The impact of climate change on crop production and health in West Africa
An underutilized Middle Belt in West Africa
In West Africa, the Northern Sahelian zone and the coastal areas are densely populated but the
The population of West Africa and the 'empty' middle belt
Middle Belt in between is in general sparsely settled. While the historical reasons for this phenomenon are only partly understood and include explanations relating to slavery, the high diversity and small size of tribes as well as to poor soil conditions, the fact remains that the Middle Belt has underutilized land resources and may, therefore, be an important asset for future development of the agricultural sector in the region. This holds particularly under climate change, because the climate in the area is expected to remain more moderate than in the drier Sahel and more humid coastal zone. Increased settlement into the area is already taking place at a significant scale from the North and the South, in response to environmental degradation and mounting population pressure. Northern regions are especially threatened by
infrastructure Benin
Infrastructure and settlement areas in the Beninese area of the ORB
encroaching deserts, the borderline of which gradually shifts to the lower latitudes, while the agricultural production capacity in the intensively cultivated South is endangered by nutrient mining.
Under climate change, this situation is most likely to worsen, with accelerated desertification in the North and more frequent occurrence of torrential rains and floods in the South, but much less in the Middle Belt. This motivates to study the impact of climate change on the agricultural income and the health situation of future inhabitants of the Middle Belt, specifically on the Middle Belt part of the Oueme River Basin (ORB) in Central Benin.
Impact of climate change on agricultural income
The agriculture component of the study makes use of a detailed spatial and temporal assessment of climate change impacts, using a calibrated hydrological model of the ORB that calculates soil moisture balances with daily time steps for a 3x3 km grid, for the prevailing land use categories. For the main crops the effects on yields, area, and revenue per ton are considered. Yields can adapt through irrigation, adjusting water availability to crop demands, and improved provision of agricultural inputs as hybrid seeds and fertilizers. Regarding cropping areas, adjustment of the cropping pattern enables farmers to adapt to new soil moisture conditions. Finally, prices may adjust in response to changed scarcity on the market at national level, as well as to changed net selling positions at commune level. As climate change will expectedly create conditions in the Basin that are similar to those in the areas surrounding it, particularly in the drier North, and the more humid South, we base our projections for the Basin on relationships estimated for the Beninese territory as a whole. With these relationships and under scenarios representing different assumptions on climate change and policy interventions, we conduct model simulations, with irrigation, improved provision of inputs, and area expansion as policy levers.
Effects of reduced rainfall and increased rainfall variability
The model simulations show that the reduced rainfall and increased rainfall variability that generally emerge under climate change have very different effects on various crops. For remunerative staples such as Maize and Yam the yields fall on average, while crop failures under drought become more frequent, whereas for Cotton, the most rewarding cash crop, and for Groundnut yields improve on average. Comparing mean farm income under climate change to the historical period, without price and area share adjustments, shows that rather dramatic income losses will be found throughout the basin except for some parts in the North-West and South.
Coping strategies
In response to these changed conditions farmers can adapt their cropping pattern, and it appears that expansion of Cotton and Sorghum at the expense of Maize and Yam in many parts of the region compensate to a great extent for the revenue loss due to climate change. Once price adjustments in response to changed scarcities of local crops are accounted for the losses are reduced further. It is even found that losses can turn into gains once fallow is reduced through application of modest amounts of fertilizer, which is a promising option for agricultural intensification since this requires few adjustments in prevailing farming practices, exploits the potential of uncultivated land and improves the water use efficiency. Indeed, reduction of fallow is key to maintaining the Oueme River Basin’s capacity to absorb migrants in the future. Nonetheless, successful development of the basin cannot rely on agricultural development alone and future growth in fact largely depends on success of urbanization, building on expansion of the trade, transport and agricultural processing sectors as well as large introduction of cash crops and expansion of livestock production, for exports to the richer neighboring Nigeria.
The health situation of the (future) inhabitants of the Middle Belt
Prevalence of diarrhea and access to safe drinking water
Diarrhea prevalence in Benin
The health and sanitation component of the project analyzes the prevalence of diarrhea in relation to the access to drinking water. Diarrhea prevalence is seen as a good indication of water impurity in general, and is in itself important as well, because it is considered the major cause of the high infant mortality in West Africa, as argued e.g. in the Human Development Report 2006. Prevalence of diarrhea, especially amongst children, has been a persistent problem and increased from 105 cases per 1000 children in 1995 to 121 cases in 1999, with as most vulnerable group the children below one year. Using outcomes from the Demographic and Health Surveys, household prevalence of diarrhea in Benin has been computed at district level. The figure shows that prevalence rates vary strongly across the communes and reaches values up to 600 per 1000 children. Overall, we observe that the most affected areas lie in the mid-north west and to a lesser extent in the south. Hence, also against the background of the foreseen immigration into the Middle Belt, it is important to identify effective strategies in fighting diarrhea. 
Differences in diarrhea prevalence between households
The relation of this high diarrhea prevalence with poor sanitation facilities and restricted access to reliable water sources is also clear: a household with good hygienic practices and access to clean water, irrespective of other conditions, will not suffer diarrhea very often. The study confirms this, showing on the basis of DHS-data for Benin that the richer and better educated segments of the population suffer much less from the disease and can secure safe water for their households. Yet, the data also point to important geographical differences within the Oueme River Basin, regarding groundwater availability and quality that reflect in diarrhea prevalence. It is also found that “stand-alone” interventions of access to water have limited effect, albeit that it is not very costly. Improving private and public hygiene seem to be at least as important in villages with ample water supply as well as in villages where there is significant stress on water resources, suggesting that “hand washing” programs as promoted by the World Bank are to be undertaken in tandem with measures to improve the quantity and quality of public service provision.