Hydrogeology and siting of micro-dams around Léo Burkina Faso

Hydrogeology and siting of micro-dams around Léo, Burkina Faso14 June 20105 Proposed sites for micro-dam construction5.1 IntroductionAs requested by A4A and Woord en Daad the five proposed sites for micro-dam construction werevisited and evaluated. The locations of the sites are presented in Figure 7.The following paragraphs give a short description of each site and some characteristics. All findingsare summarised in paragraph 7.3.5.2 KayéroKayéro (or Kayoro as indicated on some maps) is located about 14 km North of Léo, only a fewhundred metres from the CREDO compound.The catchment area of this proposed dam site has a surface area of 27.5 km 2 .Figure 21 Overview of the Kayéro dam siteAt this site an about 15 year old earth dam with a diversion spillway (the spillway is not in the dam,but next to it) is present. During the rainy season the discharge of the river is too large for the spillwayand the dam overflows. Since the dam isn’t constructed for overflowing water, heavy erosion has beentaking place. After a few more years the dam is likely to break.Figure 22 Erosion of the old dam of Kayéro because of the river overflowing the dam during therainy seasonA few options are possible:1. Remove the old dam and build a new one.2. Renovate the old dam and raise it’s crest in such a way that water no longer overflows thedam (this won’t increase the capacity of the reservoir, since the spillway remains the samelevel).3. Renovate the old dam and reinforce the sides so overflowing water won’t damage the dam.4. Renovate the old dam and enlarge (deepen and/or widen) the spillway in such a way thatwater no longer overflows the dam.24