Hydrometry Project - Somalia
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OVERSEASDEVELOPMENTADMINISTRATION • MINISTRYOFAGRICULTURE,GOVERNMENTOFSOMAUA HYDROMETRY PROJECT - SOMALIA Final Report Phase 3 Sir M MacDonald&PartnersLimited DemeterHouse,StationRoad,CambridgeCB12RS UnitedKingdom in associationwith InstituteofHydrology Wallingford,OxonOX108BB UnitedKingdom February1991 OVERSEASDEVELOPMENTADMINISTRATION MINISTRYOFAGRICULTURE,GOVERNMENTOFSOMAUA HYDROMETRYPROJECT-SOMALIA FinalReport Phase3 Sir M MacDonald&PartnersLimited DemeterHouse,StationRoad,CambridgeCB12RS UnitedKingdom inassociationwith InstituteofHydrology Wallingford,OxonOX108BB UnitedKingdom February1991 CONTENTS LIST Page Nr SUMMARY S-1 INTRODUCTION 1.1 Background to Project 1.2 Scope and Layout of Report 1.3 Terms of Reference aud Outline of Extent Achieved 1.4 The Hydrology Section - Current Position 1.4.1 Staffing 1-5 1.4.2 Data and Office Equipment 1-5 1.4.3 Field Equipment 1-6 HYDROLOGICAL REVIEW 2.1 The Hydrological System in Southern Somalia 2-1 2.1.1 Introduction 2-1 2.1.2 The Jubba 2-2 2.1.3 The Shebelli 2-3 2.2 The Hydrometric Network in Southern Somalia 2-3 2.2.1 General Development of the Network 2-3 2.2.2 The Jubba 2-5 2.2.3 The Shebelli 2-7 2.3 Data Analysis 2-9 2.3.1 Data Availability 2-9 2.3.2 Data Quality 2-10 2.3.3 Normal Flow Patterns 2-10 2.3.4 Flood Events 2-11 2.3.5 Flow Variability and Trends 2-13 2.3.6 Reliable River Flows 2-15 PROJECT ACTIVITIES AND GENERAL OPERATIONS 3.1 Introduction 3-1 3.2 Staffing 3-1 3.2.1 Expatriate Staff 3-1 3.2.2 Local Staff 3-2 3.2.3 Supervision 3-2 3.3 Field Work 3-2 3.3.1 General 3-2 3.3.2 Station Maintenance 3-3 3.3.3 Discharge Measurements and Rating Curves 3-4 3.3.4 Water Quality Measurements and Analysis 3-4 3.4 Office Work 3-11 3.4.1 General 3-11 3.4.2 Data Processing 3-11 3.4.3 Modelling and Forecasting 3-12 3.4.4 Publication and Dissemination of Information 3-15 3.5 Training 3-16 3.5.1 General 3-16 3.5.2 Overseas Training 3-16 CONCLUSIONS AND RECOMMENDATIONS 4.1 Achievements of Project 4-1 4.2 Future Needs 4-1 4.2.1 The Hydrology Section 4-1 4.2.2 The Water Sector in Somalia 4-2 4.3 Postcript 4-3 BIBLIOGRAPHY APPENDICES A Terms of Reference List of Project Reports and Publications Progress Report May-December 1990 Data Book Supplement and Review of 1990 Data Water Quality Data Rating Curve Development Inventory of Project Equipment Circulation List for Hydrometric Data Book. Computer Programs Hydrology Section General Operating Instructions Details of Current Gauging Stations Example 10-Day Bulletin from Food Early Warning System Project. Summary Data Tables LIST OF TABLES Page 2.1 Monthly Mean and Median Flows 2-12 2.2 Annual Maximum Daily Mean Flow for Upstream Stations 2-14 2.3 Estimated Flood Peaks for Various Return Periods 2-15 3.1 Discharge Measurements Carried Out During Phase 3 of the Project 3-5 3.2 Analysis of Total Suspended Sediment Load (example calculations) 3-8 3.3 Results of Sediment Sample Analysis (River Shebelli at Afgoi) 3-9 LIST OF FIGURES Following Page 1.1 Location Map 1-2 2.1 Major Drainage Basins of the Horn of Africa 2-2 2.2 General Topography of the Horn of Africa 2-2 2.3 Mean Annual Rainfall over the Horn of Africa 2-2 2.4 Typical Hydrographs - Jubba and Shebelli Rivers 2-2 2.5 River Shebelli Catchment Area Map 2-4 2.6 River Shebelli Catchment Area (Development of Area with Length) 2-4 2.7 River Shebelli Mean Annual Discharge (Change Along Length of Main River) 2-4 2.8 Average Percentages of Original Data Available, 1963-1989 2-10 2.9 Monthly Normal Flows - Jubba and Shebelli Rivers 2-12 2.10 10 Day Normal Flows - Upstream Stations, Jubba and Shebelli Rivers 2-12 2.11 10 Day Normal Flows - Comparison of Upstream and Downstream Stations, Jubba and Shebelli Rivers 2-12 2.12 River Jubba Discharges 1981 2-14 2.13 River Shebelli Discharges 1981 2-14 2.14 River Jubba at Lugh Ganana, 1977 and 1980 2-14 2.15 River Shebelli at Beled Weyn, 1980 and 1981 2-14 2.16 River Shebelli at Afgoi, 1968 and 1980 2-14 2.17 Annual Mean Discharge and 5-Year Running Mean, River Jubba 2-14 2.18 Annual Mean Discharge and 5-Year Running Mean, River Shebelli 2-14 iv LIST OF FIGURES (Could) Following Page 2A9 Annual Maximum Flow and 5-Year Running Mean, River Jubba 2-14 2.20 Annual Maximum Flow and 5-Year Running Mean, River Shebelli 2-14 2.21 10 Day Exceedance Rows - River Jubba 2-16 2.22 10 Day Exceedance Rows - River Shebelli 2-16 3.1 Sediment Measurements at Afgoi 3-8 3.2 Salinity Measurements at Afgoi 3-8 3.3 River Shebelli at Afgoi 1989/90 - Discharge and Sediment Load 3-8 3.4 River Shebelli at Afgoi 1989/90 - Discharge and Salinity 3-8 3.5 River Jubba - Discharge and Satellite Estimate of Rainfall 3-16 3.6 River Shebelli - Discharge and Satellite Estimate of Rainfall 3-16 Note on Place Names For almost all places in Somalia there are a number of alternative spellings - both in the Somali and in the Italian or English equivalents. In this and other Phase 3 reports we have tried to be consistent and to use the same spelling for each place throughout. In general the most widely accepted anglicised spellings have been used. In the case of the river Jubba an alternative spelling has been retained in reference to the Juba Sugar Project since that is the spelling used in that project's official title. Acknowledgements The Consultants would like to thank the Overseas Development Administration and the British Development Division in East Africa for their financial support of and continuing interest in the Project. Thanks are also due to many people in the Ministry of Agriculture for their support and assistance - and most of all to the Director of Irrigation. SUMMARY This report describes work carried out during Phase 3 of the Somalia Hydrometry Project between March 1988 and December 1990. This followed two earlier phases of the Project between November 1983 and June 1986, and it marks the completion of support from the Overseas Development Administration for the work of the Hydrology Section of Somalia's Ministry of Agriculture. In addition to a summary of work carried out, this report contains a review of the hydrology of southern Somalia, with particular reference to the Jubba and Shebelli rivers. An appendix lists all reports and publications produced by the Consultants during the three phases of the Project. Support was provided for all aspects of the work of the Hydrology Section, with particular emphasis on the training of local counterpart staff in field and office work so that they would have the capability to continue the collection, analysis and dissemination of hydrological data after the conclusion of the Project. At that time it was considered that reasonable success had been achieved, though the security situation was restricting fieldwork. Subsequently, however, the outbreak of extensive fighting in Mogadishu left great uncertainty about the position. This development is only referred to in a postcript to the report. During the Project, all historic river level and flow data was critically examined, with corrections to the previously accepted record being made where appropriate, and missing values infilled wherever possible. Computer models were developed to assist in this procedure, and these should continue to be of value in the future. Models were also provided for forecasting river levels and flows which should improve warnings of impending floods. All data is stored on a microcomputer in the Ministry of Agriculture, using a specialised hydrological database package; daily and monthly flow data has also been published. Fieldwork concentrated on the maintenance of gauging stations and the measurement of discharge. All rating equations were reviewed and some changes were made; full details are presented in an appendix to this report. The fieldwork programme was severely limited during the second half of Phase 3 by the travel restrictions which resulted from the deteriorating security situation in Somalia. Howe ver, sediment levels were measured regularly at a nearby station on the river Shebelli. In addition to the on-the-job training of counterpart staff, it was planned that there would be some academic and practical training in the UK. Unfortunately this did not materialise, though two local staff members did travel to courses overseas with funding from other organisations. However, neither of these people returned to their previous jobs, so the Hydrology Section did not benefit from their training. As detailed in the report, the non return of trainees had a negative impact on the attempts to arrange training using the British Council funding which had been allocated to the Project. S-1 The report concludes that further external support is required if the important work of the Hydrology Section is to continue in full. However, as noted in the postcript, such support is not likely to be forthcoming in the immediate future because of the developments in January 1991 which resulted in the departure of the British and other diplomatic staff, together with almost all other expatriates. A mission should be undertaken as soon as practicable so that the needs of the Hydrology Section can be reviewed in the light of recent developments. S-2 CHAPTER 1 INTRODUCTION 1.1 Background to Project In 1983 the Ministry of Agriculture (MOA) of the Government of Somalia in Mogadishu requested assistance from the British Government to maintain and improve its collection of hydrometric data.