development , 'Appendix^L .-"Research and Training Centre^

Volume VII -Appendix M -Infrastructure and-Secohdary Development K

Volumes II, III, IIIA, IV and V contain the basic hydrometeorologic, geologic, pédologie,/ agronomic and economic data as^collected and"'collated" during the course of the investigations. Volume VI contains the details of the development programme for irri­ gation and power and, in ;Volume VIy infrastructure, secondary development and the sociologie implications'are discussed to the-extent warranted at this stage of,evaluation.

^Volume IV has not been included in the general distribution of the Report, as that volume contains solely the record of the many thousands óf chemical analyses performed to assess the suitability of soils for irrigated agriculture. These records are of\ interest only to the specialist. HenceT copies,of this material have been deposited with the Ministry,of Agriculture, Kenya, and at FAO Headquarters, Rome,-where they will-be available for-, future referenced '•-'-.'/ - . , Scanned from original by ISRIC - World Soil Information, as ICSU World Data Centre for Soils. The purpose is to make a safe depository for endangered documents and to make the accrued information available for consultation, following Fair Use Guidelines. Every effort is taken to respect Copyright of the materials within the archives where the identification of the Copyright holder is clear and, where feasible, to contact the originators. For questions please contact soil.isricOwur.nl indicating the item reference number concerned.

SURVEY OP THE IRRIGATION POTENTIAL OP THE LOWER TANA RIVER BASIN

KENYA

158*30

: I._'..,J •...... ( K E i (sÖ. a(o PAO/SPt ; w 'Oanlnnnn, The Mo norlands 1

Survey of the Irrigation Potential of the Lower Tana River Basin

KENYA

Final Report

Volume I

General

Report prepared for the Government of Kenya "by the Pood and Agriculture Organization of the United Nations aoting as exeouting agenoy for the United Nations Development Programme

United Nations Development Programme Pood and Agriculture Organization of the United Nations

Rome, 1968 - V -

ABSTRACT

This report describes a project conducted by the Government of Kenya, with the assistance of the United Nations Special Fund*and the Pood and Agriculture Organiza­ tion of the United Nations, to assess the irrigation potential of the Lower Tana river basin. The Government's request for assistance was approved at the Kay 1$62 session of the Governing Council of the United Nations Special Fund.

The Consortium of International Land Development Consultants of Arnhem, the Netherlands, and Acres International Ltd. of Niagara Falls, Canada, were commissioned by the Food and Agriculture Organization of the United Nations to undertake the survey. This document forms the General Report on the project prepared by FAO as executing agency.

A Plan of Operation for the implementation of the projeot was agreed and signed on behalf of the Government of Kenya, the United Nations Special Fund and the Food and Agricultural Organization on 2 May 1963. The UNDP allocation to the projeot amounted to US $ 1,033,400 and this covered the cost of personnel, contractual servioes, fellowships and equipment. The Government contribution in kind, which amounted to some US $ 714,200, oovered the oost of counterpart personnel, local equip­ ment and supplies, housing and office buildings, land and transportation.

The possibility of large scale development of this region involved investiga­ tions of storage sites and water requirements in the upper portions of the catchment. Therefore, it was necessary to investigate the entire catchment as one hydrological unit and to oonsider the part that would be played by the development of hydro- eleotrio power.

Field operations were started in August 1963 and were oompleted in August 1966. The work oarried out inoluded» mapping the irrigation project area in the lower Tana basin and the middle reaches of the river} geologio and geophysical examination of foundation conditions at potential storage and diversion dam sites} soils and vegeta­ tion surveys} agronomio and irrigation experiments and hydrometeorolôgical appraisals. Preliminary engineering plans and designs, with cost estimates, and an economic ap­ praisal, were prepared for proposed irrigation development. Many miles of dry- weather roads and tracks were constructed to facilitate the surveys and to permit aocess throughout the project area.

Nine fellowships were awarded during the course of field operations, in irriga­ tion engineering, agronomy and management, and in hydraulic engineering. The first fellowship was taken up in September I965 and the last in July I966. The countries to which the fellows were sent for study included U.S.A., Canada, Sudan, Netherlands and Israel.

» Assistance to the projeot was provided by the United Nations Spooial Fund until 1 January 1966, On that date the Special Fund and the Expanded Programme of Technioal Assistance were merged into the United Nations Development Programme, which oontinued to provide assistance to this projeot. vi

The findings of the survey confirm the results of previous investigations, which have shown the possibilities of developing hydro-electric power at a succes­ sion of points in the middle reaches of the Tana river. Suoh a network could provide an installed capacity of 865 megawatts at a oapital oost of nine million pounds sterling. It is expected that the inclusive cost per kilowatt of such development would he lower than that of power from alternative thermal stations* The demand for power in Kenya is expected to rise to 800 megawatts hy the year 2000. and as the present potential for hydro-eleotrio power from sources other than the Tana river is only 18 megawatts, this points to the necessity for develop­ ing power on the Tana river as soon as possible,,

In its lower reaches, the firm flow of the Tana river is shown to he 1,100 cubio feet per second, whioh is enough to irrigate 100,000 aores of land. The regulation of flows for power would enahle the firm flow downstream to he inoreased to 2,800 cubio feet aperrsecond hy the year 2000, enough for 250,000 acres of : irrigation, ultimately, hy diverting flows from the Athi river, 330,000 aores of suitable soils could be irrigated.

On groundwater, the report concludes that there is little or none available in the projeot area, except in the perched water table to be found in the Tana flood plain adjoining the river channel.

Since the cost per acre of irrigation development will be high, field trials were concentrated on cash crops which could bring in fair to good returns. Except for cotton, whioh had consistently given good yields over a number of years, trials of other crops had not been carried out long enough to reaoh firm conclusions. More investigation and testing remains to be done before a really sound oropping pattern can be developed. Therefore, the report recommends, as a first step, the setting up of a Research and Training Centre to be supplied with irrigation water by pumping. This centre would be the first stage of development of the ultimate irrigation scheme, and at the same time would investigate the cropping patterns, conditions of tenancy and of cultivation, financial arrangements and all other points involved in the successful development, operation and management of suoh large scale schemes.

Concurrent with this first stage of development, the report recommends the setting up of a semi-autonomous organization, to be called "The Tana River Irriga­ tion Authority" and to take charge of the soheme from the beginning. Its functions would include construction and operation, marketing, research, extension and training, mechanized cultivation and the processing of crops. - vix -

TABLE OF CONTENTS

FRONTISPIECE ABSTRACT CHAPTER I INTRODUCTION 1.1 Origin of the Project 1.2 The Plan of Operation 1.3 Field Operations 1.4 Acknowledgements

CHAPTER II SUMMART OF CONCLUSIONS AND RECOMMENDATIONS A. CONCLUSIONS 2,1: The Tana River and Its Water Resources 2.2 The Use.of Water for Power and Irrigation 2.3 Lands Available 2.4 Costs of Irrigation and Agronomio Considerations 2.5 Scheme of Development for Irrigation 2.6 Infrastructure and Secondary Developments 2.7 Organization and Management 2.8 Phasing of Development of Irrigation 2.9 Economic Evaluation 2.10 Financial Analysis 2.11 Recovery of Costs from Cultivators 2.12 Size of Holdings 2.13 Animal Husbandry B. . RECOMMENDATIONS 2.1 Need to Reappraise the Scheme for Irrigation Development 2.2 Pilot Scheme 2.3 Tana River Irrigation Authority 2.4 Further Studies 2.5 Subsequent Action - viii -

Page No CHAPTER III THE COUNTRY AND THE PROJECT AREA 16 3.1 The Country 16 3.2 The Project Area 17

CHAPTER IV METEOROLOGY AND HYDROLOGY 30 4.1 Hydrometeorologio/ Data 30 4.2 Hydrometeorologio Analyses 32

CHAPTER V SURVEYS, GEOLOGY AND ENGINEERING COST DATA 41 5.1 Topographic Mapping 41 5.2 Geologic Surveys 42 5.3 Cost Estimating Data 44

CHAPTER VI SOILS AND VEGETATION 46 6.1 Semi-detailed Soil Surveys 46 6.2 Detailed Soil Survey 47 6.3 Vegetation Survey 47 6.4 Land Classification 49 6.5 Reclamation 51

CHAPTER VII AGRONOMIC STUDIES 55 7.1 Cotton Experiments and Observations 56 7.2 Experiments and Observations on Crops 56 other than Cotton 7.3 Irrigation Trials 60 7.4 Animal Husbandry 60

CHAPTER VIII AGRO-ECONOMIC STUDIES 62 8.1 Markets and Price Levels 62 8.2 Land Tenure 65 8.3 Tenant Income and Labour Requirements 66 - ix

Page Ho.

CHAPTER IX AGRICULTURAL DEVELOPMENT 67 9.1 Cropping Pattern 67 9.2 Farm Size and Layout 69 9.3 Requirements for Labour and Machinery 69 9.4 Value and Cost of Agricultural 71 Production 9»5 Processing of Farm Products 73

CHAPTER X POWER POTENTIAL AND MARKETS 74 10.1 Power Resources of Kenya 74 10.2 Present Kenya System 70 10.3 Load Growth Forecast 77 10.4 Comparative Cost of Energy 79

CHAPTER XI WATER RESOURCES PLANNING AND POTENTIAL 82 11.1 Water Resources for Power Development 82 11.2 Water Resources for Irrigation 63 Development 11.3 Implications of Water Resources 90 Development

CHAPTER XII POWER DEVELOPMENT 92

12.1 Selection of Storage and Power Sites 93

CHAPTER XIII IRRIGATION DEVELOPMENT 105 13.1 Potential Development - 106 Layout of Irrigation Network 13.2 Potential Development - 112 Groundwater Conditions and Drainage 13.3 Land Preparation 112 13.4 Road Network 113 13.5 Ko'rokora Dam 114 13.6 Capital Costs — 114 Irrigation Development - X -

Page No. 13.7 Research and Training Centre 116 13.8 Pilot Scheme - First Stage of 116 Development

CHAPTER XIV INFRASTRUCTURE A1ID SECONDARY DEVELOPMENT 120 14.1 General 120 14.2 Requirements 121 14*3 Other Aspects 122 I4.4 Processing 123

CHAPTER XV ORGANIZATION AND MANAGEMENT 124 15.1 General 124 15.2 Specific Points 125

CHAPTER XVI ECONOMIC EVALUATION 127 16.1 Internal Rates of Return 128 16.2 Recovery of Costs from Beneficiaries 142 16.3 Tenant Income 145 16.4 Financial Analysis 146 16.5 Estimate of Total Required Investment 151 16.6 Foreign Currency Aspect of 151 Project Development 16.7 Conclusions 160

CHAPTER XVII FURTHER STUDIES AND INVESTIGATIONS 162 17.1 Requirements 162 17.2 Ways and Means 164 - 3d.

r

Page No.

APPENDIX I PLAN OF OPERATION 165 APPENDIX II LIST OF PROJECT STAFF 179 APPENDIX III FELLOWSHIP AWARDS l80 APPENDIX IV REFERENCES l8l - aüLi

LIST OF TABLES

No. Page No. 2-1 Power Development on the Middle Tana 5 2-2 Irrigation Development - Internal Rates of Return 11 3-1 Long—term Average Flow - Tana River and Tributaries 23 4-1 Net Discharges at Seven Forks (Confluence) and at Koreh 33 4-2 Long-term Average Flow and Net Available Flow - Tana River and Tributaries 34 4-3 Estimates of "Design Flood" Peak Discharge Used in the Studies 35 4-4 Estimates of Diversion Flood Peak Discharge Used in the Studies 36 4-5 Average Annual Evaporation and Rainfall Rates Used in Evaluating Potential Storage Reservoirs 37 4-6 Monthly Estimates of Potential Evapotranspira­ tion for the Project Area 37 4-7 Monthly Recurrence Intervals of Effective Rainfall at Galole 38 4-8 Recurrence Intervals of Maximum Rainfall in the Project Area 39 4-9 Sedimentation Estimates at Potential Storage Sites 40 6-1 Soil Classification 48 6-2 Classification óf the Vegetation into Associations 50 6-3 Land Suitability Classification - Project Area (1) and (2) 52-53 6-4 Soil Suitability Classification - Research and Training Centre 54 8-1 Population Orowth Estimates - Kenya 63 8-2 Projected Cotton Requirements for Kenya in Tons of Cotton Lint for High and Low Projections of Population Orowth 64 9-1 Direct Costs of Agricultural Production 71 9-2 Estimation of Farm Income 72 9-3 Quantities of Produce to be Processed (30,000 acre district) 73 11-1 Long-rterm Average Flows and Design Discharges 83 11-2 Firm Flows and Energy Outputs - Tana River Development Mutonga II Sequence D 84 •xiii

LIST OF TABLES (Cont«d)

go. Page No.

11-3 Monthly Bet Water Requirements 85 11-4 Monthly Irrigation Potential of Diverted Plow at Korokora Irrigation Potential 85 11-5 F10* Availability at Korokora 86 12-1 Head, Flow and Power Potential of the Middle Tana 94 12-2 Estimates of Capital Cost - Tana River Power Project 97 12-3 Mutonga II - Sequences of Development 98 12-4 System Power Output and Growth with Variations in Load Growth and Net Water Availability 99 12-5 System Power Output and Cost with Athi River Diversion 100 I3-I Net Irrigahle Areas Commanded by Section Feeders 111 13-2 Estimates of Capital Costs - Irrigation Develop­ ment II8 13-3 Research and Training Centre - Estimate of Capital Cost 119 16-lA Investments for Irrigation Development Rate 1 - 250,000 Acres 129 16-lB Investments for Irrigation Development Rate 2 - 250,000 Aores 130 16—lC Investments for Irrigation Development Rate 1 - 300,000 Acres 131 16-lD Investments for Irrigation Development Rate 2 - 300,000 Acres 132 16-2A Irrigation Development - Annual Costs and Benefits - Rate 1 - 250,000 Aores 133 16-2B Irrigation Development - Annual Costs and Benefits - Rate 2 - 250,000 Aores 134 16-2C Irrigation Development - Annual Costs and Benefits - Rate 1 - 300,000 Aores 135 16-2D Irrigation Development — Annual Costs and Benefits - Rate 2 - 300,000 Acres 136 16-3 Internal Rates of Return 137 I6-4 Specimen Representative Finanoial Analysis Irrigation Development 150 •xiv-

LIST OF TABLES (Cont'd)

Ko, Page Ko, 16-5A Total Required Investment Hate 1 - 250,000 Acres 152 16-5B Total Required Investment Rate 2 - 250,000 Aores 153 16-5C Total Required Investment Rate 1 - 300,000 Acres 154 16-5D Total Required Investment Rate 2 - 300,000 Acres 155 16-6A Foreign Currenoy Aspects of Irrigation Development Rate 1 - 250,000 Aores 156 16-6B Foreign Currency Aspects of Irrigation Development Rate 2 - 250,000 Acres 157 16-6C Foreign Currency Aspeots of Irrigation Development Rate 1 - 300,000 Acres 158 16-6D Foreign Currenoy Aspects of Irrigation Development Rate 2 - 300,000 Acres 159

^ - XV -

LIST OP PLATES

No. Page Wo. 1 Tana River Basin 19 2 (Sheet 1 and 2) Profile of Tana River 21-22 3 Average Annual Isohyetal Pattern 25 4 Eastern Kenya General Geology 27 5 Hydrograph of Average Monthly Discharges Tana River at Kamburu 31 6 Proposed Crop Pattern 68 7 Schematic Arrangement of Rotations and Crop Phasing Related to Farm Holdings 70 Nairobi and Western Kenya System - Electrical Demand - Peak Load Forecast 78 Cost of Energy from Thermal Installation at Mombasa 80 10 Rates of Irrigation Development 87 11 Comparison between Plow Availability and Irrigation Demand at Korokora 89 12 Power Development - Middle Tana 96 13 Development Sequence Mutonga II D - Installation Schedule - Load Growth Rate 1 102 14 Development Sequence Mutonga II D - Installation Schedule - Load Growth Rate 2 103 15 Mutonga Sequence II D - Cumulative Capital Expenditure IO4 16 (Sheet 1 to 3) Layout of Project Area IO7-IO9 17 Distribution System - Layout of Irriga­ tion Blook and Typical Seotions 115 18 Korokora Diversion Dam- General Arrange­ ment Pull Supply Level 463 Feet 117 19 Irrigation Project - Schematic Management Organization Chart 126 20 Irrigation Development - Streams of Investment 138 21 Irrigation Development - Annual Costs 139 22 (Sheets 1 and 2) Irrigation Development - Annual Benefits and Expenditures to Authority I4O-I4I 23 (Sheets 1 and 2} Internal Rates of Return 143-144 24 (Sheets 1 and 2) Total Annual Benefits and Expenditures of Irrigation and Processing 147-148 - 1 -

CHAPTER I

INTRODUCTION

1.1 Origin of the Project

The need to develop the irrigation potential of the lower Tana river in the Republic of Kenya has long been recognized by the Government. Certain investigations had already been carried out prior to the inception of this project. For example, a detailed study of the water resource potential of the upper catchments of the river for both irrigation and hydro-electrio power development had been carried out by Messrs. Alexander Gibb and Partners. The middle Tana had been investigated by Messrs. Balfour Beatty, consultants as to the potential of this section for hydro­ electric power development.

The lower Tana, with its extensive areas of desert soil lying close to a good source of irrigation water, appears to be a natural region for agricultural develop­ ment and for settling surplus peasant population from densely populated areas in other parts of Kenya. Any large-soale development of this region would involve investigations of storage sites and water requirements in the upper portions of the oatchment. Therefore, for the purposes of this project it was neoessary to consider the entire oatchment as one hydrological unit in planning development of the lower portion for irrigation.

The Governing Council of the United Nations Special Fund-' agreed to a request by the Government for assistance in the Tana basin studies, at its May 1962 session. The Food and Agriculture Organization of the United Nations, appointed as the executing agenoy, in turn appointed as co-operating consultants the Consortium of International Land Development Consultants, N.V., of Arnhem, the Netherlands, and Acres International Limited, of Niagara Falls, Canada. The Government appointed its Ministry of Land Settlement and Water Development as the Government Counterpart Agency. The UNSF authorized operations to commenoe in June 1963; the project became operational on 4 August 1963 and oonoluded in August 1966.

l/ Assistance to the projeot was provided by the United Nations Speoial Fund until January I966. On that date the Speoial Fund and the Expanded Programme of Technical Assistance were merged into the United Nations Development Programme which continued to provide assistance to this projeot. - 2

In June 19^3 a preliminary mission, consisting of representatives of FAO and the consultants, undertook a pre-project evaluation, assessed requirements for equip­ ment, and established limits for the irrigation project area so that the essential ground control surveys for mapping could proceed.

1.2 The Plan of Operation

General guidelines for the survey of the irrigation potential of the lower Tana basin are set forth in the Plan of Operation as agreed and signed between the Govern­ ment of Kenya, the United Nations Special Fund, and the Food and Agriculture Organiza­ tion on 2 May, 1963. The Plan of Operation is attached as Appendix I to this report. Taking into account subsequent amendments to the Plan of Operation, it will be observed that the total cost of the projeot was of the order of US 8 1,747,600. The UNDP al­ location of US $ 1,033,400 was in the form of technical personnel and contractual services, fellowships and equipment. Details of projeot personnel and fellowships are provided in Appendix II and III of this report.

The Government counterpart contribution, estimated at U3 % 714»200 was in the form of counterpart technical and administrative personnel, local equipment and supplies, housing, office buildings, and transportation.

1.3 Field Operations

All of the necessary field investigations were set in hand with the full co­ operation of the Kenya Government. Some early delays and difficulties were experienced due to disruption of normal road communications through flooding and by the disturbed conditions in the area under investigation at the time. The delays caused through deferment of oertain investigations were largely overcome through the re-scheduling of operations, and although the field assignments for several members of the project team had to be extended, no substantial overall delay was experienced in completing the studies.

The investigations carried out for this survey included mapping the portion of the lower Tana basin containing the irrigation project area, and the middle reaches of the riverj geologio and geophysical examination of foundation conditions at poten­ tial storage and diversion damsites; soils and vegetation surveys throughout the project lands} agronomio and irrigation experiments] and hydrometeorologic appraisals, network extension and analyses. Many miles of dry-weather roads and tracks were constructed to facilitate the surveys, permitting access throughout the irrigation project area and to various locations along the main river and its tributaries. Extensive laboratory analyses in the fields of soil chemistry and geoteohnics were undertaken. All of these, together with the related engineering, agricultural and economio studies, form the basis for evaluation of project potential as described in this report.

1.4 Aoknowledgements

The Food and Agriculture Organization wishes to place on record its sincere ap­ preciation of the assistance of the Government of the Republio of Kenya and of the many individuals and organizations who contributed materially to the successful execution -3-

of the survey. The keen interest and support shown by the Minister of Agriculture, the Hon. B. McKenzie, his Permanent Secretary, Mr. O.K. Kariithi, the Tireotor of Agriculture, Mr. P.T. Mirie, and other officers of his staff are greatly appreciated; also, special thanks are due to the Government's Co-Manager, Mr. G. Manig, and his predecessor, Mr. I.D. Watts, and all of the Government counterpart staff assigned to the survey, who ensured that the numerous requirements of the survey were provided in full. The guidanoe provided hy the Tana River Steering Committee has heen particu­ larly helpful in clarifying Government policy and arranging for inter-departmental co-operation in the execution of the survey. - 4 -

CHAPTER II

SUMMARY OF CONCLUSIONS AND RECOMMENDATIONS

A. CONCLUSIONS

2.1 The Tana River and Its Water Resources (see Chapter III)

The Tana river is the largest perennial river in Kenya and its water resources, indicated below, offer the greatest potentials for hydro-electric power generation and irrigated agriculture in the country, as the following details of long-term flow show:

Place Catchment Estimated Present reser­ Present long-term vation for upper long-term average flow catchment average flow

sq.miles cusecs cusecs cusecs

Kainburu 3,500 3,125 530 2,595 Grand Falls 6,800 5,130 530 4,600 Koreh 9,500 5,580 530 5,050 Garissa 12,500 4,750 530 4,220

The actual flows of course vary widely above and below these long-term average rates, both from day to day, and from year to year. Of the 530 cusecs now reserved, up to 4OO cusecs may be released, if so decided by the Government. In addition, some diversion of water from the upper Athi river to the Tana river, via the Thika river, might provide up to 757 cusecs more.

2.2 The Use of Vater for Power and Irrigation (see Chapters IV and XI)

It is evident that whilst hydro-eleotrio power can be developed independently, large scale irrigation of the lower basin is dependent upon the upstream control of flows necessary for power generation. The optimum power complex would in fact remain the same, even if irrigation were not developed. Thus, the two major uses of the water resources of the Tana river are mutually compatible. - 5 -

Although it is apparent that the rate of development of irrigation is to some extent dependent upon 'the rate of growth of the power system, this appears to he of little practical significance, as a growing demand for power already exists. If this demand is met by development of the hydro-electric resources of the Tana, it is bound to provide the necessary flow control in advance of any reasonable schedule of irrigation development which may he foreseen.

The power system envisaged would utilize to a high level the head and flow of the middle Tana, through a complex of projects, the main features of which are sum­ marized in Table 2-1. The power system defined in this table does not include the additional 131 megawatt potential that could be developed by releasing some 400 cubic feet per second (cusecs) of upstream allocations.

Table 2-1 - Power Development on the Middle Tana

Project Estimated Gross Long-term Installed Annual capital cost* head firm flow capacity energy production

£ E.A. (millions) ft cusecs MW GWh***

Seven Forks** 63.91 1,005 2,730 320 1,630 Kiambere 23.70 334 2,730 I92 575 Mutanga 22.12 268 3,850 112 63O Grand Falls 16.39 I85 4,180 89 494 Adamson's Falls 14.77 123 4,550 65 359 Koreh 17.58 177 4,410 87 479 Athi Diversion 2.12 575

I6O.59 2,092 865 4,167

* Including capitalized value of accumulated operating defioits during development period; for load growth rate 1.

** Seven Forks development assumed as Confluence projeot to FSL 3,455 feet, plus Kindaruina as under construction.

*** GWh - gigawatt/hour -6-

Sequential development of the power complex would result in progressive control and regulation of river flows, such that a small reservoir would be sufficient to re-regulate the outflows from the power system in line with the water demands of any irrigation complex contemplated.

Without any regulation, the minimum flow to be expected at Koreh is estimated to be, in most years, at least 1,000 cusecs. Following the successive development of the power complex, the resulting firm flows at Korokora estimated to become available for irrigation are as follows:

Site of Power Firm outflow Est, firm Net firm flow Development flow entering expected to be available downstream for diversion at Korokora

cusecs cusecs cusecs Confluence 2,160 1,600 2,150 Mutonga 3,480 450 2,900 Grand Falls 3,810 150 2,950 Adamson's Falls 3,980 negligible 2,950 Koreh 3,480 — 2,810 These figures allow for average amounts of 830 cusecs natural loss from Koreh to Korokora, 100 cusecs compensation flow at Korokora, and 100 cusecs loss from evaporation in Korokora reservoir (see also Chapter XI ant* XIl).'

An irrigation complex is considered which would technically extend to 300,000 acres, for which it would be necessary to control and divert flows to the proposed irrigation area situated on the right bank of the lower river by means of a dam at Korokora. A layout has been prepared for the irrigation complex and preliminary designs have been made for the diversion dam.

2,3 Lands Available

Although the topography of the lower basin presents no special problems in the design of gravity irrigation systems, patches of suitable and unsuitable soils are intermingled, and this precludes utilization of about half of the lands under command of the diversion dam and the main supply canal. The following suitability classes and amounts of land have been identified.

Cla3s Description Gross Acres

1 Highly suitable 18,000 2 Suitable 224,000 3 Fairly suitable 323,000

It appears that the amounts of water to be made available, rather than the extent of land, will be one ruling factor in determining the ultimate potential development of irrigation. - 7 -

2.4 Costs of Irrigation and Agronomio Considerations (see Chapters VII, VIII and IX)

During the project studies, two levels of possible irrigation development were considered, namely 250,000 acres, and 300,000 acres. The estimated direct capital expenditure necessary worked out at 53 million and 60 million East Africa pounds respectively (see details in section 2.5 below). Direct investments in institutional and social infrastructure were estimated to cost an additional £E.A. 400 per net acre, and processing facilities a further £E.A. 200 per net acre. The foregoing did not include the costs of supporting productive activities such as forestry and fisheries, nor the external infrastructure related to project development.

Since the cost of irrigation development per acre seemed to be so high, at­ tention was concentrated on cash crops which could offer fair to good returns. Agronomic trials at Galole covered cotton, sugar cane, kenaf, groundnuts, castor, beans, maize, sorghum, rice, and fodder crops. Except for cotton, already well established at Galole, the tests made could not be sufficiently comprehensive in the time available, and more testing remains to be done. However, on the studies made and information available, a cropping pattern was evolved which included cotton, sugar cane, kenaf and groundnuts as major crops.

Table 9-2 shows that,of 8 crop-acres in 6 years, 6 crop-acres would be devoted to the cash crops cotton, sugar cane, and kenaf and only 2 crop-acres to groundnuts and beans. No staple food crop is included at all. The adoption of such a rotation would involve the assumption that supplies of staple foods for the whole population of the area could always be imported from elsewhere, at reasonable prices and with sufficient certainty. Considering the location and circumstances of the projeot, in a somewhat remote and semi-arid part of the country, this is quite unrealistic. Few prospective cultivators would be attracted by an economy consisting essentially of cash cropsj a man's first ooncern is to secure hie food supply, and it is es­ sential to grow sufficient basic foodstuffs every year, within the rotation.

The efficient production and handling of sugar cane calls for higly organized plantation methods, rather than cultivation by individual tenants. Further, a factory is essential, under skilled direction; to justify its heavy cost, there must also be grown from the start a sufficiently large area of cane.

The cutting, retting, and processing of kenaf requires much labour which, for efficiency, must be well organized, and even mechanized methods of decortication need further development. As was brought out in the studies made, casual labour does not exist in the area, nor is it likely to be easily attracted there in future, unless it is well organized and continually employed, at fair rates.

It is considered that the whole question of the oropping plan to be adopted requires more and very careful investigation, including trials and tests on a field scale of varieties and yields of crops over a sufficient period to establish what benefits may be expected. Such investigations are matters of some urgency.

Meantime, data are not yet available on which to make specific suggestions as to potential cropping patterns which might be further considered. It does, however, appear possible to envisage a pattern which omits sugar cane and kenaf, but maintains cotton as the main cash crop, with groundnuts and maize or sorghums as food crops. Cropping intensity would be slightly less than that envisaged in the pattern originally suggested, but it might nevertheless provide a rate of net farm revenue oomparable with the figure of E.A. Sh 950 per acre of holding, forecast in Table 9-2 for the original cropping pattern. -8-

2.5 Scheme of Development for Irrigation (See Chapters XI and XIIl)//

On the scheme of cropping originally contemplated, it was estimated that 1 cusec of flow at Kordkora would suffice for an area ranging from 70 to 119 acres, according to the month, the average over the year being 89 acres. On the basis of the 2,810 cusecs of firm flow expected to be ultimately available at Korokora, an area of about 250,000 acres could be irrigated. With releases from upstream reservations^and some diversion of flows from the Athi river^this could, be increased to about 300,000 acres. The scheme of development for irrigation contemplated for these areas comprised the following main works:—

(i) Korokora Diversion Dam and Reservoir. To divert flows of water from the river at a level suitable to command the whole of the potential ultimate irrigable areaj to provide some 196,000 acre-feet of storage capacity to re-regulate the flows arriving so as to suit irrigation needsj and incidentally, to provide some 600,000 acre-feet of dead storage, available for sediment deposit sufficient to ensure the continued life and effectiveness of the reservoir for a very long time,

(ii) Primary - Main Canal. To be aligned west of the irrigable area, which would begin at Mile 38 from the head/

(iii) Secondary - Section Feeder Canals. To take off from the main canal at suitable intervals.

(iv) Tertiary - Block Feeder Canals. To take water from (iii), through night- storage reservoirs, enabling irrigation to be given only by day. The canals would deliver water to standard irrigation units, each of 50 acres,,

(v) Drainage System. Intended to deal with surface water from rainfall and irrigation wastage,

(vi) Internal Road System. Envisaged as of various grades, but covering the whole scheme. It was contemplated in the original studies that the more important internal roads should be surfaced with stone. It is considered however that this is so costly that it should be deferred until the justification for it becomes clearly apparent. (See details on the following page). (vii) Land Clearing and Levelling for Irrigation. To include the preparation of the necessary systems of channels for irrigation and drainage within the 50-acre units. - 9 -

The capital costs of these items may be summarized as follows:

Estimated Estimated capital capital cost with cost with paved roads internal roads in earth £ E.A. £ E.A.

Korokora Dam and Reservoir 11,040,000 11,040,000 For irrigation of 250,000 acres: Irrigation and Drainage Works 20,698,000 20,698,000 Land Clearing and Levelling 7,283,000 7,283,000 Roads 3,400,000 14,070,000

TOTAL FOR 250.000 ACRES 53,091,000 42,421,000

For irrigation of an additional 50,000 acres: Irrigation and Drainage Works 2,720,000 2,720,000 Land Clearing and Levelling 1,457,000 1,457,000 Roads 2,855,000 615,000

7.032.000 4.792.000

TOTAL FOR 300.000 ACRES 60,123,000 47,213,000

The equivalent overall rates per acre are:

With paved roads £ E.A. 200 per acre With earth roads £ E.A. 154 per acre

2.6 Infrastructure and. Secondary Developments (See Chapter XIV)

If 250,000 to 300,000 acres are developed, the agricultural population, including families, would be between 400,000 and 500,000. Allowing for others engaged in administration, processing plants and commercial enterprises, transport, and so on, the total ultimate population might be from 500,000 to 600,000. Their requirements would include housing and other buildings, water supplies, sewage systems, power, and roads. In the studies made, the estimated following costs were forecast:

£ E.A. per head

Townsite Development and Services 90 Housing and Buildings 110

£ E.A. 200 •10-

For a population of,say, 500,000 on an irrigation scheme of 250,000 net irrigable acres, this is equivalent to £400 per net irrigable acre. Before this formidable figure is accepted, all aspects of the basis on which it is assessed must be most thoroughly scrutinised, including the method of sewage disposal contemplated.

Processing plants contemplated in the studies made covered the processing of sugar cane, cotton, and kenaf. Details were not worked out, but the capital cost for 250,000 acres was tentatively put at £ E.A. 40 million. This is equivalent to £ E.A. 160 per net irrigable acre.

2.7 Organization and Management (See Chapter XV)

The region in which the scheme lies is remote and sparsely populated. To attract settlers there, of prime importance will be the social and personal economic faotors, including living conditions and amenities, marketing arrangements, conditions of tenancy, and land tenure, and above all, the prospective financial returns to the individual cultivator. To him, these will be of even greater importance than techni­ cal agricultural factors, such as crops and yields, mechanized aids to cultivation, and so on.

An adequate return on the high cost of development can only be possible with high standards of husbandry and production. A proposal to set up a semi-autonomous organization, to be called "Tana River Irrigation Authority" and to take charge of the scheme, is important. Its funotions could include construction and operation, marketing, research and training, with extension servioes, and secondary activities such as forestry. For development, it would itself have to maintain a large construc­ tion force, which might also undertake the provision of other public facilities - and develop processing plants.

It must be stressed that the whole organization of the scheme, including cropping patterns, conditions of tenancy and of cultivation, financial arrangements at all levels from cultivator upwards, relationships between Government, operation and management, need to be thought out and clearly defined, and agreed with all concerned and then applied and tested on a first instalment of modest but adequate size.

2.8 Phasing of Development of Irrigation (See Chapters Xf XI, XII, and XIIl)

In the studies made, the expected rates of increase of demand for power indicated that the reservoirs and power installations down to and including Mutonga might be required by some date between I983 and 1993» and the full complex of installations by some date between 1989 and 2000, according to the rate of growth assumed. Even the amount of regulation of river flows to be provided by the reservoirs down to Mutonga would suffice to ensure a supply of water for irrigation sufficient for the develop­ ment of 250,000 acres. According to the rates of development of irrigation assumed, it was forecast that 250,000 acres might be developed at some date between 1989 and 2000, and this would correspond with the development of power foreseen.

These projections are fully reasonable on the assumptions made in the studies. But, in view of the number and importance of the points requiring further investiga­ tion and consideration — technical, economic, and social - it is considered that the development to be contemplated in the near future should take the form of a first instalment of 8,300 acres. The Research and Training Centre suggested in the studies would be part of this instalment, but the primary aims would be production and "in-service" training. Such an instalment would need at most about 100 cusecs of water, and this would always be available from even the present minimum flow to be expected in the river. The pumping installation and canal, contemplated for the Researoh and Training Centre,would therefore suffice for the supply of the whole instalment. -11-

2.9 Economic Evaluation (See Chapter XVI) Using the method of rate of internal return, with yields and values of crops as discussed in the studies made, economic evaluations over a period of 50 years showed the following, for ultimate areas of 250,000 acres and 300,000 acres, at the minimum and maximum rates of development of irrigation.

Table 2-2 - Irrigation Development-Internal Rates of Return

250,000 acres 300,000 acres Level and Rate Rate 1 Rate 2 Rate 1 Rate 2 of Development (Low) (High) (Low) (High)

Irrigation development only 9.6 10.4 9.7 10.6 Irrigation development plus processing at 20 per cent return on book value 11.2 12.9 11.5 13.1 Irrigation development plus processing at 30 per cent return on book value 12.0 13.9 12.6 14.1 ftote: Period of analysis is 50 years and residual values are disregarded.

These figures relate only to the costs and benefits involved in the scheme of irrigation itself. In considering them, however, regard must be given to all expenditure involved, whether directly or merely indirectly in the development contemplated. The capital costs of the various categories of such expenditure, as forecast in the project studies, are summarised as follows:

Irrigable Area - 250,000 acres £ E.A. Million £ E. A. /acre Irrigation Development 53.0 212 Processing Plants 40.0 160 Housing, Town-sites, and Services 100.0 400 External Trunk Road (to Mombasa) 8.5 34

201.5 806 - 12 -

Expenditure on this scale, though to be spaced over many years, calls for the strictest and most thorough scrutiny before it can be accepted. This scrutiny should include appraisal under four main aspects, viz:

(a) The standards of provision assumed, e.g. for housing, roads, etc.

(b) The designs and materials assumed, and the unit rates of cost expected. (c) The production and benefits to be expected. (d) The implications of the project, on the revised forecasts of costs and benefits, not merely on its own merits, but also on comparison with other projects, in order to assess the degree of priority which each deserves, in the national interest.

2.10 Financial Analysis (See Chapter XVT) The financial analysis dealing with one possible way of financing the expenditure on irrigation development, makes the following conclusions: (i) "if the Irrigation Authority was to be responsible for the development of irrigation only, foreign financing would be possible on "soft" terms, and on the assumption that domestic loans would be free of interest." (ii) "if the Authority were also to be responsible for processing, more realistic foreign financing would become possible, provided the Authority had full control of that financing." It remains to be seen what financial analysis, and what conclusions, may result from revised appraisals, following the further scrutiny and investigations now recommended, in line with points (a) to (d) in (2.9) above.

2.11 Recovery of Costs from Cultivators (See Chaper XVI)

It was oonoluded that, in view of the conditions of the proposed development and of its potential benefits to Kenya as a whole, an assured inoome for cultivators should have priority in the financial arrangements over the meeting of charges on the scheme, at any rate up to an income of £ E.A. 160/year/cultivator to begin with, rising gradually to a maximum of £ E.A. 250/year/cultivator. Relief to cultivators on the oost of housing was also suggested. This raises the question of the charges to be made, and how they are to be assessed and oolleoted on individual cultivators - whether on the amounts of water used, on areas of holding or of crops, or on values of the actual amounts of crops grown. All these factors require careful considera­ tion. -13-

2.12 Size of Holdings (See Chapter IX)

Under the studies made, it was suggested that a 5-acre holding per family on the proposed irrigation scheme, which would ultimately give the tenant £ 250 per annum net, would fit conveniently into the irrigation layout, in which 50-acre units would form the basic module of development. This may be convenient from an engineering point of view, but it must be mentioned that such a rigid standard of ownership could affect farm efficiency in the long run. There should be a certain degree of flexibility in the size of holdings, which would help to provide incentives. All that is required is to fix a minimum/maximum limit on the size of holding, say from 5 to 10 acres, depending on the size of family and the eagerness of the tenant to operate the holding with greater efficiency.

2.13 Animal Husbandry

The contribution which livestock might make to the pattern of agricultural output is shown in Table 9-2 to be only about 6 per cent per six-year rotation. However, with the eventual development, of the lower Tana basin, the nomadic character of the livestock industry would most likely give way to a more settled form of animal husbandry. This in turn should increase the contribution of animal husbandry to total farm output. It has been shown that fodder crops grow well on the project area, and the possibility of dairy production should be fully investigated.

B. RECOMMENDATIONS

2.1 Need to Reappraise the Scheme for Irrigation Development

In view of the magnitude of investment required to implement an irrigation development programme on the scale envisaged in the lower Tana river basin, it is recommended that the Government review this scheme- in terms of Kenya's general development strategy and priorities for investment.

2.2 Pilot Scheme

Due to the complexity of the proposed scheme, and the many technical, economic and sociological factors which require consideration prior to its implementation, the proposal to set up and develop a Research and Training Centre is fully endorsed. Such a centre should however be primarily for production and in-service training of all concerned. The Centre should form an integral part of a pilot scheme or of an initial phase of irrigation development. -14-

During the project, consideration was given to a number of locations for a centre of this type. It is considered that an area of about 8,000 acres would be necessary to provide for research and for a large demonstration training farm. The latter could eventually be converted to normal tenancy holdings, with only a part retained for continuing research and training activities. It is suggested that the centre could be located immediately adjacent to the Tana river and south of L.Hiraman, in an area representative of the major soil types of the project area and centrally located in the northern region. It could then serve as the focus of a community containing the Authority headquarters.

The pilot area could be supplied from a pumped water supply, as designed during the project, the cost of which is estimated at £ B.A. 2,915,000.

The alternative proposal is to develop further the smaller scheme at Galole, which has at present 1,200 acres under irrigation. It may be possible to extend this for another 1000 acres or so to include a more representative proportion of soils found in the project area. But, if it should be found feasible to proceed eventually with a major irrigation development, the first area mentioned would appear to be more suitable in the long term, as the central core of the project.

In the meantime, and until a final decision is taken on the location of the permanent Research and Training Centre and the Headquarters of the irrigation scheme, the agronomic research^ started during the; project and continued under Dutch bilateral assistance since, should be consolidated. Under the original agreement this aid was to terminate in March 19^9» but the Government has requested a three years' extension. During this period it should be possible to gain sufficiently reliable information ón crops, and varieties suitable for the area, and which give adequate returns, for inclusion in a cropping pattern for application in the general irrigation development of the project area.

2.3 Tana giver Irrigation Authority

It is strongly recommended that a Tana River Irrigation Authority be set up as proposed, as being the only means to ensure the requisite standard of efficiency. The whole organization of the proposed irrigation scheme, and particularly the relations between the Government, the Authority and the cultivators, should be thought out and agreed, and then tested in the first place on the pilot scheme proposed. In this way adjustments can be made as necessary in the light of experience, before full scale development is undertaken. It is also necessary to ensure that close cooperation is maintained between the Tana River Irrigation Authority and the existing Tana Steering Committee, which is responsible for the execution of the hydroelectric projects in the upper Tana.

2.4 Further Studies

In addition to the reappraisal and further studies touched on above, a number of specific points are mentioned hereunder for inclusion in the further programme of investigation.

For example, studies should be made of the implications of the control of flows for power, and the abstraction of water for irrigation, on the conditions of the river channel downstream of the offtake at Korokora, in the event of a catastrophically high flood. Observations should continue of climatic conditions, river levels and discharges, rates of runoff evaporation and river losses, at all points relevant to the development of the Tana basin, both for power and for irrigation. Observations -15-

and analyses of the results should continue of sediment loads in the flows of the Tana river, at suitable intervals of time, and at all significant points on the river as far down as Korokora.

Detailed soil survey and land classifications should be made of all areas contemplated for irrigation development as soon as possible and certainly before detailed planning is undertaken. The effects and implications of the soils of the lower Tana plains should be fully examined, particularly in respect of groundwater conditions, and salinity risks.

The sociological implications of irrigation development on a large scale should be fully examined, particularly as to the resettlement of highland people in the remote and arid Tana lowlands and also the effects on the local riverine people of the lower Tana.

2,5 Subsequent Action.

The Government of Kenya should consider how far the further action required in connection with the project can be undertaken by its own departments and agencies, and then in what manner and to what extent the Government may wish to seek for external help to carry out the remainder of the work involved. - 16 -

CHAPTER III

THE COUNTRY AND THE PROJECT AREA

3.1 The Country

The Republic of Kenya lies astride the Equator and stretches inland from the Indian Ocean to Lake Victoria, encompassing a total area of 225,000 square miles. Despite its location, a wide variety of climatic conditions are found within its borders, due principally to the existence of prominent topographical features. Along the 250 miles of coastline lies a narrow, mainly fertile, tropical belt, behind which stretches a vast area of semi- arid desert, reaching to and beyond the borders with Somalia, the Sudan and Ethiopia. Within the central high-lands, the climate and vegetation change with increasing altitude from subtropical to temperate.

Nearly three quarters of the entire country receives less than 20 inches of rainfall annually, whilst only some 15 percent receives more than 30 inches. Apart from the narrow coastal strip, the only areas of Kenya receiving enough rainfall to support non-irrigated agriculture are centres around the Kenya massif, in the Kisii Hills, and throughout the Mau escarpment and Mount ELgon areas of western Kenya.

The peoples of Kenya, apart from the recent immigrants, belong to four of the linguistically defined racial groups of Africa. It is not always easy to identify a group in Kenya, since its members are not confined to distinct geographic regions. The Bantu group is most numerous, comprising almost two-thirds of the people of Kenya, and, though they speak many dialects, they can understand each other. They include the Kikuyu and kindred tribes of the plateau, the Baluhya, Kisii and Nyanza, and a number of coastal tribes, some of which have intermarried with Arabs.

The second group, the Nilotic Jalue of the Lake Victoria shore, is more homogeneous and comprises many tribal units that are bound together by very close kinship affiliations. The Nile-Hamitic group is more difficult to define. These peoples are spread throughout the country; the Masai in the south, the Nandi and Kipsigis in the highlands above Lake Victoria, and the Turkana in the northwest. All traditionally pastoral, they have no common language and differ in their adaptability to sedentary agriculture. The remaining group is composed of the nomadic Hamitic tribes of the northern provinces, distinctive from the other African peoples of Kenya, being Caucasian in origin and Muslin by faith. - 17 -

Growth of the economy of Kenya for many years has "been largely dependent upon the intensification and extension of agriculture. Figures for the latter part of the 1950's and the early part of the I960's indicate that about 40 percent of the gross domestic product was derived from agriculture. It has been estimated that more than 85 percent of the African population is employed on the land.

The import/export situation reflects, to an even greater extent the heavy dependence on agriculture of the economy of the country. Imports into Kenya . consist almost entirely of manufactured goods for industry, transportation and agriculture, which the country is at present unable to produce. In the export field, the earnings of agriculture, including livestock, have constituted over 85 percent of total earnings in recent years. The wide range of agricultural cash crops produced in Kenya has compensated for the paucity of known mineral resources and, at the same time, has protected the country from the effects of sudden changes in the world market for particular commodities.

Prom I95O to i960, the total value of exported commodities more than doubled and reached £35 million annually. In the agricultural sector, coffee has always figured prominently in Kenya's exports, providing about,30 percent of total earnings in I96IJ sisal.and tea each provided about 13 percent and pyrethrum 9 percent, while, in the livestock sector, meat, hides and skins provided 10 percent.

The market price of coffee has been gradually falling over the past few years, and the crop has consequently accounted for a smaller portion of Kenya's total export earnings. Recent study of soils and land use in the highlands of western Kenya has indicated a great potential for growing rain-fed tea, and the rising demand for this crop on world markets appears likely to boost its export value considerably in the future. Sisal has, in the past, occupied a significant place in the export picture, but,, in recent years, due to widely fluctuating prices, the crop has occasionally not been worth cutting.

The prospects for significant expansion of agriculture depend very largely upon the availability of water supplies for irrigation.

There are few perennial rivers in Kenya and only two, the Tana and the Athi/ Galana, reach the Indian Ocean throughout the year. The wet side of thé country in ITyanza, which forms part of the Lake Victoria catchment, has several perennial streams. Por the major part of the country east of the central mountain massif, however, the Tana river, which is the largest in the country, offers by far the greatest potential of water for irrigation.

3.2 The Project Area

The Tana river basin encompasses a total catchment area of some 40,000 square miles. The headwaters rise along the eastern slopes of the Aberdare Range and the southern half of the Mount Kenya/Nyambeni massif, draining in a generally southerly direction. Below these mountain regions, the central portion of the basin is a plateau, gradually descending in steps to the eastern limit of the Basement rock system, which lies approximately along a line joining the Koreh hills and the Kitui escarpment. Between this rock system and the Indian Ocean, the river traverses a vast peneplain, extending to the north and south beyond the limits of ill-defined watersheds. -18-

Physiography

On Plate 1, the entire watershed and its perennially contributing oatch- ment are demarcated. A longitudinal axis, trending northwest-southeast through the basin from Kipini at the coast to the upper catchment boundary near Nyeri, measures some 300 miles, the mid-basin width on an axis through Garissa measures about 180 miles.

The catchment is conveniently discussed in relation to the upper, middle and lower reaches of the river. Por purposes of this report, the upper catchment is considered as the area tributary to the main stream above the Kamburü suspension bridge. This is in accord with past convention.

The middle Tana has previously been considered as that part of the basin tributary to the main stream between the Kamburu and Garissa bridges. However, geologic and physiographic considerations indicate that the middle Tana should end at the Hargasso Falls, the last visible outcrop of the Basement rock system along the main river. Thereafter, the Tana enters the sediments of the lowland plains. In this report, this latter point has been adopted for demarcation between the middle and lower catchments.

upper catchment tributaries drain much of the central highlands, a zone of high rainfall. With the exception of a few deeply-incised stream valleys, this part of the catchment lies above 3>000 feet elevation. The basin boundary passes along the crest of the Aberdare Range, which rises generally to 10,000 feet, with Mount Kinangop, elevation 12,816 feet, in the south and 01 Doinyo Lesatima, eleva­ tion 13>104 feet, in the north as the highest points of the range. Mount Kenya rises to 17)058 feet and the divide places a little more than the southern half of this mountain within the Tana basin. Above 15,000 feet, permanent snowfields and glaoiers are found. The Kyambeni Range rises generally to 6,000 feet, with Mount Itani, elevation 8,244 feet, in the west and Mount Ntoyer, elevation 6,466 feet, in the east as the highest features. The intermontane plateau of the upper catchment slopes gently downwards to the southeast so that the surface elevation decreases from near 6,000 feet at Hyeri to about 4>000 feet at the edge of the Kitui escarpment.

The middle catchment comprises land lying generally above 1,000 feet eleva­ tion. Part of the Mount Kenya Range, the southern slopes of the Nyambeni Range and the northern part of the Kitui escarpment all lie within this portion of the basin.

The lower catchment derives only intermittent runoff from an area lying almost entirely below 3>000 feet; the major part is semi-arid desert lowlands below 1,000 feet elevation.

-20-

Drainage System and Vater Resources

The upper catohment is drained by a multitude of streams descending the slopes of Mount Kenya and the Aberdares in a series of precipitous gorges. Gradually, these streams coalesce on the intermontane plateau. In the vicinity of Fort Hall, the Maragwa and Sagana join to form the upper part of the Tana river proper. Thence, the Tana flows first east to Kamburu, then gradually northward around the foothills of Mount Kenya and the Uyambeni Range. At its confluence with the Bisinadi, the river reaches the limit of its northward swing, about two to three miles south of the equator. Between Fort Hall, and Kóreh Wells, the river is augmented by many tributaries draining the southern flanks of Mount Kenya and the Nyambeni Range« Among these are the Thiha, Thura, Ena, Mutonga, Kazita, Thangatha, Ura, Rojewero and Bisinadi. The only significant tributary to join the Tana from the south is the Thika river, which enters the main Tana hear its upper limit. From the limited information available, it is believed that none of the tributaries to the middle Tana downstream from the Rojewero flow perennially.

Downstream from the Bisinadi, the Tana trends gradually more southerly until from Oarissa it flows a few degrees east of south on its final course to the Indian Ocean. In the vicinity of. Koreh Veils, the river emerges from the foothills and, thereafter, flows in a tortuous meander pattern, crossing and recrossing its flood- . plain, until its final debouchment into the sea at Kipini.

Plate 2 illustrates the precipitous character of the upper Tana and.its tributaries, the series of abrupt descents as the river traverses the foothill region, and the final gentle gradient across the desert plains to the sea.

About eighteen percent of the catchment area lies above 3,000 feet,.while forty-five percent lies below 1,000 feet. It is significant to note that the total area contributing to perennial runoff comprises some sixteen peroent of the basin. This coincidence with the area of the basin lying above 3,000 feet indicates the olose relationship between topography and rainfall.

The long-term water yield of the catchment at points on the Tana river and the inflow from important tributaries are given in Table 3-1» I* may be noted that the long-term average flow increases throughout the length of the middle catchment. Thereafter, from the point at whioh it enters the Hameye swamp at the head of its lower reaches, the river suffers a net loss of water. liOt 11JHS U2-VS-HOI-H • J*0 I 13»* UI-V«-MOI -•* - 23 -

Table 3-1 - Long-term Average Flow - Tana River and Tributaries

Tana River Tributaries Catchment Estimated area long-term average flow

square miles cusecs

Thiba R. 815 Kamburu 3,500 3,125 Ena, and minor streams 535 Mutonga 1,060 Kazita 410 Grand Falls 6,800 5,130 Thangatha 75 Ure 120 Rojewero 160 Bieinadi, and minor 95 Koreh 9,500 5,580 Garissa 12,500 4,750

•

Climate

The climate of East Africa is controlled by the northward and southward movement of the sun, which creates a zone of low pressure at the latitude of greatest heating. This zone is referred to variously as the Heat Trough, Equatorial Trough, or Intertropical Convergence Zone* Climate occurrences have generally been shown to lag behind the movement of the Trough by four to six weeks* The sun is directly overhead in March and in September« one rainy season occurs in late April and lasts through May} the other occurs in late October and lasts through November, (l)* Between the monsoon-type rainy seasons, the climate of the country is generally dry} with a cool "winter" through June and August and a hot "summer" from January to late April. However, these terms are only relative, since mean monthly temperatures in East Africa show quite small seasonal changes, the variability being much more closely related to altitude*

Rainfall is undoubtedly the most important climatic factor in East Africa, and thus the climates of the various regions of the Tana basin are largely defined by their rainfall regimen. Permanent agriculture is limited to those areas receiving 30 inches or more of reliable rainfall annually} semi-permanent and shifting cultivation is practised in the marginal zones receiving 20 to 30

* The numbers in brackets in this Chapter and throughout the report refer to the works listed in Appendix 17 (References). - 24

inches of reliable rainfall, and the under 20-inch.rainfall zone is managed largely as rangeland. As Plate 3 shows, most of the Tana basin receives less than 30 inches of reliable rain annually and more than half the basin would be classified as semi-arid, with average annual precipitation' varying from 10 to 20 inches (2)*

Vegetation

The vegetation across the basin ranges from lush tropical growth along the narrow ooastal strip, to afro-alpine heat and moorland, high mountain forest and grassland, on the upper slopes of Mount Kenya and the Aberdares. Between these extremities are the vast areas of savannah and acacia forests of the upland plateau, and the open" woodlands of low thorny species - dormant for most of the year - which cover the lowland plains.

Population and Peoples

Population density in the basin varies widely. Some areas in the upper and middle catohment plateau and foothills, occupied by a group of Bantu peoples comprising the Kikuyu, Qnbu, Meru and Mkamba tribes, have more than 600 persons per square mile. The desert lowlands in the lower basin, inhabited by several tribes of Hamitic origin (the Orma, Galla, Boran and Somali peoples) which are nomadio by tradition, have average densities of less than two persons per square mile. In the narrow riverine plains of the Tana, between the Eameye swamp and the Indian Ocean, live the Pokomo, another Bantu tribe. In the coastal strip are found the Giriama, Swahili and Arabic peoples (2).

Communications

Road systems are well developed throughout most of the populated areas of the upper basin, but, with the exception of the Nairobi-Thika-Nanyuki road, surfaces are unpaved. Many of these roads are impassable from time to time during the rainy season. The middle and lower parts of the basin are served by only a few earthen roads, impassable during the wet seasons. The chief of these are the Nairobi-Garissa road and the Garissa-Mombasa road, which passes through the proposed irrigation area, Galole, Garsen and Malindi. There are only two permanent bridges across the middle and lower Tana5 the first, at Kamburu, links the Kitui and Qnbu areas, and the second, at Garissa, gives access to the sparsely populated northeast desert region. The hand-operated car ferry at Garsen is used during low and medium river stages and links the north coastal area with the south coast of Kenya.

The main rail line between Mombasa and Nairobi passes to the southwest of the basin and serves the lower area only from these principal termini.

- 26 -

The upper basin is crossed by a branch line from Nairobi, which goes through Fort Ball and Nyeri to Nanyuki. Air communication is important, particularly to the lover basin, which, during the rainy season, is frequently isolated from the rest of the country. Garsen, Galole and Garissa have landing strips and services by light planes from Nairobi, Malindi and Mombasa - centres which are interconnected by regularly scheduled internal airline service.

Geology, Seismology and Mineral Deposits

Plate 4 shows the relationship of the Tana basin to the regional geology of eastern Kenya. The Basement System underlying the entire central massif of Kenya consists of folded Precambrian metamorphic rocks. These are overlaid in the west by younger volcanic rocks of Tertiary to Quaternary ages and in the east by sedimentary rocks of Carboniferous or Permean to Tertiary age and semiconsolidated sediments ranging in age from Tertiary to Recent,

The entire area east of the Gregory Rift was reduced to a peneplain, and parts of the final Submiocene level are identifiable along the Kitui escarpment and elsewhere (3). Subsequent volcanic aotivity resulted in the build up of the Aberdares, Mount Kenya, the Nyambenis, Mount Kilimanjaro, and the surrounding upland region of Kenya. Farther east, downwarping of the peneplain was caused by deposition of later Tertiary and Quaternary sediments in an area referred to as the Tana Embayment.

The higher-lying Old Alluvial part of the lower Tana basin, within which lies the major portion of the project lands, represents a Pleistocene erosion surface whereas the lower-lying floodplain of the Tana river is considered to be Eolocene valley fill, at least insofar as its upper soil layers are concerned. At the present time, the lower reaches of the riverlare incised within its own recent sediments.

In common with the rest of East Africa, Kenya has suffered from earthquakes related to fault movements and volcanic activity. Almost invariably, the epi­ centres of earthquakes have been in the western part of the country, in the area of the Rift fault and its volcanoes. East of the Gregory Rift, in the area of Precambrian rock and farther east in the younger sedimentary areas, there is little danger from earthquakes. Nevertheless, shocks have been felt as far east as Mombasa and Malindi. Farther inland, perceptible tremors have been reported from Voi on the Mombasa-Nairobi road and in the north near Marsabit.

No significant mineral deposits are known to exist in the middle and lower catchments of the Tana river, with the exception of gypsum, which has been identified at a number of locations west of Garissa. This, on test, has proven to be of low quality, although possibly suited to agricultural purposes. LEGEND

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SOURCES OF DATA

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80VERNMENT OF KENYA UNITEO NATIONS SPECIAL FUND

SURVEY OF IRRIGATION POTENTIAL LOWER TANA RIVER BASIN

FOOO A» aanCULTUK OMUIl«'*» Of THE UMTEO MTMS EASTERN KENYA GENERAL GEOLOGY

PLATE 4 ILWCO /ACRES- - 28 -

Irrigation Projeot Area

Early reconnaissance of the lower Tana basin below Saka quickly oonfined the area of investigation to the right bank óf the river between Bura and Valu, where soils and topography in combination afford the best prospeots for gravity irrigation. Modifications to the investigatory limits were later established from considerations of possible diversion sites for gravity development and resulted in the adoption of the project area illustrated on Plate 1.

This area is traversed from west to east by a number of dry "luggas", or streambeds, which from time to time are subject to wild flooding. The most important of these is the Thowa Galole, which drains part of the Eitui escarpment. This physical barrier has been adopted as a natural boundary dividing the irriga­ tion projeot area into northern and southern divisions.

Present Development

In the upper catchment, the intermontane plateau has been intensively developed for agricultural use. Such orops as tea, coffee, pyrethrum and sieal, which are extensively grown on estates, are sensitive to mesoclimatio differences and therefore thrive at varying altitudes. Part of the upland foothills are utilized for large-scale mixed farming and ranohing, but most of the land is cultivated by Africans growing a variety of subsistence crops. The rugged upper slopes of the Aberdares and Mount Kenya are heavily forested and provide a variety of tropical hardwoods. As wildlife abounds throughout the uplands, tourism is important in this area, and such internationally known attractions as Treetops and the Mount Kenya Safari Club are located near the upper catchment divide.

As rainfall gradually diminishes towards the Kitui escarpment, cultivation becomes less extensive and completely subsistence-oriented. Throughout the arid lowlands, the nomadic peoples pursue a pastoral existence in which cattle, sheep and goats become the index of wealth and the medium of exohange. The riverine Pokomo are principally cultivators who subsist on crops, the yield of which is dependent to a large extent on the vagaries of the twioe-yearly flood. However, their diet is augmented by fishing along the Tana, where eels a few migratory species such as barbus and labeo can be caught (4;.

A small pre-investment irrigation scheme begun at Galole in 1955 at present comprises some 1,200 acres of land. Irrigation water is supplied from a floating pump station located about twelve miles upstream at Makere.

The floodplain of the Tana gradually widens from Garissa downstream, and enters a tidal delta below Oarsen. Immediately adjacent to the coastaline, a small area has been planted with coconut and other tropical tree fruits. - 29 -

Potential Development

The Tana river is the largest perennial river in Kenya and its water and land resources offer the greatest potentials for hydroeleotrio power generation and irrigated agriculture within Kenya« The power potential of the middle reaches of the river is estimated to he some 6*00 megawatts, while irrigation for continuous cropping of 230,000 to 300,000 acres per year in the lower hasin is technically feasible. Even with full exploitation of the power and irrigation potential,however, most of the middle and lower parts of the hasin will remain virtually undeveloped.

To the extent that controlled range management praotices can he introduced, some improvement in the livelihood of the pastoral peoples outside of the irriga­ tion project area may he expected. In economic terms, this improvement would he modest, hut nevertheless, significant, With the opening up of communications and the provision of a market for the nomadic peoples, it is expected that the proposed irrigation development will reflect some secondary henefit throughout the lower hasin and surrounding regions of the northern frontier area. The economic and social significance of this likelihood are discussed later in this report.

The development of irrigation will require storage of water in a number of reservoirs which, it is believed, can be used to establish a substantial inland fishery. Such fisheries will offer further inducement to populate the desert area and increase the benefits from primary development.

The coastal area of the basin is being considered by others and forms no part of this study. It may, however, be remarked that, so far as is known, the potential of this region is quite restricted. Partial control of flooding and reduction of long-term flow reaching the delta region of the Tana as a result of the irrigation project may enable reclamation of parts of this area to be considered. Certainly, within the limits of locally adequate rainfall, future planners should not overlook this area. - 30 -

CHAPTER IV

METEOROLOGY ABI) HYDROLOGY

As there are deficiencies and anomalies in the records of basic data for much of the catchment are under consideration, prudence has suggested a conserva­ tive approach to water yield evaluations throughout all phases of the studies. Consequently, it is quite possible that the development potential which could ultimately be realized would be somewhat greater than is estimated in this report. In that case, power developments in the middle reaches of the river and irrigation development on the lower rightf^bank plains would more economic. From considerations of the value of even modest increases in water availability, as illustrated by the discussion on the value of water in Chapter XII, it is reasonable to ezpeot that future reappraisals based upon more complete hydrologie data will tend to be more, rather than less, favourable to development.

To provide the design parametres on which the studies of the engineering and agricultural layouts have been based, hydrometeorologic analyses have been under­ taken and are discussed in Section 4»2 following. Greater detail relating to these studies is to be found in Technical Report Vol.11 - Appendix A - Hydrology and Meteorology.

4.1 Hydrometeorologic Data

The climate of the basin is distinguished by two periods of rainfall and two periods of drought each year. The rainfall gives rise to semi-annual flood periods. Occasionally the rains fall and one or other of the flood periods does not occur} or, alternatively, as happened in Ootober/November, 1961, prolonged heavy rains result in floods of damaging magnitude. These characteristics, together with the normal month-to-month variation in the flow of the Tana (illustrated on Plate 5), lead to the need for storage to oontrol the natural river flow and provide for release of water in a sequence more benefioial to power and irrigation development. . Ï«Ï'J 1 1 1 t . 1 -, i _L_j__ —i i 1 too [.. _.. -- • • -' • •- — — - • 1 r 1 THC DATA INDICATED OH TMC PLATE WAS OBTAINED AS FOLLOWS '• - IMT-H4T rnrrwMis mm * NUMTALL f 1 «MOFr OWWLITKW II4T - IMI FMOH NECOWM WW BV TMC 'IÜU Jjlüü OCVCLOPMCMT OCMMTTMCMY, h •owMt-grr or ttt-m NMW - IMZ CSTtMATCO fLOOO MWT — — \ tv F. (wuNOv («trtKK* > !"

l ._. 1 I r 1 ! ! i»0 0 1 Il i 1 NOTE Mji 1 i 1 «••€» CATCHMENT AU.OCATKMS MM« . NOT «CC* DfOUCT» m i i , 1 1 H | -ht I \ i l Hl L AOVUNMIHT of klhV- *—' i i , l/l A \ i l/i J r V UIITIO NaT «Ht irCCIAL FtMO A 1 \ ƒ / i II 1/ SURVEY OF IRRIGATION MTCNTIAL y LOWER TANA RIVER iÀilN e l 1 Jv H V v T-i 1 1 L FOOD MO MRcaniK mmuHM or t« «ami MTMW rr» h*1 \ l( \ V l y ' V ü ' I \ ' » \H - h 1 ^ V V JH J fini iV HYDROGRAPH OF AVERAGE MONTHLY DISCHARGES

'• . TANA RIVER AT KAMBURU 'MT 1U it» '»«0 '»«« '•«* '*«ï «1«« j '»«5 , >'*•* '*•' ! "•• 194» "" i»it t«i IM1 l«4 193» 1*31 IMT ItSI l»9t IttO • »ei l*IS ^iftM^Sr^ PLATE 0 - 32 -

In East Africa, meteorology is the responsibility of the East African Meteoro­ logical Organization and hydrology is the responsibility of the Vater Department in Kenya, Uganda and Tanzania» At present no formal means exists of co-ordinating meteorologie and hydrologie investigations in water resources studies for agricul­ tural and engineering purposes, and the formation within Kenya of a co-ordinating organization, charged with responsibility for planning the instrumentation and operation of hydrometeorologic networks in major river basins, would assist in avoiding both repetitions and omissions in the gathering of information.

It may be noted that, as a part of the field investigations for this study, the establishment of a basio network of hydrologio stations covering the main stem and important tributaries of the middle and lower river was undertaken» Hydro­ meteorologic stations, including those established during the current studies, are shown on Plate 3.

Heteorologio information for agricultural purposes in the lover Tana has been supplemented under the project by establishing comprehensively instrumented "Penman" stations at Galole and Kayu. Bain gauges and other meteorological equipment have also been provided to augment the existing network wherever it is possibile to arrange for reliable operation» Although few stations have, so far, been added to the basic rain gauge network, the aim has been to obtain more representative coverage of the middle and lower catchments» But the scarcity of population in these areas limits the establishment of operations to a considerable extent.

The operation of these new hydrometeorologio stations has been organized under the direction of the Water Development Department. It is hoped that conscientious gathering of data will continue and thereby provide the reliable records necessary to confirm the estimates presented in the report and to facilitate revisions, as justified, at the design stages of development.

4»2 Hydrometeorologio Analyses

Water Availability

A study of the mean rainfall in the upper oatohment, based on selected stations which have been operated almost continuously since 1917* indicated that the period 1947 to 1963 for whioh discharge records are available at Kamburu, was wet in relation to the average since 1917* Therefore, so as not to place undue emphasis on a wet cyole in the estimation of irrigation and power potentials, it was necessary to extrapolate the runoff record backwards in time to cover a more representative period.

Studies indicate that the 25-year period from March 1937 to February 1962 yields the same long-term rainfall average as the longer period 1917 to I964 and, further, contains several periods between 1933 and 1950 likely to have been the driest in this century and consequently the most oritioal for the study of storage requirements.

Correlations of runoff at Kamburu and Grand Falls with appropriate rainfall indices yielded mean values within one percent and mean errors within the probable limits of accuracy of the observed data. These correlations were then used to synthesize the discharge record for the period between 1937 to 1947 to 1948. -33-

The synthetic and real data for gauging stations were then adjusted to take account of water already allocated for future demands in the upper catchment) and thus to estimate the .long-term availability of water at the damsites under consideration (see Chapter Hi). -Allowanoe for potential upper catchment demands, as reserved by the Water Apportionment Board, amounting to 338)000 acre-feet annually, has been considered in the.computation of net flow records. This volume,which is in addition to those authorizations granted prior to September 1956*, and for which an allowance of 44,000 acre-feet annually has been estimated, is in accordance with the revised authorizations issued by the Chief Hydraulic Engineer, in'October 1964.

Latterly, it has been found, as discussed in Chapter XII,that the value of water from the upper catohment to the proposed downstream power and irrigation developments is sufficient to justify further review of the needs for these upstream allocations. While no formal review has, aB yet, been made, informal disoussions have been held with the appropriate Ministries. It is understood that the projected upstream development upon whioh the present reservations were based is no longer considered valid and that a substantial portion of the allocations may be released for downstream uses« Based upon present usage and foreseeable commitments, this may be up to 400 oubic feet per second»

Some indication is given, therefore, in Chapters XI, XII and XIII of the value and additional development of power and irrigation whioh would accrue through reduction of upstream allocation reserves by 284,000 acre-feet annually. Adjustment of the flow records to represent discharges at the various damsites under review in these chapters was undertaken from intermediate tributary flow records, insofar as this vas possible, and from general considerations of rainfall distribution where tributary data was inadequate. The estimated net monthly volumes contained in Annex A-l in Technical Report Volume II are considered to be sufficiently reliable for the present evaluation of the various projeots.

To indicate the magnitudes of these flows and their distribution over the year, Table 4-1 gives the average figures for monthly and annual flows available at two sites, Seven Forks (Confluence; and Koreh, over the years 1937 to 1962«

Table 4-1 - Net Discharges at Seven Forks.(Confluence) and at Koreh

(thousands of acre-feet)

J F M A M J J A S 0 S D Tear

Seven Forks (Confluence) 82 44 51 237 411 209 121 107 88 129 263 143 1,885 Koreh 200 129 132 467 634 357 226 212 166 243 547 347 3,660 Table 4-^2 - Long-term Average Flov and Net Available Flov Tana River and Tributaries

Tana river Tributaries Catchment Estimated Upper Net available area long-term catchment long-term average flov allocations average flov

square miles cuseos ouseos ousecs Thiba H. 815 I65 65O

Kamburu 3,500 3,125 530 2,595 Ena, and minor streams 535 Mutonga 1,060 Kazita 410

Grand Falls 6,800 5,130 530 4,600

Thangatha 75 Ure 120 Rojevero 160

Bisinadi, and minor streams 95 Koreh 9,500 5,580 530 5,050

Garissa 12,500 4,750 530 4,220 -35-

It must be remembered that tbe totals for individual years have varied widely from these mean totals - at Seven Forks ranging from 31 percent up to 288 percent of the mean, and at Koreh from 40 percent up to 258 percent of the mean. In indi­ vidual months, the variations from the mean shown in this Table «ere even vider in range. These faots show clearly the great need for annual regulation on a large scale, as contemplated. For maximum use of available flows, some measure of over year regulation also would be desirable, if found to be feasible. Review of the estimated water yields should be made when longer periods of reliable reoords are available. The long-term net average rates of flow at these and other selected main-stem stations are presented in Table 4-2.

Flood Estimates

As a part of hydrologie study for storage development, it is necessary to make the best possible estimate of potential flood discharge at the site, so that adequate provision for the safe passage of such a flood past the dam can be made. Modern oonoepts of "design flood" estimation involve consideration of both "maximum probable" rainfall and the characteristics of the drainage area in transforming the rainfall into flood runoff, unfortunately, for reasons discussed in Technical Volume II (Appendix A), such an approach has not been possible for the damsites under review, and statistical methods have had to be relied upon. These are, however, quite reliable for present purposes.

For the protection of human life and property, and in the absence of more refined estimates, it is essential to seleot a flood of rare frequency for spillway design. In these studies, a return period of 10,000 years has been adopted, which is equivalent to accepting a one percent ohanoe that the selected flood will occur during a 100-year period. In Table 4-3» the one in 10,000-year flood-peak estimates adopted for the various damsites under consideration are listed, together with the I96I peak estimates, where available, for comparison.

Table 4-3 - Estimates of "Design Flood" Peak Discharge Used in the Studies

Damsite 1 in 10,000-year peak Estimated 196I peak

cusecs cusecs

Seven Forks Reservoir 115,000 45,500

Seven Forks Confluence 150,000 .74,000

Kiarabere. 150,000 a

Mutonga 200,000

Grand Falls 250,000 138,000

Adamson's Falls 320,000

Koreh 350,000

Korokora 250,000 110,000 -36-

The East African Meteorological Department was requested to comment on the return period of the rainfall causing the 1961 flood. A preliminary estimate of 100 years has been received, which value is consistent with the computed frequency of this flood.

Diversion of river discharges would be required during construction of any of the dams considered hereinafter» In accordance with normal design practice, the one in 20-year flood has been selected for the design of diversion works. In Table 4-4 the diversion flood peak discharges used in these studies are given.

Table 4-4 - Estimates of Diversion Hood Peak Discharges Used in the Studies

Damsite Estimated Diversion Flood Peak Discharges

cuseos Seven Forks Reservoir 33,000

Seven Forks Confluenoe 42,500

Kiambere 44,000

Mutonga 57,000

Grand Falls 65,000

Adamson's Falls ~ 70,000

Koreh 75,000

Zorokora 70,000

Evaporation Estimates

Estimates are required of the average monthly potential evaporation at reservoir sites, and of month by month évapotranspiration from cropped land within the irriga­ tion project area. c From the data available at eight meteorological stations, the relationship between potential' evaporation and altitude has been established and provides rates appropriate for reservoir sites. So as not to overestimate actual evaporation, the average rainfall on the reservoir surface area, selected from the isohyets shown on Plate 3, has been deducted from the potential rates to obtain the net values listed in Table 4-5* The meteorological data available for the stations at Oalole and latterly at Wayu have been used for calculating Penman estimates of potential évapotranspiration from crops in the project area. In Table 4-6 are listed the monthly average values of the Penman estimate as used in these studies» -37-

Table 4-5 - Average Annual Evaporation and Rainfall Rates Used in Evaluating Potential Storage Reservoirs

Average Average annual' . Net evaporation Damsite annual total incident rate on reservoir evaporation rainfall surface area inches inches inches Seven Porks 86 29 57 Mutongaj Grand Falls 97 26 71

Adanson's Falls 100 - 18 82

Koren 101 H 90 Korokora 103 12 91

Table 4-6 - Monthly Estimates of Potential Evapo­ transpiration for the Pro.ject Area

Potential mean Month evapo transpir ation

feet January 0.66 February 0.60 March 0.65 April 0.60 May 0.62 June 0.56 July 0.55 August 0.59 September 0.61 October 0.63 November 0.61 December 0.64

Annual total 7.32 -38-

Rainfall - Project Area

The analysis of rainfalls in the projeot area falls into two parts; first the determinations of monthly rainfall reliability« so that justifiable reductions in the volume of irrigated water required can be allowed; and secondly) the estimations of storm rainfalls* so that drainage facilities within the agricultural lands can be designed*

Plate 3 shows that the irrigation project area lies generally between the 10-inch and 20-inch average annual isohyets. Average annual total precipitations of 18 inches at Galole and 20 inches at ffayu, in comparison with 12 inches at Garissa, suggest that the southern portion of the area is wetter . than the northern part. However« the presently available data is not sufficiently detailed to justify any attempt at computing variations in rainfall reliability across the projeot area. The total rainfall« however, is less significant than that portion which can be considered reliable in conserving irrigation applications. Monthly recurrence intervals of effective rainfall for both Garissa and Galole were determined, and the results for the Galole station are presented in Table 4-7«

Table 4-7 - Monthly Récurrence Intervals of Effective Rainfall at Galole

Probability Effeotive rainfall of inches exceedance Jan. Mar. Apr. May Oct. Nov. Dec.

2 yrs in 10 1.25 1.07 1.80 0.70 1.61 3.40 1.60 4 yrs in 10 0.10 0.04 0.90 0.17 1.80 1.10 6 yrs in 10 0.40 0.80 0.80 8 yrs in 10 0.35

N.B. For the months not listed, the probability of reoeiving significant effective rainfall is negligible.

Confidence limits of effective rainfall reliability were computed for the Galole data. The results of this study indicate that significant effeotive rainfall can be relied upon only during the months of April. November and December. The most severe - rainfall recorded in the irrigation projeot area occurred from September 26 to 28, during the early stages of the 1961 flood period, when a total of 7*13 inches was recorded at Galole and 4*40 inches at Vayu. Apart from this incident, most of the falls over two inches have occurred during the months of April, November and December. Table 4-8 lists the maximum rainfall expectation in the project area for various recurrence intervals. A maximum daily rate of 2.05 inches, to be expected once every three years« was selected for the preliminary design of project area drainage channels« -39-

Table 4-8 - Recurrence Intervals of Maxi mi m Rainfall in the Project Area

Rainfäll total Recurrence interval inches 1 day 2 day 3 day 5 day

Annually 1.05 1.85 2.20 3.00 1 'year in 2 1.65 2.55 2.90 3.80 1 year in 3 2.05 2.95 3.40 4.30 1 year in 5 2.50 3.30 4.00 5.00 1 year in 10 3.20 4.50 4.80 8.60

Sediment transport estimates

The upper tributaries of the Tana river drain regions of deeply dissected, ridge- and-valley topography« where considerable areas have been cleared for agriculture. In other parts of the catchment« overgrazing is common. The incidenoe of heavy rainfall on such unprotected soil results in transport of large quantities of topsoil into the streams and rivers in the form of suspended sediment. As agricultural development in the upland areas proceeds, clearing of still larger areas without adequate soil conservation measures could result in aggravation of this problem.

The application of soil conservation measures is therefore necessary to ensure that soil erosion in the future at least does not exceed present levels. Otherwise* higher sediment concentrations in the river would have an adverse effect on the storage function of any reservoirs that are developed.

Estimates of annual sediment transportation have been made for each of the poten­ tial storage developments by combining sediment concentration data with flow duration analyses to provide time-weighted averages, as shown in Table 4-9 below.

In computing the estimates in Table 4-9 f°r downstream sites, it was assumed that the Seven Forks complex would have heen developed previously. However, it is of interest to note that concentrations of sediment below Seven Forks are substantially greater than those above, thereby indicating that the major areas of soil erosion are the eastern slopes of Mount Kenya and the Nyambeni Range. Development of a reservoir at Seven Forks, therefore, will not significantly affect the quantities of sediment that will be received at the lower sites. Estimates of sediment volumes retained in downstream reservoirs, for those cases where control has already been provided at upstream sites, are based on the assumption that a maximum of 55 percent of sediment (the estimated "wash load") may be "vented" at each of the developments. A dead- storage volume has, therefore, been included in the analysis of all reservoir sites to allow for deposition of sediment. - 40 -

Table 4-9 - Sedimentation Estimates at Potential Storage Sites

Samsite Estimated Estimated volume average oooupied by sediment annual oost after 50 years

million of tons thousands of acre-feet

• Seven Forks Reservoir 0.25 8

Seven Forks Confluence 0.35 11 Mutonga 7.00 220 Grand Falls (without'Mutonga) 12.00 375 Grand Falls (with Mutonga) 8.80 295 Adamson's Falls (with all upstream plants developed) 9.60 350

Koreh (with all upstream plants developed) 10.80 380

Korokora 23.00 720

Korokora (with Mutonga and Grand Falls developed) 17.50 600

Korokora (with all upstream plante1 developed) 1 I5.IO 525

A pertinent faotor in analyzing the effect of sedimentation on reservoir design is the estimation of the location in the reservoir where the sediment will settle. Particularly in the oase of the Koreh reservoir, and to a greater extent at Korokora, the broad shallow configuration of the storage basins might tend to result in much of the sediment settling near their upper ends, thereby occupying space normally recognized as useful or "live" storage. This subject will require further detailed study during design stages. -41-

CHAPTERV

SURVEYS. GEOLOGY AMD ENGINEERING COST DATA

To facilitate evaluation of the development potential of the lower Tana basin, various topographic, geologic and geotechnioal surveys and investigations have been carried out. In addition, to provide the basis for estimates of capital and recurrent costs of various developments considered, construction, maintenance and operation charges for works undertaken in East Africa have been assessed.

5.1 Topographic Mapping

To provide the topographic data required for the various phases of the studies, a number of special maps were.compiled by the Survey Department of Kenya, with the assistance and co-operation of the Directorate of Overseas Surveys and the Survey Section of the Water Development Department. The various map series prepared were:

(a) 1:100,000 scale. This special series of maps with 25-foot contours was oompiled in advance of the survey of irrigation potential. Coverage was provided of the lower river basin between Saka and Garsen.

(b) 1:50,000 scale. Two series of 1:50,000 maps were prepared for this study. The first comprised coverage of the irrigation project lands north of Thowa Galole and shows 5-foot contours. The second, which forms part of the national 1:50,000 topographio series, was prepared to provide coverage of the main river valley between Seven Forks and Saka. Contours at 25-foot intervals up to approximately 300 feet above river level were interpreted from aerial photography and ground control surveys»

(c) 1:10,000 scale. Mapping of an area of 10,000 acres, within which the proposed Permanent Research and Training Centre is to be located, was prepared with 2.5-foot contours interpreted from detailed ground control surveys. -42-

(d) Other. Topographic maps of potential damsites at various soales suitable for preliminary design layout studies.

5.2 Geologic Surveys

Geologic investigations were oarried out to assess foundation conditions at the proposed Korokora diversion dam and at upstream power and storage sites. In addition, investigations were made of the main canal alignment between Korokora and the projeot area, of gypsum deposits which may be needed for treatment of irrigated soils, and to locate suitable sources of rook material for road metal, concrete, riprap and other construction purposes.

The following sections summarize the general geology, seismology and economio geology of Kenya, with particular reference to eastern Kenya, wherein the Tana basin lies. Thereafter will be found brief seotions discussing the specifio geologic investigations undertaken and recommendations for further investigation.

Geology of eastern Kenya

The details of East African geology are still being olarified, but the outline of the geologic structure and history is now reasonably well-known. To help understand the regional setting within which the Tana river basin is located, Plate 4 summarizes the general geologic situation. This map is based on information obtained from several sources (references 1, 2, 3 and 4)» and was locally modified to accord with observations made during the course of the present survey.

The basement system oocupies the central part of Kenya and forms the stable platform on which the remainder of the country has been built. This system consists primarily of metamorphic gneisses and meta-sedimentary rooks, with some intrusive rooks. Most are of Pre-Cambrian age and have been severely folded and faulted at various time during the long period since they were originally formed. Some of the intrusive rocks, however, are known to be relatively young and were scarcely affected by teotonio movements. On the whole, the basement system, in which are located all of the damsites under consideration as far downstream as Koreh, affords generally good foundation conditions and some materials suitable for construction of the works envisaged.

To the west of the basement system, much of the oountry is composed of relatively young (tertiary to quaternary) volcanic materials, which form the highlands of Kenya. These voloanio rooks and ash break down to form fertile soils whioh are easily eroded, particularly when stripped of their natural cover by cultivation or over­ grazing, with the result that muoh of the sediment carried by the Tana river is derived from this upland area. Also within the volcanio zone are the rift valleys, which are features of continental soale. They are related to geologic faults, and most of the earthquakes of East Africa originate under or near these valleys (5).

To the east, outorops of the basement system slope down under younger (carboniferous or permian to tertiary) sedimentary rocks and even younger (tertiary to reoent) sediments, as shown on Plate 4* The sedimentary rooks, whioh are locally exposed in the southern part of Kenya, are mostly sandstones and limestones and are -43-

very variable in their physioal properties. Younger, flat-lying sediments underlie the site at Korokora and the surrounding area* From the engineer's point of view, these sediments are predominantly soils, although locally they have been ohanged to rook by the cementing action of calcium carbonate or by the irreversible dessioation of hydrous minerals. Small bodies of intrusive rooks of various types are present within the area of sedimentary deposits, although occurring less frequently than in the adjacent Pre-Cambrian system.

More detailed information on the geology of eastern Kenya can be found in several publications»notably in report No. 15 of the Geology Survey of Kenya (2). The files of the geological offioe of the Water Development Department and of the BP-Shell Petroleum Development Company of Kenya Limited contain the drilling records from exploration for water and petroleum in eastern Kenya. Much of this information, of course, refers to depths greater than those of interest for the purpose of this report.

Published and unpublished information on the geology in the vioinity of the various damsites will be referred to in connection with the description of each.

Seismology

Earthquake aotivity is common in the rift valleys of western Kenya, and, as previously noted in Chapter III, areas bordering the Tana basin have, in the past, reported earth tremors.

While only limited interpretation has been made of the available data, it seems probable that earthquake shook will not be a serious consideration in the design of dams and other major structures in the middle and lower reaches of the Tana river. Prudent design, however, requires that the effect should not be neglected, and for sites from Seven Forks to Koreh, some seismio forces must be allowed for, as well as due consideration given to possibilities that earthquakes might induce seiches arid landslides in reservoirs.

The ourrent information on seismology and the status of interpretation in and around East Africa is reviewed in Section B 5.1 of Technical Volume JI (Appendix B), and recommendations for appropriate design criteria presented.'

Eoonomio geolorar

The eoonomio geology of Kenya is reviewed in Section B 5»2 of Technical Volume II (Appendix B). The most recent value of mineral production available is for the year 1959, in which mineral products accounted for some £ 5,352,000 (4), representing just over two per cent of gross domestio production in that year. Investigations are currently in progress to locate and identify new mineral deposits which may contribute to the economio growth of the country.

As far as is known, there are no mineral deposits within the middle and lower reaohes of the Tana which would be affected by the power and irrigation dams envisaged in this report. Generally, good rock materials for construction purposes are found close to all damsites from Koreh upstream. Some rather impure gypsum deposits, which may nevertheless be useful for soil improvement, occur to the north of the irrigation projeot area. It is oonsidered that there is likelihood of significant new disco­ veries in the areas affected by the proposed power and irrigation oomplex of schemes. -44- •

Elsewhere within the lower Tana, all known rock outorops of various qualities liaVé leoii ejLaoiined for sources.or construction materials, for within the lower catchment rock materials are generally scarce and remote from construction locations»

Geologio 3ite Investigations

To provide basic information in respeot of each potential power storage site and at the main.diversion dam« geological exploration surveys were undertaken to provide information on foundation conditions and looate sources of construction materials in the vicinity of each development.

The main emphasis was devoted to determination of foundation conditions at Korokora, the proposed site for diversion to the irrigated lands. The location of a dam at this site, in a wide alluvial valley, poses special problems, and determination of a feasible design required some knowledge of specific foundation conditions and of the suitability of local materials for construction«

All other sites at whioh dams may be constructed lie upstream within the exposed Basement rock oomplex of eastern Kenya, into which the middle Tana has entrenched itself. Por the purposes of the present study, sufficient foundation information for these sites was obtained by walkover surveys to correlate previously published information, interpretations from aerial photographs and aerial reconnaissance.

In Section B 5.3 of Technical Volume JÏ (Appendix B), the geology of the various proposed damsites is described. Therein, it is pointed out that only a limited amount of field work has so far been carried out at certain of the sites. The oost estimates which have been made for this feasibility report must, therefore, be based upon conservative evaluations of foundation suitability. Additional information will be needed before details of design and refinement of cost estimates oan be under­ taken.

Por Korokora and Seven Porks (Sections B 5«3«1 and B 5»3»7 of Teohnioal Volume II), where considerable explorations have been made, recommendations for future work have been included in the relevant descriptions. Por other sites, recommendations whioh pertain equally to each are elaborated in Seotion B 5*3.9 of the same volume.

5.3 Cost Estimating Data

Estimates of oonstruotion costs for the various works described in later chapters of this report must take into acoount local site conditions, availability of construction materials, skilled and unskilled labour, and other factors peouliar to the type of work«

Capital costs are separated in the estimates presented herein into direct and indirect items. The former includes readily quantifiable work items supplied or executed at site, such as excavation, rookfill, concrete and equipment. Indirect items, on the other hand, are associated with the work to be oarried out but less directly measurable. Such items as construction, administration and engineering, and contingencies are inoluded in this latter oategory» -45-

The appropriate unit cost data for estimating the direot cost items have been derived from comparisons of recent large oivil engineering works in East and West Africa, correlated with up-to-date Canadian cost data. It is of interest to note that, by and large, on-site unit costs for heavy construction in various under­ developed countries are frequently quite similar to Canadian oosts, as determined from recent comparative studies, and this is so for East Afrioa.

Indireot costs generally are estimated as appropriate percentages of the total direot oosts from experience. Certain items ( notably roads)«however, are inoluded with direct items, although estimated herein from unit oosts« Schedules of direot and indirect cost estimating data are presented in Tables B 5-4 arid B 5-5 of Technical Volume II (Appendix B). The unit rates quoted are in E.A. shillings r x (1966 figures). \y . '

Annual costs are determined by the cost of money, the amortization period, and the costs of maintenance, interim replacement and operation.

Throughout this report, the rate of interest has been taken as six percent, and the amortization of permanent civil engineering works for both power and irrigation developments as over fifty years. This, it is understood, accords with currently acceptable practice for economic evaluations of power and irrigation developments by the International Bank for Reconstruction and Development.

Certain works of more limited working or useful life have been amortized over shorter periods, and in each instance, the amortization period is noted in the discussion of the particular work concerned.

Maintenance and interim replacement and operation expenses are estimated from experience data as percentages of capital cost, while neither inflation nor insurance following construction are allowed for in the economic analysis presented in this report. Further discussion of annual oost parameters is to be found in Seotion B 5«5«2 of Technioal Volume JX (Appendix B), and the periods and rates adopted for the economic evaluation of development of power and irrigation are summarized hereunder.

Interest rate 6 perdent

Amortization

Power projects 50 years Irrigation works 50 years Buildings and tenant housing 25 years R. and T. Centre pumping station and temporary supply canal 4 years

Maintenance and interim replacement

Power projects 3/4 percent Irrigation works, buildings, housing, eto. 3-l/2 percent

Operation

Power station 1/4 percent Irrigation system 1-1/2 peroent -46-

CHAPTER VI

SOILS AMD VEOETATIOff

The lower Tana basin between Saka and Garsen comprises an area of approximately 3*000.000 acres, and it was necessary to select from this large area a smaller project area for examination. Considerations of soils and topography in relation to possible diversion sites resulted in the selection of an area of approximately 700.000 acres on the right bank of the Tana river, the southern boundary of which was taken to be the L. Thowa-Galole. This forms the northern region of the project area as discussed herein. However, subsequently it was found necessary to expand the area surveyed to include an additional 300.000 acres of land south of the L. Thowa, and this southern region is included in the project area as indicated on Plate 1.

Similar soil conditions obtain on both banks of the lower Tana and between the east and west bank areas. The choice of the west bank was determined from consider­ ations of generally more uniform topography and the prospects for finding more suitable soils under command of a diversion at Korokora for a lower dam and a shorter main supply canal. Within the broad limits of investigation, semi-detailed soil surveys were carried out over the northern region, together with a vegetation survey. Correlation of the soils-vegetation relationships and reconnaissance level investigations of the southern region permitted the mapping of soil boundaries and interpretation of the suitability of soils south of the L. Thowa Galole with reasonable confidence» A detailed soil survey was made of the area selected for possible development as a research and training centre to service the scheme throughout its development period. Details of the soils and vegetation surveys are presented in Technical Volume .Ell (Appendixes C and D respectively).

6.1 Semi-detailed Soil Surveys

The first phase of the soil survey consisted of more detailed reconnaissance of the northern region. Analyses of soil samples and correlation with aerial photography established the governing criteria and indicated that the semi-detailed survey should, to a great extent, concentrate on those aspeots of geomorphologio development charac­ teristics of semi-arid conditions. Thus, the most significant soil profile factors were found to be structure as related to salinity and alkalinity« -47-

During the semi-detailed survey» soil samples were taken from test pits established at approximately one-mile intervals along a grid of east-west trace lines spaced approximately one mile apart* Soil chemistry analyses were performed on all of these samples and the reports of these are presented in Technical Volume IV (Appendix E).

Boundaries of the soil units as presented on Plate C.2 of Technical Volume /IH (Appendix C) were established from photo-interpretation on low-level photography (scale approximately 1.10.000), flown after establishing the grid of trace lines and identification monuments. It may be noted that in the soils maps there are some inaccuracies as a result of the necessity to compile them from uncontrolled mosaics. Nevertheless^ for the purposes intended} it is considered that the soils map and .the derived land suitability map reasonably represent the situation with respeot to soils throughout the project area« The investigations revealed a completely irregular pattern of soil units which have been classified in accordance with the Seventh Approximation System of the United States Department of Agriculture (l). The classification adopted is presented in Table 6-1, and it may be noted that the Great Groups and Subgroups distinguished in the Seventh Approximation do not cover all of the soil units identified within the project area. In order to complete the classification« a new Great Group, the Halorthids, and a few new Subgroups« Typio Halorthids, ITatrio Grumusterts and Natrio Grumaquaerts, have been introduced«

6.2 Detailed Soil Survey

A detailed soil survey was carried out over an area of approximately 13»000 acres« shown in Plate 16 as the area intended to be the Research and Training Centre« The lowest-lying parts, which are subject to periodic flooding« consist of heavy Young Alluvial clay soils covered with grass and some trees at higher spots« The higher- lying soils of the Old Alluvial mainland consist of scattered, sparsely covered ridges and flat« scrub-covered« plateau soils. In the depressions« heavy cracking« clay soils covered with grasses and herbs are found. A transition between the Orthids of the plateaux and the XJsterts of the depressions is found in local depressions of heavy, non-cracking clay soils, identified as Vertic Natrargids.

The classification of the different soil units within the Research and Training Centre has been determined with greater precision than with the semi-detailed survey throughout the project area» due to the more accurate mapping, especially of the vital nonsaline-nonalkaline top layer. Thus, further sub-classification of units has been possible* as may be noted from the legend of Plate C.13 of Technical Volume IV (Appendix C), and from Table 6-4«

6«3 Vegetation Survey

A survey of vegetation was carried out over the northern region of thé project area to assist in the interpolation of soil unit boundaries. The identification of soil-plant relationships should also provide useful information for the assessment of ecological conditions throughout the area, affecting animal husbandry« forestry and game migration* -48-

Table 6-1 - Soil Classification

Mapping Relative Order Suborder Great group Subgroup symbol topographical position

Entisol Ustent Psammustent Typio Psammustent . PR Highest

0 Argid Typio Natrargid Hi' L N2 Natr argid High

A Mazio Hatrargid N3 L L Aridisol TJ V Camborthid Typio Camborthid C I A Orthid L Halorthid Typio Halorthid S Transition between high and low

Ustert Grumustert Natrio Grumustert GÜ Low o Vertisol T 0 Aquert Grum aquert Natrio Grumaquert GA Lowest U N Typio Eapludent PL High a Eapludent A L Entisol Udent Vertic Eapludent U L U Regular ly US Y flooded soils I of the meandex» A plain-great P Lowest L group of sub­ order udent -49-

The vegetative associates have been identified in relationship to the morphology of the region and hence are readily comparable with the soil classification. The major associations identified are given in Table 6-2. The vegetation characteristic of the Old Alluvial part of the project area is generally classified as grasslands and bushlands, the latter comprising species adapted to the xerophytic environment. The riverine forest of the Tana flood-plain is the only area on which are found trees of a size useful for construction or as a significant source of fuel supply* The species present, however; are generally slow-growing varieties and consideration must be given to the introduction of new species to provide a local supply of fuel wood for any large-scale irrigation complex« Tsetse flies have been identified in the Tana flood-plain and this trypanosomiasis vector may penetrate into the semi-desert area along bush-covered beds or luggas. Control of tsetse flies and other insect vectors may require clearing of the riverine forest above and below the limits of irrigation development. In this way, reinfestation of a major forest unit from outside the area may be avoided.

6.4 Land Classification

A land classification map has been derived from the soil maps, in which five suitability classes of soils with respeot to irrigation have been distinguished. This map (Plate C.3 of Technical Volume III A, Appendix C), identifies acreages of suitable soils and their topographic relationship. It may be noted that the acreage of suitable soils occurs in patches. This feature is less pronounced toward the south and near the river, where large homogeneous areas of irrigable land are found. To the north and west, the suitable soils of Classes 1, 2 and 3 are intermingled with patches of Class 4 soils, which, for irriga­ tion, can be considered only marginally suitable. Soils of Class 1 are considered to be very suitable for irrigated agriculture and are not expected to present any special problems in the management of cultivation practices. Soils of Class 2 and 3 suitability are represented by the soils on which agronomic trials have been conducted at Galole; see Technical Volume ,V (Appendix F). While these soils yield satisfactory crop returns, they generally present some difficulties in management. Saline-alkali or alkali subsoils underlie the problemless topsoil layer at shallow depth. It has been found to be essential to ridge these soils to provide sufficient volume for root development. Careful management of cultivation practices and control of irrigation water applications are essential to prevent upward movement of the salts and formation of an impenetrable alkali horizon. Class 4 soils are considered to be only marginally suitable for irrigation development. Such soils have been excluded from the irrigation even if reclamation should prove technically feasible. Experience with these soils has been limited to small scale observational trials at Galole, from whioh it is evident that only shallow-rooting crops will grow in these soils, and even these require very special cultivation practices. Thus, irrigation of these soils has been ruled out, except insofar as very small patches have to be included in the layout to avoid fragmentation of the irrigation units. -50-

Tahle 6-2 - Classification of the Vegetation into Associations

Mapping symbol of the associations Description of the association

1 Semi-desert scrub 2 Deciduous scrubland 3 Shrub thicket 4 Open bushland - dominated by Cordia sp. near Gharaf and Acacia reficiens 4A Acacia bushland - usually Acacia paolii or Acacia reficiens

4B Middle terrace grassland - dominated by grass and herb species identical to those of Association 4 4C Closed bushland - dominated by Acacia reficiens. Commiphora spp., and Euphorbia grandicornis

1/4 Mosaio of Associations 1 and 4 - often dominated by Commiphora spp* 5 Thicket dominated by Terminalia orbicularis 6 Shrub grassland 7 Valley grassland - dominated by Sporobolus helvolus 8 Flood-plain - dominated by non- graminaceous herbs 9 Flood-plain bushland 10 Tana riverine forest 11 Human settlement and cultivation -51-

The acreage of soils over the 920,000 acres investigated throughout the project area are presented in Table 6-3, together with a brief discussion of their character­ istics for irrigation. In Table 6-4» a similar presentation is made of the soil suitability classification for the Research and Training Centre. Apart from topography, the presence and depth of the leached nonsaline-nonalkali topsoil primarily determines the suitability of the soil for irrigation. Causes and consequences of saline and alkali conditions are discussed in Technical Volume III (Appendix C). Leaching of the topsoil may lead to a solidified, impermeable, alkali subsoil, especially where a high content of contracting olay occurs.

6.5 Reclamation

In order to reduce the salinity of soils, leaching should be considered. Calcula­ tions have shown that great variations in initial leaching requirements exist, depending on local soil conditions and the level of desalinization desirable. These requirements may amount to as much as 2 feet 6 inches of water for one foot of soil. Given the excellent quality of the Tana water for irrigation, the normal water requirements to maintain and control the desired salinity level will be low and will probably not exceed 5 percent of the total field applications. It may be noted that, for saline-alkaline soils, reclamation with gypsum has to occur simultaneously with leaching. Physico- chemical improvement of the alkali subsoil requires replacement of absorbed sodium by calcium, for which gypsum is suitable. The amounts of gypsum required for de-alkaliza- tion of the alkali soils over a depth of 2-1/2 feet vary, for the different soil types, between 10 and 25 tons per acre.

The soluble sodium content in the irrigated water is low, and eight years of continuous irrigation at the Galole Irrigation Scheme have shown a decrease in the salt content of the top 3-1/2 feet of soil, and, moreover, a favourable, if only a very small, replacement of sodium by calcium.

»* -52-

Table 6-3 (l) - Land Suitability Classification - Project Area

Suitability Acreage Soil classification Class for in Symbol irrigation Project area unit

1 Highly suitable 18,000 Typic Cambortbids C

2 Suitable 224,000 Typio Halorthids S

Typio Hatrargids JU 3 Fairly suitable 323,000 ftatric Grumusterts GU and

Natric Grumaquerts GA Vertio Hapludents u.

4 Marginally 257,000 Typio Hatrargids »2 suitable Mazio Batrargids H3 5 Nonirrigable 159,000 Typic Hapludents PL Typic Psammustent8 PR

Vertio Hapludents US

Regularly flooded P soils of the Meander Plain -53-

Table 6-3 (2) - Land Suitability Classification - Project Area

Remarks

Deep. Porous. Nonsaline-nonalkali soils. Caliche usually found at a depth of about 50 inches; this does not interfere with permeability for roots or water. Light clearing and levelling required. Moderately permeable soils. Saline-alkali below fertile topsoil averaging 16-inch thickness. Sandy topsoil over 20 inches thick. Subsoil with impermeable illuvial alkali hardpan, which does not interfere with root growth and promotes water retention in topsoil layers. Clearing of dense bush and levelling required. Heavy contracting clay soils with porous nonsaline-nonalkali topsoil of average depth 10 inches overlying slightly permeable natric horizon impenetrable by roots* Topsoil is fertile: puddles when wet. Levelling and careful ridging necessary: light clearing.

Deeper nonsaline topsoil layer. Considerable levelling and flood protection required. Sandy topsoil less than 20 inches thick overlying impermeable natrio horizon. Removal of hardpan cap and leaching to reclaim not considered feasible. Sandy topsoil and hardpan removed by erosion. Surface layer frequently nonsaline-nonalkali as result of colluviation. Areas with prohlemless topsoil layer more than 8 inches thick more common in central and southern parts of project area. Nonsaline-nonalkali levee soils of good quality: separated, from old alluvial high terrace by low-lying river basin soils, nonirrigable from gravity system proposed - subject to flooding. High-lying sandy ridges - infrequent dispersed locations. Gullied streambed deposits: mostly planned in drainage ways. Predominantly sandy river-wash deposits. -54-

Table 6-4 - Soil Suitability Classification - Research and Training Centre

Class Suitability Acreage for in Soil classification Symbol irrigation R and T area unit

1 Highly suitable 1,615 Camborthid8 C 2A Yexy suitable 1,972 Typio Ealorthids S Vertio Hapludents U1 2B Suitable 1,510 Vertic Hatrargids N4-1 3 Fairly suitable 4,653 Vertio Natrargids N*'2 4A Marginally suitable 97 Typic Natrargids N1* N2'1 2 2 4B unsuitable 3,528 Typic Katrargids N «

„3.1 Mazio Natrargids H3*2 I,

The typic natrargids of the R and T centre have been inoluded in Class 4 suitability due to their limited acreage and unfavourable topograph!o position. This is in contrast to the inclusion of typio natrargids in Class 2 throughout the projeot area (Table 6-3). CHAPTER VII

AGRONOMIC STUDIES

The Galole Irrigation Scheme was initiated by the Government in 1955 an(l expanded to its present extent of 1,200 acres by 1964» Throughout its history, cotton has been the sole cash crop of the scheme, although some tenants have grown irrigated subsistence crops during the off-season.

The majority of tenants, drawn from the local riverine Pokomo people, have tried to maintain their traditional flood-plain wshambasw l/ in addition to cultivating their tenancies, generally to the, detriment of both« The consistent growth of cotton, which up to I964 averaged about 1000 pounds per acre of seed-cotton, seemed to indicate its general adaptability to the conditions»

Numerous other crops were suggested, agronomic experience and trials elsewhere within East Africa and Kenya*s balance of trade in agricultural produots being taken into consideration. The list of crops considered for trials in the applied researoh programme of this survey included fibre crops such as cotton and kenaf; oil crops, including groundnuts, soya beans, castor beans, sesame, safflower and othersj sugar canej food crops such as maize, millet and sorghum; fodder crops, green manure crops, and horticultural crops. For purposes of economic evaluation prudence demands that the yield levels adopted for the purposes of this report be conservative, particularly in view of the almost complete absence of irrigation tradition within Kenya. Therefore, yields considerably lower than those obtained under carefully controlled experimental conditions are suggested, and, as may be noted in ChaptersyIX and X7I, an allowance has been made for gradual improvement through experience and research by a net annual increase in estimated yield of one percen-t.

To follow up the work started at Galole, recommendations were made to the Govern­ ment to continue agronomic trials beyond the period covered under this FAO/UNDP Survey. In 1966, arrangements were concluded between the governments of Kenya and The Netherlands

l/ Shamba - Local term for small farm or garden. -56-

to continue and expand the applied research initiated at Galole under this study ust-il March 1969- In the zcantisc, thó Covéïïïïïèïvî, lia.» i-equeaieu a three-year extension of this assistance. The objectives are to find out the extent to which the tenants on the scheme are capable of adopting modern irrigation and agricultural practices; to study effective management of the scheme; to train counterpart staff and to decide on the measures necessary for the rehabilitation of the scheme. As the Galole scheme is considered to be unrepresentative of the development area in that it contains too high a proportion of good soils, the Government intends in due course to extend the Galole scheme by another 1000 acres to include a larger proportion of poorer soils.

7.1 Cotton Experiments and Observations

Experiments were conducted into varietal choice, time of planting» spacing, fertilizer requirements, weed control, insect and pest control, and the effect of crop rotations. Each of these aspects is dealt with in more detail in Section F7.1 of Technical Volume V (Appendix P). The experiments to date have demonstrated that cotton grows well on the Typic Ealorthidi/ and Natrio Grumusterti/ soils at Galole. Tields of well over 3,000 pounds of seed-cotton per acre have been obtained within six months from sowing. The main factors affecting yields are pests, weed control, and soil fertility. Fertilizer trials indicate marked response to nitrogen; as shown by combined results, 200 pounds of ammonium sulphate per acre increases the yield by 15 percent. The production of cotton in the Galole scheme has been tied to cotton-growing at the coast by a requirement to supply a medium long staple cotton to the ginnery at Lamu. The excellent grade of cotton produced in the past has, to some extent, predetermined the varietal choice. Variety UK 51 was adopted throughout, apart from the varietal trials in the later seasons. The vigour of this variety often results in excessive growth of stem and leaf which tends to suppress boll formation. Further trials are required to find a variety more suited to the climatic conditions of the lower Tana. At the present time, interpretation of the yields and agronomic conditions suggests that a tenant in a large scheme may be expected to produce 1,750 pounds of seed-cotton per acre with variations from year to year between 1»500 and 2,000 pounds.

7.2 Experiments and Observations on Crops other than Cotton

As mentioned earlier, only cotton had been grown as a cash crop under irrigation at Galole. Information on other crops that had been grown in the area was sketchy or contradictory, so that research on other crops had to commence at an early stage of the investigations.

1/ Typic Halorthid - Non-saline, non-alkali loamy topsoil of about 16 inches overlying a saline-alkali subsoil. 2/ Hatric Grumustert = Heavy but porous, non-saline, non-alkali topsoil of about 10 inches overlying an impermeable saline clay subsoil. -57-

The list of crops that might reasonably be expected to offer prospects for success­ ful cultivation was large, and the time to test them limited. Therefore, in the first season, a selection of the most promising crops was made for further study in formal experiments during succeeding seasons, as described below. Details of the various observation trials on these other crops are contained in Section 17.2 of Technical Volume v„

Sugar cane

Sugar cane has been grown in Kenya for at least a hundred years, mainly along the coast and near the shores of Lake Victoria, and small amounts elsewhere, where the climate is favourable.

To obtain reliable data, at least five years of trials are needed, as well as a large experimental area and a laboratory with a test mill. These conditions could not be met at Galole. Moreover, except for some small plots growing canes of doubtful origin, cane had not previously been grown in the area. Therefore, plant cane had to be brought in from the Sugar Research Station near Lake Victoria, some 500 miles away. Conditions for carrying out experiments were therefore far from ideal. Sub­ sequent trials under Dutch bilateral aid have not apparently been conclusive either and there has been much damage by nematodes. It appears,therefore, that sugar to date remains a doubtful proposition until more definite results are available. A tentative estimate of yield based on trials so far is 35 tons of cane per acre containing some 4 tons of sugar.

Moreover, maintenance of planting and harvesting schedules would require the provision of adequate labour and transportation facilities to ensure a steady supply of cane to the sugar mills. Co-ordination of cane planting and harvesting would need to be largely under the control of the mill organization to ensure continuous delivery throughout the milling season. This need is also an argument in favour of using plantation methods, rather than tenant cultivation.

Kenaf

Many attempts have been made in the past to grow soft fibres such as jute in Kenya. None of tbese had proved successful, although kenaf (Hibiscus cannabinus) generally seemed the most promising. Due to the lack of previous research, it was difficult to obtain seeds of suitable varieties for testing in the early stages of the survey, nevertheless, a small quantity of one suitable variety was obtained, with which fertilizer trials were carried out. Several collections of varieties were later tested on small plots. The key to successful kenaf fibre production, once adequate yields of green stems have been obtained, is in the reduction of labour requirements for processing of the crop. Cutting and bundling of the stems, transporting them to the retting facili­ ties, stripping, washing and drying the fibre, if done entirely by hand, is excessively demanding in labour. Economy in processing depends upon the introduction of meohaniza- tion,but this will require close co-ordination with processing interests to ensure production of an acceptable quality of fibre. -58-

•Pii-rfhAT rfiBflapeh with ribboning and daeortieating maohinea ia required- a« presently available equipment is not considered entirely satisfactory« Transport of the green stems to centralized retting facilities would also require careful organiza­ tion.

It is estimated that kenaf fibre yields of around 1,500 pounds per acre could be obtained from tenants' fields after a growing period of about four months.

Groundnuts

Groundnuts are grown in practically every district of Kenya but only in a few areas of the western and coast provinces does production reach a marketable surplus. Research has been carried out mainly at the coast and in the Hyanza area, where numerous varieties have been tested. Preliminary trials showed that growing this crop on low ridges usually resulted in some waterlogging, and subsequent trials on higher, more widely-spaced ridges, with two rows of plants per ridge, provedjnorei successful.

Seme varieties, especially in the earlier growth stages, showed a yellow leaf discoloration over irregularly shaped areas of the field. The discoloration responded to spraying with a one percent iron sulphate solution, although no improvement in yield could be detected. It seems reasonable to assume that some varieties suffer from iron chlorosis on these soils, whioh have a high pH value.

Ko statistically significant response could be shown to nitrogen, phosphate and potash fertilizers, either singly or in combination. This lack of response is compatible with the results of fertilizer trials with other crops. The absence of response to nitrogen is in contrast to the noticeable influence of this element upon yields with most other crops. This difference is explained by the abundant and active rhizobium l/ of groundnuts.

High yields can be obtained with varieties whioh show a marked degree of tolerance to local soil conditions. It appears reasonable to assume that yields of 1,600 pounds of shelled nuts per acre could be obtained by tenant farmers. The growing season for groundnuts is about 120 days.

Castor beans

Pour observation trials were carried out with a total of thirteen varieties on two soil types. The highest yields (over 2,000 pounds per acre), were obtained from two American dwarf varieties (see Volume V, Appendix P-ll). Insect attack occurred as suspected with this crop and was kept under control by spraying with Thiodan. But commercially this would be uneconomic. Also, a disease new to Kenya, which causes defoliation, appeared, and so far no preventative has been found. However, further research on this crop may well be justified in view of world demand for castor oil.

Groundnuts belong to the family of legumes, capable of fixing atmospherio nitrogen by means of the baoteroid nodules in the root system. 59-

Soy beans

Trials with varieties of this crop were disappointing, a fertilizer trial showed a marked response to nitrogen but no response to phosphate or potash» This result suggested a lack of.bacterial nitrogen fixation, which would normally be expected with this crop, as with' groundnuts. Indeed, at no time was any nodule formation found on the soy bean roots, and several trials with seed treated with inoculants failed to produce nodulation. This matter should be further investigated to find out whether the inoculant was at fault, or whether the bacteria specific to soy bean cannot adapt to the soils on which the trials were made»

Fodder grasses

Observation of six different fodder grass species showed that crops like Napier grass and Signal grass had a high yield potential provided that considerable nitrogen fertilizer was supplied regularly. For example, Napier grass could yield around 22 tons of field dry hay per aore per annum, but the total nitrogen application in the form of sulphate of ammonia for this would have to be 900 pounds. However, without nitrogen, 50 percent of this yield could be expected.

Maize

Twenty early-maturing varieties and hybrids of maize were tested initially in an observation trial. Symptoms of nitrogen deficiency, as well as severe rust infection, were observed. Stemborer attack was heavy but could be kept under control with repeated DDT sprayings. The highest yield of 1,900 pounds of seed per acre was obtained from variety Puccinia polysora resistant.

During the fourth season of trials maize was grown on the scheme under irrigation and also on the riverine soils in small scattered plots. The maize crop on the scheme failed convincingly due to stemborer damage, while the plots in between the riverine vegetation were only slightly affected. The reason for this difference is not known and would have to be determined by a thorough entomological investigation.

Sorghum

Twelve varieties of bird resistant sorghums, mostly developed in Uganda (Serere), were tried initially in an observation trial. There was little borer damage, and very high yields were obtained - up to 4»600 pounds of grain per acre. However, later plantings in the rotation trials suffered from extensive damage by stemborer.

Rice

Rice is a popular crop along the Tana river flood-plain and many attempts are made by tenants on the Oalole Irrigation Soherae to grow rioe on flooded land. Being an important food and oash crop, it was thought advisable to inolude the orop in the researoh programme. Unfortunately, it was only possible during the time available to try out two local varieties under both wet and dry conditions. The results were -60-

WA+ ÄW»Ä^»-«-««/»< %•*• .4.\*Ä«--A. ~—.- --«—4-4.— J4J ..4 —T J "> ü Art —* J— -.ff JJ— ar*. »*v v wuw HM. -MÇ}«*«Q y v.uw »*Q** WMW * V**. *\> W^ MAU tf A«?«fcVfr JJt^v ^*Vfc*AAVt.»» WA ^fGMAAAJT ^/Ol CfcNSJL" O • A AA O A" W are other varieties available in East Africa which should be tried, and a more thorough search should be made for varieties from other parts of the world for continued trials in the area*

Fodder, Green Manure and Cover Crops

The most promising species in this group of crops appeared to be cowpeas, velvet beans, and sunhemp. These crops were easily established and grew rapidly into luxuriant dense stands, giving large amounts of green matter for incorporation into the soil and high yields of seed.

7.3 Irrigation Trials

Extensive irrigation experiments with cotton were performed to determine à suitable irrigation regime for this crop, and, from observation trials, to infer water demands for other crops.

Details of the irrigation trials may be found in Section F7.3 of Technical Volume .V. From these trials, it has been found that a field water application of 2.5 inches with an average 12-day interval between irrigations is most suited to the soils characteristic of the trial ' fields at Galole, and has given satisfactory results with other crops. In the particular case of cotton, this application is suitable for a ridge spacing of 40 inches with intervals of 16 inches between plants, growing at a density of two plants per hole. Cotton yields were satisfactory and crop water usage was deemed to be more efficient than for other regimens tested. These figures are exclusive of conveyance and surface runoff losses, throughout the growing period. Applications must, of course, he reduced, or the intervals between irrigations extended, to allow for effective incident rainfall.

The heavy clay soils of the project area contract and crack extensively when dried out. To grow crops on them in this condition, pre-irrigation is essential.

The foregoing requirements are used to determine the criteria for the capacities of irrigation supply canals. Considerable work remains to be done, however, to refine these preliminary proposals for irrigation regimes for crops other than ootton, and to determine practical irrigation rules from field trials.

7.4 Animal Husbandry

The presence of large numbers of cattle, sheep, goats and camels within the lower Tana catchment and adjacent plains of the Northern Frontier, suggested consideration of possible improvements in animal husbandry production, either through provision of irrigated pasture or by stall feeding with fodder crops grown under irrigation. -61-

.It is estimated that, in the Tana river distriot alone, there may he about 70,000 cattle and 15,000 sheep and goats. The cattle are almost all of Zebu origin and are considered to be some of the best indigenous stock in Kenya. This animal popula­ tion is constantly on the move, their nomad owners trekking annually many hundreds of mile3 in search of water and pasture» Two major stock routes to the coast pass through the lower Tana basin, the route east of the Tana river being preferred by reason of better grazing and availability of water. Nevertheless, the western route, which roughly parallels the Tana river in the vicinity of the proposed main supply canal, is used extensively.

The long trek to the coastal markets generally results in severe loss of condition and weight by all animals before arrival at the major buying centres - Lamu, Malindi and Mombasa.

Tsetse fly is known to be present in the riverine forests of the lower Tana, and, although not penetrating far outside this narrow belt, represents a hazard inasmuch as lack of water often forces the herdsmen to drive the cattle to the river, even by day.

As indicated earlier, fodder crops, particularly grasses, grow well under irriga­ tion. It would be too hasty to assume that there is no future for animal husbandry in the area considered for irrigation development»and the possibility of dairy produc­ tion should be considered. The scale of production feasible and desirable in relation to the social and economic factors involved needs further detailed investigation.

Improved road communications into the interior of the lower Tana basin for irriga­ tion development will extend the market to the animal rearing area, and hence, in future, these desert-reared animals may be sold in prime condition and trucked to the coast. Development of the irrigation scheme may conflict with the traditional stock route along the west side of the Tana river, and, while no great difficulties are foreseen, provision of watering points for cattle along the main supply canal should be considered. -62-

CHAPTER VIII

AGRO-ECONOMIC STUDIE S

Determination of a satisfactory crop rotation plan is dependent not only upon the agronomic suitability of crops but also upon the costs of production related to prices and prospective markets. Thus, from the agronomic and soil studies described previously, an insight has been gained into the produce which might be grown and the methods of crop production costs are reviewed.

For promising crops, an acceptable rotation plan may be proposed from an assess­ ment of costs and benefits. The system of land tenure proposed is also discussed herein, as is the determination of appropriate tenant incomes and the means whereby production can be achieved. Further details relating to all of the foregoing matters are. presented in Appendix G of Technical Volume V.

8.1 Markets and Price Levels

Except for those products governed by international trade agreements, the world market in recent years has not been particularly favourable for the disposal of certain surplus agricultural produce. Free market prices have fluctuated markedly over the years and current forecasts of international trade scarcely attempt to look beyond 1970. Hence, although some part of the production from the lower Tana irriga­ tion scheme may have to be disposed of in this market, no valid forecast of prices and demand can be made at the present time. For.the purposes of this report, there is no alternative but to adopt the yardstiok of present prices. It may be noted, however, that world prices for agricultural products have been relatively low in recent years and it is believed that the use of current prices may result in a conservative evaluation of scheme benefits, particularly as there is a growing recognition in international trade markets of the interests of primary producing countries.

In recent years, consideration has been given to the formation of an East African Common Market but, as yet, such a potential market has not come close to a reality. There is little information available to indicate where production should be located within such a market area, and for the present, therefore, its influence cannot be taken into account. -63-

The internal market of Kenya; however, can be more readily evaluated in terms of population growth, and trends in income levels and consumption. Forecasts of popula­ tion growth are estimated in Table 8-1.

Table 8-1 - Population Growth Estimates - Kenya

Fertility unchanged Fertility reduced (hiRh) (low) Tear Population Male labour Population Male labour force force

1965- 9,400,000 2,260,000 9,400,000 2,260,000 1970 10,800,000 2,600,000 10,700,000 2,600,000 198O 15,200,000 3,520,000 13,200,000 3,520,000

1990 21,500,000 4,900,000 15,800,000 4,490,000 2000 31,300,000 6,980,000 19,300,000 5,280,000

Per oapita income is expected to rise by 3 percent per annum during the period I966-197O, while the gross domestic product (ŒDP) is expected to rise 6 percent per annum. These figures are based on the Development Plan (il), but the plan does not offer any detailed comment on the long-term relationship between population growth and per oapita incomes. However, in the absence of other information, assumptions as to the long-term demand for certain agricultural products must be inferred from the foregoing population forecast and past trends in consumption, for evaluation of the eoonomics of development.

Cotton

Kenya cotton falls in the long to medium-staple range, and in the past has found a ready outlet in the world market. Projections by the Cotton Lint and Seed Marketing Board indicate that a favourable market will likely be available for such high quality cotton for some time in the future. The domestic market at present consumes between 2 and 2.2 pounds of lint per capita annually, which is very low by world standards. Presuming an inorease in consumption to between 4*5 an(* 9 pounds per capita annually, as is found at present in many countries of the Near East and Latin America, projections of the cotton requirements in Kenya in terms of the population forecast may be made as shown in Table 8-2. -64-

Table 8-2 - Projected Cotton Requirements for Kenya in Tons of Cotton Lint for High ana Low Projections of Population Growth

Per capita rates of consumption Year 4.5 lb 6.5 lb 9 lb Low rate. High rate Low rate High rate Low rate High rate

1970 21,500 21,900 - — —

I98O 26,500 30,100 38,300 43,500 - - I99O - - 45,800 61,200 63,500 84,800 2000 - - 56,000 88,800 77,500 123,000

Cotton has been included in the proposed rotation plan (see Chapter IX) and the scheme might be expected to yield between 25,000 and 35,000 tons of lint annually at full development. Such an amount of quality cotton may continue to find a ready external market, with cheaper short-staple cotton being consumed locally. However, it is apparent that the local market will provide sufficient demand to absorb most, if not all, of the cotton production should the export market deteriorate, even if substitution of synthetic fibres for a substantial part of the market is presumed.

The Cotton Lint and Seed Marketing Board controls production and marketing of cotton and, at present, pays producers Sh 0.50 per pound for Grade AH seed cotton at Galole grades as BR, due to the cultivation under irrigation and the hand picking practised. Presuming a continuation of this method of harvesting, the ex-farm price may be assessed at £ 61 per ton for seed cotton, when allowance is made for transporta­ tion to Mombasa.

Sugar

Sugar consumption has been rising much more rapidly in Kenya than production, and in recent years a substantial import of sugar has been necessary. At present, Uganda provides about half of the sugar imported into Kenya, while the balance is purchased on the open market abroad.

While the continuation of the recent 8 percent per annum increase in domestic sugar production is not expected to continue indefinitely, projections indicate that the total demand in Kenya by the year 2000 should rise to between 840,000 and 1,130,000 tons. The potential level of yield of the Tana scheme, if approximately half of the area were devoted to the growing of sugar cane, has been estimated in the order of 650,000 to 750,000 tons but, as already indicated in Chapter 711, the possibilities of growing sugar on the aoheme need further examination. If this quantity could be grown it would find a profitable outlet in the local market provided the present protected price is maintained. However, the creation of an East African Common Market may influence the situation for Kenya sugar adversely, as it is understood that there are substantial areas as yet undeveloped in Uganda which could produce sugar at a competitive price. -65-

The present internal price of £ 46 per ton at the faotory is tied to a formula based on the Commonwealth Sugar Agreement price until the end of 1967* Thereafter, it is expected that Kenya will re-price sugar to reflect local conditions rather than continuing to adopt the CSÂ formula, which is based upon Caribbean costs of production. Por evaluation of benefits from the possible growing of sugar cane in the irrigation scheme, the present fixed internal price of £ 46 per ton at the faotory has been adopted^ (See also Chapter,IX).

Oil props .

Of the oil oropa included in the experimental programme at Galole, groundnuts performed sufficiently to be recommended for inclusion in the cropping pattern. In addition, a useful edible and industrial oil can be extracted from cotton seed, which is a valuable by-product from the cultivation of cotton. At the_present__time, Kenya imports cotton seed and oil, but exports groundnuts and oIi.~~Tt also imports palm oil and animal fats,* part of which could "be replaced" by soft oil. The difference between imports and exports is, currently, a net annual import of around 10,000 to 12,000 tons of soil equivalent. Recent per capita consump­ tion is calculated at about 2 to 3 pounds per annum, which is very low in relation to world standards. At this level, income elasticity is high, so that prospects for a growing home market are good. For future producers in Kenya, there seems to exist not only a growing home market but also a large potential world market. The present price for groundnuts averages approximately £ 55 Per *on °f shelled nuts and this has been taken as the ex-farm price for groundnuts produced in the project area.

Kenaf

Kenaf is a good substitute for jute in the manufacture of bags and cordage and, as a commercial crop, has been quite successful in several countries. The current prices offered to farmers for kenaf are £ 85 per ton for super grade and £ 75 per ton for Grade A, f.o.r. at factory. Assuming road transportation from the project area to the existing production facilities of the East African Bag and Cordage Company at Thika, the price level in the project area is estimated to be about £ 65 per ton for retted fibre, including the cuttings. At present, it is not realistic to assume an export market for kenaf fibre, nor to estimate when the local market might become satisfied. However, it is assumed herein that the domestic market would be able to absorb the level of production anticipated from the scheme if it should prove feasible to grow this crop on a large soale^(See Chapter Ix).

8.2 Land Tenure

Before evaluating the size of farm holdings which may be suitable for planning purposes, it is necessary.to make an assumption regarding the method or system of land tenure to be adopted. Discussion of this matter was undertaken with representatives of Government through the Tana Steering Committee. - 66

As the investment neeaasATy to Aaya\nn +>» area ^iil d»»d hi£h stzuidcxds of maintenance and consistently good husbandry with selected crops to achieve sufficient benefits to «arrant development, settlement of independent farmers vas ruled out from further consideration. Prospective farmers will require extensive training and considerable guidance to achieve target levels of production* Therefore, a Tana River Irrigation Scheme Authority, based on a Oezira-type institutional organization, operating under the general policy of the Hational Irrigation Board, has been recommended by the Tana Steering Committee* under this system, the tenant would have a leasehold on property with succession rights, but not amounting to freehold* Such a system is considered desirable to avoid fragmentation of holdings and to facilitate changes in crop patterns and cultivation practices to meet changes in market demands*

To attract settlers to the scheme and retain them as contented farmers contribu­ ting willingly,the rigorous and sustained effort demanded by irrigated cultivation requires that income levels be sufficiently attractive* A cash income of £ 160 per year, in addition to the social and institutional benefits to be derived from develop­ ment, is considered appropriate as the basic target income level for the average tenant family.

8.3 Tenant Income and Labour Requirements

Government polioy with respect to the Tana irrigation project is to provide accommodation for as many people as possible, and, at the same time, to size farm holdings so that the average farmer can achieve the target level of income of £ 160 per year. This means that a labour-intensive type of operation must be considered.

A study was made of the labour input of a small group of tenant farmers during the 1963 cotton season at the Oalole Irrigation Scheme to ascertain the average capability of a tenant family. As a result of this study and similar studies by others elsewhere in Kenya, it is assumed that the average tenant family of five will be capable of providing 10 man-days per decade over long periods of time, and will be able to provide between 15 and 20 man-days per decade during the planting and harvesting seasons. In order to smooth out the total labour demand from the growing of the various crops in the suggested rotation, it is necessary to consider the input of additional manpower and some mechanization of operations. These matters are considered in more detail in the following chapter* -67-

CHAPTER IX

AGRICULTURAL DEVELOPMENT

The classification of soils into their suitability for irrigation, as discussed in Chapter yi ; indicates that only 2 percent of the project area contains soils of Class 1 suitability, whereas Classes 2 and 3 soils together occupy some 61 percent Despite the substantial total acreage of these soils, they are irregularly distributed and, over much of the area, occur in a fragmentary arrangement with soils of Class 4 suitability. The latter are considered unsuitable for development because of the high cost of reclamation, the additional water duty demanded, the extra husbandry require­ ments, and their ultimately lesser crop yield potential. The incremental cost of development and cultivation in combination with a lower level of return of Class 4 soils would exceed the extra costs of extending the irrigation system farther south to command sufficient acreage of soils of Classes 1, 2 and 3 suitability to balance the ultimate water availability. Hence, agricultural development should be based on the irrigation of soils of Classes 1, 2 and 3 only.

Areas of floodplain soils, which are physico-chemically equally suitable for the growing of irrigated crops,as are the other soil classes, are subject to periodio inundation,and the surface is generally more dissected by drainage channels. Thus, most of the floodplain lands on the west bank of the river would be better suited to the growing of fodder grasses under irrigation to support a local beef and dairy enterprise to meet the local market. The remainder of the floodplain lands, it is suggested, can be reserved for forestry activities,should suitable species be found, thereby contributing to the local demand for fuel and minor construction materials*

9*1 Cropping Pattern

The cost of developing the area for irrigated agriculture, as described in succeed­ ing chapters, will be high, and thus together with the soils and agronomio factors, points to the desirability of intensive use of irrigated lands to maximize the output per acre* In the project studies the cropping pattern which was considered as a result of preliminary trials at Galole was a 6-year rotation based upon cotton, sugar cane, kenaf and groundnuts as major crops, as illustrated on Plate 6. In this an intensive NÖ31XVd dOdD 03SOdOtid acvHd nou»ioa won uoawjdiaMi quicvud IMU /V

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use of land is planned, resulting in a cropping intensity of 2.0. Hhile this crop pattern has formed the basis of the economic evaluation made in these studies, further consideration of it has shown certain objections to some of its aspebts^and further investigations are recommended . to evolve a pattern better suited to all the conditions. These objections are discussed in the summary of conclusions and recommendations in Chapter ^1.

9»2 Farm Size and Layout

The basic unit of agricultural development is regarded as a tenant-family holding. Studies of manual labour and mechanical equipment inputs, and gross and net values of production, in terms of the selected crop-rotation plan, lead to an assessment of farm size and layout. As discussed in Chapter 7111, it is intended that the average tenant should be able to obtain the target income of £ 160 from a smallholding, essentially relying only on family labour. To achieve an intensive crop rotation, mechanization of cultivation for field preparation and ridging, and additional labour would be necessary. With these provisos, the tenant, together with his family, would find productive year-round employment on a ^-acre holding, with an average labour requirement not exceeding ten man-days per decade, but with up to twenty man-days per decade being required during periods of harvesting and planting, at which times the entire family are presumed to contribute to these activities. Prom the layout point of view, 5-acre holdings fit conveniently into the irrigation layout, in which 50-acre units form the basic module of development. Thus, two tenants would share a 10-acre field served by one head-furrow (see Plate 7)« To further improve the efficiency of management, each holding would consist of alternate 2.5-acre plots, whereby half of each field would perhaps be cultivated under sugar cane for three consecutive years, while the other half would be under cotton, kenaf and miscellaneous orops during the same period. Every year, each plot in the soheme would be cropped in accordance with one of the years of the rotation plan, with the phase reversed after three years. Phasing of rotations and shifts in phasing along the irrigation sections is proposed to even out peaks in requirements for irrigation water, labour and machinery.

9.3 Requirements for Labour and Machinery

The requirements for labour and machinery have been estimated for the complete 6-year rotation cycle in 10-day periods. These studies indicate that the average labour requirement will be less than 10 man-days per decade, with peak demands of up to 20 man-days per decade during planting and harvesting. Machinery requirements are based on the assumption that each tractor could serve 400 acres, allowing for a maximum rate of operation of 8 effective hours of fieldwork per day, an average rate of 1,350 hours per year. In addition, for cane cutting, kenaf retting and soheme maintenance of oanals and drains, a labour force of between 2,500 and 3,000 workers would be required for each 30,000-acre irrigation district. Such labour will not be readily available on a casual basis in such a remote location, and therefore it is desirable that continuous employ­ ment be offered to such labour gangs, as is provided for in the scheduling of the rotation plan. Such year-round employment will avoid the social' problems and high costs associated with the engagement of casuals for only short periods. »LOCK 1

LEGEND

Fia «IL unit» or »LOCK < TNC ROTATION »NASI IS a-« «no TNC TIM« »MA»f li A, II1PICATE0 »T R-I-A.(»IE AL»0 FLATC 4 )

TWO fABMtn» CULTIVATIH* TWt TMIBO M-ACBt PICL» riiLP Or AN IRRIGATION UniT OP »0 ACRC3, {°A' HOLOin« or A PARMCR CONSIST» or t nor».

FARCCL ir S ACRM »TAOr i or ooTATion GOVERNMENT OF KENYA UNITED NATIONS SPECIAL FUWP SURVEY OF IRRIGATION POTENTIAL LOWER TANA RIVER BASIN row «wo MRKULtyot oiMAmzATum or THC UJITCP BAIICH» PARCEL or »ACBCJ STAM t Or ROTATIOfl SCHEMATIC ARRANGEMENT OF ROTATIONS AND CROP PHASING RELATED TO FARM HOLDINGS

9.4 Value and Cost of Agricultural Production

The direct costs to the farmer for production of a specific crop are for seeds, fertilizer and insecticides. For the various crops of the proposed rotation, direct costs of production are estimated as shown in Table 9~1»

Table 9-1 - Direct Costs of Agricultural Production

Average crop cost - Sh per acre Item Cotton Sugar cane Kenaf Groundnuts Beans

Land preparation 22 80 22 22 25 Fertilizer 92 510 " 120

Seeds 5 120 60 40 10 Weed control (chem.) 20 20 Pest control (chem.) 140 Harvest-lifting 20

Bags 10 5 10 Decortication (shelling) 80

Miscellaneous 20 8 ' 8 5 11 Total 300 750 210 180 45

The indirect costs are those related to the general operation of his farm and inolude purchase and maintenance of irrigation siphons and farm tools, a charge for periodio applications of gypsum as a land reclamation measure, interest on credit, and land and water charges. Weeding equipment, siphons, minor tools, plus an allowance ^ for periodic gypsum applications, are estimated to cost an average Sh 30 per acre per year. The total demand for interim productive and consumptive credit is estimated at Sh 600 per acre, which, averaged over the year, will cost the farmer Sh 30 per acre annually, at an arbitrarily chosen interest rate of 5 percent. The cost of land and water is the subject of discussion in Chapter XVII, wherein the eoonomio evaluation of the entire scheme is considered in relation to its over-all viahility and the finanoial situation of the individual farmer.

Although continuous oropping of the entire irrigated area is technically feasible, it would be unrealistic to assume that this high level is always attainable. Hazards from resistant strains of pests, plant diseases, slumps in market prioes and unfavoura­ ble weather conditions will likely reduce the total effective crop aoreage and, on the average, a reduction of 5 peroent in output has heen made as an allowance for suoh oontingenoies in the eoonomio evaluation. -72-

Based on the foregoing, average gross and net values of /production for the £-yeaï rotation cycle can >>e evaluatsd as presented in Table 9-2, and indicate that the basic initial net farm income will bejE 47*50 P©r acre.

These are based on the following expected rates of yield of major crops: Crop Yield per acre Seed cotton 1,750 lbs Sugar cane 35 tons Shelled groundnuts 1,600 lbs Kenaf fibre 1»500 lbs These rates are believed to be conservative. Cotton on the small Galole Irrigation Scheme has yielded up to 3,000'ilbs/acre.

Table 9-2 - Estimation of Farm Income

Per six-year rotation cycle Crop Crop-7 Gross Direct Difference acres value costs in value Shs '- ^ Shs Shs' Shs Cotton 2.00 , 1,900 600 1,300

Sugar cane 3.00 3,990 750 3,240 Groundnuts 1.67 1,330 300 1,030 Kenaf (fibre) .67 350 150 200 Kenaf (seed) .33 200 70 130

Beans .33 70 15 55

Total 8.00 7,840 1,885 5,955

Average 1.33 1,307 314 993 60 Less indirect costs Net value of farm production (gross of land and water rights) 933 Less allowance for crop failures (about 5 percent) 43 Plus additional income from livestock 890 60 Farm income (before payment of land and water rights) 95O , -73-

9.5 Processing of Farm Products

The majority of the agricultural products obtained at farm level under the proposed cropping pattern will require further processing. These activities include conversion of sugar cane into sugar« seed-cotton into lint and seed« peanuts and cotton seed into oil and cake* and kenaf fibre into bags. In order to maintain some flexibility in the cropping pattern when economically or otherwise justified, it may be desirable for the scheme authority to establish and operate some or all of the processing plants. The concentration of production and the large quantities involved will provide an opportunity to establish large-scale processing units. To provide an indication of the magnitude of processing involved, an estimate of the annual output from a 30,000-aore irrigation district has been shown in Table 9-3*

Table 9-3 - Quantities of Produce to be Processed (30«000-acre district)

Processed Crop-acres Total output of Product Yield Extraction product in per acre factor per acre irrigation processed district produce - (tons) (tons) sugar 35 tons 4.00 15,000 60,000 cane cotton lint 1,750 lbs .35 .27 10,000 2,7O0!/ seed cotton seed-cotton 1,750 lbs .60 .47 10,000 4,7O02/ seed cotton oils - cotton (.47 ton) .15 .07 (10,000) 700^/ seed groundnuts 1,600 lbs .45 .32 8,000 2,600 nuts cenaf 1,500 lbs .67 3,000 2,000 retted fibre

l/ Equivalent to approximately 15,000 bales. 2/ Either seed or oil. -74-

CBAPTER X

POWER POTENTIAL AND MARKETS

The development of a major hydro-electrio complex at Seven Forks near the upper limit of the middle Tana represents the first significant development intended to control and utilize the water resources of the main stem of the river. The proposed complex of projects at Seven Forks will include a major storage reservoir to regulate the natural flows of the river* It was recognized in planning the survey of the irrigation potential of the lower Tana basin that the effectiveness of this and all subsequent developments on the river would have to be carefully studied to determine how each project would influence the downstream irrigation potential.

The long-term average flow of the Tana river immediately downstream from the proposed Seven Porks complex represents only about one-half of the long-term average flow estimated at the Koreh site, the lowest point on the river at which an economically feasible hydro-electrio development could be constructed. Therefore, despite the regulation implicit in the storage development planned at Seven" Forks, one-half of the total flow of the river enters the main stem below this complex, and additional storage must be developed farther downstream if the optimum irrigation potential of the lower basin is to be realized. Thus, a study of the entire river has been carried out to ascertain where further storage capacity could be developed economically.

Throughout these evaluations, due regard has been given to preserving the hydro- electrio potential of the river. Insofar as it has been determined that the irrigation potential of the lower basin may be realized by providing for uniform regulation of upstream flows, with only limited storage capacity for re-regulation at the point of diversion, there is no significant conflict of interest between irrigation and power development.

10.1 Power Resources of Kenya

Before discussing the studies carried out to evaluate the benefits of developments associated with power and irrigation on the Tana, it is the water power potential of the Tana that should be placed in its proper relationship to the power resources of Kenya.

In a recent review of the resources of East Africa (l), the hydro-electric power potential of the country was estimated to total only 17*9 megawatts, apart from the potential of the middle reaches of the Tana. This estimate comprises a number of small developments varying in size from 0.2 to 4.5 megawatts. -75-

The total power potential of the Tana river between Seven Forks and Koren is now estimated to be some 800 to ipOO megawatts at 55 percent capaoity factor. Consideration of the general hydro-meteorologic regime of Kenya and its rivers confirms that there is little prospect for any substantial hydro-electrio developments elsewhere. In the absence of any known fossil fuel resources, and with the geothermal potential of the eastern rift valley not yet established, the Tana river represents the only known significant power resource of the country. Looking into the future, after the internal power resources of the country are fully developed, continuing growth of Kenya's economy will ultimately depend upon importing energy, either in the form of fuel for thermal or nuclear power stations, or through import of further hydro-eleotrio energy, probably from Uganda, as more of the large potential recognized on the Uganda Uil e is developed. In terms of Kenya's economic development for the next two to three decades, it will undoubtedly be necessary to consider development of the Tana power resources as a means of conserving foreign exchange which.would otherwise be spent to import energy in one form or another. Therefore, throughout the investigations of the irrigation potential of the lower Tana, it has been incumbent upon the project to recognize the necessity to optimize its hydro-eleotrio development insofar as is compatible with other water demands.

Just as the Tana possesses the greatest power potential of any river in Kenya, so too the prospects for irrigation in its lower reaches represent the largest potential within the semi-arid regions of the Republic. With nearly three-quarters of the country falling within the semi-arid zone, this important potential should also be realized, if it oan be shown to be economically feasible, to support the planned growth of the national economy. The upper catchment potential for irrigation has already been investigated (2), and appropriate reservations made by the Water Apportionment Board to secure for the future the possibility of realizing the optimum development of these upper reaches. Bo significant irrigation potential has been recognized in the middle reaches of the Tana river and therefore the major foreseeable water uses below the Seven Porks development will be in the realization of the hydro-electric potential of the middle reaches and of the irrigation potential farther downstream in the lower basin. The proposed Seven Forks hydro-electric project, as conceived in the 1959 report of the consultants to the Power Securities Corporation (3), envisaged a complex of three developments, as discussed in Chapter 3ŒI» (i) The Re servoir development. (iiJ The Gtaru development, (iii) The Kindaruma development. The Reservoir development was to consist of a rockfill dam, located approximately 3.5 miles above the confluence of the Thiba and Tana rivers. This project, developed to a full supply level of 3»432;feet (Kenya datum), would have provided an estimated total storage capacity of 935*000 acre-feet, of which some 820,000 acre-feet would be live or usable storage. The development included provision of a powerhouse with a planned installation of 40 megawatts«

The Gtaru development would consist of a low-level barrage across the Tana a short distance below the Tana-Thiba confluence. Water would be diverted through a headrace and pressure tunnel approximately 20,600 feet in length to an underground powerhouse and thence returned to the Tana river through a 13,500 feet tailrace tunnel. The total head developed in this way was to be 660 feet and provision was to be made for an installed capacity of 170 megawatts in the powerhouse. -76-

The Kinda-rnma développent ooûoisied or a low dam some 2.25 miles below the exit of the Otaru tailrace tunnel, diverting water across a sharp l80 degree bend in the river to a powerhouse located farther downstream. This run-of-river development was planned to have an installed capacity of 30 megawatts and to develop a gross head of approximately 120 feet.

In the consultants' revised report on the Seven Porks development (4)» the concept proposed in 1959 remained substantially unaltered with the exception that the reservoir dam would be built after the Kindaruma development, and be increased in height to a full supply level of 3t438»5 feet, providing 935,000 acre-feet of live storage capacity. In addition, some minor changes in planned turbine installation were indi­ cated. It was also indicated therein that the height of the storage dam could be raised by a further 15»5 feet to provide an additional 450,000 acre-feet of usable storage which, it was suggested, might be beneficial to downstream irrigation develop­ ment. The cost of this increase in dam height was estimated to be about £ 2,100,000.

In I964 FAO was requested to advise the Government as to the benefits to irrigation of the live storage proposed for the Seven Porks Reservoir Development, and, further, as to the desirability of requesting irrigation purposes. This advice was requested as a matter of urgency in view of the imminent necessity to proceed with construction of new generating capacity to meet the growing load demand of Kenya. Interim reports (5, 6) dated July and September, 19^5» were issued to provide preliminary advice on this matter.

It was also agreed that, in order to evaluate fully the benefits to irrigation from storage at Seven Porks,it would be necessary and desirable for the PAO Tana survey team to evaluate not'only the benefits from the proposed reservoir development, but also the advantages, if any, of creating other storage at the proposed reservoir site, or at an alternative site below the junction of the Thiba with the Tana, herein­ after referred to as the Confluence Site. It was also agreed that the Kindaruma development might proceed without prejudice to the upstream storage development, or to subsequent development for power and irrigation downstream.

The East African Power and Lighting Company Limited, Power Securities Corporation Limited and, subsequently, following its formation in July 1964, the Tana River Develop­ ment Company Limited provided the project team with additional reports, plans and general information on the Seven Porks hydro-electric development (7, 8, 9» 10f H» 12, 13)* In addition, through their consultants, Messrs. Balfour, Beatty and Company Limited, the power company provided basic topographic mapping covering the alternative damsites under consideration and the river reach upstream to be inundated by the various storage proposals. Additional technical details and comments have been received through correspondence with representatives of the power companies and their consultants, and in direct discussion.

As mentioned earlier, a significant hydro-electric power potential has been identified in the middle reaches of the Tana river, downstream from the Seven Porks complex. The total potential of the Tana river for hydro-electric development is considered in Chapter XII and Appendix J of Volume VI. Therein, a complex of economically attractive developments which could provide between 800 and 1000 megawatts of installed hydro-electric capacity are discussed.

10.2 Present Kenya System

Electricity is supplied and distributed in Kenya by the East African Power and Lighting Company Limited, and its associate company, the Kenya Power Company Limited. Both companies operate under exclusive licence granted by the Government. -77-

There are, at present« two separate main supply areas: Nairobi and western Kenya« and the coast. The former comprises the larger system« with a total installed capacity of approximately 102.7 megawatts, consisting of 25.94 megawatts of hydro-electrio capacity« 36.37 megawatts of thermal capacity« and a net 40»4 megawatts of capacity imported under bulk supply contract from the Uganda Electricity Board. It may be noted that the hydro-electrio capacity is restricted in a normal minimum year to 15*5 megawatts« and in a year of absolute minimum flow to only 8.3 megawatts. The UEB provide, at Tororo, 30 megawatts, under terms of a 50-year supply contract which commenced in 1958, and a further I5 megawatts under a short-term supply contract. Of the 36.37 megawatts of thermal capacity, a number of units are not now considered reliable, and the remainder are to be maintained as standby reserve when new generating capacity is constructed.

The coast system, oentred on Mombasa, consists of 46 megawatts of thermal capacity in operation and currently under construction. The area served by this system extends northward along the coast to Malindi and south to Likoni.

10.3 Load Growth Forecast

The load factor in 1962 for the Nairobi and western Kenya system was 65.8 percent while for the coast system it was approximately 63.8 percent. Whilst interconnection of these two systems has been considered, this possibility has for the purpose of this report, been disregarded and the two systems have been considered as developing independently. In 1963, the East African Power and Lighting Company Limited commissioned Messrs. Merz and McLellan to carry out a comprehensive survey of the future market for electricity in Kenya (ll). The forecasts of peak demand and energy requirements indioate a general tendency for the "system load factor to decrease gradually to about 60 percent by 1980 and to remain relatively oonstant thereafter during the forecast period.

It may be noted that the present high load factor for the Nairobi and western Kenya system is achieved through off-peak heating of domestic water supplies utilizing a ripple-current system. This has proved to be most effective in balancing the system loads. However, future growth of the system is expected to result in a larger portion of the demand arising from commerce- and light industry,^ resulting in a gradual over-all reduction of the system load factor.

The power sequences studied in detail in Appendix J of Volume,71 have been scheduled in accordance with an assumed rate of load growth similar to that forecast by Messrs. Merz and McLellan, and as shown on Plate 8. However, the market for eleotricity in any country is subject to fluctuations, depending on the state of the general economy. This may, on the one hand, provide the stimulus for vigorous development, resulting in a sharp increase in load growth or, alternatively, may have a restraining influence on industrial growth, leading to a levelling off in the demand for power. It may be stated, however, that even during periods of economio recession, past experience in most countries of the world has shown that the demand for electricity has continued to grow, though at a reduced rate.

Information on the growth of the Kenya system since I964 has shown that the rate of increase in demand for electricity forecast by Messrs. Merz and McLellan has not yet materialized. It is possible that this may be only a short-term trend, which may change radically as a result of increased economic activity. Nevertheless, for the purposes of the present report, it has been considered prudent to assess the effect PEAK DEMAN O (MW X K)0) T 3 • 4 t S 1 « CO 197 0 198199 0 2 1 i ! i i i i y GROWT» RATE 1 / 1 / GROWTH «0 IATE 2 NAIROBI ANDWESTERNKENY A SYSTEM FOOD ILA«> SURVEY

AHO UNITED NATIONSSPEIIIALFUN LOWER TANARIVICBASIN PEAK LOADFORECAS T ELECTRICAL DEMAND

/ ASMCUlTUIIt OMAMZATON GOVERNMENT OF ACRES IRRIGATIONPOTENTIAL OF KENYA PLATE 8 OF TMCKHTDHAT10K» i -79-

of a somewhat lower rate of load growth on the economy of the power development pro­ gramme» Hence, on Plate 8, an alternate load growth curve has been presented, based on an annual rate of increased demand of seven percent. Such a growth rate is representative of more industrialized countries and is believed to represent the lower limit of growth whioh may be expected under the development programme planned for Kenya.

For the purpose of this report, a plant oapaoity factor, or system load faotor, of 55 percent has been assumed in assessing the potential of hydro-electric projects on the middle Tana.

10.4 Comparative Cost of Energy

In order to facilitate evaluation of potential hydro-eleotrio projects on the Tana, a study has been made of the cost of providing energy at Nairobi from thermal generating plants located at Mombasa. A separate analysis confirmed that transmitting energy to Nairobi from plant located at Mombasa would be more eoonomio than installing equivalent plant in Nairobi and shipping fuel from the coast. Units of modern design, comparable in size to those anticipated for installation in the hydro-electric stations, i.e. 30, 40, 50 and 60 megawatts, have been considered.

On Plate 9» the variation in at-plant oost of energy for units of various sizes operating under different load factors is illustrated. For.comparative purposes, the cost of thermal energy has been taken, in this report, to be represented by a 50 megawatt unit operating at a 55 percent load factor with an at-plant cost of produc­ tion of E.A. Sh O.O52I per kilowatt-hour.

To provide an estimate for transmitting this energy to Nairobi, the load forecast prepared by Messrs. Merz and McLellan (ll) was used, and it was assumed that the Seven Forks development would provide all requirements of the Nairobi area in the immediate future. The existing generation, together with Seven Forks, would provide sufficient firm capacity to meet the anticipated Nairobi and western Kenya load for at least the next decade. It was assumed that thereafter a transmission system from Mombasa would oome into operation and carry all the subsequent load growth.

Cost estimates were prepared for 275 kV, 345 kV and 400 kV schemes. In the case of the 275 kV scheme, once the capacity of three lines had been reached, it was assumed that subsequent construction would be at 500 kV. For the 345 kV and 400 kV systems, later developments were assumed to be at 735 kV. The unit oosts of transmis­ sion lines were based on the use of rigid steel structures since, although generally cheaper, neither flexible nor guyed structure are suitable for use in an area infested by large wild game.

The analysis indicated that the scheme operating initially at 275 kV provided the greatest economy and resulted in a weighted average cost transmission of E.A. Sh O.OI49 per kilowatt-hour transmitted from Mombasa to Nairobi.

The hydro-electrio power potential of the Tana may be developed independently of any downstream irrigation complex, although, as noted in Chapter XII, the converse is not true. While some indication of the probable rate of growth of demand for elec­ trical energy is available, the programme of irrigation development discussed herein has yet to be approved. Hence, while alternative growth rates of irrigation have been studied in terms of the earliest possible starting date to assess potential conflict between the two major water users, power and irrigation, it may be noted that there is, as yet, no firm commitment to initiate irrigation development by any particular date. Therefore, the economics of power and irrigation developments have been treated independently. 10

30 MEGAWATT i UNIT

40 MEGAWAJT UNIT

50 MEGAWATT UNIT oc 60 MEGAWATT UI UNIT Q.

1

< ui o CE UI as ui

S-21 E.A. «h. $

8 -

o' ol 3

1 1

20 40 60 80 100

LOAD FACTOR PER CENT

GOVERNMENT OF KENYA UNITED NATIONS SPECIAL FUND SURVEY OF IRRIGATION POTENTIAL LOWER TANA RIVER BASIN FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS COST OF ENERGY FROM THERMAL INSTALLATION AT MOMBASA -81-

The power potential has heen evaluated in terms of the comparative cost of energy produotion as delivered to the major load centre. Thus, for comparison with the hydro-electric plants, the cost of energy delivered at Uairobi from thermal generating stations has heen taken as E.A. Sh O.O67O per kilowatt-hour.

It may he noted that this cost does not take into account the effeot of the somewhat lesser life of thermal generating plants, a much greater portion of the capital investment and interim replacements in such ' being subject to the effects of inflation. It has been suggested (14) that, under conditions of a long-term inflationary trend of 2 to 2.5 percent per year, the actual cost of thermal energy should be some 20 to 30 percent lower than that of hydro-electric energy at the outset to be strictly comparable. Since such factors have not been taken into consideration herein, it is considered that the comparison, when favouring hydro­ electric development, is valid and sufficiently conservative to outweigh any design detail variations whioh may be introduced in the development programme. -82-

CHAPTER XI

WATER RESOURCES PLANHTKO ATO POTENTIAL

It has already been shown that, on the basis of geographic and geologic considerations, the Tana baBin can be subdivided into upper, middle and lower catchments. This division is also convenient from the water resources planning point of view since it defines an upper catchment within which some irrigation potential and a few small power plants may be developed, a middle catchment in which there is a very significant power potential but virtually no irrigation potential, and a lower catchment wherein the development potential is essentially agricultural.

In Chapters XII and XIII, proposals for development of the power resources of the middle Tana and the irrigated agriculture potential of the lower Tana are discussed in further detail. The planning aspects of utilizing the available water resources to meet the needs of both of these major uses is discussed hereundor, and in further detail in Technical Volume VI (Appendix i).

11.1 Water Resources for Power Development

The natural flow regime of the Tana river is reviewed in Chapters III and IV and in more detail in Technical Volume II (Appendix A). Therein, a description is given of the existing and future water demands anticipated within the upper catchment. In Table 11-1 following, the long-term available gross flows and the net available flows after deduction of reservations for anticipated use in the upper catchment are given, together with design floods developed for the specific projects to be discussed in succeeding chapters.

Prom the foregoing data, it may be noted that the average flow availability on a long-term basis increases in a downstream direction up to the Koreh site, and from that point onward the flows decrease. This factor is particularly important in relation to the planning of water resources utilization. It is apparent that to achieve maximum benefits through development of storage projects along the middle Tana, these reservoirs must be located well upstream from Koreh. -83-

Table 11-1 - Long-term Average FL oVB and Designs Discharges

Potential dam site Long-term Net available Design discharges 2/ Average flow potential flow l/ Potential Diversion peak flood flood rate rate cusecs cusecs cusecs

Seven Forks - "Reservoir" 2310 1950 115,000 33,000 Seven Forks - confluence 3125 2600 150,000 42,500 Kindaruma 3125 2600 150,000 42,500 Kiamhere 3125 2600 150,000 44,000 Mutonga - upper 3660 3130 170,000 48,000 Mutonga - lover 4720 4190 200,000 57,000 Grand Falls 5130 4600 250,000 138,000 Adamson's Falls 5485 4955 320,000 138,000 Koreh 5580 5050 350,000 138,000 Korokora 4750 4220 250,000 110,000 l/ After deduotion of 36O cusecs from upper Tana flows and 170 cusecs from Thika flows to allow for reserved allocations in upper catchments. 2/ Ignoring potential reductions by routing floods through storage upstream. From Technical Volume VI, Appendix I, Table 11-1.

In the original studies made for the evaluation of combination of developments which have been considered on the middle Tana, a simple waterbalance computer pro­ gramme was developed. This programme was used to simulate the flow regulation and power outputs from various sequences of developments over the 25-year period of synthesized and actual records from 1937 to I962, to facilitate the calculation of benefits from particular levels of development at each of the sites considered. To illustrate the foregoing, the average annual firm flows and energy outputs from the Mutonga II system, sequence D, as discussed in Chapter XII, are presented in Table 11-2.

11.2 ffater Resouroes for Irrigation Development

In Chapter XIII and in Technical Volume VI (Appendix K), the proposals for development of an irrigation complex in the projeot area of the lower catchment are discussed in detail. It may be noted that, whilst a complex of power develop­ ments may be considered on the middle reaches of the Tana independently of down­ stream irrigation, the converse is not true. From preliminary studies it was evident that irrigation could not be economically Justified without the advantage of regulation of river flows, which will be required in any case for the power development, as a free benefit to irrigation. It has thus been eosential to recognize the dependence of irrigation upon power, and to plan for maximum irriga­ tion complex consistent with the optimum power development of the middle river. -84-

Tttule xi-d - Firm Flows and Energy Outputs - Tana River Developments Mutonga II Sequence D

Development Full supply Firm flow Annual energy level output

feet cuseos Gtfh

Confluence 3,437 2,160 1,284 Kiambere 2,242 2,160 454 Mutonga 1,908 3,480 540 Grand Falls 1,640 3,810 430 Adamson's Falls 1,167 3,980 314 Koreh 987 3,840 416 Total annual average energy 3,438 aBceecs

Successive construction of hydro-electrio power generating stations along the middle Tana will result in a gradual increase in the available firm regulated flow at the lowest power site on the river and, hence, also at the proposed diversion barrage at Korokora. The use of this gradually increasing firm flow for irrigation from Korokora is discussed hereunder to define the limits to the growth of irrigated agriculture.

In determining criteria for the design of distributary systems for irrigation, it is usually necessary to consider throughout peak rates of water demand. However, the possibility of storing in the reservoir at Korokora river flows from the power stations upstream when these exceed the current demands of irrigation, and thus make them available to meet peak crop demands at other times of the year, makes it feasible to plan the ultimate extent of irrigation development on the average rather than the peak rates of requirement.

The basis for the evaluation of water demands discussed in this chapter is the original crop rotation pattern as suggested in Chapter IX. Since this included a considerable proportion of area to be under sugar cane, for which requirements are heavy, the review and investigation of other cropping patterns now suggested cannot result in increase of demand, as compared with the overall rates assessed for that pattern. If anything, decrease seem rather more likely. For present purposes, therefore, these overall rates may be used, and the peak rates used for the sizing of canals. Vater requirements for individual crops were determined from irrigation trials made at Galole. Combining these with pre-irrigation requirements gives average monthly net water requirements (E.) as set out in Table 11-3« -85 -

Table 11-3 - Monthly get Vater Requirements

Month Evaporation Crop Net vater requirements coefficient

(Bt in feet) feet (E. in acre-feet per aore)*

January 0.66 0.72 0.475 0.475 February 0.60 0.76 0.456 0.456 March 0.65 0.71 O.46I O.46I April 0.60 0.62 0.372 0.338 May 0.62 0.62 O.385 0*385 June 0.56 0.61 0.342 O.342 July 0.55 0.56 O.3O8 O.308 August 0.59 0.54 O.319 O.319 September 0.61 0.74 O.45I O.45I , October 0.63 0.83 O.523 O.523 November 0.61 O.84 •O.512 0.445 December 0.64 O.84 0.537 O.47O

* Deduction of effective rainfall allowed as discussed in Section A4.2.4.1 of Volume II (Appendix A).

Taking into account the effect of orop staging and phasing over large areas of irrigated cultivation, the average monthly irrigation requirements of the project area have been determined for gross efficiencies of 50 and 60 percent. The former efficiency is expected to apply during the initial stages of development. Thereafter, a gradual improvement to 60 percent overall efficiency is anticipated as tenants and management become more familiar with the operation of the system. The numbers of acres which could be irrigated on this basis by each cusec diverted from Korokora during each month of the year are presented in Table 11-4.

Table 11-4 - Monthly Irrigation Potential of Diverted Flow at Korokora Irrigation Potential

Month Oross effioienoy Gross efficiency 50 percent 60 percent

acres per cusec acres per ousec . of diverted flow of diverted flow January 65 76 February 60 73 March 65 79 April 86 104 May 78 94 June 85 103 July 98 119 August 94 114 September 65 79 October 58 70 November 65 79 December 64 Average 72 -£- -86-

Irrlgation potential

Although the progressive development of power projects in the middle Tana will result in a gradual increase of the firm flow, the river will, in the future, continue to suffer a net loss of water as it traverses the Hameye Swamp and its meander plain between Koreh and Korokora. Although only limited information is available, the few measurements which have been made, suggest that the present loss can be accounted for entirely by évapotranspiration from the riverine forest,which is a conspicuous feature of the desert landscape. Thus, in assessing the.irrigation potential, an average net monthly loss of 50,000 acre-feet has been assumed to occur between Koreh and Korokora. On the basis of this loss, which is equivalent to some 830 cusecs, the firm flows which would become available for diversion at Korokora, as the power storage projects are constructed, are presented in Table 11-5«

Table 11-5 . ~ Flow Availability at Korokora

Firm Estimated firm Het firm flow Stem of power out-flow flow entering to be available development river downstream for diversion at Korokora* cusecs cusecs cusecs Confluence 2160 1000 2150 Mutonga 3480 450 29OO Grand Falls 3810 150 295O Adamson's Falls 3980 Negligible 2950 Koreh 3840 — 2810

* Allows for approximately 83O cusecs loss between Koreh and Korokora, 100 cusecs compensation flow at Korokora, and 100 cusecs average incremental evaporation loss from the Korokora reservoir.

In terms of the two rates of power development which are discussed in Chapter ,X, it is possible to provide a schedule indicating the rate at which this increase in firm divertible flow would become available.

Since irrigation growth will ultimately be dependent upon the availability of regulated firm flows in the power system, it is also necessary to consider the rates at which irrigation may be developed. For purposes of evaluation, two rates of irrigation growth have been determined as illustrated on Plate 10* It may be noted therein that Rate 1 easusec the steady development of 10,000 acres of newly reclaimed land each year following an initial build-up over three years to the foregoing rate. Bate 2 parallels Bate 1 for the first six years and then increases to 15,000 acres of development per year for the next five years . Thereafter, further expansion would take place at an annual rate of 20,000 acres.

In considering these potential irrigation rates, it has been necessary to keep in mind that, for Kenya, development of a major irrigation complex such as is proposod herein will be a pioneering effort. It will be necessary not only to construct the physical facilities to undertake irrigated cultivation of crops, but also to train adequate numbers of tenant cultivators and supervisory staff. Hence, while much higher rates of irrigation development have been undertaken elsewhere, it is not considered prudent to base the economic evaluation of irrigation development on a faster rate óf growth than seems practicable under present circumstances. 400

/ 350

300 / DEVEI.OPMEN T / RATE N° 2

/ DEVELOPMENT / RATE N° 1

230 o

QÇ

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so

GOVERNMENT OF KENYA UNITED NATIONS SPECIAL FUNO 0 SURVEY OF IRRIGATION POTENTIAL 20 25 30 35 40 49 LOWER TANA RIVER BASIH WOC AW ««»ICULTUHi OUtAWMTIOII OF THE UMTCO MTUB YEAR RATES OF IRRIGATION DEVELOPMENT

PLATE IO, ILACO / ACRES -88-

On Plate 11, the schedule at which firm flows would become available for diversion at Korokora under the two rates of per«ox- growth discussed previously is illuBi/rated, together with the growth in water demands to support irrigation in terms of the foregoing irrigation development rates. Por illustrative purposes only, it has been assumed on Plate 11 that crop production would commence in 1972, which would require commencement of construction not later than 1970. Taking into consideration the lead time necessary to determine the desirability of proceeding, the arrangements for financing, the preparation of designs, and awarding of contracts - for construction services and equipment, the foregoing date is considered to be the earliest by which it is reasonable to assume a commencement of irrigation.

It may be noted that there would be little conflict between the water demands if irrigation grows at the slower rate. An apparent conflict would arise if Growth Bate 2 for power development occurred in combination with Development Rate 2 for irrigation. However, the apparent shortage of water to the irrigation system under such circumstances would, in fact, not arise, as the Korokora diversion dam must, of necessity, contain considerable capacity for regulation in the early years of its operating life. This capacity is eventually given up to sedimentation. In the design of the diversion reservoir, as discussed hereunder, provision has been made to store the sediment that would accumulate over 50 years.

Storage of the Korokora Diversion Site

Provision of regulating storage oapacity at upstream sites has been found to be more economio than at the diversion site. Nevertheless, a limited storage capacity must be provided behind the diversion dam so that re-regulation of water releases from upstream power developments can be undertaken in conformity with the monthly crop water demands noted in Table 11-^. : This re-regulating requirement amounts to some -eight per cent of the total annual diversion volume, which, for a net irrigable area of 300,000 acres, is estimated to be approximately 196,000 acre-feet.

As mentioned earlier, in addition to the foregoing re-regulating requirements, sufficient capacity must also be provided to' accommodate deposited sedimentB which, over 50 years, are expected to ocoupy some 600,000 acre-feet.

To provide the necessary re-regulating and sedimentation storage capacity at Korokora, a crest elevation for the barrage of 470 feet has been selected in combination with a minimum offtake elevation of 427 feet to the main supply canal. The normal full operating supply level at Korokora would be at elevation 463 feet, corresponding to a total storage capacity of approximately 750,000 acre-feet, which is slightly less than the sum of the foregoing requirements. However, it is considered to be adequate to support the irrigation development for the first 50 years of its life, since during the initial development period less water is required, and in the early years part of the sediment load could be passed through the Korokora spillway by maintaining the operating level somewhat lever than the design full supply level.

Ultimate irrigation potential

Based upon the available flow of the Tana river, excluding present reservations for upstream use, the ultimate limit of irrigation development is estimated to be some 250,000 acres. However, as has been noted in Chapter IV recent planning by the Ministry of Agriculture suggests that much of the upstream 'reservation may in fact become available to downstream power and irrigation development. 4000 r- / ADDITIONAL FLOW / / DIVERTED FROM THE ESTIMATED AVERAGE DEMAND FOR 300,000 ACRES .- 3430 :.F.« >. ATHI RIVER. UP TO f 600 CUBIC FEET PER SECOND / A ADDITIONAL ACREAGE SUPPLIED CA ü_ 3000 FROM 400 CUBIC FEET PER SECOND OF UNUSED UPPER CATCHMENT FLOWS. ESTIMJ TED AVERi ME 0EMAN0 FOR r \ S X '\ . ' , t. -, _ m 1 —• — -" -• — I ,| 0 < CD e •1 o a 1 i * isoo V£ LEGEND o 1 1 i (O MRKSATION DEMAND AT KOROKORA DEVELOPMENT RATE I. IRRI6ATI0N 1 EFFICIENCY ASSUMED TO MIPDOVE »- ORADUALLY AFTER YEAH 10 J ( «MNJATION DEMAND AT KOROKORA tooo © DEVELOPMENT RATE I. INRWATION EFFICIENCY ASSUMED TO BtPWOVE -i •RAOUAU.Y AFTER YEAR 10 £ 7 [T| FIRM FLOW AVAILABILITY FOR OIVERSON AT KOROKORA. ELECTRIC LOAD GROWTH RATE I. 1300 HI FIRM FLOW AVAILAMUTY FOR • OIVERSON AT KOROKORA. ELECTRIC 3 LOAD 0ROWTM RATE 2. _i NOTES' COMPENSATION FLOW TO LOWER TANA ' 100 CUBIC FEET PER SECOND. AOUTMNAL EVAPORATION LOSS FROM KOROKORA RESERVOIR > 100 CUBIC 1 . FEET PER SECOND i i 300 I I GOVERNMENT OF KENYA i UNITED NATIONS SPECIAL FUND l • SURVEY OF IRRIGATION POTENTIAL i i i LOWER TANA RIVER BASIN i FOOD «HO MRICVLTWE OMAKHATIOK OF THE UMITtO MTKm i i ^ 1 i COMPARISON BETWEEN FLOW CO A f>J Kl 8 O S 8 OJ 2 Î 2 0) at O 8 8 O O AVAILABIUTY AND IRRIGATION "" — N N

As discussed in Chapter X. fn? purposes of «valuation it has been assumed herein tuai, as much as 400 cusecs of the 530 ouseos of the 530 ouseos of recent reservations would, in fact, become available. Should this prove to be true, irrigation might be extended to approximately 280,000 acres. In addition, as discussed in Chapter XII, diversion of the Athi river would contribute a significant benefit to the power complex, and the regulation and the use of the diverted flow, up to a limit of a net 575 cusecs, is considered to be feasible. Under these circumstances, taking into consideration both the foregoing additions to the present flow availability in the Tana, an ultimate potential irrigation development of some 330,000 acres may be contemplated.

Therefore, in the eoonomio evaluation of the ultimate potential irrigation development as discussed in Chapter XVI of this report, two levels of irrigation development have been considered, 250,000 and 300,000 acres. These two levels serve to demonstrate the degree of economic feasibility of large-scale development and also illustrate the significance of the rate at which development ocours upon the economic viability.

In other projects, elsewhere, it may be found that irrigation development is planned on less than absolute assurance of water supply. Consideration of this aspect has been given to the development proposed herein. Whilst it has been found that, at intermediate levels of development of the power oomplex, a reduction in the requirement of reliability of irrigation flows would permit some expansion of the irrigation complex, the flow utilization achieved would have become so high that a further extension of the irrigation system, based upon reduotion of reliability to even 80 percent, would net not more than one percent additional irrigated land* Hence, in the economio evaluation, no further account has been taken of the slight extension of irrigation facilities possible through allowanoe for a reduction in the reliability of water supply.

11.3 Implications of Vater Resources Development

Inevitably, full exploitation of the water resources potential will change the natural regime of the Tana river significantly, and these changes will reflect upon the way of life of the population, who are dependent upon the river for their livelihood. Except in the lower river, the effects of development are considered to be entirely benefioial. It is evident, however, that along the lower Tana floodplain, the indigenous Pokomo would find their traditional way of life untenable, as more and more of the available water is diverted. These changes would not only reduce the semi-annual floods on which much of their cultivation depends but also virtually eliminate the use of the river for local transportation and fishing.

Nevertheless, as discussed in Section III.3 of Technical Volume 71 (Appendix I), the value of water to power and irrigation is considered to be so significant es to warrant solving the sooiologi? problems which might arise in moving and rehabilitating the present riverine population.

It is impossible at the present time to do more than speculate as to the possible effects of changes in the flow regime and upon the hydraulic characteristics of the lower river. Between Koreh and Korokora, for purposes of present evaluation, an average long-term loss through évapotranspiration of some 830 cusecs has been allowed. It is evident that there is a considerable potential benefit being lost to irrigation development through this circumstanoe. -91-

It may be noted that, under the changed flow regime which would be imposed upon this reaoh of the river through upstream regulation, the frequent overbank flooding would be gradually eliminated in most years and therefore lesser'losses from the higher areas of the Hameye swamp may be anticipated. Conversely, a higher average year- round flow stage may result in an inorease in peroolation into the lower-lying areas of the floodplain because the river gradient is superelevated throughout much of its length. It is not possible at the present time and state of knowledge to predict the net result of these opposing effects, and it has been assumed herein that the net ohange would be negligible.

However, it will be important to assess the effect of long-term variations in hydrologio regime as they occur, in order that, at such time as the irrigation development is approaching full utilization of the available water, it will be possible to consider whether some conservation of flows may be aohieved by appropriate remedial works. Should this be possible, some further increase to the ultimate extent of irrigation development may well be feasible.

Within the lower river below Korokora it is evident that, as the irrigation oomplez grows, the river itself will be gradually reduced to a minor stream except at times of extreme flood. Under such ciroumstances, it may be expeoted that the riverbed will aggrade, that vegetation will encroach upon the present channel, and that in consequence the conveyance capacity of the river channel will decrease. Thus, it may be expected that, over the long term, the occasional catastrophic flood, which would not be retained within the reservoir system, would cause even higher flood stages in the lower valley than at present. Therefore, in planning for any future use of flood-plain lands for forestry activities, irrigation of pasture lands or other purposes, this potential hazard must be borne in mind. -92-

CHAPTER XII

POWER DEVELOPMENT

As has been indicated elsewhere in this report, the water resources potential of the Tana river for power and irrigation development represents a substantial part of the total of such potential in Kenya. Evaluation of the interrelationship between development of the middle and lower catchments of the Tana for both of these purposes is essential if optimum pover and irrigation developments are to be defined. It is important to recognize that, while power generation in the middle reaches of the river may be considered as an independent development, it is not possible to consider a large-scale irrigation complex as such. To be even marginally favourable in economic terms, the irrigation complex must ultimately be as large as may be practicable, and its size is fundamentally dependent upon the amount of storage provided upstream. As is shown in this chapter, this regulatory storage is, in any case, essential to the optimum development of the power complex itself.

Since it is possible to consider development of the Tana river to meet the anticipated future demand for power, whether or not irrigation development is to be realized, evaluation of the economics of the hydro-electric power complex has been dealt with separately. Since it has been well beyond the scope of the terms of distribution systems, the selling price of energy has not been determined. Hence, the economics of power development have been evaluated in terms of the comparative cost of energy produced and delivered at the load centre at Nairobi to meet the growing demand for the Nairobi and western Kenya power system. This approach is considered to be valid, recognizing that the irrigation scheme could not possibly be economic if any of the costs, based upon total user benefits of providing storage facilities for power, were chargeable to irrigation.

The selection and evaluation of sites leading to an economically viable programme of development of six major power projects, in addition to the Kindaruma project currently under construction, is described in detail in Technical Volume VI (Appendix j)# Capital cost estimates for each development are presented, together with analyses of the various sequences of development, leading to selection of the one which . could best meet the future power load growth. The modified flow regime from this sequence has been adopted for evaluation of the downstream irrigation potential. -93-

12,1 Selection of Storage and Power Sites

. f- • In Chapter XI, it is shown that the regulation of river flows is essential if a substantial portion of the power and irrigation potential of the river is to he developed* Since regulating storage capacity is essential to "both resource uses, it is readily apparent that it will he desirable to achieve as high a rate of flow utilization as possible upstream from the major power reaches so that the regulated flow available to all downstream developments will be as large as economically practicable.

Examination of topography and geology, in conjunction with flow analyses, indicates that the potential for developing large-oapacity storage reservoirs and major power projects is confined to the main stem of the middle Tana from Kamburu to Koreh Hills. The upper catchment and tributary streams to the middle Tana offer only limited opportunities for construction of storage projects, because of the steepness of the terrain and the variability of the flows* In terms of the magnitude of storage required for optimum resource utilization, such minor projects can be eliminated from further consideration.

Immediately below Kamburu, the river descends some 650 feet over a river distance of about 15 miles*. This drop occurs around a loop in the river course within the Seven Forks area, where, for many years, attention has been focussed upon a variety of schemes for developing the power potential.

At the lower end of the middle Tana, the Koreh Hills form the most downstream location having a significant topographic control feature at which a power dam can be contemplated. Below Koreh, the river suffers a progressive loss of gross available flow through évapotranspiration losses from its floodplain as it traverses mile after mile of semi-arid desert lands.

On Plate 2, the profile of the main stem of the river is shown, and reaches between Kamburu and Koreh, which are considered to have significant power and storage potential, have been identified thereon. In Table 12-1, the head and long-term average flow in the middle reaches of the Tana are summarized, and indicate that, in terms of gross power potential, the Kamburu to Mutonga reach is by far the most significant. -94-

Tabje, JL2"J. ~ Head, Flow and Power Po-fcggtial cf ths Mi dól o xana

Long-term Hiver River average Gross Gros s Site mileage eleva­ flow at head in power ^_ tion station reach potential*'

ft . cusecs ft HP i Tana Power - Station 418 3,450 to 250 59,000 Kamburu 392 3,200 2,600 ; ,- to 1,560 595,000 Kuntoga 335 1,640 4,200 to 150 63,000 Grand Falls 321 1,49P 4,600 to 680 321,000 Eoreh 240 810 5,050

Total ; 2,640 1,029,000

QHe * Computed as HP - 8.8 nrher e H is the gross head in the reach, and Q the long-term average flour at the downstream end of the reach. Efficiency e is taken1i a s 80 per c ent.

It would, of course, be impracticable to use completely the long-term average flow through the gross head as indicated in Table 12-1. Nevertheless, with some 50 percent of the maximum long-term average flow concentrated in the river at Kamburu and over 80 percent at Mutonga, the relatively large portion of the total power potential that is concentrated upstream from Hutonga focusses attention upon the desirability of achieving the maximum economic utilization in respect of both flow and head within this reach.

Preliminary studies indicated that the cost of energy at Nairobi from potential storage power developments on the middle Tana would likely exceed that from alternative thermal sources. However, it was also apparent that the regulation available from such storage would result in economically favourable costs for power generated at a number of downstream run-cf-river projects and hence, in terms of the system cost ,- of energy, bring the development of hydro-electric potential on the Tana into a oost range competitive with thermal power« -95-

In all some ten projects on the Tana have been evaluated. Not all of these are independent, since some are alternatives to others in the same reach. The projeots considered, grouped by reaches, as shown on Plate 12, are:

Upper reach of middle Tana — Reservoir Otaru Confluence Kindaruma

Central reach of middle Tana - Kiambere Mutonga (run-of-river) Mutonga (storage) Grand Falle

Lower reach of middle Tana - Adamson's Falls Koreh

In addition, sinoe power generation and irrigation will ultimately be limited by water availability, diversion of surplus flow of the Athi river into the Tana catchment has been considered.

In Technical Volume VI, (Appendix J), the considerations relative to site evaluation and the determination, of the costs and benefits from various combinations of developments and their interrelationship are discussed. In Table 12-2, estimates of capital costs for various levels of development of all the projects considered on the Tana river are summarized.

The foregoing sites have been considered in various combinations of sequences and levels of development and lead to selection of the Mutonga II sequences, as illustrated in Table 12-3» as the most appropriate. Of the several Mutonga II systems as discussed in Seotion J12.4 of Technical Volume VI (Appendix j), sequence D is considered to be the most appropriate for optimum utilization of the power resouroes of the river. In Tables 12-4 and 12-5, the power whioh may be achieved from this particular sequence, under circumstances whereby additional flows are made available through release of present upstream reservations and diversion of the Athi river, are presented. Also shown in these tables are the comparative cost of energy at each site and the total system, as development proceeds under the two rates of load growth discussed in Chapter X.

On Plates 13 and 14 the installation schedule for the basio Mutonga II sequence D power system is illustrated for each of the two rates of load growth discussed earlier, and on Plate 15 the accumulated capital expenditures for this basio sequenoe under the two growth rates is illustrated. Therein, it may be noted that the foregoing basio sequence would meet the fast rate of load growth until well after the middle 1980*8} and, taking into consideration the additional flow and energy generating capability through release of upstream allocations and diversion of Athi flows, into the 1990's. The basic power system of the Mutonga II sequence D under the slower >•• growth of energy demand, _Bate 2, as shown on Plate 14, would be sufficient to meet the internal requirements~"of the Nairobi and western Kenya system until well after the turn of the century. H-o\ \ ~ ~

PLATE 12 -97-

Table 12-2 - Estimates of Capital Cost - Tana River Power Pro.iect

Development Full supply- Formal maximum Total oost level tailwater level

ft ft £ Reservoir 3438.5 3260 13,178^000 Reservoir 3454 326Ó 15,098,000 Qtaru (low 3260 2558 18,149,000 Reservoir) Qtaru (high Reservoir) 3260 2558 18,849,000

Confluence 3392 2558 30,317,000 Confluence 3412 2558 34,617,000 Confluence , 3437 2558 41,828,000 Confluence . 3455* 2558 51,138,000 Kindaruma 2558 2450 7,240,000 Kiambere 2192 1867 14,704,000 Kiambere 2192 19O8 14,542,000 Kiambere 2192 1964 14,380,000 Kiambere 2242 1867 17,786,000 Eiambere 2242 1908 17,622,000 Kiambere 2242 1964 17,459,000 Mutonga 1867 I64O 14,932,000 Mutonga 19O8 I640 20,523,000 Mutonga 1964 I640 28,795,000

Grand Falls 1640 1455 15,593,000 Grand Falls I665 1455 18,802,000 Grand Falls I69O 1455 22,425,000 Grand Falls 1725 1455 28,656,000 Adamson's Falls 1163 1040 14,256,000 Koreh. 987 810 16,866,000 Coreh 1007 810 18,953,000

Athi River Diversion 4415 4382 2,120,000 * Estimate provisional d lie to limitations of site data TABLE 12-3 MUTONGA II - SEQUENCES OF DEVELOPMENT

• f.l.t. • CtfitM CMt * MttUROt - I CNHMKl • ».«» . WH l«M> KMUftS *l lltl - «.V.l. M.nt.wt • iMtlUt» CIMCIT* il un . «.*. t.m • tatuim (Ulam umin • a.t. • «il t m • CMT f (KM! tï lltl • Mit I m • MMfM Cttl m WW • Mil • «.M •.M

ICOUCNCC * tCOUCKCC • SfOUCNCC C sequence o

UMMN - l.'M IIMHH • t.w •IMKM • t.m •IMKM • I.M H.MI,M it.IM.MB . tt.IM.Mt H.MMM *M Mt ta «M M •1 IM M JM »l tn M*' ».M «.Il t. M i.tt • M ».»•.M. t.U

ij, i • VTMU • .M' r^r .Ht lt.Mt.MI tt.m.Mt II.Ml M* tt.m.Mt •M Hut •M Mt M Ht. M' ut m Ml M» t. M t.l» I.H . «•t. it •.IT I.« «.It *.u

• • ' ' • M. i ' «w nus • '.•• MM» (IUI • I.Mt MUt Util - 1 -MO MM» MU» • I.Mt it.m.M •I.M.Mt u.at.Mt II.Mt.Mt m

IMOM'I 'IU I I.IU UMMTI f4Ul • 1.1*1 IMMM'I ftUl - I.IU IMMM'I P1U1 • LUI IO.Mt.Mt it.m.oa It.Mt.Mt o.nt.Mt m ii« Ml i» •i n M w* m M«>t •M - • ».M t.*» » «.M I.U •.«1

"—i i.otr «M» - HT • 1« K» . i.ot». IOTO • Ml U •U • Mttl • «T Util • i.Ml UNI - Ml • MBU • I.MT* • ».MO. 000 i »9 .MO. 000 n.tn.MB ».<• l.OM II.MI.tM to. 00t.000 irtn.Mo a.iM.tM m t «Il ' «Il «U W «Il «ii •M M M •7 M M M M •n •i «1 RM m Mf HT m i LU rn 1.« • .N I.U I.T» I.M i.tt I.lt I.H • I.U 1.1« i.u • .M I.U I.M I.M

•ont •. eut m MU» «nu it nmis» n t.*. MIU>M UNI H» •.*••• t. tH MHMItrt IMtULU (»«'!» Ml HMtKT «*t ff IHM«. IT !«• uni. 'Kun ut MUfCTi IM«I n« um •••um. TABLE 12-14

SYSTEM POWER OUTPUT AND COST WITH VARIATIONS IN LOAD GROWTH AND NET WATER AVAILABILITY

MUTONGA 11-0 SEQUENCE MUTONGA 11-0 SEQUENCE • «00 cfs LOAD GROWTH RATE ADDITIONAL FLOW FAST SLOW FAST SLOW COWFLUEWCE - 3.127 CAPITAL COST £5«,785,000 £63,594,000 £58,101.000 £69,073,000 ENERGY - GWH 1,28« 1.284 1,520 1,520 CAPACITY - I« 270 270 270 270 TOTAL CAPACITY - Ml 270 270 270 270 SITE COST OF ENERGY 6.60 7.115 5.87 6.80 TOTAL COST OF ENERGY 6.60 7.45 5.87 6.80

KIAMBERE - 2,242 CAPITAL COST £18,800,000 £19,400,000 £24.600.000 £25,600,000 ENERGY - QMH 454 454 538 538 CAPACITY - MM 94 94 225 225 TOTAL CAPACITY - MM 364 364 495 495 SITE COST OF ENER6Y 6.30 6.50 6.96 7.23 TOTAL COST OF ENERGY 6.52 7.14 6.15 6.95

MUTONGA - 1,908 CAPITAL COST £22,123.000 £22,750.000 £22,123,000 £22,750,000 ENERGY - GWH 540 540 602 602 CAPACITY - MM 112 112 112 112 TOTAL CAPACITY - MM »76 4?6 607 607 SITE COST OF ENER6Y 6.16 6.34 5.53 5.70 TOTAL COST OF ENERGY 6.43 6.96 6.01 6.63

»AND FALLS I ,610

CAPITAL COST £16.369,000 £16,716,000 £16,389.000 £16.716,000 ENERGY - GWH 430 430 475 475 CAPACITY - MM 89 89 89 89 TOTAL CAPACITY - MM 565 565 696 696 SITE COST OF ENERGY 5.80 5.93 5.25 5.35 TOTAL COST OF ENERGY 6.33 6.78 5.90 6.46

ADAMSONS' FALLS - 1.163 £14.769.000 £14,940,000 CAPITAL COST £14.769.000 £14,940,000 346 346 ENERGY - OWN 314 314 65 CAPACITY - MM ..'•'•• 65 ' 65 65 761 761 TOTAL CAPACITY - MM 630 630 6.45 6.51 SITE COST OF ENERGY 7.11 7.15 5.96 6.45 TOTAL COST OF ENER6Y 6.42 6.83

KOREN - 987 £17.515.000 £17,879.000 CAPITAL COST £17.875,000 £17,879,000 470* 470 ENERGY - GWH 416 416 87 87 CAPACITY - MM 87 87 848 848 TOTAL «PACITT - MM 717 717 5.62 5.72 SITE OF ENERGY 6.20 6.31 5.91 6.37 TOTAL COST OF ENERGY 6.40 6.78 TABLE 12-5

SYSTEM POWER OUTPUT AND COST WITH ATHI RIVER DIVERSION

ÄUDITIONAC FIRM FLOW - ATHI RIVER DIVERSION

200 cfs 575 cfs

LOAD »ROWrH FAST* SLOW* FAST* SLOW*

CONFLUENCE DEVELOPMENT FSL 3,»37 ... 3, »55" CAPITAL COST - ATHI DIV. £ 2.2»0.0OO £ 2,330,000 £ 2.2HO.OOO £ 2,330,000 CAPITAL COST £56,»»3,000 £6«, 96», 000 £63.909.000 £76,8|9,000 ENERGY - 6WM 1,390 . 1,390 1.630 . 1,630 CAPAC fTY - MW • 270 270 320 • 320 TOTAL CAPACITY - MW 270 270 320 320 SITE COST OF ENERGY 6.S0 7.»3 6.25 7.20 TOTAL COST OF ENERGY 6.S0 7.»3 6.25 .7.20

KIAMBERE - 2.2»2

CAPITAL COST £20,600,000. £21,300,000 £23,700.000 £2»,600,000' ENERGY -GWH »97 »97 575 575 CAPACITY - MW l»l 191 192 192 TOTAL CAPACITY - MW »II »II 512 . 512 SITE COST OF ENERGY 6.30 6.52 6.27 6.51 TOTAL COST OF ENERGY (.«$ 7.19 6.25 7.01

MUTONGA - 1.908

CAPITAL COST £22.123,000 £22.750,000 £22,123.000 £22.750,000 ENERGY - GWH 570 " 570 630 630 CAPACITY - MW 112 112 112 112 TOTAL CAPACITY - MW S23 523 62» 624 SITE COST OF ENER6Y S.«» 6.01 5.28 • 5.14 TOTAL COST OF ENERGY 6.30 6.90 6.05 6.66

GRAND FALLS .6» O

CAPITAL COST £16.389,000 £16.716,000 £16.389.000 £16,716.000 ENERGY - GWH »52 »52 »9» »52 CAPACITY - MW M 89 89 '89 TOTAL CAPACITY - MW 612 612 713 713 SITE COST OF ENERGY *•** 5.6» 5.05 5.15 TOTAL COST Of ENERGY 6.16 6.71 5.90 6'.»5

AOAMSONS' FALLS - .113

CAPITAL COST £l».769.000 £l«.9*0,000 £l».769.000 £|H,940.000 ENERGY - GWH 330 130 359 359 CAPACITY - MW 65 « 65 ' 65 TOTAL CAPACITY - MW 677 •77 778 ' 778 SITE COST OF ENERGY 6.77 6.81 6.21 6.27 TOTAL COST OF ENERGY 6.S 6.72 5.92 6. »3

KOBEN - 987

CAPITAL COST £17.179,000 £17.679.000 £17.575.000 £17.879.000 ENERGY - GWH »M »36 »79 »79 .87 CAPACITY - MW 87 87 87

TOTAL CAPACITY - MW 76» 7»» 865 865 5.62 SITE COST OF ENERGY 6.0t 6.1» 5.52 5.87 TOTAL COST OF ENERGY 6.22 6.65 6.31

'FM MUTONGA 11-0 SEQUENCE. -1 or-

; This very significant power potential whiob, if fully developed, may yield up to 1,000 megawatts of capacity at 44 percent load factor, is undoubtedly one of the major natural resouroes of Kenya, and, regardless of whether or not the irriga­ tion development, as discussed hereinafter is considered sufficiently attractive to warrant development, has been shown to be self-justifying.

: Therefore, in all future planning it is recommended that the power potential represented by this river should be preserved for the benefit of the country. It must be recognized' that it has not been possible, within the terms of reference and the time available, to evaluate in detail the optimum role and plant installation of each project within the basic, sequences described. Nevertheless the Kutonga.II sequence D is fundamentally suited to the optimum development of the power potential of the river. Further studies of the integration of this power complex with downstream irrigation should permit evaluation in detail of the future role of each plant within the Kenya power system. Such a sequence study would be facilitated through development of a more sophisticated mathematical computer model than that used fori these preliminary studies. Such a model will permit optimization analyses of all facilities, including transmission and distribution. Potential interconnections with the ooast or other power systems should also be evaluated.

It will be appropriate, when such a system study is initiated, to review in ; detail the projected load growth forecasts, and provide for updating and periodic review as the system develops. KOREH B7MW NAIROBI AND WESTERN KENYA SYSTEM

o o X » 9 .a o

4 Ul 0.

GOVERNMENT OF KEN VA UNITED NATION» SPECIAL FUND SURVEY OF IRRIGATION POTENTIAL LOWER TANA RIVER ÎASIN FOOD »«0 »MICULTUSE OKAmZtTlOII OF TNi! URITEO NATIONS DEVELOPMENT SEQUENCE 1*60 2000 MUTONGA ITD INSTALLATION SCHEDULE LOAD GRQWTH RATE I o o I

too s

GOVERNMENT OF KENT» UNITED NATIONS SPECIAL FUNO SURVEY OF IRRIGATION POTENTIAL LOWER TANA RIVER BASIN FOOO MO »MICULTU« OKMIUTIO* OF TNI UHItlO UTIOIS DEVELOPMENT SEQUENCE MUTONGA HD INSTALLATION SCHEDULE LOAD GROWTH RATE 2 PLATE \A 1 —1 —i i— r~ r—i <~ r— (•».tTV.ÓOO : i i y/\ 00 ! J - ..,

r !

—MOVTII MTt t I-

— MWVTH MTt t.

NOT! um» imrarjifi OMLT. NOTMCUaN nvurriD rum. non n« Tsimun , «on «CLUU er utracM «m RM»,

i . ! • | • : l i ; SURVCT OF inmSâTION POTENTIAL l i : • .".• • ' LOWER T«M» KIVIII BMI rgoo no —ami ci wanoi or TK wino mnm i • 1 '•••: •-. : • 1 i L_ MUT0N6A SEQUENCE II -0 CUMULATIVE CAPITAL EXPENDITURE

Jrli&coi»c»ts PLATE IB -105-

. CHAPTER XIII

IRRIGATION DEVELOPMENT

In Chapter XI the ultimate irrigation potential of the lover Tana "basin is estimated to he at least 250,000 acres. An increase to over 300,000 acres is considered possible if reduction of the present upper catchment allocations and diversion of the Athi river flows are acceptable to the Government of Kenya. Therefore, these two levels of development -- have been selected as the basis on which to assess the economic evaluation of large-scale irrigation from the lower Tana.

Apart from the recent floodplain deposits, the lower basin,a large portion of the project area,consists of fragmentary patches of suitable soils intermingled with unsuitable soils. Thus, of a total of 349,000 aores of soils considered suitable for irrigation within the northern region of the project area, only some 136,000 acres occur in:contiguous relationships which permit reasonable economy in the layout of an irrigation network. Hence, development of at least 164,000 acres of suitable soils is presumed to be practicable south of the lower Thowa.

From reconnaissance soils surveys, it is evident that essentially similar conditions prevail with respect to soils and topography throughout the southern region of the project area as are to be found in the northern region between the lower Thowa and the lower Hiraman. There is little doubt that similar soil types persist beyond the southern limit of the surveyed areas, so that it is reasonable to presume that water and not soils will form the ultimate limitation to irrigation development*

The proposed layout of the irrigation and drainage.network, and the internal road system and townsites for the region north of the lower Thowa are illustrated on Sheets 1 and 2 of Plate 16, while, on Sheet 3, the general alignment of major conveyance canals for the southern region is indicated.

The Korokora diversion dam, the irrigation and drainage networks and suitable fann-to-market roads, as well as land clearing and levelling, are considered as essential features of the ultimate potential of irrigation development. Detailed consideration of these aspects has been possible only for the northern region of the project area, for which considerable information on soils, drainage and topography has been gathered. Nevertheless, sufficient reconnaissance information has been obtained for the southern region to permit reasonably reliable extrapolation of cost estimates to cover development to a level of 300,000 acres. -106-

13«1 Potential Devaioptent - Lajoal of irrigation Network

As indicated on Plate 16, the irrigation network envisaged comprises three types of conveyance canals» The primary main-supply canal would lead water south­ wards from the Korokora reservoir to the west of the Tana river, and the secondary section-feeder canals would command the lands between this main canal and the Tana floodplain. Tertiary block-feeder oanals, drawing from night-storage reservoirs, would convey water to the irrigable lands in accordance with daily irrigation demands at the field level.

The main-supply canal would offtake from the head regulator at Korokora at a full supply altitude in the canal of 427 feet above sea level and would follow a gentle gradient for some 38 miles southward until it reached the northern limit of the project area at which point it would lie some 11 miles west of the Tana flood- plain« Thereafter, it would continue southwards, feeding the seotion canals which ... would offtake at intervals of about 3.5 miles« Seotion canals would flow eastwards and feed into a herringbone pattern of block-feeder canals through night-storage reservoirs located at approximately half-mile intervals. The block canals would convey water to the unit-feeder canals which, in turn, would supply the field head- furrows. Irrigation on the fields would be accomplished by siphoning water from these head-furrows into the individual field furrows.

As indicated on Plate 17» a mirror-image pattern of drains would interlock with the distribution system to return surplus irrigation water and runoff from the fields to the main channel of the Tana river. The drainage system has been designed to handle surplus irrigation water together with one-day maximum storm rainfall at a recurrence interval of once in three years« A portion of this return flow can be applied to the irrigation of portions of the flood-tolerant forests and fodder crops.

The general configuration of irrigation canals and drains is illustrated sche­ matically on Plate 17. Therein, it may be noted that an irrigation unit of 50 acres is proposed as the standard unit of development. This unit is divided into five 10-aore fields. Each field comprises two 5-acr« parcels which, in turn, are sub­ divided into two plots of 2.5 acres« A tenant's farm holding of five acres consists of alternate plots«

Determination of the daily duration of irrigation activity is fundamental to the design of the irrigation network. Field application of irrigation water during hours of daylight only is believed to be fully justified from considerations of the intensive cropping pattern proposed, the lack of irrigation tradition among Kenyan cultivators, and the relatively high cost of water as delivered to the field. These factors favour the adoption of a daily application schedule, although it is recognised that the cost of development is thereby somewhat increased through the need to provide night-storage capacity within the irrigation system.

Experience with daylight operation in the Gezira and other Nile irrigation schemes has shown that less wastage of water and higher crop yields result from such a system. The improved control of irrigation practices by day leads to an increase in benefits, which more than offset the additional .cost of night-storage reservoirs.

(ril ^ -^

-110-

Thô large developments of irrigation in the Sudan are probably the most representative of the operational and water management problems to be ezpeoted in the proposed Tana development* The generally high standards of operating efficiency maintained in the Gezira development are in distinct contrast to recent experience with new projects such as the Khashm el Girba project on the Atbara river and other schemes in the Sudan which have been designed for continuous irrigation throughout twenty-four hours of each day. It must be recognised that the considerable experi­ ence in irrigation practices developed over the last fifty years in the Sudan has nonetheless not in all cases resulted in efficient adaptation of the ouiti va tors to such practiceso Floodings of fields or complete failure to irrigate occur (through insufficient control of night-time operations) and result in reduotion of orop yields.

As a matter of Government policy, the Tana Steering Committee has confirmed a deoision to make provision in the design for daylight irrigation» Hence the layout} as presented herein, has been designed for irrigation during daylight hours only, which, for the equatorial location of the scheme, are considered to be es­ sentially a uniform twelve hours daily throughout the year.

Alternative locations for night-storage within the system were considered in the studies. It was concluded that night-storage reservoirs located adjacent to the section-feeder canals at the head of each blook-feeder canal is the most economio arrangement. The alternative, to provide suoh oapacity within the blook-feeder canals themselves, as is the praotice in the Gezira scheme, was found to be more costly, although offering certain operating advantages. It is believed that the night-storage reservoir system can be readily adapted to the cultivation practices and the rotation plan, or to variants of it as presented herein. The proposed arrangement requires refilling of the blook canals before irrigation can begin again each morning. Since control weirs are necessary along the block canals immediately downstream from eaoh irrigation offtake, it has proved practicable to design these controls to retain some water in the canals overnight. This allows for rapid fil­ ling and start-up of the system each morning as required by the irrigation schedule.

Prom the foregoing, it follows that the main-supply canal and all section-feeder canals can be designed for continuous flows throughout the twenty-four hours of each day. Block-feeder and field-distribution canals must be designed for twelve-hour operation, with the night storage reservoirs providing hydraulio balance to the whole system. The design of the irrigation network is discussed in detail in Technical Vol.VI, Appendix K, wherein eaoh canal type and its controls are described, and appropriate cost estimates for development are presented. It may be noted that, in the design of the entire irrigation conveyance system, all canals have been sized on the basis of the initial irrigation efficiencies discussed in Technical Volume VI Section K13.1.1.3 of Appendix K, with the exception of the main-supply canal which, in itself, must be designed for the ultimate conveyance capacity anticipated.

The net irrigable areas commanded by eaoh of the section feeders illustrated on Plate 16 are summarized in Table 13-1« -Hi-

Table 13-1 - ffet Irrigable .Areas Commanded by Section Feeders

Section feeder Old Alluvial land Floodplain land Total canal acres acres acres I 7,300 1,200 8,500 II 9,000 2,000 11,000 III 13,400 3,200 16,600 IV 10,000 2,700 12,700

V 10,200 - 10,200

VI 17,500 - 17,500

VII 42,700 - 42,700

VIII 16,800 - 16,800

(forth of L. Thowa 126,900 9,100 136,000

Is 9,900 - 9,900 lis 47,100 6,000 53,100

Ills 39,900 - 39,900

IVs (part) 11,100 - 11,100

South of L. Thova 108,000 6,000 114,000

Total 234,900 15,100 250,000 Completion of IVs plus Vs 50,000 50,000

Ultimate total 284,900 15,100 300,000 -112-

13.2 Potential Dev^Topssst - Gx-imndwater Conditions and Drainage

The drainage requirements for irrigation schemes in general are determined from considerations of both surface and subsurface flows. Throughout the project arsa, the very limited information available suggests that, with the exception of the perched water table found in the Tana floodplain, there is no groundwater near the surface. Seep exploratory holes drilled at widely dispersed locations have encountered mostly saline water at depths of.between I50 and 200 feet. It is also common to find small quantities of groundwater in the sandy stream beds of luggas long after each rainy season. The latter provide a major source of water during dry periods for the cattle herds of the nomadic tribes.

Experience in irrigation schemes elsewhere has shown that water-logging may develop over a long period of time. However, there are two reasons which suggest that changes in the present groundwater situation in the project area would occur only •very gradually. First, sloping-furrow irrigation promotes losses by surface runoff rather than through deep percolation, even in cases of gross inefficiency in water application. Secondly, the rather impervious nature of most of the soils will tend to inhibit deep percolation. Consequently, construction of a drainage system for control of groundwater has not been considered to be necessary in the present evaluation« It is, however, advisable to provide for the removal of rainfall, runoff and excess irrigation.

It is recommended, further, that studies of subsoil stratigraphy and groundwater conditions should be undertaken and the changes in levels and qualities of groundwater should be observed from the initiation of development so that, if necessary, steps could be taken to prevent any tendency to waterlogging developing.

13*3 Land Preparation

Clearing and land levelling of the fields to be irrigated will be necessary. In estimating the costs of these activities it has been asBumed that clearing of an area some 25 percent greater than the net area of irrigated lands will be necessary. Grubbing of only^the net irrigated area has been considered. The available information on topography is not sufficiently detailed to determine with any reliability the extent of land levelling which may be required throughout the projeot area to facilitate irrigation with long field-furrows. Nevertheless, the detailed surveys carried out for the Research and Training Centice have indicated that the general layout as presented herein is reasonably representative of what may be anticipated, and is believed to be satisfactory. In the irrigation layout it has been assumed that as average furrow length of 500 feet will be appropriate. However, shorter or longer furrows may have to be adopted in certain areas. -113-

Levelling must he carefully planned in view of the shallow depth of nonsaline- nonalkaline topsoil prevalent throughout much of the project area. Therefore, land planning to smooth out minor surface irregularities may be all that is practicable, and the adoption of shorter field furrows would necessitate the provision of an additional head-furrow in each field. For the purposes of this report, it has been assumed that half of the net irrigable area will require some form of land levelling and this will average some 200 cubic yards of earth movement per acre. It has been recognized that the levelling of floodplain lands will, in fact, be more oostly than for the remainder of the lands throughout the project area. However, the minor additional cost for the small area of floodplain lands included in.the proposed development has not been estimated separately,since a detailed land survey was not available. In any case, a less elaborate distribution system for irrigation of floodplain lands is all that will be necessary, as only flood-tolerant fodder crops to support local dairy enterprises are contemplated for cultivation on the floodplain soils. The unit cost estimate of development of floodplain lands has been made equal to that of the remainder of the project lands.

13.4 Road Network

The internal road network throughout the project area north of the lower Thowa is illustrated on Sheets 1 and 2 of Plate 16. In addition to those shown, the network includes block and unit roads to complete the farm-to—market system. External communications are proposed through development of a major truck road linking the project area to Mombasa, and relocation óf the Nairobi-Garissa road to pass through the Eandelongwe Hills and connect the project area directly to Nairobi.

The internal road system, consisting of section, block, and unit roads is shown on Plate 17. It is recognised that the successful operation of.the scheme will require adequate farm-to-market communications. In the original studies made for the project, it was assumed that traffic densities would justify paying with stone section roads for the two main north-south roads through the scheme. It is possible that the time may oome when this is found to be so, but in view of the local conditions and of experience in similar conditions elsewhere, earthen roads throughout the scheme should be adequate to begin with. They could be graded and cambered, with suitable provision for drainage. With appropriate maintenance, it is to be reasonably expeoted that they could be open for traffic almost all the time, exoept possibly for short periods immediately after considerable rainfalls. If a suitable method of soil stabilising can be applied, so much the better. The estimates of cost presented in the second column of Table 13-2 assume the construction of earth roads.

In the economic evaluation of irrigation development, all internal roads have been considered to form an essential part of the projeot oosts, whilst the external road connections to Mombasa and Nairobi are oonsidered to be part of the general development of the national road system. However, it has been recognized that the Mombasa-project area link will be needed for the oonstruotion purposes before it is required for the normal transport of goods and persons. Henoe, a charge to irriga­ tion development has been included whioh is equivalent to the full operating and maintenance charges for this road up to the time at which some 100,000 acres of irrigated land would be in production. It is believed that thereafter the oonstruo­ tion of this road would be justified by the volume of traffic generated between the soheme area and its entrepot, Mombasa« -114-

The full cost of derslcpssüt or a quarry road between the Eandelongwe Hills and the project area has also heen included in the development costs of the scheme, since these hills form the nearest available source of rock material for construction purposes. Hence, only the extension of this link to the existing Hairobi-Garissa road has been excluded from the development costs. It is considered that this link would be provided from general government expenditure on roads, as required and justified by the volume of traffic to be carried.

Discussion with the Ministry of Works, Communications and Power indicated that the realignment of the Hairobi-Garissa road would not seriously inconvenience persons travelling beyond the project area to the hinterland of the northern Frontier District. Obviously, most of the development of that district will be restricted by lack of adequate rainfall. Managed rangeland will be the major use of the area. Access for delivery of cattle to coastal, interior and project markets would be substantially improved through the new access links to Mombasa and Nairobi via the Korokora diversion dam.

/ 13,5 N Korokora Dam

As has been shown in Chapter XI, the development of power generation on the middle reaches of the Tana will involve regulation of the natural flows to more or less steady flows below Koreh. The fluctuating seasonal demands of irrigation call for these steady flows to be re-regulated to correspond with these demands. Thus provision of a re-regulating reservoir at Korokora forms an essential item in the development of the full potential area of irrigation. In Section K 13.5 of Technical Volumeyi (Appendix K), the design of the dam at Korokora is discussed in detail. On Plate 18, the general arrangement of this work is shown. The capital cost of the dam and headworks is estimated to be S.A. £ 11,040,000.

I3.6 Capital Costs - Irrigation Development

Table 13-2 gives summarised estimates of the capital costs of all items comprised in the irrigation development, in two forms. The first form shows the original estimates framed in the studies made for the project) the ultimate total, for a potential area of 300,000 acres, is some £ E.A. 60,000,000. The seoond form gives a tentative forecast of the reduced costs that may result if roads within the scheme are merely earth roads throughout, unpaved. For this the ultimate total is forecast as some E.A. £ 47,000,000,which is equivalent to an over-all rate of some E.A. £ I57 per acre. It should be noted that the figure0 corresponding to the first f era are used in the full economio evaluations discussed in Chapter XV". ! rWtm (MM* If, Jrt

JMU ««•»?«•

jpmmza&enai

£^k i&Ë$L

SECTION E - E

SIMVEV OF IRRIGATION POTENTIAL LOWCR TANA HIVCH IM« jron» urn MM njiaji I'IUTHI»! w _ni apTOMni DISTRIBUTION SYSTEM LAYOUT OF IRRIGATION BLOCK AND TYPICAL SECTIONS .

PLATE IT -116-

13.7 Research and TVajsis^ Pontic

As a result of the project studies made, it is suggested that,as an integral part of irrigation development, there is a need for continuous agronomic research into new crops, fertilisers, insecticides, farm machinery, and so on* There is also a need, during the period of development, to train agricultural staff, and cultivators. To meet these needs, -it is proposed to set up a permanent Eesearch and Training Centre under the Irrigation Authority which would be responsible for the whole scheme. It is contemplated that an area of some 8,300 acres would be suitable for this purpose, to be located so that the soils in it should be reasonably representative of the major types to be found in the scheme area, and also so that it should be fairly centrally sited in the northern part of the area, which would be the first part to be developed. Close to the Centre could alBO be the site for the headquarters of the Authority, and the local administrative offices of the central government, envisaged as being in a township area of some 700 acres. The whole is proposed to be sited near the Tana river and south of the Lugga Hiraman.

To make the Centre available quickly and avoid the need to await the completion of the Korokora Sam and the main canal from it, it is proposed that a pumped water supply be provided to be taken from the Tana river at a suitable point and conveyed in a special canal on an alignment different from that of the ultimate main canal.

Particulars of the layout and estimated costs of the Research and Training Centre are given in Technical VolumeVI - Appendix L. The costs are here summarised in Table 13-3, totalling some E.A. £ 2,915,000.

13,8 Pilot Scheme - First Stage of Development

It is considered that a first development as that proposed for the Centre should from the first be regarded as a pilot scheme, primarily for production, rather than as merely a centre for training and research. Part of the area should be set aside for research and testing) the rest should be operated primarily for production, to be combined with "in-service" training and experience for all concerned, from managers down to cultivators and subordinate staff. Initial development such as this would need at most some 150 cusecs of water, out of the 1,100 cusecs minimun flow available in the river under natural conditions, i.e. before the completion and operation of upstream storage reservoirs for power generation. The need for the Korokora Dam, to obtain command of the ultimate proposed main canal, and to provide storage oapacity for re-regulation to suit the incidence of irrigation needs, oould be deferred until a decision could be reached in the light of aotual experience of results from this first initial development.

-118-

Tebls 13- Zatimates of Capital Costs-Irrigation Development

Estimate of oost Estimate of cost Item using using paved roads earth roads

£ E.A. £ E.A. £ E.A. £ E.A.

Korokora diversion dam 11.040.000 11,040,000 11.040.000 11,040,000

Main canal 5.450.000 5,450,000 5.450.000 5,450,000

Section-feeder canals 2,476,000 2,476,000

Night-storage reservoirs 429*000 429,000

Block-feeder oanals 2,665,000 2,685,000

Unit-feeder canals 257,000 257,000

Drainage 1.280.000 7,127,000 1.280.000 7,127,000

Internal roads 7»561,000 2,000,000

Ploodplain lands 1,040,000 1,040,000

Land clearing and levelling 3.962.000 12.563.000 3.962.000 7.002.000

Subtotal for 136,000 acres north of L. Thowa 36,180,000 30,619,000 add costs of 114,000 sores south of L. Thowa

Hain canal extension 1,107,000 1,107,000 Irrigation and drainage 5»974»000 5,974,000 Internal roads c= 6,509,000 1,400,000 Land olearing and levelling 3.321.000 16.911.000 3.321.000 11.802.000 Subtotal for 250,000 acres irrigation development 53,091,000 42,421,000

A.dd costs of additional 50,000 acres south of L. Thova:

Ilain canal extension 100,000 100,000 Irrigation and drainage 2,620,000 2,620,000 Internal roads 2,855,000 615,000 Land clearing and levelling 1.457.000 71032,000 1.457.000 4,792,000 Srand total - 300,000 acre irrigation development £60.123.000 £47.213.000 -119-

Table 13-3 Research and Training Centre - Estimate of Capital Cost

Item

Temporary water supply system:

Pumping station 176,000 Conveyance canals 254.000 430,000

Research facilities!

Offices, laboratories, workshops, housing, etc. 400,000

Training facilities:

Offices, housing, transport,, etc. 650,000

Total additional costs of Research and training centre 1,480,000

Irrigation development (as included in totals presented in Table 13-2):

Irrigation, drainage and road networks 1,159,000 Land clearing and levelling 242,000 Floodplain lands 34.000 1,435,000 Total development cost of Research uii Training Centre £ 2,915,000 -120-

CHAPTER "XIV

INFRASTRUCTURE AND SECONDARY DEVELOPMENT

14 »1 Genexaj-,

The development of irrigation on a large scale on the almost uninhabited lowland plains of the Tana basin will necessitate very substantial investments in institutional and social infrastructure, in addition to the works involved on the irrigation network and processing plants. While such infrastructural investments are not considered in the evaluation of the economic viability of irrigation development as such, it is apparent that they must be taken into account in an over-all appraisal» Hence, although it was beyond the scope of the studies made for the project to detail a comprehensive plan for the over-all development, a preliminary assessment of basic infrastructural requirements was made to provide at least some indication of the order of magnitude of the investments involved. The discussion of infrastructure, secondary developments and sociologie implications is contained in Technical Volume VII (Appendix M).

The basic infrastructure there considered included such items as external road communications, townsites and service, tenant housing and general government administration. In addition, local secondary developments such as forestry and inland fisheries, which might be justified to provide the scheme population with part of their food and fuel requirements, were given preliminary consideration. Certain aspects of such secondary development are discussed briefly here, as is the potential hazard of a conflict between wildlife and agricultural development within the lower basin.

The social implications of development are discusssd only to indicate the special conditions which could ar-iee through the resettlement of a large population in an. isolated area and to suggest the need for timely studies to determine what provisions would be required to meet the demands of health, education and other social services. -121-

The population ultimately to he settled in the scheme area will consist largely of tenants and other agricultural workers and their families. These would all he directly associated with the primary production of crops and are "estimated to numher between 400,000 and 500,000 persons, assuming an average of five persons per family. In addition, it has heen assumed that government transportation services and other activities would provide employment opportunities for a further 25,000 to 30,000 workers and thereby increase the population by between 100,000 and 150,000 people. While admittedly approximate, it appears reasonable to envisage an ultimate population of some 500,000 to 600,000 people, directly supported by the ultimate irrigation development.

14.2 Requirements

The functional requirements of the irrigation system and the layout of irrigable lands dictate to a great extent the pattern of social development and land use. Although only some 300,000 acres of land are considered to be irrigable, it must be • noted that this is a net acreage and that, in addition, a substantial part of the project area would be occupied by canals, drains, roads and townsites. Nevertheless, about half of the project area would remain unproductive, either through lack of water or because of inherently unfavourable topographic and soil characteristics. The administrative and institutional organization therefore must be planned for an ultimate 'population of over half a million people, spread out across an irrigation complex occupying more than one million acres of land.

From the point of view of scheme management and from considerations of the level of social service desirable, it is understood that the Government of Kenya, through the Tana Steering Committee,wishes planning to provide.for settlement of the farming population in rural communities, each of which is expected to serve an irrigation subdistrict of approximately 10,000 acres.

As described in Technical Volume VII (Appendix M), communities have been envisaged as groupings of village units around a town centre in which the social amenities and general services necessary to support community living would be provided. The level of services and standards of construction as proposed therein were reviewed with the Tana Steering Committee to ensure that they conform to Government policy. Cost estimates were prepared for townsite development and services and for housing for communities of two sizes, for 12,000 and 25,000 people. Over-rail, these work out approximately as follows:

Townsite development and Services 90 ) Housing 110 )E.A. £/head £ 200 ) -122-

For a total porulaticn assumed to he 500,000, in a scheme of 250,000 net irrigahle acres, this is equivalent to £400 per net acre. Investments for commercial . or private enterprises, or for processing industries, are not included in this already formidable figure.

Communications will also he an important aspect of development. Road connections have heen proposed throughout. The internal road network and the external links to Mombasa and Nairobi have heen discussed in Chapter £111, where it is noted that the"- cost of both the internal roads and of the quarry road to the Kandelongwe Hills are assumed to form part of the direct investment in irrigation. Of the external roads, the cost of the link to Nairobi was not estimated, the cost of the surface trunk road from the scheme to Mombasa was estimated to he nearly E.A. £ 8.5 million. The cost of other facilities for communication, such as airstrips, and telephone and telegraph service, were not estimated in the studies. It appears obvious that an airstrip will be essential, but it is for the Government to consider on what standard provision should he made. From experience of large and intensive irrigation schemes elsewhere, a comprehensive telephone service throughout the irrigable area and to all important points such as headworks is quite essential, for purposes of water control, management, and agricultural administration; otherwise the standard of efficiency requisite for economic viability is unattainable. This service can probably best be provided and operated as part of the national telephone service, at standard charges.

It is recognised that there are special health hazards involved in the use of irrigation in the tropics. For development in the lower Tana, these were assessed by a WHO mission, the results of which are included in Technical Volume VII (Appendix M). It is therefore recommended that adequate standards of water supply and of sewage disposal, appropriate to the local conditions, should be provided.

In the figure of £ 90 per head, mentioned above as the estimated cost of townsite development and services, the studies, may \ appear to have allowed for water-borne sanitation for sewage disposal. For the local conditions, certainly in the early stages of development, this seems unnecessary) various other methods have been used elsewhere with acceptable results. Certainly this and other items of expenditure involved in the provision of the infrastructure should be most carefully scrutinised ' before they are adopted for development.

/ 14.3 Other Aspects In Technical Volume .vfI (Appendix M) is included a preliminary report on the fisheries potential of the Tana river, as it is at present, and as it is foreseen when the reservoirs envisaged provide new sources for inland fisheries. The opinion was expressed that the various dams would be unlikely to have significant adverse effects on migratory fish, and that in the new reservoirs, species of commercial interest would become established and make possible considerable increased production.

In the same,volume there is a report on the possibility of conflict between agriculture and elephants, in the lower Tana Irrigation scheme. The conclusion \ reached is that there is little likehood of this. Changing ecological conditions have resulted in the desertion of the area by most of the former game population. However, it is recommended that control measures be planned by the"Game Department of Kenya, so that they can be applied if occasion should arise. -123-

Also considered in the same, volume is the potential of the flood-plain of the. Tana river and other limited areas of the scheme, for the development of forestry* Little is at present known about this, in this area, and it is recommended that experimental work be undertaken to determine what species óf trees would be best suited to the local conditions. If successful, well-managed forests could supply a large part of the local demands for fuel and rough timber, and also provide additional employment,

14 »4 Processing

This has already been briefly discussed in Chapter IX. It is mentioned here again, since the provision of processing plants can approximately be inoluded in the picture with that of Infrastructure. The items considered inoluded pressing and refining of sugar, ginning of seed cotton, pressing of cotton seed and other oil seeds for oil, and converting kenaf into bags. In the studies made, details of the factories and equipment required were not worked out; but for an ultimate developed area of 250,000 acres, an over-all figure of £40,000,000 was envisaged as investment cost.. If, as is now suggested, the cropping pattern is modified, some of these items may be reduced in magnitude, or even eliminated. For the present, however, it may be suitable, to assume this figure of cost tentatively, until the picture can be further olarified. -124-

CHAPTER XV

ORGANIZATION AND MANAGEMENT

15«1 General

The area of the scheme is remote, and at present sparsely populated* To attract settlers there, the social and personal economic factors are of prime importance* Living conditions and amenities, marketing arrangements, conditions of tenancy and land tenure, and above all, financial returns to the individual cultivator, are at least as important as, if not more so,than cropping patterns and questions of agricultural technique.

An adequate return on the high rate of investment required for the develop­ ment of irrigation can only be aohieved with high standards of husbandry and production. To ensure these, the whole development and its management should be in the charge of a semi-autonomous "Gezira,,-type organization, to be called the "Tana River Irrigation Authority". This would be responsible for the construction and operation of the scheme, as well as for the marketing of produce* It should also undertake research, the training of staff and cultivators, and the organiza­ tion services, with the control of secondary agricultural activities suoh as forestry. It might well also own and operate processing plants. Por the work of development, including land clearance, levelling and the construction of distri- butory canals, it would have to maintain quite a large construction force ; it might then undertake also the construction of publio faoilities such as cultivators* housing* It is stressed that the only effective means of seouring the requisite standards of efficiency is through such an Authority.

Furthermore the whole organization of the scheme, including cropping pat­ terns, conditions of tenancy and of cultivation, financial arrangements at all levels, relations between Government, Authority, and cultivators, and all the other points which will be involved in development, in operation ' and management, should at first be defined and agreed upon by all concerned. When this has been done, the arrangements should be applied and tested on a first development of modest but adequate size, so that any adjustments suggested by actual experience can be made, before full-scale development is undertaken. -125-

15.2 Specific Points

There is no doubt that many of the technologic and managerial skills required during the initial years of construction and development of such a large complex will have to be imported* At the same time, provision must be made to train Kenya citizens in the management and administrative aspects of the scheme.

Infrastructural development will need to be closely, controlled and scheduled to remain in balance with the construction of productive facilities. Hence, a strong case can be made for utilizing the construction forces of the Authority to oversee the construction of all physical facilities and installations required within the project area.

A schematic organization chart, indicating the primary functions of an Authority such as has been discussed herein, is presented on Plate 19. Therein, it may be noted that operations are divided between agricultural management and engineering, whilst construction forms a special division of the engineering arm.

The agricultural division of the Authority would be concerned with the provision of research facilities, supervision and training of tenant farmers, and with marketing and related functions. The engineering division would be responsible for water control and the scheduling of irrigation deliveries, as well as the construction of all physical works and installations, and the maintenance and opera­ tion of mechanical plant and construction equipment.

Within the headquarters administration, a tenant affairs section has been suggested to deal with grievances and suggestions which, no doubt, will, arise as à consequence of the natural aspirations of the tenants for an increasing -voice in the operation of the scheme as time goes by. Details have not been considered at present} however, it is suggested that, as early as possible, tenants should be given some degree of self-government at the village level. As their experience increases, they might well be asked to participate, through co-operatives, in operating mecha­ nical plant in their own districts and in supervising various other community activities. Much can be learned from the history of social and political develop­ ment in the Gezira scheme in the Sudan.

Although it is not appropriate at this time to oonsider these matters in , great detail, it is apparent that the proper organization and administration of the scheme will be.fundamental to its success. For the purposes of this report, a Tana River Irrigation Authority has served as the model for estimating the costs of operation, and as the appropriate level from which to view the economic evaluation of development. Whatever form of organization is ultimately adopted, the funotions and number of staff required, as well as the essential costs of operation and maintenance of the development, will be more or less the same. NATIONAL IRRIGATION BOARD

GENERAL MANAGER ZL.

DEPUTY GENERAL MANAIIER DEPUTY OINENAL. MANAGER LOCAL GOVERNMENT TENAIT' OPERATIONS ADMIN. ANO FINANCE ADVISORY COMMITTEE ADVISORY COMIIITTtl

ACCOUNT! MARKETING PERSONNEL PURCHASING STORES TENANT AFFAIR!

S

M AMICULTURAL ENGINEERING I OIVItlON DIVISION e «e

EXTENSION AMI EDUCATION OPERATION AND • •••ARCH ANO ITIAMMOf TECHNICAL STA« CONSTRUCTION DEVELOPMENT ANO TENANT») MAINTENANCE ] E OISTRICT MANAGEMENT ANO OPERATION iMSTMCT MANAGER ISCAJOJ c 10,000 ACRES SECTION MANAGEMENT SECTION I CJMAL SUPERINTENDENT AND OPERATION SECTION MANAMA (A.0.1 M.000 ACRES CAN AL MEAOWORK OR STAFF

I AMt CANAL SUPT. C'HAL MAINTENANCE STAFF GOVERNMENT OF KENIA UNITED NATIONS SPECIAL FUND IS WATER GUARDS AI ST MST. MANAGERISP.AXU UNIT MANAGEMENT SURVEY OF IRRIGATION POTENTIAL I AGST. A a'S S >k.a SPECIALISTS AND OPERATION LOWER TANA RIVER BASIN FMO AH MMCUITUK OMAMUTlOa OF TKt UHTtS MTOa I WORKSHOP SUPT. IRRIGATION PROJECT IRRIGATION UNIT-IOOO AC SCHEMATIC MANAGEMENT A.F.A. ORGANIZATION CHAITT I HEAD CULTIVATOR TO BLOCK 4 EVERY IRRIGATION SUS UNIT ISLOCK t I SLOCKÎ - 127 -

CHAPTER XVI

ECONOMIC EVALUATION

In the studies made under the project to evaluate the economic aspects of projeot development, the discounted cash flow method of analysis was adopted. The advantages of the method are that it not only eliminates problems of selecting suitable interest rates, but usually also provides a more explicit answer than other methods, especially at the national planning level when comparisons have to be made with other projects whioh oompete for limited development funds. The method results in streams of invest­ ments, annual costs and benefits, and leads to an internal rate of return.

This evaluation was made for two stages of project development. First,the irrigation development alone and, secondly, the irrigation project together with certain processing activities included. The streams were assumed to originate from and accrue to a Tana Irrigation Scheme Authority.

The investment and oost streams include only those expenses which are directly attributable to the project or form imputable indireot costs, such as maintenance of the trunk road between the project area and Mombasa during an initial period. The benefit streams inolude the values of production, at farm level and ex-processing factory respectively, after deduction of costs for inputs such as fertilizers, fuel, spare parts and skilled labour. Farmers' labour and unskilled labour employed in the processing industries are considered to have zero return opportunity and are therefore not oounted as a cost. Their remuneration is still included in the project benefits, so that the internal rates of return obtained provide an indication of the profitabi­ lity of the projeot to the national economy.

To complete the economic picture, an approximate schematio finanoial analysis was made which took into account all the actual expenses of the authority, including those to farmers and unskilled labourers. The purpose of this assessment was to il­ lustrate the order of magnitude of the funds required annually during the first period when expenses still exoeed proceeds, and what types of loans might suit best in financing the projeot, taking into aocount the positive balance of proceeds over expenditures during the seoond part of the theoretical lifespan of the project.

Finally, some comments were inoluded on the foreign currency aspect of the project. -128-

16.1 Internal Rates of Return

Irrigation development

The various cash flows were based on the following considerations and assumptions» together with the costs and benefits derived in previous sections of this report«

(a) For each of the two levels of development, 250,000 and 300,000 acres, two rates of development were assumed. Rate 1 envisaged, after an initial period, a uniform development of 10,000 acres of newly reclaimed land per year, as discussed in Chapter,XI.

(b) The time required for construction and land reclamation would be between 20 and 30 years, depending on the size and development rate of the scheme« In accordance with current practice of such agencies as the International Bank for Reconstruction and Development, the economic analyses were made for a period of 50 years, even though the useful physical life of well-maintained works would be much longer. Although reinvestments in plant and maintenancetcosts of works would continue, as discussed in Chapters XII and XIII effective water control could be foreseen for 100 years or more from the power complex and the Korokora diversion dam, and hence no major reinvestments in works for water control nor irrigation are foreseen within practical limits of economic evaluation.

(c) The land would be cleared two years before it is taken into production, so that the irrigation and drainage canals and internal roads could be constructed and the farm land levelled in the remaining year before cultivation started.

(d) The on-farm investments and reinvestments included the cost of initially supplying each new farmer with irrigation siphons, working capital and consumptive credit. Further, they comprised the purchase and regular replacement of agricultural machinery, estimated to cost about £ 2,000 per unit including implements, and the installation of workships for maintenance and repair of the fleet of machinery.

(e) Farm income, before payment of any land and water charges, would start at a level of t 47.50 per aore and increase gradually as explained in Technical Volume V, Section H9.5.5 °* Appendix H. The improvement was taken to be equivalent to a compounded annual increase of one percent over the basio level. Further, it was assumed that only 75 sLaà $0 percent respectively of the yield level, at that time, would be obtained during the first two year» of cultivation on newly reclaimed land«

(f) The on-farm costs, which were subtracted from the gross value of produce to obtain farm income, included such items as interest on credit and charges for mechanization services. In order to be consis­ tent, these costs had to be considered as income or revenue to the authority which would provide these services. The apparent profit on training of new farmers has also been considered as a revenue in the cash flow. . TABLE.I6-IA

INVESTMENTS FOR IRRIGATION DEVELOPMENT

RATE I - 250,000. ACRES

£ x 1,000

COL. 3. 5.

Y MAIN CANAL, IRRIGATION/DRAINAGE E TWORARY SYSTEM,* A WATER SUPPLY INTERNAL ROAOS, RESEARCH ON-FARM R RESEARCH ANDTRAININ6 HEADQUARTERS AND INVESTMENTS QUARRY ROAD" CENTRE KORWOM DAM AND SCHEME TRAINING CENTRE AND RE-INVESTMENTS TOTAL

1 1,044 83 32 1,159 •2 347 1,06« 705 239 9 2, «5 3 2,128 1,259 300 13 3,700 4' • DISLOCATION 2.128 1,998 360 23 4,509 ALLOWANCE s\- 300 2,660 3,126 40 45 6,171 s -.'' «-.••'-ja» -f.-;. r. -:' ' 45 . 2.660 1,612 40 445 5.102 5.:'• 1,736 40 453 2,229 8 1,644 40 157 a;«i

••:»• '••>' '• ""• ''••''• 1,813 465 2,278 lb 1,777 485 2,262 n 1,725 485 2.2IÖ 12 1,507 493 2,000 13 1,508 497 2,005 14 1,555 505 2,060 15 1,728 525 2,253 16 1,851 525 2,376 17 2,159 533 2,682 18 1,516 537 2,053 19 1,561 545 2,106 20 1,446 566 2,011 21 1,445 566 2,0 tO 22 1,447 573 2,020 23 1,472 577 2,049 2» 1,48« 585 2,071 25 1,514 605 2,119 26 1,446 606 2,051 27 1,446 613 2,059 28 1,286 617 1,903 29 580 580 30 600 600 31 200 200 32 200 200 33 200 200 3i| 200 200 35 200 200 36 290 290 37 290 290 38 200 290 39 200 200 40 200 200 HI 200 200 42 200 290 43 290 200 14 200 290 45 200 • 290 46 200 290 47 200 390 48 200 200 49 290 290 50 200 200

TOTAL 1,044 475 ».« 43,800 1,050 17,525 75.134 600

* INCLUDING CLEARING AND LEVELLING TABLE 16-1B

INVESTMENTS FOR IRRIGATION DEVELOPMENT

RATE 2 - 250,000 ACRES £ x 1,000 COL. I. 2. 3. ». 5.

Y MAIN CANAL. IRRIGATION/DRAINAGE E TEMPORARY SYSTEM, A MTER SUPPLY INTERNAL ROADS, RESEARCH ON-FARM R RESEARCH AND TRAINING HEADQUARTERS AND INVESTMENTS QUARRY ROAD CENTRE KOROWRA DAM AND SCHEME TRAINING CENTRE AND RE-INVESTMENTS TOTAL

1 1,044 83 32 1.159 2 347 1.064 705 230 9 2,355 3 2.128 1.259 300 13 3.700 4 DISLOCATION 2.128. 1.998 360 .23 4.509 ALLOWANCE 5 300 2,660 3.126 40 45 6.171 6 300 45 2,660 1.666 40 445 5,156 7 1,899 40 453 2,392 8 2.567 365 479 3.411 9 2,530 488 3,018 10 2.479 707 3.186 II 2,309 708 3,017 12 2.S62 715 3,277 13 3.404 325 762 4,491 m 3.599 770 4,369 IS 3.034 990 4.024 16 2.933 990 3,923 17 2,959 998 3,957 18 2,813 .042 3,855 19 1.928 .028 2,956 20 980 980 21 780 780 22 200 200 23 200 200 24 200 200 25 200 200 26 200 200 27 200 200. 28 200 200 29 200 200 30 200 200 31 200 200 200 200 32 200 200 33 200 200 34 200 200 35 200 200 36 200 200 37 200 200 38 39 200 200 200 200 11 200 200 200 H2 200 200 200 13 200 200 44 200 200 15 200 200 46 200 200 17 200 200 48 200 200 49 200 200 50

TOTAL ,044 475 .43,802 1.700 18.225 76.486 600 TABLE 16-IC

INVESTMENTS FOR IRRIGATION DEVELOPMENT

RATE I - 300,000 ACRES

£ x 1,000

COL. I. 2. 3. ». 5. 6. 7.

* MAIN CANAL, Y IRRIGATION/OMUIASE E TEMPORARY SYSTEM, WATER SUPPLY INTERNAL ROADS, RESEARCH 0N-FAB4 A RESEARCH AND TRAINING HEADQUARTERS AND INVESTMENTS R QUARRY ROAO CENTRE icOROKOJU DAM AND SCHEME TMIRIN6 CENTRE AND RE-INVESTMENTS TOTAL

1 1,044 83 32 1,159 2 347 1,084 70S 230 9 2,355 3 2.128 1,259 300 13 3.700 4 DISLOCATION 2,128 1,998 380 23 4,50» ALLOWANCE 5 300 2.6» 3,126 40 45 6,171 6 300 45 2,660 1.612 40 445 5,102 7 1.736 40 453 2.229 B 1,6*4 40 457 2,141 9 1,613 465 2,278 10 1,777 485 2,262 II 1,725 48S 2,210 12 1,507 493 2.000 13 1.508 497 2,005 14 1,556 505 2,060 ts 1,726 525 2.253 16 1,651 525 2,376 17 2,159 533 2,692 18 1,516 537 2.053 19 1,561 545 2,106 20 1,446 565 2,011 21 1,445 565 2,010 22 1,467 573 2.020 23 1,472 577 2.049 2* 1,466 565 2,071 25 1.514 605 2.119 26 1,446 60S 2.051 27 1,466 613 2,079 28 1,476 617 2.093 29 1,466 625 2,120 30 1,447 645 2.092 31 1,445 645 2,090 32 1,446 663 2,099 33 1,266 657 1,943 34 620 620 35 640 640 36 240 240 37 240 240 38 240 240 39 240 240 40 240 240 «1 240 240 42 240 240 43 240 240 m 240 240 «5 240 240 46 240 240 47 240 240 48 240 240 49 240 240 50 240 240

TOTAL I.»1» 475 10.640 61,129 1.060 20.430 66.368 TABLE 16-ID INVESTMENTS FOR IRRIGATION DEVELOPMENT RATE 2 - 300,000 ACRES £ x 1,000

COL. 6. 7.

WIN CANAL, Y IRRIQATION/DRAIIUGE E TEMPORARY SYSTEM, MATER SUPPLY INTERNAL ROADS, RESEARCH ON-FARM A RESEARCH AND TUININB NEAOOVA«TERS AW INVESTMENTS R QUARRY ROAD . ... CENTRE MO SCHBC TRAINIM CENTRE AW RE-INVESTMENTS TOTAL

1 1.044 83 32 1,159 2 347 1,06» 705 2*0 9 2.355 3 2,12» 1.25« 300 13 3,700 i» DISLOCATION 2,128 ' I.SM 3« 23 ' 4,509 ALLOWANCE 5 300 2,80) 3,126 40 '45 6,171 6 300 45 2,6*0 1,666 no 446 5,156 7 *. r" l,*M 40 453 2,392 8 2,567 365 479 3,411 9 2,530 488 3,018 10 2,479 707 3,186 M 2,309 703 3.017 12 2,562 715 3,277 13 3,Mm 325 762 4,491 m 3,509 770 4,369 15 3.0» 990 4.024 16 2,933 990 3,923 17- - 2,959 968 3,957 18 2,913 1,042 3,955 19 2,921 1,050 3,971 20 ** 3,023 1,070 4,093 21 1,215 1,093 4,308 22 1,9» 1,040 23 1.240 1.240 24 240 240 25 240 240 26 240 240 27 240 240 28 240 240 29 240 240 30 240 240 31 : - 240 240 32 2*0 240 33 240 240 3>» 240 240 35 240 240 36 240 240 37 240 240 38 240 240 39 240 240 MO 240 '40 41 240 240 12 240 240 u3 240 240 44 240 240 »5 240 240 46 240 240 47 240 240 48 2H0 240 19 240 240 50 240 240

TOTAL 1.044 475 10.« 54,133 1,700 21,610 87,202 TABLE 16-2A IRRIGATION DEVELOPMENT - ANNUAL COSTS AND BENEFITS RATE I - 250,000 ACRES £ x I,000 COL. 2. 3. ». - 5.

COSTS BENEFITS

MANAGEMENT AUTHORITY, Y RESEARCH TRAINING E OPERATION ANO CENTRE. A HAINTENANCE- HEADQUARTERS AND SCHEME, REVENUES TO MAINTENANCE OF OAM, IRRIGATION/ ANO OPERATION AUTHORITY FROM R QUARRY ANO DRAINAGE SYSTEM, AND MAINTENANCE. NET VALUE OF TRAINING, CREDIT TRUNK ROAD' ANO ROADS OF MACHINERY TOTAL FARM PRODUCTION AND MACHINERY TOTAL

1 m 14 2 37 119 156 3 37 22 241 300 40 40 4 '37 62 303 402 100 100 5 . 331» 1» 370 828 ' ' 200 200 6 33* 250 398 982 356 248 604 7 334 376 4SI 1.191 792 296 1,088 8 334 427 563 1,324 1.284 344 1,628 9 331» 171» 615 1,423 1,786 392 2.178 10 331» 528 668 1.530 2.298 440 2,738 II 334 580 720 1.634 2.820 488 3.308 !2 334 630 773 1.737 3.353 536 3.889 13 33» 672 825 1.831 3.895 5«4 4.479 It 334 7Î5 '878 1,927 4.449 632 5.081 IS 37 '759 927 1.723 5.012 680 5.692 16 " 18 809 976 1.803 5.587 728 6.315 17 ' 864 I.02S 1.869 6.172 776 6,948 18 929 l;074 2.003 6.769 824 7,593 19 ' 972 1.123 2.095 •7,378 872 8.250 20 1,017 1.172 2.189 7,997 920 8.917 21 1.057 1.221 2,278 8.629 968 9,597 22 1.098 1.270 2.366 9.272 1.016 10.288 23 1.138 1.319 2,457 9.928 1.064 10.992 ri 1.179 - 1.368 2.547 10.595 1.112 H.707 25 1.221 1,417 2.638 11.275 1.160 12.435 26 1.26« 1.466 2.730 »1.967 1.206 13.175 27 1.304 1.515 2.819 12,672 1.256 13.928 28 1.345 1,56» 2.909 13.391- 1.304 14,695 15.473 29 1.385 1,613 2,998 14.121 1.352 30 1.385 1.613 2.998 14,86« 1.200 16,066 31 1.385 1,613 2,9*8 15,167 1.200 16,367 1.200 16,560 : 32 1.385 1.613 2.998 15.380 33 1,385 1.613 2.998 15,535 1.200 16.735 34 1,385 1.613 2.998 15.690 1,200 16.890 35 1.385 1.613 2.998 15.848 1.200 17.048 36 1.385 1,613 2.998 16.005 1.200 17.205 37' 1.385 1,613 2.998 16.166 1.200 17.365 38 1.385 1.613 2.998 16,326 1.200 17.528 39 1.385 1.613 2.998 16.490 1.200 17.680 40 1,385 1.613 2.998 16.655 1.200 17.855 41 1,385 1.613 2.998 16,823 1.200 18.023 42 1.385 1.613 2.988 16.990 1.200 18.190 43 1.385 1,613 2,998 17,160 1.200 18,360 '14 1.385 1,613 2.998 17.333 1.200 18,533 1.200 18.705 45 . 1.385 1.613 2.998 17,055 •tc 1,385 1,613 2,99« 17.680 1.200 18.880 47 1.385 1,613 2.998 17.658 1,200 19.059 48. 1.386 1,613 2.998 18,036 1.200 19.236 49 1,385 1,613 2,999 18,215 1.200 19,415 50 1,385 1,613 2.998 18.398 1,200 19.598

511,924 44.740 556.664 TOTAL 3.506 50,286 59.891 113,603 TABLE I6-2B IRRIGATION DEVELOPMENT - ANNUAL COSTS AND BENEFITS RATE 2 - 250,000 ACRES t x 1.000 COL. 2. 3. H. 5. 6. COSTS BENEFITS

MANAGEMENT AUTHORITY, Y RESEARCH TRAINING OPERATION AMD CENTRE, E NAINTEMNCE- HEADQUARTERS AND SCHEME, REVENUES TO A HilRTEN/UKE OF .DAM, IRRIGATION/ AND OPERATION AUTHORITY FROM R QUARRY AND DRAINAGE ÏYST94, AND MAINTENANCE NET VALUE OF TRAINING, CREDIT TRUNK ROAD . AND ROAOS OF MACHINERY TOTAL FARM fRODUCTION AND MACHINERY TOTAL

1 1« 14 2 37 119 156 3 37 22 241 300 40 40 4 37 62 303 402 100 100 5 331 124 370 828 200 200 6 334 250 398 982 356 218 604 7 331 378 484 1.196 792 296 1.088 8 33« 432 570 1,336 1.284 344 1.628 9 334 506 647 1,487 1,786 492 2.278 10 331 580 724 1.638 2.484 •564 1.018' II 331 661 801 1.786 3.232 c.36 J. 666 12 334 717 878 1,929 4.021 708 4.729 13 18 788 952 1,756 4,825 780 5,605 n 887 1.060 1,937 5,644 952 6.596 15 993 1.148 2,141 6.674 .048 1. '12 16 1.078 1.246 2,324 7.764 1,144 8.908 17 1,161 1,344 2.506 6,901 1,240 10.111 18 1,244 1,442 2,686 10.060 1.336 •1.396 19 1.325 1,540 2.866 11.242 1.432 12.671 20 1.385 1,613 2.998 12,447 1.428 13.875 2< 1,385 1,613 2,998 13.399 1,200 11.599 22 1,385 1,613 2,998 13,811 1.200 15.011 23 1.365 1,613 2,998 14.063 1.200 15.263 21 1,385 1,613 2,998 - 14.203 1,200 15.403 25 1,385 MI3 2,998 14.345 !.200 15.545 1,385 26 1,613 2,998 14.488 . 1.200 15.688 27 1,385 1,613 2.9*8 14.633 1.200 15.813 28 1,386 1,613 2,998 14,780 1.200 15.930 29 1,385 1.613 2.998 14.928 i.200 i 't. 1U 30 1,386 1.613 2,998 15.078 1.200 i6.2'8 31 1,385 1,613 2.998 15,228 1.200 : 6,128 32 1,385 1,613 2.998 15,380 1.200 33 i6.580 1,885 1,613 2,998 15.535 1.200 3« :6.73S 1,385 1.613 2,998 15,690 1.200 35 16.890 1,385 1,613 2,998 15.846 36 '.200 17.018 1,185 1,613 2.998 16.005 37 1,200 17.205 1,385 1.613 2,998 16,166 38 1.200 17.366 1,385 1,613 2,998 16.328 39 1.200 17.528 1,385 1.613 2.998 16,490 «O 1.200 :7.690 1,385 1,613 2,998 16,655 «1 .200 17.855 1,385 1,613 2.998 16.823 1 <*M4 12 18,023 1,386 1.613 • M« 16.990 «3 1.200 18.190 1.613 2,998 17.160 1.200 1.385 18.360 1.613 2.998 17.333 45 1,385 1.200 • 8.5J3 1,613 2.998 17,505 16 1.385 1.200 18.705 1,613 2.998 17,680 17 1.385 1.200 '8.880 1.813 2.998 17.858 18 1,385 1.200 19.058 1,613 2.998 18.035 19 1.385 1.200 . 19.235 1,613 2.998 16.215 50 1.385 1.200 19.115 1.613 2.998 18.398 ••200 19.598

TOTAL 2,801 54.133 •4,274 121,208 580.561 18.988 609.549 TABLE I6-2C IRRIGATION DEVELOPMENT -ANNUAL COSTS AND BENEFITS RATE I - 300.000 ACRES £ x 1,000 COL. 2. 3. "»• 5. 6. COSTS BENEFITS

MANAGEMENT AUTHORITY, RE3EARU TUINIM OPERATION AMD CtRTM, MAINTENANCE- HEAOOUUTEM AND SCJEME, REVENUES TO MAINTENANCE OF DAN, IRRIGATION/ AND OPERATION AUTHORITY FROM QUARRY AMD DRAINAGE SYSTEM, AND MAINTENANCE MET VALUE OF TRAINING, CREDIT TRUNK ROAD ' AMD ROADS Of MACHINERY TOTAL FARM PRODUCTION AND MACHINERY TOTAL

i IN 14 119 156 2 37 800 40 40 .3 37 22 »1 303 100 100 4 37 62 /«« 370 828 200 200 5 334 12« 250 398 982 356 248 604 6 334 334 376 «II 1.191 792 296 1,088 7 1.628 334 427 5«3 1.3» 1,284 344 8 2,178 334 474 6IS 1.423 1,786 392 9 2.738 334 528 6« 1.530 2.2*8 440 10 3,308 334 580 7» 1.634 2.820 488 II 3,889 334 630 773 1.737 3,353 536 12 4,479 334 672 825 1,831 3,895 584 13 5.081 715 •78 1,927 4.449 632 14 334 5.692 759 927 1,723 5.012 680 IS 37 6.315. 809 976 1.803 5.587 728 16 18 6,948 864 1,025 1,889 6.172 776 17 7,593 1.074 2,003 6,769 824 18 92» 8,250 1.123 2,095 7,378 872 19 972 8,917 1.172 2.189 7,997 920 20 1,017 9.597 1.221 2.278 8,629 968 21 1,057 10,288 1.270 2,368 9,272 1.016 22 1,098 10,992 1.319 2,457 9.928 1.064 23 1,138 11,707 1.368 2,547 10,595 1.112 24 1,179 12.435 1,417 2,638 11,275 1.160 25 1,221 13.175 1,466 2.730 11,967 1.208 26 1,264 13,928 1.515 2,819 12.672 1.256 27 1.304 14,695 1,564 2.909 13.391 1.304 28 1,345 15.473 1,613 3.000 14.121 1.352 29 1,387 16,266 3,091 14,866 I.4O0 30 1,429 1,662 17,071 1.711 3,180 15,623 1,448 31 1.469 17,831 1.760 3,270 16,395 1,496 32 1,510 18,726 1,809 3.359 17.182 1.544 19,572 33 1,550 3,449 17.980 1.592 20,235 34 1,591 1,85« 3,449 18,795 1.440 20,582 35 1.591 1,858 3,449 19,142 1,440 20,838 36 1,591 1,858 3,449 19,398 1.440 21,033 37 1,591 1,858 3,449 19,593 1,440 21,223 38 1,591 1,858 3,449 19,788 1.440 21.426 39 1.591 1,858 3,449 19,986 1,440 21,627 40 1.591 1,858 3,449 20,187 1,440 21,826 41 1,591 1,858 3.449 20,388 1,440 22,032 42 1,591 1.85« 3,449 20.592 1.440 22,239 43 1.591 1,858 3,449 20.799 1.440 22,446 44 1.591 1,858 3,449 21,006 1,440 22.656 45 1,591 1,858 21,216 1.440 22,869 46 .1.591 1,858 3,449 21,429 1,440 23,082 47 1.591 1,658 3,449 21,642 1.440 23,298 48 1.591 1,858 3,049 21,858 1,440 23,517 49 1,591 1,85« 3,449 22,077 1.440 50 1,591 1.858 3,449

621,800 64,546 122,260 571.740 50,060 TOTAL 3,506 54.208 TABLE lfr-20 IRRIGATION DEVELOPMENT - ANNUAL COSTS AND BENEFITS RATE 2-300,000 ACRES £ x 1.000 COL. Z. 3. ». 5. 7.

COSTS BENEFITS MANAGEMENT AUTHORITY, Y RESEARCH TRAINING OPERATION AND E COTRE, MAINTENANCE- HEADQUARTERS A» SCHWE, REVENUES ID A MAINTENANCE OF OAM, IRRIGATION/ AND OPERATION AUTHORITY FROM R QUARRY AMD - DfUIMfiE SYSTEM, AND MAINTENANCE HCT VALUE OF TRAINING, CENTRE TRUNR MAO AMD ROADS OF MACHINERY TOTAL FARM PRODUCTION MO MACHINERY TOTAL

1 1» 1» 2 37 IS 156 3 37 22 2W 3X 40 40 4 37 62 93 402 100 WO 5 334 1» 8TO 828 200 200 6 334 2Ï0 39 " '*© 356 . 248 8Ä- •• 7 334 378 ** Ù-W- 792 296 .-Mes 8 334 43J 5» •,33* 1,26« 344 ..-.-;. 1,62« 9 »34 SB« •. m h*87 1.786 492 ' i0à 10 334 590 TU 1,633 2,484 564 3,048 II 334 651 SOI 1,786 1,232 636 3,868 12 334 717 878 1,929 4,021 708 4,73 13 18 788 962 1,758 4,825 780 5,605 14 887 1,050 1,937 ~ 5,644 952 6,596 15 993 1,1« 2,141 6,674 1,046 7,722 16 1,078 1.24« 2,324 7,764 1,144 8,908 17 1,161 1,344 2,505 6,901 1,240 10,141 i8 1,24« 1,442 2,686 10,060 1,336 11,396 19 1,325 1,5« 2,865 11,242 1,432 12,674 20 1,407 1,638 3,046 12,447 1,528 13,975 21 1,490 1,736 3,226 13,675 1,624 i5,299 22 1,591 1,858 3,449 14,925 1,820 16,745 23 1,591 1,858 3,449 16,411 !,440 17,851 24 1,591 1,858 3,449 • 16,901 1,440 18,341 25 1,91 1,856 3,449 17,214 1,440 18,654 26 1,591 1,858 3,449 17,385 1,440 18,876 27 1,591 1,858 3,449 17,559 1,440 18,999 28 1,591 1,85t 3,449 17,736 1,440 19,176 29 1,591 1,858 3,449 17,913 1,440 19,353 » 1,591 1,858 3,449 18,093 1,440 19,533 31 1,591 1,858 3,449 18,273 1,440 19,713 32 1,591 1,858 3,449 18,456 1,440 19,896 33 1.591 1,858 3,449 18,642 1,440 20,082 34 1,591 1,658 3,449 18,828 1,440 20,268 35 1,591 1,858 3,449 19,017 1,440 20,457 36 1,591 1,858 3,449 19,206 1,440 20,646 37 1,591 1,858 3,449 19,398 1,440 20,838 38 1,591 1,858 3,449 19,593 1,440 21,033 39 1,591 1,858 3,449 19,788 1,440 21,228 40 1,591 1,858 3,449 19,986 1,440 21,426 41 1,591 1,858 3,446 20,187 1,440 21,627 42 1,591 1,858 3,448 »;»? i,44û 21,828 43 I.SBi i.ôâè 3,449 20,592 1,440 22,032 %'-i i',a\ 1,858 3,449 20,799 1,440 22.239 45 1,591 1,858 3,449 21,006 1,440 22,446 46 1,591 1,858 3,446 21,216 1,440 22,656 47 1,591 1,858 3,449 21,429 1,440 22,869 48 1,591 1,858 3,449 21,642 1,440 23,082 49 1,591 1,858 3,449 21,858 1,440 23,298 SO ^___ 1,591 1,858 3,449 22,077 1,449 23,517

TOTAL 2,801 60,234 71,527 134,562 651,705 56.852 708,557 -137- '

The various investment, annual cost and benefit streams connected with irrigation development only have been presented in Tables 16-1A to 16-1D and 16-2A to 16-2D, in which the two levels of development and the two rates of development, as previously discussed, may be compared. The same information is shown in graphical form on Plates 20, 21 and 22. The resulting internal rates of return for each of the four combinations of level and rate of development are presented in Table 16-3 and also on Plate 23«

Table 16-3 - Internal Rates of Return - Percent

Level of development 250,000 acres 3,000,000 acres Rate of development Rate 1 Rate 2 Rate 1 Rate 2

Irrigation development only 9.6 IO.4 9.7 10.6 Irrigation development, plus processing at 20 percent return on book value 11.2 12.9 11.5 13.1 Irrigation development plus processing at 30 percent return on book value 12.0 I3.9 12.6 14.1

Note: Period of analysis is 50 years and residual values are disregarded.

Irrigation development and processing

It can be argued that the rates of return calculated in the preceding section might not present a fair measure of the profitability of the project. The benefits are based on a certain level of farm income, which, in turn, is based on ex-farm prices of agricultural produce or raw material. In some cases, the bases of valuing crops are somewhat unusual. For example, sugar cane, which is valued as standing mature cane, and kenaf, for which an ex-farm price as bundled green material was established. Such values, however, facilitate evaluation of the farmer's income. These ex-farm prices are such that processing is a profitable operation, as can be deduced from the fact that such plants already exist elsewhere in Kenya, using raw materials costing more or less the same. Since at least sugar cane has to be processed shortly after cutting, an additional calculation of internal rates of return has been carried out, taking into account the related benefits which oould be obtained from processing. As no refined calculations as to the exact type of plant and timing of construction could be made, the results should be considered as indicative only. Two alternative levels of benefits from processing are assumed, which bracket the range within which any development in this respect would probably lie. In justification of this approxi­ mate approach it may be noted that the assumed levels of return have been found to be acceptable to similar private enterprises. - — - „

'• i 1 1

i f i ! f i i 1 i ! f • 1 loiv :iopMtin •ATI t « rs. 1 1 1 "\ l MD.M O AC t» ! ƒ II .... ._j i _.. _. 4 7 two X> ACIC» 3 f I 1 X • Z A < 1 1 ' 1 ƒ • y\\ ~ i 1 1 >. j *x - ^ «ATI «> A\ '. MO. OO ACtCI OtVt[0PMKNT r " : 1 j ; \ l\ ƒ i ! \ ttO. IOO ACtCI \C- f ! 1 1 ƒ 1 'v '\ \ \ \ i \ L K l ^ 1 \ -4 \ , -W ^._ i 1

VIA«

«OVCINMCNT IF KtllVA UIÏITIO HATIONS »FECIAL FUNO NOTE: IMCLUDeS RllMVt»TMENT» FOI AGRICULTURAL MACHINERY. SURVEY OF IBII6ATI0N l'OTENTIAL LOW» TA0A RIVER BASIN FM» AH» MUCIATUH MUICATBW «f TUI UWTtOmlWB

IRBI6ATI0N DEVELOPMENT STREAMS OF INVESTMENT

PLATE 20 "UACO / ACRES

u^. ,., ,

—- T v »••.••< AMI» f •1 IIUIHII T 1WTI t \ v"»«i Acat*

_. t— 'vumiJMiin •» rt 4 ,

1 ! /

3 i ! \ s ! z 4 I • ~ i / S\ •

Y I Af

NOTE: INllUOC» COM Or OMVATION OF AtlICUlTUCAl MACHINtBY. OUT EXCLUDE» Alt OTHCf FAtM COSTS. tOVCBHMtHT or KENYA UNITED NATION» SMCIft rUNO SURVEY OF IRRI6ATI0H. POTeHTIAL LOW« TANA RIVES »A« h m* âm AMKuiutt miantia w m i

IKKI6ATI0N DCVCLOPMCHT ANNUAL COSTS ^^

»mem»

-^

^v/5^—- / ~1 »««OU llll/ / / / ) / \

/ / / / • '-< $ s /' 1 / • 1 ) "\ / \ i , / \ V . / / \ ' / / — ••— , ,.*s'*V — .— \_ C«»T» 't- ,^- -f • ^_ . ^MM • OH . «HB . , ^»•IM • « i^ • ^^«1 • > ^M^B • 1• » / / ' / /

tui »•VIINMINT IF KINYA (INITIO NATIONS »PtCIAl PUNO l ttlRO. NOTt: SUBVIY OF irtlCATION POTENTIAL CO»T» : TOTAL OF IMVtSTMENT ANO ANNUAL COSTS FOK 150.000 ACCÏ& ANO OtVHOPMtMT RATI 4. LOwte TANA tlVCC »ASin EXPtNOITMC»: CO»T» • fAKMCK»' INCOME. FM» AM* AMWATIMU KAAMttTmi *t TUI UBFTl» WW* »fntrn» fitT VALUE or AÜIICULTUCAL PÏOOUCI • etVtMUtS TO AUTHOtlTY. IKI6ATI0N DEVELOPMENT ANNUAL BENEFIT) AND EXPENDITIIR» TO AUTHORITY

.3BE P l AT* •-•'•! ttW^ >g»^Tt"/iM¥* " ', ' ,i. vmfiM i " ! ' ^

L t G e no 1 liHtnn i COSTS: TOTAL Or INVESTMENT AHO ANNUAL COSTS. tIPCNOITUir.) : COSTS • FABMtlS' INCOMt. ^ erntrns N[T VALUE or AGIICULTUIAL PIODUCE »UVENUtS 70 AUTHORITY.

r> ^ —T tl»l*»>V t™»/

1 j NOTE:

/ FOI «00.000 ACItS AND DEVELOPMENT RATE l / / / / - - / \ t ! f ï 1 / ! 1 t / 1 1 J / f i r A ! / •.•""" 1! ! / \ / f/~ ^'^ \ ! ! I ^ \ xr w / y -Ai: i_ \'r /- cjm»/ ' 1 fcOVEENHtNT OF KENYA A .-— UNITIO NATIONS SPECIAL runO A i. 1 y t SURVEY or ICBI6ATI0N POTENTIAL / — :... LOWCS TANA KlVCt BASIN -• y/ FOOS ABB AHtcmtuU MAAWUTIOII Of Tut UIMTIS MIU 1 - - - -t IRRIGATION DEVELOPMENT i j ANNUAL BENEFITS AND EXPENDITURES TO AUTHORITY

p i A T e it IL A CO / ACRES SNItT tHt -142-

Thc t"o alternative levels or processing benefits are expressed in terms of a return on average book value of capital investment in factory equipment and civil works, including staff and skilled labour housing* of respectively 20 and 30 percent. This return is assumed to be the difference between the gross ex-factory value of processed produce and the combined value of agricultural raw material at the factory, depreciation and costs for purchase of goods and services, such as fuel, spares, skilled labour and management. It thus includes interest claims on the capital invested, remuneration of unskilled labour and profits.

The investments which are required annually, and the corresponding book values, were obtained by means of rather schematic and simplified calculations, as explained hereinafter.

The amount of capital required to process the produce resulting from the selected crop rotation plan into sugar, cotton lint, bags, oils and cakes was found to be in the order of £ 200 per acre of fully productive land. Allowance was also made for a compounded annual increase of one percent in plant capacity to cope with the similar increase assumed for land productivity. The accumulation of the foregoing investments provided the appropriate value of available capacity at any stage as development expanded.

Factory and civil works were assumed to have an average economio life of 15 years, hence a stream of reinvestments similar to the original investment stream was taken into account with a time lag of 15 years. Total annual investment required for new capacity and renewals were called gross investment.

The linear depreciation method was used, and the depreciation allowance for each year thus amounted to 6-2/3 percent of the new value of available capacity at the end of the previous year. The difference between gross investment and depreciation allowance was called net investment, and the accumulation of net investments resulted in the book value of existing capacity.

To calculate the aggregate internal rate of return of irrigation development and processing together, the two streams of benefits, as defined above, were summed, whilst on the cost side the stream of net investments for processing was added to the investment plus annual cost stream for irrigation.

Schematic streams of aggregate costs and benefits for two of the eight possible combinations of levels and rates of development and returns from processing are shown on Plate 24* For all eight combinations the internal rates of return have been listed in Table 16-3 and are presented graphically on Plate 23.

16.2 Recovery of Costs from Beneficiaries

The charges to be levied on the farmers for the use of reclaimed land and the availability of irrigation water would depend on a variety of factors. One of these would be the farmers' capacity to repay which, in its turn, would depend on farm income and tenant target income levels. DISCOUNT BATE - PER CENT

L E 6 E tl O

BI IRRIGATION BENEFITS. DEVELOPMENT RATE t. B.2 IRRIGATION BENEFITS. DEVELOPMENT RATE Î. Cl TOTAL OF INVESTMENT AND ANNUAL COST» OF IRRIGATION DEVELOPMENT. RATE «. C.2 TOTAL OF INVESTMENT AND ANNUAL COSTS OF IRRIGATION GOVERNMENT OF KENYA DEVELOPMENT. RATE 2. UNITE» NATIONS SPECIAL FUND P MET INVESTMENT IN PROCESSING FACILITIES. SURVtY OF* IRRI6ATI0N POTENTIAL P.20 PROCESSING BENEFITS: 20 PER CENT OF BOOK VALUE OF INVESTMENTS. LOWER TANA RIVER BASIN P »O PROCESSING BENEFITS: 50 PER CENT OF BOOK VALUE OF INVESTMENTS. rtop Aito «ticuuim ottAniuTion OF THI unmo IUTIOIK

NOTES: INTERNAL KATES OF RETURN PERIOD OF ANALYSIS 50 VEARS. RESIDUAL VALUES AT END OF PERIOD DISREGARDED. 250.000 ACRES

PLATE 23 IL A CO / ACRES »MltT * 0' 1 o »e

« « n DISCOUNT BATE - PEK CENT

LEGEND

8 4 IBBI6ATION »ENEFITS. DEVELOPMENT tATE I. IEBI6ATI0N BENEFITS, DEVELOPMENT IATE » Cl TOTAL Of INVESTMENT AND ANNUAL COST» IP IttlûATIOH DEVELOPMENT.BATE <. C.ï TOTAL OF INVESTMENT AND ANNUAL COST» OF IB8I6ATI0N • OVttNHINT Of KENYA DEVELOPMENT. BATE I. URITfO NATIONS SPECIAL FUND NET INVESTMENT IN PEOCESSINO. FACILITIES. P SUBVEY OF I8BI6ATI0N POTENTIAL PtOCEiMI*. BENEFITS: 10 PEB CENT OF »OOK VALUE OF INVESTMENTS. P.IO LOWEB TANA Bivee BASIN P»o PBOCESSING BENEFITS:» PEB CENT OF »OOK VALUE OF INVESTMENTS. MM AH» ÀÉItUlTUtr WtAMgATmi » THE Ullino MTlDtll

NOTES: INTERNAL SATES OF SÏTUSN ?:::ss a «nâivâi» »o TEABS. S00.000 ACRES BISIOUAL VALUES AT END OF PEBIOP DI»BEBABOEO.

PLATE 23 IL A CO / ACtES <• 1HMT Jtf 1 -145-

On the other hand, the type of development envisaged is of such magnitude that it would"' not only involve a large number of other nori-agricultural people in the area but also provide considerable benefits to the country. This makes it unreasonable to expect the farmers to cover all of the annual costs of operating the project, and .. also to repay the capital cost. Such a course would be especially unfair to the ijjeéi generation of farmers. It would be reasonable to recognize that during the ini^rfal years many unexpected frustrations and disappointments would be encountered, which should not be aggravated by a high level of levies, rigidly imposed to meet a fixed repayment schedule.

Further, the proposed Tana River Irrigation Authority would presumably be responsible for research, for the training of staff and tenants and for the provision of extension services also. The cost of these tasks is included in the economic analysis. Since farmers in traditional farming areas usually do not pay directly the costs for demonstration farms and extension services, a similar approach might be advocated for the Tana development.

In view of these considerations, it is proposed a reverse point of view be adopted and tenant income be given priority over scheme debts, so that the pioneer farmers especially are induoed to contribute willingly the rigorous and sustained effort demanded by irrigated cultivation. Assuming that the scheme Authority will be a semi- governmental institution, backed financially by the Government, the financing of scheme debts can be achieved in various ways. In Seotion I6.4» one particular method of finanoing is discussed in some detail» PossiDie arrangements as to how charges on cultivators should be individually assessed and collected include:

(a) on measurements of the actual amounts of water used;

(b) at uniform rates per acre of holdings;

(c) at uniform rates per acre of each of the various crops grown;

(d) at a percentage of the actual or assessed value of the crops actually grown each year by each cultivator.

Each of these has merits and disadvantages, (a) Tends to economise in the use of water, but is not easy to apply in practice, especially with inexperienced cultiva­ tors, (b) Is very rigid, and puts all the risk of variations in yields (e.g. in bad years) on the individual cultivator, (c) Is similar, though slightly less so; it involves elaborate records, (d) Is fair to the cultivator, and flexible, but in application it involves centralised marketing of the crops to which it is applied; it is the method used in the Sudan Gezira Scheme, being applied there to the cotton crop.

Fo specific recommendations are made for a particular method. But the need to consider the point very thoroughly is stressed, so as to reach sound conclusions about it before development begins. Its implications are practical, social and economic.

I6.3 Tenant Income

In the studies made, the target level of tenant income was set at £ 160 per family. It was assumed that this level would apply to the very first farmers who start in the -146-

scheme area proper after a year of training i» +>>e P.esesreh ind Tz aluin« Centre.. Thermal lex-, it was assumed that the same annual increase in real income of 2 percent as adopted for scheme authority personnel, would also apply to the tenants.

"*>^hi8 could not continue indefinitely, because the productivity of the land was assumed to increase only at one percent per annum. Thus, in the course of time, the land use pattern would have to be changed toward maximizing output per farmer rather than per acre as assumed in the initial labour-intensive stage of development. How this change would be realized was not further discussed in the studies. For the eoonomio analysis, it was assumed that it would take place once tenant incomes reached a level of £ 250 per original five-acre holding. From then onwards, farmers' income would remain at £ 50 per acre. As it was assumed that lower yields would be obtained by farmers during the first two years of cultivation on new land, the same reduction was applied to income as well.

As discussed in Chapter XTV, nousing is a consumer good for which, in principle, users should pay the costs. The initial target level of income, however, is suoh that it would be almost impossible for a tenant to pay the full cost of the proposed type of housing. The relevant cost is estimated to be in the order of £ 40 P©r annum or 25 percent of the basic income level. In the finanoial analysis discussed in Section 16.4, a gradually decreasing rent subsidy to tenants by the scheme authority was taken into account.

16.4 Financial Analysis

The internal rate of return analyses made in the studies provided a macro-economic assessment of the situation. The financial analysis was based upon the concept that the authority had to take care of itself in the procurement of funds and in servicing them with project revenues remaining after all other payments had been made. The previous analyses of internal rates of return did not take into account the remunera­ tion of what might be called labour with zero return opportunity. In practice, however, the scheme authority would have to leave the farmers a sufficient part of the farm output as income, and processing industries would have to pay wages to the un­ skilled labour as well. This means that, in fact, the authority would require addi­ tional funds for quite a considerable period to finance the development programme (see Plates 22 and 24).

Hereunder, an attempt is made to set out whit are the implications of a particular form of financing. The basio assumptions and considerations have been as follows:

(a) Two form8 of funds have been distinguished, domestic and foreign loans. The types and terms of foreign loans available are restricted aüd less flexible than those which may be possible with funds obtained domestically. Therefore, by adopting certain alternative terms for the domestio component, the analysis leads to various conclusions as regards the possibilities which remain open for the foreign component.

Following the same procedure as in previous calculations, invest­ ments and annual costs for infrastructure and tenant housing have not been included. In Section 16.3, a gradually decreasing rent subsidy to tenants has been suggested. This subsidy has .

•••

It • * •latriT» ••>

1* ' "«• •• » - i:

=*~~ N ~i r~ * 5- ' s \ // t •• $ rt •>- X 1 M • V ! — n ^y i s8 J: ^" 7 ^ ^ ^ ^ _.^ 1 •N 1 / * * V • 4 C»T» s. • —""" • è V ... - 1

1 • www it «e M *• *i ' •» VI AI

I t GC NO NOTt: CO»T» : TOTAL Of INVt»THCNT ANO. ANNUAL C04λ FOI IttlGATION rot 1(0.000 ACBf.4 ANO DtVlLOPMtNT RATC 1. «NO HIT INVIÏTMtHT IN PIOUMIN6 fACILITHS tlPtNDITUtt»: CMTS • fACHt»' INCOMf AND WAGt» Or UNftKILLtD OtVltNMtNT Or KtNVA UNITt* NATIONS »PtClAl »UN» LAtOUl IN PBOCtSilN«. fctMtriTS NET VALUt Of A6IICULTUIAL PKOOUCt • ttVtNUt» TO SUBVtV Or I»BI6ATI0M POTENTIAL AUTNOtlTV • JO PCt CtNT ttTURN ON MOK VALUt Or 10W(S TANA BIVtC «ASIN invt»TMtNT m Pioctssmo rACiiiTieo. row An» AMICWTMC uttmxnm or m uaim «mom TOTAL ANNUAL BENErTTi AND'EXPENDITURES OF IRRIGATION AND PROCESSING

PLATE 24 !£_•_•__„ n. [_ IL A 1 oyActt» •MIT ( m % I "^ •intrus , S^

-^"

« *• S "

~0=

> —- E H .—- T' i

// s." / il S: / ! i i f -"* | i 1 = s .-/' ! / ^ S~ I / \ • 1 X ^

s ttw/ \.-, . ^•"""~ / . Y /

YEAR ttVERNMENT OF KENYA L E CENP NOTE: UN1TCP NATIONS SPECIAL »UfO COSTS: TOTAL OF INVESTMENT ANP ANNUAL COSTS FOR IRRIGATION FOR SOO.OOO ACRES AND SURVEY OF IRRI6ATI0N POTEIITIAL ANP NET INVESTMENT IN PROCESSING FACILITIES. PEVELOPMENT .RATE 1. LOWER TAMA RIVER »ASM EIPENPITURES: COSTS • FARMERS' INCOME ANP WAGES OF UHSKIllEO f000 AHO AttlCUlTUtt OttAIMATION OF THE UTII1 (S IUTBIIS LABOUR IN PROCESSING. BENEFITS: NET VALUE (IF AGRICULTURAL PROPUCE • REVENUES TO TOTAL ANNUAL AUTHORITY > SO PER CENT RETURN ON BOOK VALUE OF INVESTMENT IN PROCESSING FACILITIES. BENtflTS AND EXPCNDITUIteS OF IRRIGATION AND PROCESSING

PLATE 24 ILACO / ACRES SHItT II -149-

been assumed to be £ 20 per tenancy in the base year and to decrease by £ 1 per year, which amount is lower than the assumed two percent increase in real income. The real expenditures at tenant level for the scheme Authority start thus at £ l80 per five acres or £ 36 per acre. ¥hen the subsidy ends after 20 years, per-acre income would have reached a level of £ 47.60. Three years later it will have reached £ 50» at which level it is assumed to remain constant. The cost of wages for unskilled labour has been assumed tofbe one-third -- of the return obtained in processing, as defined in Section 16.1. ^

(c) Within the 50-year period of over-all analysis, two sub-periods have been distinguished. During the first period, I, total expenditures still exceed benefits, whilst during the second period, II, benefits exceed scheme expenditures for investments, operation, maintenance and payments to tenants and labour (see Plates 22 and 24).

(d) During period I, 50 percent of the deficits will be financed by domestic loans from the central Government, on which interest charges will not be paid, but accumulated to the outstanding, growing debt. Two alternative rates of interest have been used, as indicated in Table 16-4.

(e) The accumulated domestic debt at the end of period I will not be amortized, but perpetuated as a permanent loan. This procedure is acceptable as long as the perpetuated debt stands in good proportion to the residual value of the project at the end of the period of analysis.

(f) During period II» the excess benefits will be used in the first instance to pay interest on the permanent domestic loan. As it is possible that the benefits would not be sufficient to cover this charge during the initial years of period II, a temporary additional deficit could occur.

(g) As a result of the previous calculations, it appears that there would be a balance of deficits during period I and possibly during the first part of period II, and thereafter a balance of excess benefits.

It has been assumed that the stream of defioits woul be matched by foreign loans, which could be fully amortized out of the excess benefits by the end of the period of analysis. The internal rate of return corresponding to this "foreign finance" stream indicates the average rate of interest and the average maturity period at which foreign loans could be contracted. It does not, however, provide an answer as to how, in reality, certain types of foreign loans should be finanoed and refinanced. Insofar as, in practice, debt servioe on foreign loans - that is payment of interest or amorti­ zation - will be required during the period of continuous defioits, the assumptions used herein imply that these payments would be refinanced by additional loans.

Analyses have been made based upon.the foregoing for the two extreme alternative developments; that is, development of irrigation on 250,000 acres at the slow rate of development, and on 300,000 acres at the fast rate. In addition, the alternatives with processing included have been considered. The results of these various calcula­ tions have been summarized in Table 16-4« Table 16-4 - Specimen Representative Financial Analysis Irrigation Development

Irrigation Irrigation Unit development pitta development processing

Level of development acres 250,000 300,000 250,000 300,000 Rate of development 1 2 1 Return on investment in processing 20 30

Length of sub-periods=/ years 28/22 23/27 23/27 18/32

Rate of interest on dom«stic debt 0 3 0 3 3 6 3 6

Accumulated domestio debt, including million interest, at end of period I and £ 35 58 39 53 45 71 41 54 during period II

Residual value of assets at end of million period IlS/ £ 60 70 100 120

Annual interest charge on permanent million domestic debt during period II £ 0 1.7 0 1.6 1.3 4.3 1.2 3.3

Rate of return on foreign finanoe 1.0 0 1.5 0 4.5 1.0 8.0 5.5

Foreign debt still outstanding at million end of period II £ 27 21

l/ Period of analysis 50 years.

2/ Residual value obtained by assuming that Korokora dam and the irrigation, drainage and internal roads systems are well-maintained and still have a value close to their original construction cost. On-farm and processing investments have been taken at their book value. -151-

Frora the preceding analyses, the following conclusions can be formulated:

(a) When irrigation development alone becomes the responsibility of the scheme Authority, foreign financing is only possible at soft terms, provided the domestic funds are available to the Authority free of interest« Even low interest charges on domestic capital would exclude any payment of interest on foreign loans.

(b) The situation becomes more favourable when processing is included. In that case, more realistic types of foreign financing are possible. A prerequisite is, however, that the scheme Authority has full control over the processing activities, so that the profits therefrom are directly available for debt service.

I6.5 Estimate of Total Required Investment

Tables I6-5A to 16-5D present summaries of the order of total investment required for project development» including the related investments for trunk road, infrastruc­ ture, tenant housing and processing facilities.

16.6 Foreign Currency Aspect of Project Development

Expenditures in foreign currency are required for initial capital investments and reinvestments, maintenance of the various works and purchase of inputs for agricul­ tural production and processing.

Gross revenue consists of the sales value of agricultural production» of which part would be exported and the balance would save foreign currency by import-substitution.

For the irrigation or agricultural part of development, a summary of the situation with respect to costs and benefits is presented in Tables 16-6A to 16-6D. Therein, gross proceeds from the sale of agricultural produce have been calculated at the processed level, that is, in the form of sugar, cotton lint, and groundnut and cotton seed, oil and cakes. As import values for some products, such as sugar, may be some­ what lower than the ex-factory values, the foreign exchange value of agricultural produce has been taken at £ 125 Per acre in the base year (year 6 of the cash flow stream). The expenditure consists of 50 percent of the capital investments for the irrigation system, excluding the dislocation allowance and credit to farmers, and the annual running cost, which has been estimated at 15 percent initially. This latter cost is assumed to decrease gradually to 10 percent per annum. The foreign currency component of capital expenditure for processing has been taken at a similar level of 50 percent of gross investments.

The annual expenditures in agricultural production and processing for the purchase of goods and services such as spare parts for agricultural machinery, fertilizers, chemicals, fuels and, initially, expatriate managerial skill, have been estimated only approximately and taken as £ 20 per acre throughout the whole period of analysis. - 152 - TABLE I6-5A

TOTAL REQUIRED INVESTMENT RATE I - 250.000 ACRES . £ x I.000

COL. 2. 3. 4.

Y INFRASTRUCTURE E ' TOWNSITES A IRRIGATION AND PROCESSING DEVELOPMENT TRUNK ROAD R HOUSING FACILITIES TOTAL

I I.I50 1,700 800 3,650

2 2,350 3,400 1,200 6.950

3 3,700 3,400 2,000 9,100

4 4,500 4,000 8,500

5 6,150 4,000 1,500 11,650

6 5,100 4,000 1,750 10,850

7 2,200 4,000 1,850 8,050

8 2,150 4,000 1,750 7,900

9 2,300 4,000 1,650 7,950

I0 2,250 4,000 1,550 7,800

II - I5 10,500 20,000 6,150 36,650

I6 - 20 11,200 20,000 4,800 36,000

2I- 25 10,300 20,000 10,500 40,800

26 - 30 7,200 8,000 6,200 21,400

3I - 35 1,000 500 1,500

36 - 40 1,000 550 1,550 m - 45 1,000 600 1,600

46 - 5Û I.OUO 650 1,650

TOTAL 75,050 8.500 100,000 40,000 223,550 - -.; 153 -

TABLE I6-5B

TOTAL REQUIRED INVESTMENT RATE 2 - 250,000 ACRES £ x I,000

COL. I. 2. 3. 5.

Y INFRASTRUCTURE E TOWNSI TES 'A IRRIGATION AND PROCESSING R DEVELOPMENT TRUNK ROAD HOUSING FACILITIES TOTAL

1 1,150 1,700 800 3,650

2 2,350 3,100 1,200 6,950

3 3.700 3,100 2.000 9.100

1 1,500 1,000 8,500

5 6,150' 1.000 1.500 11,650

6 5,150 1.000 1,750 10,900

7 2,100 6,000 1,850 10,250

3 3,100 ."• -•-• 6,000 1,750 11.150

9 3,000 6,000 2,100 11,100

10 3,200 6.000 2.150 11.650

II - 15 19.200 38.000 12,250 ' '69.450

16 T 20 15.700 22.000 11.100 18,800

21-25 1,600 1,700 3,300

26-30 1.000 1.750 2,750

31 - 35 I.OOÖ 1.800 2.800

36 - HO 1.000 • 1.850 2.850

HI - 45 1.000 • 1.900 2.900

46 - 50 1.000 . 1 .950 2,950

TOTAL 76,500 8:500 100,000 16.000 231.000 - 154 -

TABLE I6-5C TOTAL REQUIRED INVESTMENT RATE I - 300,000 ACRES £ x 1,000

COL. I. 2. 3. t. 5.

Y INFRASTRUCTURE E TOWNS 1 TES A IRRIGATION AND PROCESSING R DEVELOPMENT TRUNK ROAD HOUSING FACILITIES TOTAL

1 1,150 1,700 800 3,650

2 2.350 3,400 1,200 6,950

3 3,700 3,400 2.000 9,100

4 4.500 4,000 8,500

5 6,150 4,000 1,500 11.650

6 5,100 4,000 1.750 10,850

7 2.200 4,000 1.850 8,050

8 2.150 4,000 1.750 7.900

9 2,300 4,000 1,650 7,950

10 2.250 4,000 1,550 7.800

Il - 15 10,500 20,000 6,150 36.650 " 16 - 20 11,200 20,000 4,800 36,000

21 - 25 10,300 20,000 10.500 40,800

26 - 30 10,400 20.000 8,300 38,700

31 - 35 7,400 8,000 2,900 18,300

36 - 40. 1,200 3,000* 4.200

41 - 45 1,200 3.100 4,300

"»6 - 50 l,2fK) 3,200 4.400

TOTAL 85,250 8,500 120,000 52/000 . 265,750 - 155 -

TABLE I6-5D

TOTAL REQUIRED INVESTMENT RATE 2 - 300,000 ACRES £ x I,000

COL. I. 2. 3. *.

Y INFRASTRUCTURE E TOWNSITES A IRRIGATION AND PROCESSING R DEVELOPMENT TRUNK ROAD HOUSING FACILITIES TOTAL

I 1.150 1.700 800 3.650

2 2,350 3.400 1.200 6.950

3 3,700 3.400 2,000 9.100

4 4,500 4.000 8.500

5 6,150 4.000 1.500 11,650

6 5.150 4,000 1.750 10,900

7 2,400 6,000 1.850 10,250

8 3,400 6,000 1.750 11,150

9 3,000 6,000 2,400 11,400

I0 3,200 6,000 2.450 11,650

Il - IS 19,200 38,000 12.250 69,450

I6 - 20 19,900 42,000 12.300 74.200

21 - 25 7,100 6,750 13,850

26 - 30 1.200 1.200 2,400

31 - 35 1.200 1,300 2,500

36 - 40 1,200 1.400 2.600

41 - 45 1,200 1,500 2,700

46 - 50 1,200 1,600 2,800

TOTAL 87,200 3.500 120.000 50,000 265,700 - 156 -

TABLE I6-6A FOREIGN CURRENCY ASPECTS.OF IRRIGATION DEVELOPMENT RATE I - 250,000 ACRES £ x I ,000

COL. I. 2. 3. 4. EXPENDITURES

Y IRRIGATION SYSTEM FARMING AND E INVESTMENTS PROCESSING A GROSS AND INVESTMENTS AND TOTAL BAUNCE R PROCEEDS ANNUAL COST ANNUAL COST (2 + 3) (1 -4)

I 600 600 - 600

2 1,200 1,200 - 1,200

3 1,900 1,900 - 1,900

4 2.300 2,300 - 2,300

5 3,050 750 3,800 - 3,800

6 950 2,400 1,100 3,500 - 2.550

7 2,100 1.100 1,450 2,550 - 450

8 3,400 1,100 1,650 2,750 + 650

9 4,700 1,200 1,900 3,100 + 1,600

I0 6.050 1,200 2.100 3,300 + 2,750

II - I5 51,400 5.500 13,800 19,300 32,100

I6 - 20 89.200 6,000 20,200 26,200 . 63,000

2I - 25 130,700 5,800 30,200 36.000 94,700

26-30 176,300 4.500 35.600 40,100 136.200

3I - 35 204,100 2.000 33,900 35,900 168,200

36-40 214,700 2,000 39,000 41,000 173,700

HI - 45 225,700 2,000 39.400 41,400 184.300

46 - 50 237.200 2,000 35,800 37,800 199,400 - 157 -••

TABLE I6-6B

FOREIGN CURRENCY ASPECTS OF IRRIGATION DEVELOPMENT

RATE 2 - 250,000 ACRES

£ x I,000

COL. I. 2. 3. ¥. 5.

EXPENDITURES

Y IRRIGATION SYSTEM FARMING AND E INVESTMENTS PROCESSING A GROSS AND INVESTMENTS AND TOTAL BAUNCE ; R PROCEEDS ANNUAL COST ANNUAL COST (2 + 3) (I -1)

i 600 600 - 600

2 1,200 1,200 - 1,200

3 1,900 1,900 - 1,900

1 2,300 2,300 - 2,300

5 3,050 750 r 3,800 - 3,800

6 950 2,100 1,100 ' 3,500 - 2,550

7 2,100 1,200 1,150 2,650 - 550

8 3,100 1,750 1,650 3,100 0

» 1,700 1,600 2,250 3,850 + 850

10 6,550 1,600 2,700 1,300 2,250

Il - 15 61,200 9,800 19,600 29,100 34,800

16 - 20 132,600 8,000 32,100 10,100 92,500

21 - 25 183,600 2,100 33,300 35,700 117,900-

26- 30 191,100 2,000 36,100 38,100 156,300

3II - 35 201,300 2,000 39,200 11,200 163,100

36-10 211,700 2,000 35,100 37,100 177,600

Il - 15 225,700 2,000 37,900 • 39,900 185,800

16 - 50 237,200 2,000 11,100 13,100 191,100 - 158 -

TABLE I6-6C FOREIGN CURRENCY ASPECTS OF IRRIGATION DEVELOPMENT RATE I - 300.000 ACRES £ x 1,000

COL. I. 2. 3. "*. 5.

EXPENDITURES

Y IRRIGATION SYSTEM FARMING AND E INVESTMENTS PROCESSING A GROSS AND INVESTMENTS AND TOTAL BALANCE R PROCEEDS ANNUAL COST ANNUAL COST (2 + 3) (1 -M)

1 600 600 - 600

2 1.200 1,200 - 1,200

3 1,900 1,900 - 1,900

M 2.300 2.300 - 2,300

5 3,050 750 3,800 - 3,800

6 950 2. MOO 1,100 3,500 - 2,550

7 2,100 1,100 I.M50 2,550 - M50

8 3, MOO 1,100 1.650 2.750 + 650

9 M.700 1.200 1,900 3.100 + 1,600

10 6,050 1.200 2,100 3.300 + 2,750

II - 15 51,MOO 5,500 13,800 19,300 32,100

16 - 20 89.200 6,000 20,200 26,200 63,000

21 - 25 130,700 5,800 30,200 36,000 9M.700

26 - 30 176,300 6.000 36,500 M2.500 133,800

31 - 35 226.100 5.000 M2.600 M7.600 178,500

36 - MO 257,500 3.000 MM.MOO M7.M00 210,100

Ml - M5 270.800 2.600 M5.700 M8.300 222,500

16 - 50 28M.600 2,300 M6.800 M9.I00 235,500 - 159 -

TABLE I6-6D

FOREIGN CURRENCY ASPECTS OF IRRIGATION DEVELOPMENT

RATE 2 - 300,000 ACRES

£ x 1,000

COL. I. 2. 3. *. 5.

EXPENDITURES V IRRIGATION SYSTEM FARMING AND E INVESTMENTS PROCESSING A GROSS AND INVESTMENTS AND TOTAL BALANCE R PROCEEDS ANNUAL COST ANNUAL COST (2 + 3) (1-4)

1 600 600 - 600

2 1,200 1,200 - 1,200

3 1,900 1,900 <- 1,900

4 2,300 .2,300 - 2,300

5 3,050 750 3,800 - 3,000

6 950 2,400 1,100 3,500 - 2,550

7 2,100 1,200 1,450 2,650 - 550

8 3,400 1,750 1,650 3.400

9 4,700 1,600 2,250 3,850 + 850

10 ^ 6,550 1,600 2,700 4,300 . 2,250

II - IS 64,200 9.800 19,600 29.400 34,800

16-20 132,600 10.000 32,700 42,700 89,900

21-25 208,100 4,500 42.500 47,000 161,100

26 - 30 233,700 3,000 41,400 44,400 189,300

31 - 35 247,600 2,800 45,200 48.000 199.600

36-40 260,200 2,600 45.900 48.500 211,700

41-45 273,500 2,400 43,600 46,000 227,500

46-50 287,500 2,300 47,400 49,700 237,800 -160- \.

16.7 Conclusions

The methods adopted for the economic evaluations and financial analyses made in the original project studies, the results of which are set out above, were, well suited to the purposes envisaged. These results will, however, have to be re-estimated and re-presented. In one respect, it is true, no major change in the basis of evaluation need yet be assumed; while the cropping pattern used in the studies is queried (see paragraph 9»6), other cropping patterns can be envisaged which can provide similar rates of net farm revenue per acre. To this extent, the eoonomio evaluations set out above remain valid. The need to consider other various points must be stressed, in particular the economie implications of providing incentives, financial and other, to attract cultivators, and to ensure adequate efficiency of production as well as social satisfaction.

The eoonomio evaluation made indicate internal rates of return ranging 'from 9,6 percent to 14.1 percent on the cost of the ultimate development, on various assump­ tions, as set out in Table 16-3. However, no economio appraisal can be regarded as fully adequate, which does not take into its scope all the various items of expen­ diture which are involved, directly or indirectly, in the development contemplated, so as to present a comprehensive pioture of the whole. In the case of the Lower Tana Scheme, aooount has to be taken of the costs of all items of the infrastructure and ancillary costs, as well as those items which are directly concerned with the development of irrigation. For convenience, the main figure are summarized as followst Assumed irrigable area - 250,000 acres E.A. £ million £,/acre Irrigation development 53.0 212 Processing plants 40.0 160 Housing, townsites and services 100.0 400 External trunk road (to Mombasa) 8.5 34

201.5 806

It is true that about half of this formidable total represents provision which might conceivably be necessary, if not on the lower Tana, then somewhere else in Kenya. However, expenditure on this scale, even though spaced over many years, cannot be contemplated without the most thorough and critical scrutiny. This scrutiny must include realistic appraisal under four main aspects, viz : (a) the standards of provision assumed, e.g. for housing, for roads, and for public services, such as water supply, sewerage systems, and so on; (b) the designs and types of material assumed, and the unit rates of cost involved in the execution of the works; (c) the production and benefits to be expected; (d) consideration of the resulting scheme and all its various implications, with the revised forecasts of its benefits, not merely on its own merits, but also in the broader field of the advantage to Kenya of undertaking such a scheme, and the degree of priority that it deserves in comparison with other potential investments in the country. -161-

Erom the financial analysis discussed in paragraph 16*4» the results of which are set out in Table 16-^4, the studies reached the following conclusions: (i) If the Irrigation Authority is responsible for the development of irrigation only, foreign financing is possible only on "soft" terms, and on the assumption that domestic funds are available free of interest. (ii) If the Authority is also responsible for processing, more realistic foreign financing becomes possible, provided that the Authority has full control of that processing. It will be noted that the financial analysis does not take within its scope the provision of infrastructure and the external trunk road to Mombasa. On the basis assumed, the analysis is clear and well presented, and there is no reason to disagree with the resulting conclusions (i) and (ii) above. It remains to be seen what conclusions «nay result from a revised appraisal and economic evaluation, following the re-consideration recommended in this report, in line with points (a) to (d) set out above. -162-

CHAPTER XVII

FURTHER STUDIES ABD INVESTIGATIONS

17«1 Requirements

The development of the water resources potential of the Tana river represents an undertaking so vast in terms of commitment of financial resouroes and manpower as to warrant the most careful consideration of all aspeots in muoh greater detail than has been appropriate under the terms of the studies made for the project. It is believed^ as discussed in earlier chapters of this report, that an economically viable power development of the middle Tana is possible. It must be recognized however, that economic evaluation of the irrigation potential has been based upon the results of only two years of agricultural experiments and trials« Hence, although, as discussed in Chapter XVI, a marginally economic development.of irrigated' agriculture may be postulated, there are a great many matters which require further investigation, particularly in respeot of irrigated cultivation, before undertaking suoh a major development«

The small irrigation projeot whioh was started at Qalole some ten years ago has since been operated by the Kenya Government essentially as a settlement scheme. At a later stage, it was set up as a pilot projeot for the development of a major scheme, but has yet to serve this purpose« At the present time, it requires a major overhaul of physical facilities, and of its organization and administration, if it is to function effectively.

As a result of the preliminary indications,apparent in the course of the projeot studies,that technically a large-scale irrigation scheme appeared to be feasible, the Government of Kenya has put in hand arrangements to rehabilitate the existing Galois scheme to serve as a small pilot demonstration unit« It is hoped that it will be possible to complete the refurbishment of the existing scheme before the end of 1968. Once oompleted, Galole may continue to serve as a pilot demonstra­ tion scheme, in which investigation of some of the many problems that remain to be solved can be undertaken. If a major irrigation development is to be undertaken, it is 'imperative that the agronomic investigations be oontinued and extended, both in time and space, to provide a sound basis for further assessment of its feasibi­ lity. -163-

Further agronomio studies are also necessary to extend the experimental results carried out under olose oontrol of research personnel to conditions of tenant farming. A study should be made of the systems of mechanization best suited to the requirements of smallholdings and to cropping patterns envisaged« Labour- intensive and mechanized cultivation practices should.be studied in further detail.

. Geomorphologie^ hydrologio and pedologio studies are recommended to evaluate further such matters as the possibility of creating, by irrigation, a perched water table, or of raising the generally deep groundwater level. Such information is necessary to ensure that the unfortunate experiences of water-logging and saliniza- tion whioh have occurred in other irrigation schemes can be avoided.

As indicated in the report, it has been necessary to plan for the cultivation of soils which must, in fact, be considered marginally suitable, even though satisfactory crop yields have been obtained on such soils under experimental trial conditions. These soils are generally saline and/or saline-alkaline at depth, and there is an urgent need to ascertain the feasibility or otherwise of reclamation measures to improve and maintain the fertility of subsoils over long periods of time, particularly in respect of soils of Class 3 suitability.

Whilst a technically sound irrigation scheme may be designed, its success or failure is ultimately dependent upon the peoples who must grow the orops and process them for market. Studies should be made of the methods and eriteria for selection of prospective tenants, their training, and of the rules and regulations under which the rigorous discipline necessary for irrigated cultivation may be successfully imposed.

Sinoe, as has been mentioned throughout this report, the irrigation scheme postulated herein is dependent upon developing a major series of dams and reservoirs to control and regulate the flows of the river, for hydro-electric power it is es­ sential that the planning and development studies for this power system be carried further. The additional investigations considered essential at this time are the proving of site foundation conditions at those sites recommended for development and, in oonsequence, the review and reconsideration of layouts and cost studies as presented herein. As a part of the general evaluation of the power system proposed for the Tana river, it is recommended that a system power study be made which will enable economies to be realized at various projects through recognizing more fully the function and capability to be achieved at each projeot. A re-appraisal of the load growth forecast will be necessary at the same time. It may well be desirable to inolude in these studies the effeot of interconnection of the coast with the Nairobi and western Kenya system and also, as has been indioated recently, the pos­ sibility of further interconnection between the Kenya and Uganda power grids.

The sociological implications of development have been referred to in this report. It is emphasized that the brevity of these discussions should not, by any means, be taken to be indicative of the relative importance attached to such factors. In faot, it is strongly recommended that the sociological aspeots of settlement of the proposed irrigation scheme in the lower Tana be investigated without delay, and also that, at the same time, the related matter of the displace­ ment and rehabilitation of the riverine Pokomo population be given due consideration. -164-

In order to as«««« *W« ?ooiolosicil, ëocrrc=ic. and financial i'üplioa'tluxiH of development, both at the scheme level and to the nation as a whole, detailed surveys and investigations must be carried out on communications networks, urban development, governmental services, project organization and administration, secondary production activities, processing facilities, warehousing and marketing of produce.

Further, and in particular, the proposed 8,300-acre pilot scheme should be primarily a productive unit rather than merely a centre for research and training. The technical design and layout of this should be undertaken as soon as its social, practical, and economic implications can be satisfactorily assessed, and its advanta- es and disadvantages realised. It should be appraised, both as a scheme in itself feven if it only so continues as such for a limited period of years), and as an instal­ ment of the full development, in both oases not only in its own merits, but also in comparison with other potential developments in Kenya, and thus receive its appropriate degree of priority in the national programme of development.

17»2 Ways and Means

Many, perhaps most, of the recommendations made in this report for the further collection of data, and of the use of such data in analysis and comparative studies, will involve work which can best be done by Government departments and agenoies in Kenya. It will primarily be for the Government to decide how far this course will be possible, and then in what manner and to what extent they may wish to seek for external help in carrying put the remainder of the work involved.

It appears desirable, however, to emphasize the importance of early action to resolve the various problems and carry out the various studies, so that planning for and decisions about this very large and important projeot can proceed without undue delay, and on sound foundations. -165-

ATPMPIX I

PLAN OP OPERATION UNITED NATIONS SPECIAL POND.

KENYA - SURVEY OF THE IRRIGATION POTENTIAL OF THE LOWER TANA RIVER BASIN

SUMMARY

Special Fund Allocation* S 974,100 Including: a) Special Fund Contribution (including Agency overhead costs) $888,500 b) Government payment towards local operating costs ? 85,600 Government Counterpart Contribution in Kind Equivalent of» $ 619,800

Duration t 3 years

Cooperating Government Agency« Ministry of Land Settlement and Vater Development

For the purpose of the survey of the Tana River basin for development of the irrigation potential to be undertaken by FAÖ acting.as the Executing Agenoy for the UN Speoial Fund, this Plan of Operation shall be the Plan of Operation provided for in Article I, Paragraph 2 of Agreement signed on 7th January I96I by.the Government of the United Kingdom, on behalf of the Government of Kenya, and the UN Special Fund.

* Agenoy overhead oosts and Government payment towards local operating costs are inoluded in the Speoial Fund Allocation. -166-

1. PURPOSE AND DESCRIPTION OF THB PROJECT

A. Purpose

1. The purpose of the Project is to provide for Government an assessment of the potential development of irrigated agriculture in the Lower Basin of the Tana River, which may facilitate the settlement there of surplus peasant people from densely inhabited areas elsewhere in Kenya. In the Lower Basin, extensive plains of empty lands, lying close to a good source of water for irrigation, offer natural prospeots for agricultural development at moderate cost. In the middle reaches of the river are the main potentialities of developing hydro-electric power. In the Upper Basin, the more rolling country offers better prospects of sites for storage reservoirs than the flat plains of the Lower Basin; some irrigation possibilities also exist there, which have in part been already developed. Although the present project relates only to development in the Lower Basin, it is clearly necessary in. the investigations to consider the whole basin of the river as one hydrological unit. The headquarters of the project will be in Nairobi.

B. Description

2. The period of the Project will be 3 years. The work to be done consists of the following items:

(i) Preliminary reconnaissance survey over an area estimated to be about 3 million acres, with the object of selecting areas, expected to be a total of about 0.6 million acres, for more detailed examination.

(il) Carrying out Ground Control, and basic levelling, and mapping of 600,000 acres of selected areas on suitable scales for soil surveys and other purposes of the project.

(ill) Semi-detailed soil survey over the areas to be mapped under (II). Selection and detailed soil survey of about 60,000 acres most suitable in location, topography and soils for the first development.

(IV) Location and preliminary survey and investigation of possible sites for storage dams, and for other major works for river control, such as barrages and canal headworks. The investigation will include geological studies and, when necessary, drilling. In the case of storage dams, the capacities of the reservoirs which they will provide will be estimated. -167-.

(V) Hydrologlcal investigations, using all existing data, and also the additional data to he observed under this Project, covering the Upper, Middle, and Lower reaches of the river (a) to estimate what amounts of water can be made available for the optimum use of the reservoirs found feasible under (IV), for existing and potential water usages in other reaches of the river, for irrigation, power and other purposes, such as the need to control flooding in the Tana Valley, (b) to examine as early as possible the effect on the regime of the Tana River, of the proposals for present and future hydro-electric development in the Basin, with particular reference to the Seven Porks Power Project, and to suggest to the Kenya Government, if possible before construction work begins at Seven Porks, any modification in the development of this site which might lead to improved water distribution. Close consultation with the appropriate Power Authority will be necessary during this part of the investigation.

(VI) Taking account of the results of (ill), (IV) and (v), (a), the assessment of the ultimate potential irrigable area in the Lower Tana Region and the preparation of an outline plan for its develop- ment, and (b) a preliminary layout plan of the area proposed for development in the first phase, expected to be about 60,000 acres. Por both (a) and (b) alternative schemes of agricultural cropping will be proposed, with estimates and discussions of their respec­ tive economic benefits, as detailed under (IV).

(VII) Agronomical studies will cover: a) land preparation and irrigation practices; b) research on crops, varieties and their rotations and their water requirements; o) methods of cultivation (sowing time, spacing, fertilizers, pest control, etc.): d) research on irrigated agriculture on the various types of soils available in the Project Area, including the. preparation, equipment and operation of several experimental plots.

(VIII) Technical Assistance to Government in Extending the experimental work on irrigation already being done on the Pilot Scheme at Galole, which is being enlarged by Government from 500 to 1200 acres. (iX) Economic evaluation of potential irrigation development a) Overall appraisal, lower Tana Basin; crop patterns, for each available soil type, which will best meet the country's economio needs. Most suitable sizes and types of farms. Rough estimates of full potential agricultural production and of cost of full development, including ancillary expenditure on Research, Health, communications, etc. b) Detailed economio assessment of selected 60,000 acres: Estimates of Project's initial and operational costs for alternative cropping schemes, with breakdowns by types of work, by years and by currencies. Estimates of farm costs and anticipated net farm incomes for each scheme. -168-

Estimated production by years, expected agricultural benefits, i-oooinmended governmental extension and credit policies.

(X) In-Service further training of Kenyan counterpart-staff, in survey and appraisal methods and in modern agricultural practices will be given a high priority.

(XI) Fellowships! Six one-year fellowships will be granted to Kenyan specialists for training in the various technical fields covered by the project.

(XII) Health, problems: In carrying out the investigations described above under (I) to (X), full account shall be taken of consider­ ations which may affect public health, particularly in respect of:

(a) the needs of water for domestic supplies as well as those for irrigation} (b) the present liability to bilharzia, fascioliasis, malaria, filaria and generally all water-borne diseases in the project area, and the probable effects on this of these diseases consequent upon the development proposed in river control and irrigation.

In so doing the Kenya Ministry of Health, the Department of Veterinary Services, and WHO shall be consulted.

II. WORK PLAN

A. Participation and Contribution of the UN Special Fund

3. The Special Fund will provide the following through the Executing Agency:

(l) Exports Man-Years

River Basin Development Engineer (Project Manager) 3 Civil Engineer (irrigation and Drainage Layout) 3 Hydrologist 2 Civil Engineer (Location and Design of Dams) 1 Engineering Geologist •§• Driller 2 Irrigation Agronomist (Cotton Specialist) 3 Research Agronomist 3 Soil Surveyors (2) 4 Soil Scientist 2 Agricultural Economist 2 Land Surveyors (4) 4 Consultants 1

Total man-years 29 s US$ 570,500 -169-

(II ) Fellowships - each for 1 year Man-Years Irrigation Engineering 1 Hydrology 2 Irrigation Agronomy 2 Agricultural Economics 1 •

Total man-years 6 - US$ 30,000

Fellowships awarded under the Plan of Operation shall be administered in accordance with the fellowship regulations of the Executing Agency. The Government shall- continue to pay salaries and allowances for fellows in Government service during the period of study abroad. Within the total allocation of $ 30,000 for fellowships, minor adjustments of individual fellowships may be made, if this is found to be in the best interest of the project. (ill) Equipment and Supplies US $ Equipment for trace clearing 22,000 Machinery for irrigation experiments, ) Checkgates, etc. ) 34,000 Pumps, pipes, etc. ) Soil analyses abroad 3,000 Hydrological equipment and pontoon 58,000 16 Landrovers, 2 two-ton trucks and 1 lab. truck 54,000 Camping equipment, including caravan, etc. 33,000 Equipment for soil testing, drilling, ) and experiment work, radio sets . ) Expendable supplies, (seeds, fertil- ) 45»000 izers, insecticides, etc.) not ) available locally ) Printing of maps and reports. 8,000

Total 257,000

The total cost of the equipment will not exceed $ 257,000. The Project Manager will establish the detailed list of equipment to be purchased under the above provisions, in consultation with the Co-Manager. -170-

(IV) Miscellaneous and Contingencies US $ To cover: Secretarial assistance ) Postal expenses and cables ) 30,200 Contingencies )

4. Sub-contracts The Executing Agency may provide the personnel mentioned in 3 (i) above, partly or wholly, through a sub-contract (or contracts) with a firm (or firms) of consulting engineers acceptable to the Government. Such a sub-contractor may also be asked by the Executive Agency to arrange, subject to the approval of the latter, the supply of part or the whole of the equipment to be paid for by the Special Fund, as under 3 (ill) above*. If so, such equipment, though used by the sub-contractor for the project, will remain the property of the Special Fund until the title to it is transferred as provided for in paragraph 38 below. A sub-contractor shall assume the same obligations as those devolved on the Executing Agency under Article II of the Agreement, referred to in the Preamble to this Plan of Operation. The overall responsibility for the parts of the Project entrusted to sub-contractors will however remain with the Executing Agency.

B. Participation and Contribution of the Government 5. Government contribution in kind (i) Counterpart personnel US $ Technical staff, including assistants for topographical and soil surveys, hydrology, engineering, agronomy, etc. for a total of 308 man-months 154,000 Health assistants, for three years each 14,000 Administrative and service staff 84,000 Drivers, labour and local contracts 50,000

302,000 (il) Equipment and Supplies Reconnaissance survey, including the preparation of 1:100,000 maps 25,000 Base lines and mapping, including precision levelling and reprinting of existing photographs and maps 25,800

* The purchase of such equipment, when paid for by the Special Fund, will be subject to the usual FAO rules and regulations for such purchases. -171-

(il) Equipment and Supplies (Cont'd) US $ Aerial photography at 1 : 20,000 scale of approximately 600,000 acres of selected areas mentioned in para. 2 (i), to be carried out by the Directorate of Overseas Surveys, on behalf of the Government 37,000 Special surveys, including dam sites 20,000 Agricultural equipment and supplies, locally available 10,000 Operation, maintenance and hire of vehicles 80,000

197,800

Particulars of the items to be supplied at the cost of the Government will be decided on by the Executing Agency in consultation with the Government, as soon as the circumstances permit in each case. (ill) Miscellaneous

Living and office accommodation and furnish­ ing for UN and Government personnel and labour. 30,000* Transportation, including insurance, within the country of personnel employed by the Executing Agency and by the Government. 10,000 Storage, transportation, handling and insurance within the country of equipment used for the Project and related expenses. 5,000 Research on consumptive use or other irrigation methods and practices to be conducted in the project area on existing irrigation schemes 75,000

120,000

6. The Government shall issue entry visas to the personnel of the Executing Agency and of the Executing Agency's contractors employed on the Project.

*Accommodation 1 House Project Manager existing 1 Office (PAO) Nairobi existing 1 House Co-Manager existing 1 Office (PAO) Galole 5,000 1 Lie s s Government 8,000 1 Office Government 5,000 1 Mess PAO. 8,000 Furniture etc. 4,000

Total 30,000 -172-

sucn personnel shall also have the right to the following:

immunity from legal process in respect of: all acts performed by them in the execution of the project;

immunity from national service obligations; immunity from immigration restrictions;...

the privilege of bringing into the country reasonable amounts of foreign currency for the purposes of the. Project or for personal use of such personnel, and of withdrawing any such amounts brought into the country, or, in accordance with the relevant foreign exchange regulations, such amounts as may be earned therein by such personnel in the execution of the project;

and

the same repatriation facilities in the event of inter­ national crises as diplomatic envoys.

7. All personnel of the Executing Agency's contractors shall enjoy inviolability for all papers and documents relating to the project.

8. The Government shall either exempt from, or bear the cost of, any taxes, duties, fees or levies which it may impose on any foreign firm or organisation which may be retained by the Executing Agency and on the foreign personnel of any such firm or organization in respect of: *

(a) The salaries or wages earned by such personnel in the execution of the project; (b) Any equipment, materials and supplies brought into the country in connection with the Agreement or which, after having been brought into the country, may be subsequently withdrawn there-from;

(c) furniture, personal property and household effects (including one privately owned automobile per employee), imported by the firm or organisation for its personnel for their personal use or consumption, in accordance with the terms of the first arrival privileges agreed between the Government and the Regional Representative of the UN Technical Assistance Board as being generally applicable to UN exports. -173-

9. The privileges and immunities to which such firm or organization and its personnel may he entitled, referred to in paragraph 6 of this Plan,of Operation,, may he waived hy the Executing Agency where, in. its opinion, the. immunity would impede .. the course of justice and can he waived without prejudice to the successful completion of the Project or to the interest of the Special Fund or the Executing Agency. The Executing Agency shall waive such immunity in any case in which the Managing Director of the Special Fund so requests.

10. The Executing Agency shall provide the Government with the list of" personnel to whom the privileges and immunities enumerated above shall apply.

11. Import of Equipment and Supplies

The Government will issue permits for the import free of customs dues of equipment and supplies.hy the Special Fund of UN for the Project through the Executing Agency, or will themselves pay the customs charges when the equipment or supplies are imported.

12. Other Obligations of Government

The Government of Kenya shall furnish the. Executing Agency with such relevant., documents, accounts, records,.statements, and other information, as the Special Fund . may request concerning the execution of the Project, or concerning the compliance by the Government of Kenya of its responsibilities under this Plan of Operation. After the completion of the Project, the Government will also make available to the Executing Agency all information necessary or appropriate to an evaluation of the benefits derived from and activitie.s undertaken to further the purpose of that project.

13. Local Operating Costs

With reference to the payments to be made by the Government under Article V, paragraph 1 (a) to (d) of the Agreement referred to in the Preamble.of. this Plan of Operation, excepting the costs within the country of the storage and transportation of equipment and supplies for the Project, which are counterpart contributions, the Government shall pay to the Special Fund, in local currency, the equivalent of US $ 85,600, towards local operating costs. This amount represents 15$ ..of the total estimated cost to the Special Fund of foreign project personnel. The equivalent of the above amount shall be deposited by the Government in local currency to the credit of the Special Fund account with.the Midland Bank Ltd., 60 Gracechurch Street, London, E.C.3 (Acct. No. 1039)» in accordance with the following schedule :.

Equivalent of US $ 5,000 on signature of the Plan of Operation Equivalent of US $ 12,100 on.or before 1st August 1963 Equivalent of.US S 31,800 on.or before 1st January 1964 . Equivalent of US. $ 26,750: on or. before 1st January 1965 Equivalent.of US.$ 9,950 on or before.1st January 1966 -174-

C. Organization

14« Overall responsibility for the organization and execution of the Project rests with the Executing Agency who shall plan and direct operations through the Project Manager appointed by the Executing Agency and acceptable to the Government.

15. The Minister of Land Settlement and Water Development will represent the Govern­ ment on the Project as far as matters related to Government policy are affected. He shall appoint a senior technical officer of his Ministry acceptable to the Executing Agency as Co-Manager.

16. The team of experts of the Executing Agency shall be attached to and work in close cooperation with the Ministry of Land Settlement and Water Development.

17. All equipment and supplies provided under the Plan of Operation shall be used exclusively for the execution of the Project during its currency. The movement of such equipment and supplies shall come under the authority of the Project Manager.

18. The Project Manager, under the general supervision of the Executing Agency, shall be responsible for the detailed planning, administration and execution of the Project, including timing and budgeting of the various elements, the preparation of technical reports, and the organization and supervision of related training programs. In undertaking these responsibilities the Project Manager shall work closely with the Co-Manager.

19« The Ministry of Land Settlement and Water Development shall ensure co-ordination of the work of governmental and other organizations which may be called upon to part­ icipate in, or carry out, work related to the Project.

20. Selection and employment of counterpart personnel and of candidates for fellow­ ships shall be made jointly by the Project Manager and Co-Manager.

D. Sequence of Operations

22. The Executing Agency shall begin execution of the Project upon receipt of written authorisation to do so from the Managing Director of the Special Rind.

23» Immediately after the Project becomes operational the Executing Agency shall proceed with the employment of experts as foreseen in Paragraph 3 of this Plan of Operation and shall place orders for vehicles, equipment and supplies required for the Project. If it is decided to carry out part or all of the Project by sub-contract with a consulting firm, the Executing Agency shall select and submit to the Govern­ ment the names of a limited number of consulting firms which it wishes to consider for employment on the Project. After receiving clearance from the Government for the employment of any of these consulting firms, the Executing Agency shall initiate negotiations with them, and after selection of the most favourable offer, will conclude a contract accordingly for the part of the work to be carried out by sub­ contract. -175-

24. Upon the arrival of the Project Manager in Kenya, the Government shall take immediate steps to appoint the Co-Manager, to assign to the Project the necessary counterpart and other personnel and labour, to make available the necessary services, and to place orders for equipment and supplies to be provided by Government, all in accordance with the terms of'this Plan of Operation. The date of arrival of the fully appointed Project Manager in Kenya will be taken as the date from which the period of the project will be measured.

25. A detailed Work Plan for the first year of operation of the Project will be prepared by the Project Manager in collaboration with the Co-Manager, within two months of the arrival of the Project Manager in the country or the appointment of the Co-Manager, whichever is the later. Similar Work Plans shall be prepared each year by the Project Manager in collaboration with the Co-Manager not later than 1st December, to cover the following year. These V/ork Plans shall include overall schedules for the project operations, detailed lists of equipment, supplies and materials to be purchased, staffing plans, and arrangements for transport and other services.

26. Within tv/o months of the signature of the Plan of Operation, the Government shall make available to the Executing Agency two sets of all existing aerial photographs, photographic lay-downs, and topographical survey maps covering any part of the basin of the Tana River, as well as all existing reports and documents relevant to the Project.

27. Within one month of his arrival in Kenya, the Project Manager shall, in collabor­ ation with the Co-Manager, initiate the collection of existing data, reports and other information, and the starting of preliminary studies. These will follow the first general reconnaissance of the project area, to cover the main aspects of the project, including topography, hydrology, soils, existing land use, forest, grasslands and crops. On the results of this reconnaissance will be selected the areas for basic levelling and mapping and for semi-detailed soil survey, as described in paragraph 2 (il) and (ill). At the same time will be selected the potential site for storage reservoirs, dams, and other major works, to be surveyed on larger scales and examined more closely, as described in paragraph 2 (TV). Hydrological investigations, including the location and installation of any additional gauging stations necessary, will also be initiated, in accordance with paragraph 2 (v) above.

28. As soon as progress with the various surveys and investigations makes it possible, the total area which is potentially irrigable in the Lower Tana in respect of topo­ graphy, soils, water, and agricultural economics, will be determined, and from this area will be selected a part, expected to be about 60,000 acres in extent, to be proposed for development in the first phase. More detailed studies, planning, and estimates for this part will then be carried out, in accordance with paragraph 2 (Vi) to (IX) above.

29. A tentative timetable showing the timing of employment of the various specialists is given in the diagram below; this will be subject to review and modification, within the total or man-years of export services, with the preparation of each suc­ cessive Work Plan. The commencement of operations is cheduled for 15th May 1963. -176-

Specialist . 1963 1964 1965 1966

Bàsin Development Engineer

Civil Engineer - Irrigation and • - Drainage layout

Hydrologist

Civil Engineer — Dams

Engineering Geologist

Driller

Irrigation Agronomist (Cotton Specialist)

Re search.Agronomist

Soil Surveyors

Soil Scientist

Agricultural Economist

Consultants ? 7 ? •• ?

Land Surveyors

30. During the course of all surveys and investigations, every opportunity will be taken to train further the Kenya counterpart personnel. Training will include lectures, laboratory or drawing office work (where applicable) and field work. Details will be decided by the Project Manager and Co-Manager in consultation with the specialists concerned in each particular case.

31. Candidates for fellowships will be selected by the Project Manager and Co-Manager jointly as soon as possible in the course óf the training programs= After completion of their fellowship studies they will be engaged on the work of the project in their respective fields, bearing increased shares of responsibility according to their abilities. -177-

III • BUDGET

32'.' In. addition to the' services and facilities described in paragraph 5 -above', which shall be provided in kind to the. project by ,the Government and estimated to cos1!; an amount of E.A. Shillings" equivalent to US '$ 619,800 as detailed in Appendix II, the estimated total cash project budget amounting to. the equivalent of US $ 974,100. will consist."of. the following:

(a) the gross cost of exports, fellowships, contractual services, equipment and miscellaneous expenses, described in paragraph'3 , above to be met by the Special Fund and amounting .to an estimated - ; total of US $ 887,700 which includes an amount estimated at the equivalent of US $ 85,,600, "representing ,cash payments in local \ currency tto be made by the Government to the Special Rind towards ; local operating costs described in paragraph 13 above (see "" Appendix I)

(b) the overhead costs of the Executing Agency US $ 86,400 to be met by the Special Fund (See Appendix i).

IV REPORTS

33« The Executing Agency shall submit to the Government the following reports on the Projeot:

(a) an Inception Report, to be supplied not more than 6 months after the initiation of the project,"'containing the/results of the preliminary reconnaissance surveys arid propo'saTs on the further planning of the Project;

(b) an Annual Report to reach the . Government by/ï,lïarch each year, covering the period of the previous calendar year;

(c) a Mid-year Report to reach the Government by 1 September each year, covering the work up to 30 'June of that'year; and

(d) a Final Report after the project has ended.

34« The Government shall submit to the Executing Agency annual progress reports at the end of each year and a final report at the conclusion of the operation-of-the Project.

35» The Government and the Executing Agency jointly shall submit to the .Special Fund at the end of each calendar year a certified inventory of equipment purchased"with the funds allocated by the Special Fund. -178-

V CONCIPSIONS

36. Upon completion of the Project, a report will be submitted by the Government to the Executing Agency and the Special Fund on the benefits derived from the project and the activities planned by the Government to further the purpose of the projeot.

37« After the completion of the Project, the Government undertakes to continue research programs and investigations on all major aspeots of the Project which will have been studied during its course, so far as it may find these feasible in the circumstances of the time.

38. At the successful conclusion of the Project, the Government, the Executing Agency and the Special Fund, will consult with a view to transferring the title to the equipment from the Special Fund, in whose name it has been held by the Executing Agency, to the Government or an Agency nominated by the Government«

Agreed on behalf of the parties by the undersigned«

For the Government of Kenya For the UN Special Fund

N. S. Carey Jones George Ivan Smith Permanent Secretary - Ministry of Land Settlement and Water Development

Date 11 April 1^63 Date 2 May 19.63

For the Food and Agriculture Organization of the UN

Norman C. Wright Deputy Director-General

Date 2 April 1963

röx' tlio uOvoi'iuuônt öi. A.enya

Jomo Kenyatta

Date 2 April 1963 -179-

APPENDIX II

LIST OP PROJECT STAFF

Project Managers R.W. Walker/C. Freyburg Project Co-Managers I.D. ¥atts/G. Manig Irrigation Engineers H.D. Ayers/J. De Wolf Hydrologist Engineer J.B. Kirch Dam Engineer G. Mitchell Geologist L. Holofsky Senior Soil Surveyors J. Schilstra/K. van de Meer Soil Surveyors K. Tanis/F. Voncken/T. Pompen Soil Chemists A. Muller/H.A. Leyder Research Agronomist G.A. Kan Cotton SpeoialistB L. Bannink/Q.J. Kerkhouen

Irrigation Specialist C.U. Freyburg Economist V.J.M. Joosten

Administrative Offioers V.R. Kibble/R. Marshall Chief Draftsman R.H. Randall -i8ó-

APPENDIX III

FELLOWSHIP AWARDS

Countries Name Field of Study of Date Date Study Begun Concluded

Alex Augustine Ojwang Irrigation Agronomy and Sudan 20.9.65 19.3.66 Agricultural Production Vijay Kumar Duggal Irrigation Engineering U.S.A. 22.2.65 5.IO.66 Canada Pravinehandra Juthalal Hydraulic Structures U.S.A. 16.5.65 22.6.66 Shah Canada Prawin D. Shah Hydraulio Engineering Nether- I7.IO.65 21.9.66 lands

Jilo Francis Saiseli Irrigation Scheme Menage- Sudan 1.10.65 18.5.66 ment Israel

A.M. Benjamin Irrigation' Agronomy Israel - 1*7.66 25.9.66 S.S. Yako Irrigation'Agronomy Israel i.7*66 25.9.66 -181-

APPENDIX IV

REFERENCES

1. Climatic Seasons of East Africa. Pamphlet Series No. 8, East African Meteorolo­ gical Department, January, 1962. Z» The Natural Resources of East Africa. Edited "by É.W. Rüssel, East African Literature Bureau, June, 1962. 3. Shape of the Submiocene Erosion Land in Kenya. W. Pulfrey, Bulletin No. 3, Geologic Survey of Kenya, I96Ö.

4. A Preliminary Report on a Survey of the Fisheries of the Tana River, Kenya. M.J.' Mann, East African Freshwater Fisheries Resëaroh Organization, April, 1966. ••-'•"• --.-'-.

5. Unpublished filési BP-Shell Petroleum Development Company of Kenya, Ltd. Mombasa. 6. Report Nó. 15. F. Diiëy, Geological Survey of Kenya., 1948. 7. The Geology and Mineral Resources of Kenya (revised). W. Pulfrey, Geological Survey of Kenya, Bulletin No. 2, i960. (A more up-to-date and detailed aocount of Kenya's mineral resources was in press in April, I966, and should he" available from the Geological Survey of Kenya in the near future).

8. The Geology of East Africa. E.P. Saggerson, the Natural Resources of East Africa, edited by E.W» Russell. East JLfrioän Literature Bureau, 1962. 9. East Afrioan Plateaux and Rift Valleys* B. Willis, Carnegie Institute of Washington, Studies in Comparative Seismology, Noi 470, 1936« . 10« Soil Classification, A Comprehensive System, Seventh Approximation. United States Department of Agriculture, I960. 11. Development Plan, 1965-1970. Government of Kenya. -182-

12. The Natural Resources of East Africa. Edited by E.W. Russell, Kenya, June, i?62.

13* upper Tana Catchment Water Resources Survey. Government of Kenya, Sir A. Gibb . and Partners (Africa), Kenya, April, 1959« 14* Reassessment of Seven Forks Hydro-electrio Project, Kenya. Pover Securities Corporation Ltd., Balfour, Beatty and Company, Ltd., London, August, 1964* 15» Seven Forks Hydro-electric Projeot. East African Power and Lighting Company, Ltd., Balfour, Beatty and Company Ltd., London, August, 1964. 16. Survey of the Irrigation Potential of the Lower Tana River Basin, Kenya. Interim Report,- Advance Information on Seven Forks Storage and Operation, FAO, July, I965. 17. Survey of the Irrigation Potential of the Lower Tana River Basin, Kenya. Interim Report, FAO, September, 1965* 18. Seven Forks Hydro-electrio Project, Reservoir Development, Geology Report. East African Power and Lighting Company Ltd., Balfour, Beatty and Company Ltd., London, February, 1962* 19« Seven Forks Hydro-electrio Project, Gtaru Development, Geology Report. East African Power and Lighting Company Ltd., Balfour, Beatty and Company Ltd., London, June, 1963* 20. Seven Forks Hydro-electric Project, Kindaruma Development, Geology Report. East African Power and Lighting Company Ltd., Balfour, Beatty and Company Ltd., London, June, 1963* 21. Estimates of Maximum Demand and Memorandum on Plant Provision, 14th Edition. East African Power and Lighting Company Ltd., Nairobi, Hay, 1963. 22. Report on Harket for Electricity. East African Power and Lighting Company Ltd., Merz and McLellan, London, February, 1964« 23. Reassessment of Seven Forks Hydro-eleotrio Development Plans submitted with Water Permit Application. Power Securities Corporation Ltd., Balfour, Beatty and Company Ltd., London,. May, I960« 24. Seven Forks Project, Kenya. Notes on Economic Irrigation Storage at Seven Forks (revised). Tana River Development Company Ltd., Balfour, Beatty and Company Ltd., London, March, 1965*

25« CA.TIA/H aw Power Develops!ent Concept-s — A Challenge. T.R. Anand, E.I.C. Journal, May, 1965. 26. Gezira - A Story of- Development in the Sudan. Arthur Gaitskell, Fab er and Fab er, London, 1959.