Hydrological interventions (i.e. dams and irrigation schemes) aim to increase economic independence and food security in the unstable Sahel environment. Tapping the Niger’s flow, however, is Th e Niger, a lifeline not without consequences. The costs and benefits of expensive hydrological structures have to be carefully balanced. In this study Effective water management in we incorporate downstream interests into our analysis. the Upper Niger Basin Downstream outcomes are inherently difficult to quantify, and are therefore often omitted in similar enquiries. The aim of this study LEO ZWARTS,PIETER VAN BEUKERING,BAKARY KONE,EDDY WYMENGA is to develop a decision-support system for effective river manage- ment in the Upper Niger, in which ecological and socio-economic impacts and benefits of dams and irrigation systems can be analy- sed in relation to different water management scenarios. Multidisciplinary in nature, this study draws on the fields of hydro- logy, ecology and environmental economics. Introduction 3 POVERTY REDUCTION STRATEGY PAPER 3 BALANCING INTERESTS 3 Hydrology 4 NATURAL VARIATIONS 4 DAMS 5 DEPENDENCIES 6 SCENARIOS 7 FLOODING 7 Ecology 8 HUMAN IMPACT 8 HABITATS 8 BIODIVERSITY 9 Sectors 10 FISHERIES 10 CATTLE 10 RICE 11 TRANSPORT 12 Economics 12 IMPACT PATHWAY APPROACH 13 FINANCIAL COSTS 14 ECONOMIC BENEFITS 15 NET PRESENT VALUE 15 POVERTY AND EQUITY 16 CLIMATE SENSITIVITY 17 Conclusions and policy recommendations 19 Th e Niger, a lifeline Introduction document highlights the need to exploit the country’s hydro-electric potential in the order of 5,000 GWh/annum. So far, high costs of both Water shortage has been identified by energy equipment and distribution networks the United Nations Environment have prevented expansion on such a scale. Programme as one of the most serious Mali’s potential hydro-agricultural capability is problems of the new millennium. For also substantial, estimated at 2 million hecta- many decades, however, it has already res. A review of the PRSP by the International been a dire problem for millions of peo- Development Association (IDA) and the International Monetary Fund (IMF) confirms ple living along the southern fringe of this, stating that “further development of Mali’s the Sahara desert. untapped hydrological potential for agriculture and drinking water purposes is a critical need, For the communities living in the semi-arid, as it directly addresses one of Mali’s core vul- western Sahel zone the Senegal and the Niger nerabilities, that of the temporal and spatial rivers are a lifeline. Indeed, Mali is a classic variability in rainfall, as well as the uncertainty case of a ‘river-dependent economy’ that is of climatic conditions” (IDA & IMF 2003). subject to enormous seasonal variation in rain- fall and river flow. A popular solution to this Although Mali’s hydro-electric and hydro-agri- climate dependency in the western Sahel zone cultural potential has yet to be fully realised, it has been the development of hydro-electric is widely questioned whether the costs and and hydro-agricultural irrigation schemes benefits of such mega-investments are proper- (Figure 1). ly estimated. Besides the economic feasibility (i.e. direct costs and benefits) of additional 3 dams, it is still unclear what the indirect effects of hydroelectric and hydro-agricultural sche- mes are on downstream beneficiaries of rivers. These beneficiaries include fishermen, cattle breeders, shipping companies and farmers, as well as the biodiversity of the river and connec- ted floodplains. BALANCING INTERESTS Hydrological interventions (i.e. dams and irri- gation schemes) aim to increase economic Figure 1.The Niger Basin (red outlining). The Niger originates in Guinea and Ivory Coast, passes independence and food security in the unsta- through Mali and Niger, and enters the Atlantic ble Sahel environment. Tapping the Niger’s Ocean from Nigeria. The Niger Basin also extends flow, however, is not without consequences. over Algeria, Burkina Faso, Benin and Cameroon. The existing dams are indicated by red dots. Figure 2 shows how irrigation takes a fixed amount of water throughout the year, while hydro-electric structures store water at peak POVERTY REDUCTION STRATEGY PAPER flood levels and subsequently release it. The hydrological effects of both are felt most pro- The Poverty Reduction Strategy Paper (PRSP) foundly during the dry season and in years of Mali constitutes the sole framework for with low floods. The following explanation Mali’s development policies and poverty reduc- helps to illustrate this: a natural river discharge tion strategies (GoM 2002). This influential of 10 to 20 km3 varies annually by a factor of 2. When extracting 5 km3, the downstream dis- Hydrology charge fluctuates between 5 to 15 km3, in other words, by a factor of 3. Would this increasing With its origins in Guinea, the Niger downstream instability also lead to a decrease in food security? flows through Mali, and finally spills into the Atlantic Ocean 4200 km from its The costs and benefits of expensive hydrologi- source. The water discharge of the Niger cal structures have to be carefully balanced. In River fluctuates significantly over time. this study we incorporate downstream inte- These fluctuations are both natural and rests into our analysis. Downstream outcomes man-made. This study’s hydrological are inherently difficult to quantify, and are the- refore often omitted in similar enquiries. The assessment increased our understanding aim of this study is to develop a decision-sup- of the Upper Niger River’s hydrology, port system for effective water management in highlighting natural variations as well as the Upper Niger Basin, in which ecological and the impact of human-made structures. socio-economic impacts and benefits of dams and irrigation systems can be analysed in rela- tion to different water management scenarios. NATURAL VARIATIONS Multidisciplinary in nature, this study draws on the fields of hydrology, ecology and environ- The annual rainfall in the catchment area of mental economics. The tentative outcomes of the Upper Niger amounts to an average of the study are described in this executive sum- 1,500 mm and varies between 1,100 and 1,900 mary. mm. Although the river discharge of the Niger 4 is determined by rainfall, its annual variation between 600 and 2,300 m3/s is much more pro- HIGH FLOOD LOW FLOOD nounced than that of rainfall. This can be witheld to fill explained by the fact that peak river flow is not reservoir only dependent on the rainfall of preceding months, but also on groundwater aquifers. extra flow effect of dams Because groundwater levels are determined by remaining flow rainfall during previous years, the river flow declines during a series of dry years. 2500 annual discharge annual precipitation effect of irrigation water intake remaining flow 2000 1500 Figure 2 Schematic hydrological effects of dams and water intake for irrigation during the flood 1000 cycle in years with a high and low flood. The flood annual precipitation or discharge cycle in the Western Sahel zone runs from June to December. Lowest flood levels occur from March to 500 May. 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 Figure 3 Annual rainfall in the Upper Niger region and discharge of the river at Koulikoro. This is what occurred during the period of dry The Sélingué dam, which was constructed in years in the mid-eighties known in western 1982, is presently the only hydropower reser- Africa as ‘La Grande Sécheresse’ (the Great voir in the Upper Niger. Theoretically, the capa- Drought), when the flow of the Niger River city of the Sélingué hydropower plant is 47.6 declined to unprecedented low levels. Years MW. Yet, with its size of 2.2 km3 (equivalent to with peak discharges in September below 6.8% of the average river discharge) the volume 4,000 m3/s occurred only twice between 1900 of the Sélingué reservoir is limited. Due to eva- and 1980; in the last 20 years, they have rarely poration from the reservoir’s surface (34.2 been above this level (Figure 3). km2), approximately 0.5 km3 of water flow is lost annually. The role of Sélingué in the hydro- logy of the Inner Delta varies considerably bet- DAMS ween the wet and dry seasons. On average, 1.8 km3 of river flow is stored in the reservoir The recent decrease in flow of the Niger River during the wet period (August to September). cannot be solely attributed to reduced rainfall In years of high river discharge, this is equiva- and depleted groundwater aquifers. Dams and lent to only 10-20% of the peak flow of the irrigation schemes in the Upper Niger region Niger. However, in years of low discharge, this (Figure 4) are also expected to have had a mea- fraction increases to as much as 20-30%. The surable hydrological impact. This study analy- water stored in the Sélingué reservoir during ses the impact of two existing man-made the rainy season is gradually released throug- structures in the Niger River: the Markala bar- hout the rest of the year. Without these ‘relea- rage (Office du Niger, ON) and the Sélingué ses’ from Sélingué, river discharge in the dry dam. The potential impact of a planned dam in period would be around 0.2-0.4 km3 per the Upper Niger region in Guinea (the Fomi month; they add 0.2 km3 per month to the 5 dam) is also assessed. natural discharge. This is particularly critical during years with a low flood, when river flow in the Inner Niger Delta from March to May is largely dependent on the management of Lac Sélingué. The construction of the Fomi dam in a tributa- ry of the Niger in Guinea, is still under conside- ration. The Fomi project involves a hydro- power plant of a maximum installed capacity of 90 MW, as well as hydro-agricultural activi- ties over an irrigated area of 30,000 ha.