Study on the Enhancement of Flood Early Warning System and Installation of Additional Equipment in the Kainji Reservoir Zone )>,Version En Anglais

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ROYAL HASKONING

HASKONING NEDERLAND B.V. WATER World Bank a l'attention de M. Ousmane Dione 1818 H Street, NW Barbarossastraat 35 Washington, DC 20433 Botte Postale 151 USA 6500 AD Nijmegen les Pays-Bas +31 (0)24 328 42 84 Telephone Votre reference -- +31 (0)24 323 16 03 Fax Notre reference 9R8996.B0/L0097/403030/Nijm [email protected] E-mail Numero direct :+31 (0)24 328 4289 www.royalhaskoning.com Internet E-mail [email protected] Arnhem 09122561 CdC Date le 29 decembre 2006 Annexe(s) 1

Objet Projet de Developpement des Ressources en Eau et Preservation des Ecosystemes dans le Bassin du Niger

Monsieur,

Je vous prie de bien vouloir trouver ci-jointe une copie du rapport provisoire a Study on the Enhancement of Flood Early Warning System and Installation of Additional Equipment in the Kainji Reservoir Zone )>,version en Anglais.

Je vous souhaite bonne reception et je vous prie d'agreer, Monsieur Ousmane, l'expression de mes sentiments distingues.

Nann n t, Secretaire pour Frederik Mabesoone Directeur Amenagement des Ressources en Eau et Ecologie International

/)( _) G

O Membre ONRI ¾. " World Bank Niger Basin Authority

* 11

* 'NC-LC 'j^ r LU.____b>'-j *' - * '

* Study on the Enhancement of Flood Early * Warning System and Installation of Additional *Equipment in the Kainji Reservoir Zone 0 0U. * Water Resources Development and * Ecosystem Preservation in the Niger River Basin 0 * Draft Report

* December 2006

* ROYAL HASKONIN | ~~th in k ing i n Wnaall dditmensions Study on the Enhancement of Flood Early Warning System; Installation of Additional Equipment in the Kainji Reservoir Zone Review of Status and Options for Improvement

Niger Basin Authority

19 December 2006 Draft Report 9R8996.BO * DE 0 0 0 * ROYAL HASKONING

HASKONING NEDERLAND B.V. v WATER

Barbarossastraat 35 P.O. Box 151 Nijmegen 6500 AD The Netherlands +31 (0)24 328 42 84 Telephone +31 (0) 243 231 603 Fax [email protected] E-mail S www.royalhaskoning.com Internet Arnhem 09122561 CoC

* Document title Study on the Enhancement of Flood Early Warning System; Installation of Additional Equipment in the Kainji Reservoir Zone * Review of Status and Options for Improvement * Document short title Flood Early Warning Study * Status Draft Report Date 19 December 2006 Project name Development of Water Resources and * Restoration of Degraded Zones of the River Niger Basin * Project number 9R8996.BO * Client Niger Basin Authority Reference 9R8996.BO/R001/ToTN/Nijm

* Drafted by Teun op ten Noort Checked by D ate/initials check ...... * Approved by * Date/initials approval ......

40 ROYAL HASKONING

CONTENTS Page

1 INTRODUCTION 1 1.1 General 1 1.2 The role of the Niger basin Authority 1 1.3 Objectives and methodology of the Study 2 1.3.1 Objectives 2 1.3.2 Methodology 2 1.4 General context of the study 3 1.4.1 Overview of the hydrography and hydrology of the Niger River 3 1.4.2 The Niger River in Nigeria 3 1.4.3 Summary of the hydro-electric characteristics of Kainji dam 6

2 ACTIVITY 1 - EVALUATION OF EXISTING EQUIPMENT AND PROCEDURES 10 2.1 Analysis of existing practices and directives 10 2.2 Analysis of the management of historical floods 10 2.2.1 Four most important floods at Kainji GS 10 2.2.2 The 1998/99 White Flood 11 2.2.3 The 1999/00 White Flood 15 2.2.4 Conclusions with respect to flood early warning at Kainji 17 2.3 Evaluation of flood early warning equipment 18 2.3.1 Location and description of instruments 18 2.3.2 Modes and means of transmission 20 2.3.3 Information sent to stakeholders 20 2.4 Evaluation of flood operation structures 20 2.4.1 Spillway gates 20 2.4.2 Power production 21 2.5 Evaluation of the data quality 22 2.5.1 Rainfall data 22 2.5.2 Hydrometric data 25 2.6 Evaluation of the budget reserved for flood warning 26 2.7 Conclusion with respect to Flood Early Warning 26

3 ACTIVITY 2 - DRAFT OF AN IMPROVED SYSTEM FOR FLOOD EARLY WARNING 27 3.1 General 27 3.2 Identification of additional equipment and infrastructure to rehabilitated 27 3.3 Improvement of the monitoring, transmission and processing of data 28 3.4 Identification of capability improvement of staff involved in flood operations 28

4 ACTIVITY 3 - PREPARATION OF THE CONCEPTUAL FRAMEWORK AND THE DETAILED TERMS OF REFERENCE FOR THE DEVELOPMENT OF A FLOOD EARLY WARNING TOOL INTEGRATING A DATA BASE, A HYDROLOGICAL FORCASTING MODEL AND A RESERVOIR OPERATION MODEL 30 4.1 Hydrological and GIS data bases 30 4.1.1 Present situation 30

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4.1.2 Hydrological data base 30 4.1.3 GIS data base 33 4.2 Hydrological forecasting model 34 4.2.1 Introduction 34 4.2.2 Rainfall-runoff model 34 4.2.3 Routing model 34 4.3 Reservoir operation model 36 4.3.1 Introduction 36 4.3.2 Present operation 36 4.3.3 New reservoir operation model 36

5 CONCLUSIONS AND RECOMMENDATIONS 38 5.1 Flood forecasting procedure 38 5.2 Improved flood forecasting 38 5.3 Improvement of the dam operation procedures and the analysis of information 38 5.4 Flood early warning tool 39 5.4.1 General 39 5.4.2 Hydrological and GIS data base 39 5.4.3 Hydrological forecasting model 40 5.4.4 Reservoir operation model 40

LIST OF FIGURES Figure 1.1 Niger river basin 4 Figure 1.2 The Niger River and its main tributaries in Nigeria 4 Figure 1.3 Map of a portion of Niger River and its tributaries showing the hydrographical stations and Kainji Lake 5 Figure 1.4 Elevation-area-capacity curves 7 Figure 1.5 Part layout of main dam and powerhouse 8 Figure 1.6 Service spillway 8 Figure 1.7 Emergency spillway 9 Figure 1.8 Empty bays for 4 additional units 9 Figure 2.1 Kainji service spillway capacity, including turbine releases 12 Figure 2.2 1998/99 White Flood: Total reservoir inflows divided over contributions from Niger (u/s Jidere Bode), Sokoto/Rima (Kende) and Malando (Malando) rivers 12 Figure 2.3 1998/99 White Flood: reservoir and tailrace levels at Kainji GS and reservoir levels at Jebba GS 13 Figure 2.4 1998/99 White Flood: inflows, outflows and reservoir levels at Kainji GS 14 Figure 2.5 1998/99 White Flood: inflows, outflows and reservoir levels at Jebba GS 14 Figure 2.6 1999/00 White Flood: Total reservoir inflows divided over contributions from Niger (u/s Jidere Bode, Sabon Gari), Sokoto/Rima (Kende) and Malando (Malando) rivers 15 Figure 2.7 1999/00 White Flood: reservoir and tailrace levels at Kainji GS and reservoir levels at Jebba GS 16 Figure 2.8 1999/00 White Flood: inflows, outflows and reservoir levels at Kainji GS 16 Figure 2.9 1999/00 White Flood: inflows, outflows and reservoir levels at Jebba GS 17 Figure 2.10 Defunct u/s HYDRONIGER PCD 19 Figure 2.11 Corroded bubble tube of u/s HYDRONIGER PCD 19 Figure 2.12 OTT Automatic Water Level Recorder (AWLR) 19

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Figure 2.13 Rainfall meter at Kainji meteorological station 19 * Figure 2.14 Discontinued d/s HYDRONIGER PCD at Southern tip of Kainji Island 20 Figure 2.15 Service spillway rating curve 21 Figure 2.16 Kainji - monthly rainfall depths 1965 - 2005 and mean (dotted bar) 24 * Figure 2.17 Kainji - annual rainfall depths and 5-year moving average and standard deviation 25 * Figure 2.18 Location of hydrometric stations monitored by Kainji hydrological staff 26

LIST OF TABLES * Table 1.1 Four most important floods by peak discharge in descending order at Jidere Bode*) 6 * Table 2.1 Four most important White Flood reservoir inflows*) 11 Table 2.2 Hydrometric and meteorological stations used for Kainji reservoir operation 18 Table 2.3 Monthly rainfall at Kainji meteorological station 23 Table 2.4 Coordinates of stations monitored by Kainji 25 * Table 4.1 Hydrometric and meteorological stations used for Kainji reservoir operation 35

* LIST OF ACRONYMS AND ABBREVIATIONS AWLR Automatic Water Level Recorder * CEO Chief Executive Officer d/s downstream * DNH Direction Nationale de I'Hydraulique FMWR Federal Ministry of Water Resources * GS Generating Station MSL Mean Sea Level (vertical datum used in Nigeria) * NBA Niger Basin Authority (= Autorit6 du Bassin du Niger, ABN) seated in Niamey, Niger * O.D. Ordinance Datum (= MSL) PHCN Power Holding Company of Nigeria (State Electricity Generating * Company) PM Principal Manager * SDAP Sustainable Development Action Plan UPS Uninterruptible Power Supply * u/s upstream WAN Wide Area Network as opposed to LAN, Local Area Network * WMO World Meteorological Organisation

* ftUNITS *ftUNfeet (1 foot = 0.3048 m) GWh gigawatt-hour (=109 watt-hour) hm3 cubic hectometre (100x100x100 m3) m+MSL metres above Mean Sea Level * Mm3 million cubic metre (= hm3) MW Megawatt (=106 watt)

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1 INTRODUCTION

1.1 General

The Niger river is the 3rd longest river of Africa after the Nile and Congo with a length of 4200 km. Together with its tributaries it drains a basin of about 1.5 million km2 shared by 9 riverine states (Benin, Burkina Faso, Cameroon, C6te d'lvoire, Guinea, Mali, Niger Nigeria and Chad) who together have founded the Niger Basin Authority (NBA), the regional body responsible for the development of its natural resources. Although these resources are important, until now they have been poorly developed, and are deteriorated as a result of climatic and human impacts.

Indeed the climatic factors, in particular the endemic drought which is still rampant in the Sahelian zone, the increase of the demographic pressure and the industrial expansion, have caused important failures in the equilibrium of the water resources and associated ecosystems of the Niger basin. The most important occurring problems are:

* Significant decrease in water resources (small floods, certainty of low flows, lowering of the groundwater table); * Reduction in biological diversity, in particular due to the loss of habitats; * Proliferation of floating vegetation; * Sedimentation and/or silting up of river beds and reservoirs; * Deterioration of water quality caused by uncontrolled dumping of waste water; * Insufficient cooperation between the various institutions responsible for the management of the natural resources in the basin; * Degradation of living conditions of the riverine populations in general and those whose socio-economic activities are directly linked to the river in particular.

It is in this perspective that the NBA, with the support of technical and financial partners has decided to execute a number of projects including "development of water resources and protection of the ecosystems if the basin". The present study on flood warning is one of the components of that project.

1.2 The role of the Niger basin Authority

The NBA is the principal regional institution responsible for the development of the natural resources of the Niger Basin, founded in November 1980 by the Convention of Faranah (Guinea) to replace the defunct Niger River Commission (NRC) by the 9 riverine member states (Benin, Burkina Faso, Cameroon, C6te d'lvoire, Guinea, Mali, Niger Nigeria and Chad), of which 7 are French speaking, Cameroon is French and English speaking, and only one, Nigeria, is English speaking. As a result the NBA is a bi-lingual institute.

The objective of the NBA is to promote to cooperation between the members, to ensure the integrated development of the Niger basin in the areas of energy, hydraulics, agriculture, cattle breeding, fisheries, forests, transport, communication and industry. Furthermore, the NBA organs took a certain number of resolutions and decisions aimed at redefining the mandate of the NBA and making the Executive Secretariat more efficient, through the conduct of an organizational and institutional audit. With this in view, the 6th and 7th Summits of the NBA Heads of State and Government asked for the development of a Clear and Shared Vision for the NBA with the support of the

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development partners with the World Bank as Team Leader. The main objective aimed * at is to create an "environment favourable" to cooperation and to develop a "Sustainable Development Action Program (SDAP)" accepted by all the actors operating in the basin. The shared vision process was then launched through a regional workshop held in * Abidjan in September 2002 and led to a consensus on the following basic steps:

* Information, sector studies and strategic analyses; Exchange of information, consultations and meetings; * Capacity building and institutional development; Regional and international cooperation and donors coordination.

For the implementation of this plan, several partners are supporting this NBA program. * So, the World Bank, in line with its commitments and on the basis of its prior experiences with other international river basins, decided to finance the project titled * "Development of Water Resources and Preservation of the Ecosystems of the River Niger Basin". The purpose of the project is to enhance in a sustainable manner the * productivity of water resources so as to reinforce economic development in the countries of the basin where the project shall be implemented.

One of the key components of the project is the safety and enhancement of the situation of the existing hydraulic infrastructures, especially the Kainji and Jebba dams in Nigeria, * of which the present "Study on the enhancement of flood early warning system and installation of additional equipment in the Kainji reservoir zone" is a part.

* 1.3 Objectives and methodology of the Study

* 1.3.1 Objectives

* The objectives of the study are to: * evaluate the flood warning system and practice in the region of the Kainji dam, * * propose an enhancement of the system and associated practice, * identify the necessary equipment, * prepare an integrated flood warning tool which could form the basis of a decision support tool for the integrated management of the hydro power production of Kainji and Jebba.

1.3.2 Methodology

* The study has been executed as follows: * * From 20 Sep 2006 until 4 October 2006 the Royal Haskoning team was in Nigeria. * On 21 September a meeting was held at the Federal Ministry of Water Resources *@ in Abuja attended by representatives of the NBA, Federal Ministry of Water Resources (FMWR), Ministry of Environment, Power Holding Company of Nigeria * (PHCN), CEOs of Kainji and Jebba Power Stations, PMs Hydrology of Kainji and Jebba Dams, Royal Haskoning Team, other Consultants and Stakeholders. * . From 25 - 27 September the Team visited Jebba Dam * From 27 - 3 October the Team visited Kainji dam. * * From 3- 4 October the Team stayed in Abuja, visits to FMWR and PHCN. * During this period many interviews with officials responsible for hydrology and flood * warning at both dam sites were held, data related to the study collected, reports 0 studied, photographs taken, field inspections held, etc. In Abuja further visits were

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paid to the Federal Ministry of Water Resources and the Power Holding Company of Nigeria On the evening of 4 October the Team returned to the Netherlands where the reporting was prepared.

1.4 General context of the study

1.4.1 Overview of the hydrography and hydrology of the Niger River

For geomorphologic and hydrological reasons the Niger Rver has been geographically divided into four reaches (see also Figure 1.1):

The upper reach, also called Upper Niger, stretching from its source in Guinea to Kemacina just upstream of the so-called Inner Delta in Mali. It includes the course of the Bani River from its source in Cote d'lvoire until Douna in Mali, its confluence with the Niger. The annual precipitation in the Upper Niger basin varies from 2200 mm in Kissidougou (Guinea) to 650 mm in Kemacina. The mean annual discharges observed during 1952 - 2002 are 239 m3/s in Kouroussa (Guinea) and 1280 m3/s in Markala (Mali) at the entrance of the Inner Delta (source: DNH-Mali). The Inner Delta runs from K6macina to Taoussa (Mali) on the Niger and from Douna to Mopti (Mali) on the Bani. The annual precipitation in this zone varies from 650 mm in Kemacina to 200 mm in Dire. This reach is characterised by the lack of important tributaries. On the other hand almost a quarter of the flow is lost to evaporation and infiltrations. The Middle Niger runs from Taoussa to Gaya-Malanville (Benin) close to the Nigerian border. In this reach the precipitation increases from an annual 200 mm to 900 mm and small tributaries originating in Burkina Faso and Benin have little influence on the river regime. The mean annual discharges run from 926 m3/s at Taoussa (Mali) to 925 m3/s at Niamey (Niger) to 1058 m3/s at Malanville (source: NBA). The Lower Niger runs from Malanville to the Niger estuary in Nigeria. In this reach the river enters the Sudanese and Guinean climatic zones where the annual precipitation increases from 900 mm to more than 4000 mm per year. Here the river receives water form its most important tributaries (Sokoto/Rima, Kaduna and Benue rivers). The discharge of the Benue at its confluence with the Niger at Lokoja is almost the same as that of the Niger itself. The annual discharges are 1454 m3/s at Jebba and 5800 m3/s at Onitsha (source: NBA).

1.4.2 The Niger River in Nigeria

The Lower Niger in the Federal Republic of Nigeria is further divided into Upper Niger, running from the border to Kainji dam, the Middle Niger from Kainji to Lokoja and the Lower Niger from Lokoja to the mouth in the Bight of Benin (see Figure 1.2).

Kainji dam is located at the head of the Middle Niger in Nigeria near New Bussa (see Figure 1.2).

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Figure 1.1 Niger river basin

* NIGERIA

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Figure 1.2 The Niger River and its main tributaries in Nigeria

The most important tributaries between the border and Kainji dam are (see Figure 1.3):

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* Malando river * * Sokoto/Rima river * Danzuki river (not shown, because non-perennial) * Kainji reservoir is subject to two major flooding periods: * The Black Flood originating in the Upper Niger Basin (Guinea/Cote d'lvoire/Mali), peaking period December. This flood does not carry much sediment, which has been deposited in the Inner Delta, hence the name Black Flood. * White Flood originating in the upstream Nigerian part of the basin (Sokoto/Rima, * Malando, etc.), peaking period September/October with a normal peak discharge of 4000 - 6000 m3/s. This flood does carry lots of sediment giving the water a light * brown colour, hence its name White Flood.

30' 40- So- GO- 70-

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* Figure 1.3 Map of a portion of Niger River and its tributaries showing the hydrographical stations and Kainji Lake * The four most important White and Black Floods measured at Jidere Bode since Kainji * dam came into service are presented in

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Table 1.1. It can be seen that the peaks of the White Floods are higher than those of the Black Floods, while the total duration of the Black Floods is a bit longer.

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Table 1.1 Four most important floods by peak discharge in descending order at Jidere Bode*) Peak Hydrological . Date of Days to Total duration Rank [m3/s Year**) Begin Peak End peak [days] White Floods: 1 3719 1998/99 18/05/98 28/09/1998 22/11/98 133 188 2 3480 2003/04 29/05/03 01/10/2003 24/11/03 125 179 3 3271 1999/00 01/06/99 14/09/1999 28/11/99 105 180 4 3047 1994/95 07/06/94 25/09/1994 15/12/94 110 191 Black Floods: 1 2375 1969/70 17/11/69 20/03/1970 06/07/70 123 231 2 1990 1975/76 02/12/75 31/01/1976 02/06/76 60 183 3 1935 1979/80 23/11/79 16/01/1980 20/05/80 54 179 4 1906 1971/72 15/11/71 23/01/1972 20/06/72 69 218 *) I.e. Niger + Sokoto/Rima, the most important tributary with respect to the White Flood, but excluding Malando *) The hydrological year runs from 1 July this year to 30 June next year

From a flood warning point of view, the White Flood is the most important. It is the one that can cause problems and has done so in the past1 . Due to the regime of the Niger as explained above, it is impossible for both floods to coincide.

1.4.3 Summary of the hydro-electric characteristics of Kainji dam

The hydro-electric works at Kainji came into operation in 1968. With a reservoir of about 12000 Mm3 at a maximum operating level of 465 ft (141.73 m) and 2900 Mm3 at top of dead storage level of 435 ft (132.59 m), the active storage is about 9100 Mm3 over a level range of about 9.1 m as indicated in Figure 1.4. It is also the main flow regulating instrument in the Lower Niger basin.

The basic layout of Kainji main dam and powerhouse with the location of the units and their rating is indicated in Figure 1.5. Pit 1, 2, 3 and 4 are reserved for further extension (see also Figure 1.8).

... on the aftermath of mid-October, 1998, heavy flood which swept off more than 15 settlements around the dam and along the coast of River Niger." (The Punch, Tuesday, February 2,1999, Page 28)

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* i'SERVOIR AREA A CAPACIrY CURPES.

Note: the area is expressed in 108 M2 (or 102 kM27not l0 M2 Figure 1.4 Elevation-area-capacity curves

*The various structures of Kainji are indicated below.

A. Reservoir. *0 Normal maximum operating level 141.73 m+SL * Minimum operating level: 132.59 m+MSL *Top of dead storage level: 100.58 m+MSL * * Reservoir surface area at maximum operating level: 1260 kM2 *Maximum length of reservoir: 136 km * * Maximum width of reservoir: 24 km

*B. Closure and saddle dams x Type: rockfill and earthfill embankments * Total crest length: 7750 m Maximum height above foundation: 70 m

g C. Main dam and intakes * Type: mass concrete 0 Crest length: 550 m * Maximum height above foundation: 65.5 m * Intake: 12 no. 4.9xl10.8 m, each with 2 openings and sliding gates, (8 in use) * Penstocks: 12 no. 8.65 m diameter (8 in use)

D. Spillways: v* Service spillway: 4 overflow tainter gates, each 15x15 m, total capacity 7900 m3/s Fiu(see Figure 1.6) * Emergency spillway: uncontrolled lateral spillway in navigation channel, capacity 1400 m3/s (see Figure 1.7) * Te Saddle dam acts as a break-away emergency spillway . Flood Early Warning Study 9R8996.Bo/R.01/ToTN/Nijm Draft Report - 8 - 19 December 2006 Te S cooo

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Note: saddle dam and navigation locks not shown Figure 1.5 Part layout of main dam and powerhouse

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Figure 1.6 Service spillway

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Figure 1.7 Emergency spillway

E. Powerhouse, turbines and generators (8 units installed space for 4 more units): * A single 350 m long closed powerhouse at d/s toe of concrete dam * 4 Kaplan units, each 80 MW (nos 7, 8, 9 and 10) * 2 Kaplan units, each 100 MW (nos 11 and 12) * 2 Francis units with fixed propellers, each 120 MW (nos 5 and 6) * Additional pits for 4 more units (see Figure 1.8)

F. Navigation locks: 195 m x 12 m upper and lower lock connected by a 2.4 km long canal with emergency spillway.

* 2006 1-A l

Figure 1.8 Empty bays for 4 additional units

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2 ACTIVITY 1 - EVALUATION OF EXISTING EQUIPMENT AND PROCEDURES

2.1 Analysis of existing practices and directives

There are no official directives on flood warning at Kainji. Floods in the past have not caused disastrous results, although, sadly enough, some human life was lost since the dam came into operation in 1968. Problems were encountered with the population settled in the flood plain and islands in the Niger who refused to evacuate, even after flood warnings were issued.

The existing practice is that a standard Flood Warning bulletin, shown in Appendix A, is issued in the following circumstances to the downstream riverine population: * When the reservoir level reaches 141.73 m (= 465 ft, the trigger level for spillway operation) as forecasted by the PM Hydrology by extrapolating the hydrographs of the most important tributaries into the reservoir with a lead-time of 2 weeks or more and the flow at Jidere Bode reaches 3000 m3/s, measures are taken to inform in writing (the flood warning bulletin) the concerned authorities (village or community chiefs, police, Local Government), to have the flood plain evacuated by the riverine population. * This bulletin is distributed by motorised messenger. The local population is then informed by town criers and local/state radio transmissions. At the same time the management at Jebba dam downstream is warned by (mobile) telephone.

As can be seen from Appendix A, the bulletin lacks the following detailed information: * no mention is made about the expected time of occurrence (next week, two weeks?) * no mention is made about expected flood levels * no mention is made about specific areas subject to flooding

Although this practice seems to have worked, since there were very few casualties in the past, it can be concluded that there is way for improvement as described in the following.

2.2 Analysis of the management of historical floods

2.2.1 Four most important floods at Kainji GS

As mentioned before, the White Floods are the ones that can cause problems from a discharge point of view. The 4 most important, ranked according to their peaks, were presented in Error! Reference source not found.. However those were the floods observed at Jidere Bode, i.e. excluding the reservoir inflows from the Malando River. The most important White Flood reservoirinflows in the period 1966 - 2005 are indicated in Error! Reference source not found.. In the following we will keep the same ranking with respect to flood warnings, although the maximum Kainji reservoir levels do not exactly follow the same ranking. For instance the maximum reservoir level in the 1999/00 was 141.70 m+MSL, while the highest reservoir level in the period 1970 - 2000 was 142.01 m+MSL on 11 April 1977, actually a Black Flood level of which the associated peak inflow is not known.

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Table 2.1 Four most important White Flood reservoirinflows*)

Rank Peak Hydrological Date of 3 [m /s] Year**) Peak 1 5141 1999/00 17/09/1999 2 4240 1967/68 5/10/1967 3 4074 1994/95 22/09/1994 4 3892 1998/99 2/10/1998 I.e. Niger + Sokoto/Rima + Malando inflows 0 The hydrological year runs from 1 July this year to 30 June next year

It is interesting to see that the inflows from the Malando River can contribute greatly to the total reservoir inflows. This in particular illustrated when the 1994/95 flood at Jidere Bode in

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Table 1.1 (peak 3047 occurring at 25/09/1994) is compared with that of the total reservoir inflow in Table 2.1. Apparently, due to the contribution of the Malando River, the reservoir peak inflow was increased by 927 m3/s and reached 3 days earlier! Note that the actual inflow peaks are even higher, as these measurements do not even include contributions from the other tributary rivers (Danakil and some small streams, see Figure 1.3).

In the following, the 1998/99 and 1999/00 floods for which figures were readily available in digital format are further elaborated. It is interesting to see how the floods are managed at Kainji and Jebba by comparing graphs of the respective reservoir levels, reservoir inflows from the Niger and main tributaries, turbine outflows and spills. However, in this discussion the condition of the turbines and generating sets is not taken into account. Neither is the link with the national electricity grid and a combined operation with Shiroro GS, the 3rd large hydro power station of PHCN, taken into account. These links fall under Activity 3 and are discussed elsewhere in this report. Furthermore, it should be borne in mind that even the highest observed flood peak to date of 5141 m3/s is well below the service Kainji's spillway capacity of 7900 m3/s as shown in Figure 2.1.

2.2.2 The 1998/99 White Flood

This flood is the 4th worst. Figure 2.2 shows the contributions from Niger, Sokoto/Rima and Malando rivers to the total reservoir inflow. It is interesting to see that although earlier peaks were indeed caused by inflows from the Malando River, the Niger River itself was causing the peak discharge around 1 October 1998. This must be attributed to tributaries u/s of Jidere-Bode, i.e. the Sirba River in Benin.

Because there is no direct communication between the dam operators at Kainji and other agencies across the border, no direct forecasting could be made.

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ioo I 470

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-KAJNJI REsER CBSR-cwV ------KEa3E CBSFLI US IRDI assRC. R-aNEW OiLANDs

Figure 2.2 1998/99 White Flood: Total reservoir inflows divided over contributions from Niger (u/s Jidere Bode), Sokoto/Rima (Kende) and Malando (Malando) rivers

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From Figure 2.3 we can see that at the onset of the flood, the reservoir level at Kainji increased to the maximum operating level (141.73 m+MSL) at which the turbines have their maximum output and is more or less kept there. At the same time, we see that the reservoir level at Jebba is fluctuating within a narrow range around its maximum operating level (103 m+MSL).

The tailrace level at Kainji is about 2m higher than the reservoir level at Jebba. Only during half September - half October, the difference increases to 4.5 m, a maximum reached around 1 October 1998, coinciding with the peak reservoir inflow. 0 140

135 -

130

0 125

120

115...

110

0 ~~~~105- = -'- -

100-,,,, Aug Sep Ct Nov Dec Jan 1998 | 1999 - KNNi ( (PI SS-V- -- KAJNJIG0BSTA TL PACE P- - JEMAC CBS01IES PA

Figure 2.3 1998/99 White Flood: reservoir and tailrace levels at Kainji GS and reservoir levels at Jebba GS Figure 2.4 shows how Kainji reservoir was actually operated. The duration of the early peaks due to inflows from the Malando River was too short to cause problems because the reservoir was not yet full. The second peak had a different effect. The spillway gates had to be opened and the maximum spill was higher than the peak inflow, while the spilling continued, several days after the flood had reached its peak. Although this is normally an indication of less than optimum operation (waste of water), it was probably due to diminished turbine flow as a result of one or more generating units being unserviceable.

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145 1 40 - - - -. . .. , 135 - 130 - 125- * 120-.. 115 - 110 105 ------.- 100 4500 4000 - 3500I

2500 - 2000 -

15DD ---- l n-W, 500

Aug Sep Odt NWV [c Jan 1998 1 1999 IKANJIGS(SI S VL ------KNJI CFSC]TAJLRACE AL JEaBLACSCBSFES VW KAJNJIIESHEORCBS FES IN'LCW KANJICS CS TL FLON K4NJI CS CS SRLL Figure 2.4 1998/99 White Flood: inflows, outflows and reservoir levels at Kainji GS

The situation at Jebba is shown in Figure 2.5. The generating units were running at maximum capacity during the flood, while the peak was discharged by spilling. In fact, the spilling curve follows the inflow curve almost perfectly thereby keeping the flow through the turbine within a narrow range. From an operating point of view, this is the best one can do. It is unknown what caused the relative dip in reservoir level around mid-August.

103.2 -

103- 0 102.8-

102.6-

102.4

10 2 .2 - ______6000-

5000 -f

4000f. v-----

1000

Aug Sep Oct Nov Dec Jan 1998 | 1999 JEBBA GS OBS WL - JEBBAGSOBSINFLOW JEBBA GS OBSTURBINE ------JEBBA GS OBSSPILL Figure 2.5 1998/99 White Flood: inflows, outflows and reservoir levels at Jebba GS

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2.2.3 The 1999/00 White Flood

The 1999/2000 flood (Figure 2.6) is the considered to be the worst until now. As with the flood in 1998/99 a large portion comes from the Niger itself, but actual peaks are caused by the inflow from the Malando River, both early and later peaks.

6000 -

5000 d

* 4000-

3000-

2000- *o 1000

Aug Sep Od Nbv De

Figure 2.8 shows how Kainji reservoir was actually operated. The duration of the early peaks due to inflows from the Malando River were too short to cause problems because the reservoir was not yet full. The second peaks, both from the Malando and Niger rivers had a different effect. The spillway gates were opened and the maximum spills were lower and later than the inflow peaks.

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145 -

140 -

135

130

125.

120

115

110

105 - =.. =

100 Aug Sep OC> Nov Dzec Ja 1999 2000 KAINJIGS CBSES VL -'-- KAIJJICEES TAJLFACEMWJEBeA CE CBS FES WL Figure 2.7 1999/00 White Flood: reservoir and tailrace levels at Kainji GS and reservoir levels at Jebba GS In this case the operators did foresee they had to spill according to the inflow peaks, but because the reservoir was not yet at full supply level, the spills could be better timed and the flows through the turbines kept more constant then in 1998, presumably because the generating units were in a better condition. Although spills were unavoidable, they were considerably less than the inflow peaks and the whole dam operation was much better than in 1998.

145 140 - 135 -.. 130 -

X 125- 120

115 110 105

100 6000 - 5000

4000 -

3000

12000 : - -

0- --- r Aug Sep Ct Nbv Dec Jan 1999 | 2000 K:AIII S(CBS RES VSL ...... KANJI 3( C3BSTALPRCE V\ JEEQACE-CBS [ES \M KAENJIFESERVCIRCBS FES IWFLW KAJN GS CBS TLE FL•W KENJI GSC135 SILL Figure 2.8 1999/00 White Flood: inflows, outflows and reservoir levels at Kainji GS

The situation at Jebba is shown in Figure 2.9. Similar to the 1998/99 flood there is a dip in the reservoir level around mid-August. The generating units were running at maximum capacity during the flood, while the peak was discharged by spilling. Like in 1998 the

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spilling curve follows the inflow curve almost perfectly thereby keeping the flow through the turbine within a narrow range. From an operating point of view, this is the best one can do. It is unknown what caused the relative dip in reservoir level around mid-August.

100

102.5

9~+ 102.0

101.5

7000 6000-

4000- S 3000 2000- ;

Aug Sep Oct Nov Dec Jan 1999 1 2000 9JEBBAGS OBSWL - JEBBAGSOBSINFLOW JEBBAGSOBSTURBINE ------JEBBAGS OBS SPILL Figure 2.9 1999/00 White Flood: inflows, outflows and reservoir levels at Jebba GS

2.2.4 Conclusions with respect to flood early warning at Kainji

In this report we only consider the flood warnings issued at Kainji as mentioned in the TOR. Actually, a similar procedure exists at Jebba. It should be borne in mind that the operation in Jebba also depends on the tributary inflows between Kainji and Jebba, notably from the Kontagora River. The reservoir inflows were ranked by peak, not by associated reservoir level. As already indicated in Section 2.2.1 above there can be a difference of up to 30 cm.

1998/99 White Flood This flood caused the reservoir level at Kainji to rise from 134.43 m+MSL on 1 August 1998 to 141.20 m+MSL on 1 October 1998, a very steady rise of about 11 cm/day, hardly something for which timely urgent flood warnings for loss of human life, cattle, possessions, etc. would have made a significant difference. After that steady rise it took another week to reach the maximum total outflow from Kainji of 4955 m3/s on 8 October 1998, at an almost constant reservoir level. In the same period the tailrace water level increased from 104.81 m+MSL on 1 August 1998 to 106.68 m+MSL on 8 October 1998.

1999/00 White Flood This flood caused the reservoir level at Kainji to rise from 132.74 m+MSL on 1 August 1998 to 141.07 m+MSL on 1 October 1999, a very steady rise of about 14 cm/day, hardly something for which timely urgent flood warnings for loss of human life, cattle, possessions, etc. would have made a significant difference. After that

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steady rise it took another week to increase the level by another 0.5 m, or 7 cm/day coinciding with the maximum total outflow from Kainji of 4713 m3/s on 8 October 1999. In the same period the tailrace water level increased from 103.42 m+MSL on 1 August 1999 to 106.70 m+MSL on 12 October 1998.

In conclusion: Although it is not known when exactly the warnings (see Appendix A) were issued for both floods, the rise both in reservoir and tailrace levels was so gradual that emergency flood warnings would not have been very effective. Reportedly most "accidents" occur because the riverine population, although quite experienced with the annual phenomena of the Black and White flood, refuse to evacuate the flood plain. Therefore from a flood warning point of view it can be concluded that the present procedure, although certainly not perfect, is sufficient. Measures for improvement relate in the first place to the total reservoir operation of both Kainji and Jebba, including hydrologic data collection, analysis and storage as will be discussed later in this report.

2.3 Evaluation of flood early warning equipment

2.3.1 Location and description of instruments

The hydrometric stations on which the (flood) operation of Kainji is based consist basically of the 8 hydrometric and 1 meteorological stations indicated in Table 2.2 with their particulars. Table 2.2 Hydrometric and meteorological stations used for Kainji reservoir operation Stations Location/river Type Condition Remark Kainii u/s powerhouse intakes Staff gauge good AWLR OTT good See Figure 2.12 PCD HYDRONIGERunserviceableSee Figure 2.10 and Figure 2.11

Southern tip of Kainji AWLR OTT good Island (d/s powerhouse) PCD HYDRONIGERdiscontinued See Figure 2.14 Sabon Gari Illo Niger river u/s Sokoto/ Staff gauge good No rating curve available Rima confluence Jidere Bode Niger river d/s Sokoto/ Staff gauge good Principal hydrometric station Rima confluence for reservoir inflows; rating curve PCD HYDRONIGERdiscontinued needs updating Kowara Niger river d/s Sokoto/ Staff gauge good No rating curve available Rima confluence Yelwa Niger river u/s Kowara Staff gauge good No rating curve available

Kende Sokoto/Rima river u/s Staff gauge good Sokoto/Rima river isthe main Niger confluence White Flood contributor; rating curve needs updating Malando village Malando river Staff gauge good Malando river isanother important White Flood contributor; rating curve needs updating Ganwon Danzuki river Staff gauge good Danzuki river is non-perennial; No rating curve available Kainji Near Kainji dam Meteorological good See Figure 2.13 Source: Hydrological staff at Kainji Hydro Electric PLC, see also map in Figure 1.3 and Figure 2.18

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* -'

Figure 2.1 0 Defunct u/s HYDRONIGER Figure 2.1 1 Corroded bubble tube of PCD -u/s HYDRONIGER PCD

-ii

Figure 2.12 OTT Automatic Water Figure 2.13 Rainfall meter at Kainji Level Recorder (AWLR) -meteorological station

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Figure 2.14 Discontinued d/s HYDRONIGER PCD at Southern tip of Kainji Island

2.3.2 Modes and means of transmission

The modes and means of standard hydrometric data transmission are as follow. Once a month, usually 2 or 3 days in the new month, the gauge keepers come by public transport, motor cycle or bicycle to Yelwa, where PHCN has a small office, to meet with someone of the hydrologic staff at Kainji who receives and roughly checks the data, and records remarks about the situation at the associated hydrometric stations (repairs necessary, etc). On the same or next day the gauge keepers get paid by someone from the financial staff at Kainji after the hydrological officer has approved the data. In emergencies only, a gauge keeper who has a private mobile phone goes to a spot where he has coverage and calls the hydrological staff at Kainji dam. It is obvious that this is a fragile system and does not give the latest information.

Another problem is that the hydrologic department at Kainji only gets information from the PHCN-managed stations mentioned in Table 2.2, not from other hydrometric or rainfall stations managed by others. Nor is information directly transferred from upstream regions outside Nigeria. For instance, water levels and discharges at Niamey in Niger are not communicated to Kainji dam.

The ways and means the warning bulletin is issued have already been discussed in Section 2.1 above

2.3.3 Information sent to stakeholders

As can be seen from the standard Flood Warning Bulletin presented in Appendix A, the information is very rudimentary as already discussed in Section 2.1 above.

2.4 Evaluation of flood operation structures

2.4.1 Spillway gates

The 4 spillway gates in Kainji are of the tainter overflow type as shown in Figure 1.6, with a total maximum capacity of 7900 m3/s, including 1500 m3/s through the turbines.

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The rating curve is given in Figure 2.15. The maximum recorded flood peak was 5,141 m3/s, well below this maximum capacity.

Moreover there is also an uncontrolled fixed crest emergency side-spillway in the middle portion of the navigation canal, just u/s of the lower locks with a capacity of 1,400 m3/s. However, since the upper navigation lock doors are unserviceable at the moment, this spillway is also unserviceable. Finally, the saddle dam on the left bank can act as a breakaway emergency spillway.

The structural and operational condition of these structures is described in detail in the report on Dam Safety, but it is evident that some remedial work has to be carried out on the upper navigation locks doors to get at least the emergency spillway operational. 07

0S =_ _=- _ _ =

450 -- -_ -

} 4J0 =- _ = ==- ~415 za .&#-0z 00oemoYi -X-0 owo -),fwA 44' -- = = -- =- spLiA #Am cf-R-- -- -AEuiroEl

4 15 f_ _ - _ - _ .- -- Figre2.5 Seric_silwayraincrv

0 1000 2000 .>> 4000 5000 5)000 70070 90*00 tVOSO .i0tttOOOtZ

SPILt AY RATNSs CURVE - GATES FPUt I r OPEN.

Figure 2.15 Service spillway rating curve

2.4.2 Power production

Kainji GS consists of 8 generating units and 4 empty bays for an additional 4 units as shown in Error! Reference source not found. and Figure 1.8. Although 4 extra units could be used for generating peak power, it is unlikely that this would be economically feasible, even if there were enough water available. Already 8 units are not fully operational because of overdue maintenance. This could further be illustrated by plotting reservoir inflows, spills and turbine flows. At the moment, for the present assignment, these data were not readily available in digital format.

However, it should be borne in mind, that due to the very flow regimes of the Niger river at Kainji and Jebba and the Kaduna river at Shiroro, the operation of these three most

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important hydropower stations owned by PHCN is closely interlinked, and cannot be * separated if their total output has to be optimised.

* During the designs of Kainji and Jebba, much emphasis was put on the navigation on * the Niger from its mouth to Niamey in Niger. This was the reason why expensive shipping lock systems were incorporated and built at Kainji and Jebba dams. Thus the * operation rules of Jebba, Kainji and Shiroro GS included releases for navigational purposes. However, reportedly only once in the very beginning a shipping convoy * passed these locks. This means that the emphasis of the operational rules for the reservoirs could be changed and optimised for hydropower production, while satisfying * navigational requirements only up to Lokoja2 at the confluence of the Benue. There are plans to divide PHCN up into separate independently operating generating * units. It is evident that Jebba and Kainji GS cannot be independently operated. Their operation should most probably include Shiroro as well. Only then it is possible to get the most hydropower from the available waters.

2.5 Evaluation of the data quality

2.5.1 Rainfall data

During the construction of Kainji GS a meteorological station was built nearby which has * been in operation since. The station does not fulfil the WMO standards and is the only rainfall station in the local catchment area up to the border with Niger, where a number * of at least 5 stations would be required according to WMO recommendations. Monthly rainfall depths are shown in These monthly rainfall data are shown again in graphical * format, together with the, mean (dotted bar) in Figure 2.16. It shows that July, August 40 and September are the wettest months, a in preparation for the White Floods as it were.

2 The Niger dredging project carded out by NEDECO / Royal Haskoning concems the promotion of IWT from the mouth up to Baro some 100 km upstream from Lokoja

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Table 2.3. At the station also the following standard meteorological parameters are * measured: max/min temperatures, sunshine, wind, evaporation, etc.

* These monthly rainfall data are shown again in graphical format, together with the, mean * (dotted bar) in Figure 2.16. It shows that July, August and September are the wettest months, a in preparation for the White Floods as it were. 0 0 0

40 0 0 0 0 0 0 0

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Table 2.3 Monthly rainfall at Kainji meteorological station

Hydro- year JUL AUG SEPT OCT NOV DEC JAN FEB MAR APR MAY JUN Annual 1964 ------7 3 68 100 145 - 1965 230 178 210 46 0 0 0 0 7 12 51 179 913 1966 212 177 258 43 0 0 0 0 15 61 61 169 997 1967 203 148 182 61 0 0 0 5 56 116 105 208 1 084 1968 224 185 304 24 0 0 0 0 0 181 167 85 1171 1969 256 207 112 77 9 0 32 0 0 32 131 124 979 1970 101 161 190 18 0 0 0 14 0 20 127 124 756 1971 237 328 189 54 0 0 0 0 5 43 160 46 1062 1972 177 292 103 72 0 0 0 0 0 18 42 124 829 1973 78 319 225 103 0 0 0 0 5 8 92 201 1 032 1974 190 148 257 37 0 0 0 0 0 47 144 120 943 1975 217 77 179 106 0 0 0 7 0 57 141 147 931 1976 55 153 86 166 3 0 0 0 10 4 145 152 775 1977 123 219 129 88 0 0 0 0 86 106 140 119 1011 1978 107 146 179 55 0 0 0 0 5 100 100 290 982 1979 154 228 197 51 7 0 0 0 0 31 97 151 918 1980 172 247 194 109 0 0 0 0 0 40 178 102 1 041 1981 201 243 183 17 0 0 0 0 0 91 163 92 989 1982 153 244 211 80 0 0 0 0 15 21 135 109 969 1983 113 94 133 20 0 0 0 0 30 128 146 173 837 1984 163 197 170 42 0 0 0 0 8 5 173 81 838 1985 185 315 189 24 0 0 0 0 25 71 76 180 1065 1986 216 108 259 93 0 0 0 0 0 16 86 144 921 1987 141 279 217 66 0 0 0 2 0 87 53 126 972 1988 143 271 173 4 0 0 0 0 0 34 210 212 1 046 1989 141 283 169 130 0 0 0 0 0 36 167 172 1 097 1990 327 212 197 70 0 0 0 0 12 53 239 247 1 358 1991 272 327 96 38 0 0 0 0 0 14 91 114 952 1992 126 88 283 39 0 0 0 0 12 0 91 158 796 1993 301 205 202 47 0 0 0 0 0 97 157 135 1144 1994 344 175 253 67 0 0 0 0 21 24 100 217 1 200 1995 172 284 172 104 6 0 0 0 0 21 153 90 1 001 1996 168 149 152 80 0 0 0 0 19 86 169 193 1017 1997 88 277 195 84 5 0 0 13 36 50 143 323 1214 1998 287 253 120 124 0 0 0 0 4 47 111 170 1117 1999 191 448 212 112 0 0 0 0 0 9 70 227 1269 2000 115 254 246 50 0 0 0 0 0 49 96 230 1 039 2001 165 111 212 120 0 0 0 0 0 49 35 103 794 2002 151 159 123 74 3 0 0 3 19 45 82 203 862 2003 111 111 126 147 110 0 0 0 3 67 168 177 1 021 2004 231 158 266 112 1 0 0 0 28 53 59 179 1 088 2005 185 106 329 110 0 0 0 0 0 30 168 226 1 154 2006 226 167 ------Mean 182 208 192 72 4 0 1 1 10 51 122 161 1 005

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500

*450-

400

E 350

* 300

* 250

200

* 150

100

*0 JAN FEB MAR APR MAY JUN JUL AUG SEPT OCT NOV DEC

Figure 2.16 Kainji - monthly rainfall depths 1965 - 2005 and mean (dotted bar)

A rough estimate of the influence of the climate change on the rainfall at Kainji is indicated in Figure 2.17. The annual rainfall depths vary, from a low of 640 mm in 1983 to a maximum of 1349 mm in 1998. When the 5-year moving average is plotted we see that the tendencies of dry and wet years are restricted within a fairly narrow range. We notice a gradual decrease from 1969 to 1977, an increase to 1982, again a dip and finally an increase to 2001 after which a steep decline is shown. It looks as if after the dip in 2004, the moving average is on the rise again.

Also the moving average of the standard deviations is plotted, indicated by the bars at the bottom. In a number of places on earth, it has been shown that as a result of the increased instability of the weather, standard deviations - a measure for deviations from the mean, i.e. droughts and wets - have increased also. This moving average shows that this is not the case at Kainji meteorological station.

Inconclusion it can be said that at least at Kainji, there is not yet an indication of change in rainfall pattern on an annual basis. The same conclusion can, of course, not be drawn for the whole Niger basin.

An illustration of the latter is shown in

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Table 1.1: the four most important Black Floods occurred in the distant past while the four most important White Floods are much more recent. Unfortunately, at this stage no data were readily available in digital format to do a further analysis with respect to discharges rather than rainfall. However, human interventions in the catchment resulting in degradation cannot be ruled out to be an important cause for increasing floods in recent years.

1 400

1 200

E 1 000

*, E 800

600 0400

200

(o L o 0)(I'.O g- am) Co) ton 0 ) 0a ) 0 0) 0) 0) 0) 0) a0 ) a) a) 0) 0) 0 0) 0 0 ------c\JCm CmJ

I- 5-yr rAobvStDev - 5 per. Mov. Avg. (Annual rainfall)|

Figure 2.17 Kainji - annual rainfall depths and 5-year moving average and standard deviation

2.5.2 Hydrometric data

Hydrometric data are collected at 8 locations, as shown in Table 2.2 above. Except for the PCD HYDRONIGER equipment, the other equipment - AWLRs and staff gauges - is in good condition. Staff gauge locations are inspected by the Kainji hydrological staff at least once a year and repairs made if and when necessary.

The AWLRs are located close to Kainji GS. Staff gauge locations are shown again in Figure 2.18, and their geographical coordinates in Table 2.4. Table 2.4 Coordinates of stations monitored by Kainji Latitude Longitude Elevation Station name River name (dd.dd) (dd.dd) (m+MSL) Jidere Bode Niger 11.38 4.12 152.40 Kende Sokoto/Rima 11.53 4.27 173.74 Kowara Niger 11.05 4.58 212.14 Malando Bridge Malando 10.70 4.80 152.40 Sabon Gari Niger 11.53 3.85 152.40 Yelwa Niger 10.88 4.75 167.64 Source: JICA + ENPLAN 1993

The staff gauges are read 3 times a day, at 07:00, 12:00 and 18:00 hours by the gauge keeper. Discharge rating tables are only available at the following locations:

* Jidere Bode

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* Kende ** Malando

* However, these tables have never been updated and therefore their accuracy remains doubtful. Another returning problem is vandalism. Staff gauges are often wrecked by acts of vandalism by roaming tribes.

* I< ~nOde f .

- Y ELWA Ka

SEGB I

(\ij'~. L ,,,20 ' km

Figure 2.18 Location of hydrometric stations monitored by Kainji hydrological staff

* 2.6 Evaluation of the budget reserved for flood warning

* There is no special budget reserved for flood warning, all costs incurred are paid from the regular budget reserved for hydrological operations.

2.7 Conclusion with respect to Flood Early Warning

In general one can say that the system has worked adequately until now. Although the *0 bulletins are lacking detailed information, the question remains if more details and earlier * warning is really necessary in view of the nature of the floods as described above.

* The main problem is most probably that of people living in areas not fit for development, that is to say living in the flood plain. No permanent construction should be allowed in * the flood plain. Cattle grazing and agricultural activities should only be allowed on a seasonal basis. .

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3 ACTIVITY 2 - DRAFT OF AN IMPROVED SYSTEM FOR FLOOD EARLY * WARNING

* 3.1 General

* Improved flood early warning may not be a priority in terms of safety considerations for downstream population or hydraulic structures, this aspect is needed for improved operation of the dams and optimisation of electricity production.

Although this section focuses on Kainji as per TOR, the same holds for the situation at * Jebba GS. The plans to divide PHCN in separate power production units affect flood early forecasting and hydrologic operations at Jebba and Kainji3. For instance, both * hydrology departments could share the expensive current metering equipment and staff. Also data collection, processing and analysing should be the same in both departments, * in order to exchange experience, software and processed data on a daily basis via mobile telephone and/or Internet/email or WAN. This would have the advantage of an * extra backup at the other station.

* 3.2 Identification of additional equipment and infrastructure to rehabilitated

* It is clear from the previous section that the flood early warning system is not very * detailed, with respect to time of occurrence, duration and level of the flood. Neither are the means of communication of such information to target groups living in flood prone * areas modern.

* However, it remains to be seen if an improvement of the warning system itself would really contribute to more safety against floods. The only way to get an insight into the * development of floods at an earlier moment, in technical terms, is to increase the lag time. This can only be done by taking (forecasted) rainfall into account and thus needs * the development of Rainfall-Runoff models which need a large number of hydrological, hydraulic and geometric data. Moreover, it requires real-time (or forecasted) rainfall data to be fed to the model. Because only rainfall data at Kainji GS are readily available, at * present, implementing this idea is very costly and hence most likely not feasible.

* Experience4 learns that sophisticated automatic stations where water level and/or discharges are measured cannot be durably operated and maintained in the Niger basin * at remote locations. The causes are various, but most important are maintenance costs and acts of vandalism. Therefore in the following, in proposing equipment to be left at * remote locations in the field, the emphasis will be on proven and simple non- sophisticated equipment. Thus the following is proposed for all station other than Kainji GS:

* . water levels: standard staff gauges to be read three times ad day by a competent * and adequately paid gauge keeper rainfall gauges: at all monitoring stations, to be read three times a day by the * same gauge keeper discharge rating equipment one or two complete sets of standard OTT (or * equivalent) flow current metering equipment, including dinghies, jibs, etc. and

*3 As well as the opportunity to optimise power generation from the basin as a whole as described before. 4 E.g. the HYDRONIGER project implemented in the 1970s

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4WD transport * * GPS sets for accurate locations * Rehabilitation of the PHCN office in Yelwa

At Kainji GS all current metering equipment and dinghies and all other equipment not necessary for day to day monitoring should be kept under lock.

3.3 Improvement of the monitoring, transmission and processing of data

* The monitoring improvement must consist mainly of more accurate reading, and more * frequent and faster transmission to the head office at Kainji GS. The set up of two-way radio links between stations and head office should be considered. This would greatly * enhance the monitoring effort and certainly flood early warning. More accurate reading could imply the use of binoculars.

For the processing of data the following is recommended:

* Two sets of computers and one printer and scanner, with UPS and backup * hardware and software * Standard software: Microsoft Office, Antivirus, etc * * Internal cabled network * * Hydrologic database software, such as: * HYDRACCESS (free of charge; * http://www.mpl.ird.fr/hybam/outils/hydraccess-en.htm) in use with many of the NBA countries * * HYMOS (dongle-license protected; http://www.wldelft.nl/soft/hymos/inVindex.html) in use in a number of countries m world wide * TIDEDA (dongle-license protected; * http://www.niwascience.co.nz/rc/instrumentsystems/tideda) in use in a number of countries world wide i * DSL Internet connection * Additional software could include hydraulic and hydrologic models from HEC * (http://www.hec.usace.army.mil/) which are well-known and documented, and can be downloaded and used completely free of charge. Refinements and more * detailed analyses could be done using GIS using ArcView GIS 3.3 (http://www.esri.com/software/arcview/arcview3x.html) as a start. 0 It is also recommended to have information (outflows, spills, turbine flows, rainfall) from * the two main dams in the Sokoto-Rima river system, Goronyo and Bakalori, since that river system contributes significantly to the White Floods. These connections could be via Internet/email and/or mobile telephone if available.

In a similar way connections should be established via InterneVemail/telephone to the * u/s stations on the Niger, notably Niamey the seat of the NBA.

* 3.4 Identification of capability improvement of staff involved in flood operations

* At Kainji GS there are two hydrologists and one Principal Manager Hydrology, plus a number of field staff, gauge keepers. It is necessary to provide training in the field of: 0 * Hydrologic Database Management software adopted

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* Preparation of Hydrologic yearbooks, (website?) * Internet data publishing * Hydrologic and Hydraulic packages adopted * Standard Excel data manipulation * Standard Back-up methods * Current metering and discharge calibration, this has to include equipment maintenance * Two-way radio procedures.

The basic analysis of information can be done for the hydrologic part by any of the hydrological database packages proposed. To include hydropower production optimisation requires dedicated software developed by one of the international hydropower such as ABB (Asea Brown Boveri).

Nevertheless it is quite possible to develop software that can optimise both head and water volume. A preliminary analysis using a monthly or weekly time-step can already be developed in Excel.

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4.1 Hydrological and GIS data bases

4.1.1 Present situation

At present the collected hydrological data - as described in the Report on Activity 1 and 2 - are registered on paper and inputted in Excel spreadsheets. The latter are not well laid-out and not stored in a logical folder structure on a PC. Nor do backup procedures exist. Hence backups are not carried out in a regular structured manner. Thus many hydrological data were lost when the hard disk of the PC in the Hydrological Department crashed some years ago. Fortunately the paper hardcopies did still exist. Neither GIS data bases nor software does exist at the Hydrological Department. In fact no good maps of the catchments of the Nigerian rivers feeding Kainji reservoir are available at the Department.

It is obvious that for a good (hydrological) operation of the reservoirs, and hence flood warning, a good reliable hydrological database is imperative. This database could be complemented by a GIS for better understanding of the spatial impacts. However, the setting up of a GIS system including maps and relevant data is time consuming and expensive, apart from the GIS software. Moreover, experienced personnel are required to operate such a system.

However, it should be clear that even perfect databases and reservoir operational models cannot optimise the hydropower output of the system if the hardware itself (turbines, generators, gates, etc.) is not in good operational condition. E.g. at present in Kainji, only 5 out of 8 generating units are more or less in good operational condition.

4.1.2 Hydrological data base

The hydrological database should contain all the hydrological data associated with reservoir operation. In general, data in the database must: * contain sufficient detail so that users-even years later-can understand how the results flow from the raw data, without having to make interpretations or, worse still, investigations of their own. * include an assessment of their quality that describes the accuracy and precision with which the data have been collected and/or analyzed Data quality assessments will allow secondary users to "weed" out questionable data more easily. * include a description of the data collection, recording, and analysis methodology or protocols. Having this information in-hand allows for the most comprehensive and appropriate use of data by others.

System Requirements of the hydrological database system are presented in the following: * A flexible information system The database is comprehensive, well tuned and easy to use. The graphical and map-based user interface offers a pleasant and efficient working environment. The system facilitates processing of a wide range of water-related data. Fields of

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application include: * surface and groundwater hydrology * meteorology * water quality and ecology * water resources management

The database is time series oriented with common facilities for spatial analysis. In combination with a geographical information system (GIS) for comprehensive geographical data analysis, it covers all data storage and processing requirements for planning, design and operation of water management systems. Exchange of data between the database and common geographical information systems is easy and user friendly. The database uses an open data structure ensuring convenient interaction and data transfer with other database and modelling systems.

* Operating system The database is designed for the stand-alone computers as well as in a network system, running the WINDOWS XP operating systems.

* Entry and editing A data editor allows for user-friendly entry and editing of data. Monitoring network information and time series data can be entered manually, exchanged with spreadsheets and databases by using the clipboard or imported from file. Data from recording monitoring stations can be downloaded automatically.

* Validation and completion Validation and completion is an important first step in data processing. The database offers a wide range of tabular, graphical, computational and statistical validation techniques among which: * tabulation of series and flagging of outliers * plotting of time series * relation curves and double mass analysis * near-neighbour checks and series homogeneity tests Various options are available for series completion. Among these are interpolation techniques which use series relations derived with regression techniques or spatial relations.

* Analysis of meteorological data The database must be able to process meteorological data like rainfall, wind speed and radiation. Typical analyses are the computation of catchment rainfall (for example based on Thiessen polygons) and evapotranspiration. The evapotranspiration module must at least include methods such as Penman with or without FAO-correction, pan evaporation, and the mass transfer method.

* Discharge measurements and stage-discharge analysis The stage-discharge analysis options include the elaboration and validation of current metering data, the computation and validation of discharge rating curves and the extension of rating curves. Rating curves can be represented by parabolic or power type equations, with up to three different water level ranges at a time. The Jones correction for unsteady flow can be applied and a procedure for effectively eliminating backwater effects while modelling the rating curve is available.

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Water levels can be converted into discharges based on rating curves or (pre- * programmed and user defined) structure equations.

* * Statistical and time series analysis An extensive statistical package is available covering amongst others: * * computation of basic statistical parameters * fitting distributions including normal, lognormal, various Pearson types, log- * Pearson, exponential, various Goodrich extreme types, and P.O.T. distributions * * correlogram and spectral analysis * range and run analysis * computation of frequency and duration curves * * polynomial, multiple and step-wise regression analysis * time series analysis, e.g. cross and autocorrelation and spectrum

0 * Reports and graphs * The database has a graph server and standard templates for the graphical output of all analysis modules. The flexible graph server allows the user to easily tailor * graph layouts to individual requirements. A wide range of formatted tables is can be generated for presentation in annual reports. For final editing - when required - * the output graphs and reports can be easily transferred to other WINDOWS programmes such as the MS OFFICE components EXCEL and WORD. . There are a number of hydrological database systems available that satisfy more or less * the requirements described above. They can be divided into commercial packages for which a license has to be bought and completely free packages. * Examples of commercial packages are:

* * TIDEDA (www.niwascience.co.nz/rc/instrumentsystems/tideda), is a software package for making databases to store and analyse any time series data. It is particularly suitable for processing environmental and hydrological data. Tideda evolved from a hydrological database system first developed in New Zealand in 1969. It has been continuously developed and used ever since, making it amongst * the most durable software in the world. HYMOS (www.wldelft.nl/soft/hymos/int/index.html), is the information system for water resources management in general. It covers all data storage and processing requirements for analysis, planning, design and operation of water management * systems. With HYMOS data becomes information. HYMOS is time series oriented with common facilities for spatial data analysis. A wide variety of data processing and analysis features make HYMOS a powerful tool in water related studies, research and consultancy. It is used by a number of government agencies world- * wide.

* Examples of freeware package are:

* * HYDRACCESS (www.mpl.ird.fr/hybam/outils/hydraccess-en.htm) is an extensive, homogenous and user friendly software, which allows importing and managing * various kind of hydrological data in a Microsoft Access 2000 database, and to realize all processing that an Hydrologist can need. It was developed by an * hydrologist for other hydrologists. Its development began in year 2000, and was regularly continued since. Its author is Philippe Vauchel, Hydrologist in the IRD * (French Research Institute for Development), and the software is a property of IRD. This package is in use by a number of ABN countries, notably Mali and

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Guinea. French, English and Spanish versions exist. * HEC-DSSvue(www.hec.usace.army.mil/software/hec-dss/hecdssvue- dssvue.htm), is a Java-based visual utilities program that allows users to plot, tabulate, edit, and manipulate data in a HEC-DSS database file. The graphics produced by HEC-DSSvue are highly customizable and can be saved in various formats, including "jpeg" and "png" (portable network graphics), or for printing or copying to the clipboard for inclusion in reports. HEC-DSSvue incorporates over fifty mathematical functions that were available in the DSSMATH program. Along with these functions, HEC-DSSvue provides several utility functions that provide a means to enter data sets into a database, rename data set names, copy data sets to other HEC-DSS database files, and delete data sets.

This is a simple timeseries package which allows for easy exchange with the various HEC models (HEC-HMS, HEC-RAS etc) which are also public domain, hence license free. However, analyses, statistics, etc are not included but have to be programmed using the built-in scripting language.

4.1.3 GIS data base

None of the Hydrological Databases mentioned in section 4.1.2 are GIS based, that is, do require a GIS. A hydrological database that is completely integrated with a GIS adds a large additional complexity, apart from manpower and financial issues, without adding additional information. The only advantage would be that thematic maps can be more easily generated.

However, all packages mentioned, except HEC-DSSvue, can use GIS maps as background to facilitate the presentation of the hydrometric network, in addition to some special analyses. E.g. Hydraccess can use ArcGIS shp files to generate catchment rainfall series based on Thiessen and/or Kriging averaging methods. In addition, GIS maps could be produced indicating for instance the extent of (potential) flooding. However, the TOR requires that a GIS is proposed and some implications and requirements will be discussed in the following. It should be understood that the setting up of a GIS with relevant information in layers to be included is a considerable task both in manpower and time. If layers are not readily available they have to be acquired from outside sources or (manually) digitised from good large scale (e.g. 1:250000) maps. Map layers that should be included in the GIS, in diminishing order of importance, are:

* river network (polylines, polygons) * water bodies (polygons) * streams (polylines) * (sub-)watershed boundaries (polylines) * location of hydrometric stations, rainfall stations, etc (points) * location of dams, hydropower stations, irrigation intakes, etc (points) l*anduse, irrigation schemes, etc (polygons) * location of roads, railways, tracks etc (polylines) * location of towns, villages, hamlets, etc (polygons, points)

For good and easy connection with existing GIS data in the ABN area, the GIS software should come from ESRI, e.g. ArcView GIS 3.3 or the newer ArcGIS 9.1 Desktop. While the former is simpler and easier to use without too much experience, the latter is the later version completely rewritten to adhere to MS-Windows standards. Note that both packages run in the MS-Windows environment. Both packages should have the

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additional extensions Spatial Analyst and 3-D Analyst. These extensions allow for special hydrologic (catchment boundary delineation, Thiessen nets, etc) and hydraulic operations (flood plain delineation, etc). However, for these extensions to be really useful, the geo-data must be sufficient.

4.2 Hydrological forecasting model

4.2.1 Introduction

A hydrological forecasting model is proposed to forecast the inflows into Kainji reservoir thereby increasing lead time for flood warning on the one hand and improving reservoir operation for power production on the other. Such a model could exist of two modules:

* a rainfall-runoff module, whereby the time it takes for real-time measured rainfall to contribute to runoff further increases the lead time * a hydrologic or hydraulic routing model to route the runoff through the river system to the reservoir

If it is feasible to forecast the rainfall itself, the lead time can be even more increased. However it should be understood that the larger the lead time, the less accurate the forecast becomes.

4.2.2 Rainfall-runoff model

Rain-fall runoff models need a fair amount of data, not only for operation in real-time, but also for calibration. In the case of Kainji reservoir these data - catchment rainfall data in particular - are not readily available. Although there are rainfall stations in the catchment available, no links exist between those stations and the hydrological department at Kainji Dam. Thus the implementation of a rainfall-runoff model would be time-consuming and an expensive exercise.

As has been shown in Activity 1, the changes in water levels and discharges which would have an significant impact on reservoir operation are so gradual that there is ample time for issuing flood warning bulletins, and hence prepare changes in reservoir operation. Thus a rainfall-runoff model would not significantly contribute to an improvement of this process.

Because of the cost involved and the doubtfulness of its usefulness it is not recommended to implement a rainfall-runoff model and rather concentrate on resources for Activity 2.

4.2.3 Routing model

As indicated above, the routing model is needed to calculate the change in runoff hydrograph during its travel through the river network to Kainji reservoir. Thus it is necessary to have a number of observation points where daily water levels are observed, and can be converted to discharges via an up-to-date stage discharge relationship.

In order to have enough lead time (3 days - 1 week) it is necessary that the observation points (hydrometric stations) are located far enough upstream from Kainji reservoir. In

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order for this approach to work correctly it is necessary to have up-to-date stage- * discharge relationships and direct links to the stations such that daily data can be conveyed to the control centre within the Hydrological Department at Kainji Dam.

* The routing model itself can be a hydrological routing model (Muskingum) or a hydraulic model (Mike 11, HEC-RAS), or statistical relationships (regression, relation curves). Of * these approaches the hydraulic model requires the most data, followed by the hydrological model. The statistical approach, which can be implemented as a * spreadsheet model, is by far the simplest approach. In the present context it is recommended to use the spreadsheet approach as a first step.

Such a model would be operated on a daily basis (updating), thereby providing forecasts * for the next 3-days or 1-week, depending on the travel time of the hydrogrpah from key observation point to Kainji Reservoir. The weekly forecasts could then form the basis for the hydropower production plan.

* In case the lead time of the information from the key observation points is smaller than * 1-week, it is possible to include a simple Autoregressive Model of the first order, that is using the information from the previous time step and some normal variate, with or * without additional statistical parameters of the station for the particular week.

* Hydrometric stations to be used for forecasting are basically the ones mentioned in Activity 1, shown here in Table 4.1

* Table 4.1 Hydrometric and meteorological stations used for Kainji reservoir operation Stations Location/river Type Condition Remark Kainji u/s powerhouse intakes Staff gauge good * AWLR OTT good Southern tip of Kainji AWLR OTT good Sabon Gari Niger river u/s Sokoto/ Staff gauge good No rating curve available * Illo Rima confluence Jidere Niger River d/s Sokoto/ Staff gauge good Principal hydrometric stationfor Bode Rima confluence reservoir inflows; rating curve - PCD discontinued needs updating HYDRONIGER Kowara Niger River d/s Sokoto/ Staff gauge good No rating curve available C Rima confluence Yelwa Niger River u/s Kowara Staff gauge good No rating curve available

Kende Sokoto/Rima River u/s Staff gauge good Sokoto/Rima River is the main * Niger confluence White Flood contributor; rating curve needs updating * Malando Malando River Staff gauge good Malando River is another village important White Flood contributor; rating * curve needs updating

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Stations Location/river Type Condition Remark Ganwon Danzuki River Staff gauge good Danzuki River is non-perennial; No rating curve available Kainji Near Kainji dam Meteorological good

The stations mentioned in Table 4.1 should be complemented with Niamey on the River Niger and e.g. Argungu on the Rima River or any other reliable station with a long discharge record that is operational on the Rima River.

4.3 Reservoir operation model

4.3.1 Introduction

The reservoir operation model is the model that, based on the (forecasted) inflows into Kainji Reservoir optimises the operation of the reservoir with respect to flood management and hydro production. Thus the reservoir should be operated such that no water is spilled (released without producing power) on the one hand, and that total releases, turbine flow and spillway flows, do not cause downstream damage on the other.

In the case of Kainji Dam water spilled at Kainji is not necessary completely lost for power production thanks to the Jebba reservoir, where it still could be used for power production at Jebba GS. Needless to say that optimum power production can only be achieved if the power generating units are in good condition.

4.3.2 Present operation

The present operation is based on the reservoir emptying and filling curves developed during the design of Kainji Dam (Balfour & Beatty and NEDECO, 1961, 1963, 1967,1968, Begemann 1973) and updated in 1973 (NEDECO 1973). These curves did not take the operation of Jebba reservoir and GS into account. By estimating inflows into the reservoir based on daily data provided once a month (or more often in case of emergency) as described in Activity 1, recommendations for the operation of the reservoir were provided by the Hydrological Department at Kainji GS.

Because of the fact that the full power production capacity was not always available during the last decade, no optimum operation of Kainji GS could be achieved.

4.3.3 New reservoir operation model

Principles The operation of the reservoir cascade consisting of the Kainji and Jebba GSs, (we assume that they continue to be jointly operated), can be optimised using two approaches: * updating the old approach using updated filling and emptying curves for various generating capacities, or * preparing new up-to-date rule curves for three water availabilities: dry, normal and wet situation with respect to Black and White Floods

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which describe both an average situation for a long-term optimisation, and

* a weekly operation model, to optimise the situation as it occurs in real-time

* Updating the filling and emptying curves The old curves were based on a very limited set of data. However, since the commission * of Jebba GS in 1985, about 21 year of data are available to carry out this analysis using the approach followed by Begemann for the original design of Kainji (Begemann, 1973). * Once these curves have been established, the idea is to follow the se curves as much as possible during weekly operation. In case the curves cannot be followed, the weekly * operation model (described below) can be used to bring the system as soon as possible back to the preferred state on the curves. Preparing rule curves * Rule curves can be prepared by using a standard water balance simulation model, such as the public domain model HEC-RESSIM (www.hec.usace.army.mil/software/hec- * ressim/hecressim-hecressim.htm) or commercial models such as MikeBasin (www.dhigroup.com/Software/WaterResources/M IKEBASI N .aspx) or RIBASI M (www.wldelft.nl/soft/ribasim/int/index.html). By carefully examining the change in reservoir levels when using historical reservoir inflows and manually maximising * hydropower output, rule curves can be established for e.g. dry, wet and normal periods.

* These so-called rule curves are then an indication where the reservoir level should be in * time, to obtain maximum hydropower output related to a long period of reservoir operation, while at the same time minimising spills, preventing flood damage.

Weekly operation model * Either of the two approaches described above determine average situations, which if followed result in optimum reservoir operation in the long run. Of course, as the actual * situation will deviate, a procedure is required to bring the reservoir levels back to those indicated by the rule curves or the emptying and filling curves.

This procedure could be modelled using a spreadsheet model which simulates a water balance during a single year - a moving window of 52 weeks. During 51 weeks, inflows, * outflows, spills, power production etc. are kept and updated as they have actually occurred, while at the same time with the forecasted inflow for the 52nd week, oufflows d are calculated such that power production for that week (or the whole period) is optimised, subject to arriving at the required reservoir storage level as close as possible * and at the same time not causing flood damage.

* The rate at which deviations from the required storages levels have to be "repaired" are part of the constraints of the model. For instance it may be inconceivable to not * generating power at all for the next week(s) if that is the only way the reservoir levels can be brought back to the levels dictated by the standard curves.

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5 CONCLUSIONS AND RECOMMENDATIONS

5.1 Flood forecasting procedure

During the flood season, the rise both in reservoir and tailrace levels is a gradual process. This circumstance provides sufficient lead time to issue flood warnings. * Although certainly not perfect, the present procedure of flood warning appears to be fairly adequate.

In the current situation most "accidents" occur because the riverine population refuses to * evacuate the flood plain. The main problem is the fact that people live in areas not fit for development, that is to say living in the flood plain. No permanent construction should * be allowed in the flood plain. Cattle grazing and agricultural activities should only be allowed on a seasonal basis. . The flood warning procedure can only be made more effective if the information * provided to the people at risk can be made more precise, both in time and space. To 0 arrive at such more effective procedure, important investments are needed in terms of hydrologic data collection and analysis and communication with the target population.

5.2 Improved flood forecasting

It has been concluded that improved methods and procedures for early flood warning * are not likely to contribute to an important improvement of the safety of the downstream population. However improved flood forecasting is an element in improved operation of * the Kainji and Jebba Dams.

* The only way to get better insight into the development of floods at an earlier moment, in technical terms, is to increase the lag time. This can only be done by taking (forecasted) * rainfall into account and thus needs the development of Rainfall-Runoff models which need a large number of hydrological, hydraulic and geometric data. Moreover, it requires real-time (or forecasted) rainfall data to be fed to the model.

Improved hydrological information would require more accurate water level observations * and regular updates of water level - discharge relations. Also needed is information (outflows, spills, turbine flows, rainfall) from the two main dams in the Sokoto-Rima river * system, Goronyo and Bakalori, since that river system contributes significantly to the White Floods. These connections could be via InterneVemail and/or mobile telephone.

5.3 Improvement of the dam operation procedures and the analysis of information

Due to the very flow regimes of the Niger River at Kainji and Jebba and the Kaduna * River at Shiroro, the operation of these three most important hydropower stations owned * by PHCN is closely interlinked, and cannot be separated if their total output has to be optimised.

Specific dam operation procedures for flood conditions may need updating. The * operation in the past has not caused great problems, although during the White Flood of 1998/99 the total outflow was higher than the total inflow, a sign of under optimum * operation, which can attributed to not having the correct information at one's disposal in time. This could be improved by enhanced communication systems as described above.

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The rule curves used by the dam operator are basically the same as formulated during the design of Kainji GS and later updated in 1972 (NEDECO, 1972). Although at that time already the factor navigation was already left out of the rule curves - the operation of the Kainji - Jebba - Shiroro system with respect to Hydropower coincides to a large extent with navigational requirements anyway - the curves did not include Jebba and Shiroro Generating Stations.

Therefore, it is recommended that new rule curves be formulated that take the integrated operation of Kainji, Jebba and Shiroro into account in order to maximise the hydropower output from the available water.

However it is obvious that the formulation of new optimal rule curves is of no use if the turbines and generators are not in optimum condition. Inthis respect the situation at Kainji GS is far from ideal, with only 5 of 8 units operational, and that not even full time. The situation at Jebba is much better. It is not known what the situation at Shiroro GS is, since it was not part of the present TOR to take Shiroro into account.

5.4 Flood early warning tool

5.4.1 General

Although the following conclusions and recommendations focus on the operation of Kainji reservoir, the same approach should be used for Jebba, with the exception that it is not recommended to install a separate GIS package at Jebba. GIS requirements for Jebba should be included in GIS operations at Kainji, in a similar way as it is recommended to share special hydrologic equipment such as current metering equipment between the two GSs.

5.4.2 Hydrological and GIS data base

Hydrologicaldatabase system It is recommended to download a copy of HYDRACCESS hydrological database system and start using and filling it as soon as possible. It is also recommended to continue to use Excel for preliminary data storage as done at present, including the tips and advice given during last October's site visit.

This could easily be handled by the existing staff at the Hydrological Department. However, some training in the use of HYDRACCESS and some refresher course for Excel is recommended.

GIS software It is recommended to use ArcGIS 9.1 Desktop package, including the Spatial Analyst and 3-D Analyst extensions. The existing staff in the Hydrological Department should be extended with a hydrologist with some GIS experience or with a GIS person with some background in hydrology. This person would do the day-to-day GIS tasks, preparing and improving special maps for reports etc. The GIS layers described in section Error! Reference source not found. should be acquired through an external party.

Hardware and additional software For both packages the following should be available,

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Hardware: * * 2 Desktop computers: CPU comparable to Pentium 4, 250 GB hard disk, 1 GB RAM memory, 4 USB ports, 1 LAN port, 1 optical mouse, CD/DVD+/DVD- * rewriter, 1200*800 video card and 17 inch LCD screen * 1 Printer HP LaserJet 1320 (or comparable), A4 format * * 1 Printer HP DeskJet 1120 (or comparable), A3 format with colour . 2UPS

* Standard Software for each computer, apart from the GIS and HYDRACCESS: * Windows XP professional * * MS Office Professional 2003 * Free antivirus software (AVG, Avast!, or similar) * * Good backup software (Acronis True Image, or similar)

* 5.4.3 Hydrological forecasting model

* In view of the limited additional contribution to the accuracy of the forecast compared to the high cost in setting up and maintaining, it is not recommended to include a rainfall- * runoff model. In case the lead time of the information is less than 1 week, it is recommended to prepare a Lag-1 Autoregressive model with weekly parameters (if enough data available) for the relevant stations.

* Furthermore it is recommended to use simple regression methods to route the * hydrographs from the observation points to Kainji reservoir.

* 5.4.4 Reservoir operation model

* In order to keep it simple and robust such that the system can be handled by the present staff at the Hydrology Department after some training, it is recommend to develop up-to- * date rule curves from the historical data using HEC-RESSIM, and use those as the primary curves on which to base the reservoir operation with respect to flood and * hydropower operation.

* It is further recommended to adjust deviations of the optimum rule curve trajectory using a specially developed Excel spreadsheet including NLP optimisation for hydropower * under a number of constraints, e.g. minimising spill, limiting total outflows to full bank level, etc. In case Excel's built-in solver cannot handle the problem adequately, it is recommended to acquire a special solver Add-In such as the Premium Solver Platform * from Frontline Systems Inc. (www.solver.com/xlscompare.htm).

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REFERENCES 1. Balfour, Beatty & Co. and NEDECO, 1961: Niger River Dams Project- Volume 2, Part 2: Hydrology and Reservoir Operation, Niger Dams Authority

2. Balfour, Beatty & Co. and NEDECO, 1961: Niger River Dams Project - Volume 4, Part 4: Kainji Project, Niger Dams Authority

3. Balfour, Beatty & Co. and NEDECO, 1961: Niger River Dams Project - Volume 4, Part 4: Kainji Project, Niger Dams Authority

4. Balfour, Beatty & Co. and NEDECO, 1963: Niger Dams Project- Additional Note on Hydrology and Reservoir Operation, Flood Routing Kainji Reservoir Energy Production of Kainji System Alone, Part 2 Chapter 4, Niger Dams Authority

5. Joint Engineering Consultants, 1963: Niger Dams Project - A brief Description, Federal Government of Nigeria, Niger Dams Authority

6. Balfour, Beatty & Co. and NEDECO, 1967: Niger Dams Project- Note on Reservoir Operation, Part l: Kainji System Alone, Niger Dams Authority

7. Balfour, Beatty & Co. and NEDECO, 1967: Operation Manual for the Operation of Kainji Reservoir (Draft), Niger Dams Authority

8. Balfour, Beatty & Co. and NEDECO, 1968: Operation Manual for the Operation of Kainji Reservoir (Kainji Alone), Niger Dams Authority

9. NEDECO, 1972: Niger Dams Project- Review of Kainji Hydrology and Reservoir Operation, Niger Dams Authority

10. Begemann, Ir C.L., 1973: Utilising significant head by a dam and later on a series of dams whereby the reservoir thus created is exploited to get the optimum of energy production, increase of low flows and flood control, paper S.1-3 presented at the XXlllrd Navigation Congress PIANC, Ottawa, Section l: Inland Navigation, Subject 3: Planning of waterways for power generation and navigation

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APPENDIX A: Standard Flood Warning Bulletin

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Form N.E.P.A. 259 *NJNATIONAL ELECTRIC POWER AUTHORITY Kainji Power Station, P.M.B. 1111, Kainji, New Bussa.

Telegram:

Telephone

Ref: NEPA/GMG/KPS/1.1/Vol.1.4/ /2004 Date:

Dear Sir,

FLOOD WARNING

The black flood event, a natural phenomenon of the lower Niger has already peaked for the 2003/2004 hydrological year. Although the trend of hydrological events in the environment of Kainji are still being monitored, recent high inflow receipts into our reservoir constitute good indices of excess inflow from the upper Niger. This high magnitude of inflow merged with out already filled reservoir has made spillage unavoidable.

It would be recalled that very high magnitude of inflow also occurred in 1988, 1994 and 1998 among other years. High intensity and long duration rainfalls especially in the upper Niger being the major causes of channel and Urban floodings and resultant runoff into our reservoir should be recognized as an act of God to which National Electric Power Authority has no control.

Therefore we wish to alert you and or your organization and community of the possible flooding of River Niger down stream of Kainji in the current 2003/2004 hydrological year. It is necessary for riparian settlers and all water related agencies in the Niger River Basin to closely monitor the behaviour of the Niger or its tributaries in their environment in order to avoid the catastrophic consequences of flood.

This flood warning message is not to create panic, but to enable you take precautionary measures to safe guard lives, properties and installations in the Basin of the Niger.

Yours faithfully,

Engr. l.C. Okoli General Manager (Gen.) Kainji Power Station.

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