Small dams, major effects

1In the 1980s, the Sahel was hit by severe drought, prompting scientists to explore the agronomic potential of mud flats, i.e. the wetlands that African populations were forced to flee because of onchocerciasis. As this disease was now under control since the parasite that caused it was eliminated, new development opportunities were opening up to populations. Researchers tested new small and medium-sized stormwater management infrastructures: permeable rock dams in Burkina Faso, partially subsurface dams in Mali, and small dams in Côte d’Ivoire and Senegal. This research inspired NGOs which, in turn, started installing small reservoirs.

Onion cultivation using rainwater stored in a small dam, Burkina Faso.

2The interest was such that, in 1996, research was initiated on these small reservoirs in the Sahel (Burkina Faso and north of Côte d’Ivoire), Latin America (Mexico and Brazil), North Africa (Morocco and Tunisia) and the Middle East (Lebanon), as part of the “Small Dams” multidisciplinary project. Hydrologists, agronomists and fisheries experts improved the techniques, while geographers, ecologists, sociologists and economists began to gauge their effects, as hundreds of thousands of small dams have been built since the 1980s.

Livestock by a reservoir, Burkina Faso.

••• Research focuses on hydraulic developments for the reclamation of mud flats •••

Hillside dam in Tunisia.

3While their economic performance has been regularly criticised as being sub-optimal, research emphasises the value of these small dams and demonstrates that they are an effective tool for mitigating the effects of global changes. Numerous and widely dispersed, they provide a variety of services (domestic use, irrigation, livestock watering, fishing, groundwater recharge, etc.) in close proximity to rural populations. They are good sediment traps, thereby significantly extending the operational life of major structures further downstream. They also provide wetlands which contribute to maintaining aquatic and terrestrial biodiversity. Small dams are currently instrumental in land use planning in the most vulnerable regions of the tropical belt.

“Research was conducted on hillside dams in Tunisia to support an ambitious land use planning project implemented by the Ministry of Agriculture. It resulted in the creation of an observatory used as a reference for current water and soil conservation projects. Exchanges between scientists from the Mediterranean region, sub-Saharan Africa and Latin America have also underlined the fundamental role of these infrastructures in the sustainable development of arid areas.” 
Professor Akiça Bahri, National Institute of Agronomy of Tunisia, former head of IWMI for West Africa and former coordinator of the African Water Facility with the African Development Bank