Hydrogeology and siting of micro-dams around Léo Burkina Faso

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Hydrogeology and siting of micro-dams around Léo, Burkina Faso14 June 2010technician was hired before the field visit in February 2010, but unfortunately this didn’t work out.However, CREDO should find and hire a technician as soon as possible to work on the micro-damprojects and other technical issues.Besides hiring a technician CREDO should make sure all documentation on the project (missionreports, designs, drawings, maps, measurements, etc.) is properly archived and can be made availableif needed.7.3 Suitability of proposed and potential sites for micro-dam constructionThe following table give a summary of properties of the proposed and potential sites for micro-damconstruction and their expected effect on drinking water availability.old dam presentsurface waterpresent duringvisit halfFebruary 2010gardening aroundpotential damsiteshallow wellspresentSissili Tékoura Onliassan Kayérobo Kayérodo shallow wellsdry up?drinking watersituationtopographyexpected effecton drinking wateryes,currentlyfullyfunctioning,buterodingyes(driesup everyyear)yesyes (for nogardeningand drinking)borehole present invillage and people drinkfrom wells in gardens(water tastes betterbecause of the clay)no no no no - borehole present invillageno yes no yes (forwashing)noyes(driesup mostof theyears)noyes (forwashing andanimals)yes,broken,has beentried tofixed ano yes yes (forwashing andanimals)number oftimesyesforages and deep oldwell (doesn't dry up)no (but water only one deep well,level drops to forage has been built6 m below last year by CREDO but isground broken, constructorsurface) won't fix it properly.yesborehole present invillage and people drinkfrom wells in gardensold dam should fairbe renovatedand raised,made erosionproof or spillwayenlargedvery suitable low (when no drinkingwater wells areconstructed along withthe dam),fair (if drinking waterwells are constructed)quite flat on one low (when no drinkingside, erosion risk water wells aredue to bush fires constructed along withthe dam),fair (if drinking waterwells are constructed)relativly flathole in old damshould be filledup and spillwaycreatedlow (when no drinkingwater wells areconstructed along withthe dam),fair (if drinking waterwells are constructed)fairYelbougaBonapiayes,brokennono no no yes (altoughquite deep)no(notanymore)? ? borehole present, butvery busyyesvery few water pointspresent, no suitablelocations for boreholeshole in old damshould be filledup and spillwaycreatedsuitableonly indirect (when nodrinking water wells areconstructed along withthe dam),fair (if drinking waterwells are constructed)uncertain (although theneed for drinking wateris high, the soil is moreclayey than at otherplaces)At all sites a micro-dam will increase the availability of surface water during the dry season. Thissurface water can provide a good source of drinking water for cattle, brick making, washing andirrigation.32
Hydrogeology and siting of micro-dams around Léo, Burkina Faso14 June 2010At the sites of Kayéro, Sissili and Yelbouga there is an old broken dam present. The repairs of thedams at these sites can be done at relatively low costs (compared to the construction of a new dam).At Kayéro and Sissili the people also get drinking water from the shallow wells near these dams. Sothe repairs of these dams will increase the drinking water availability at these sites. However, thewells that are being used for drinking are open wells and are therefore easily contaminated. It istherefore recommended to convert these wells into safe drinking water wells by covering the well andinstall a (hand) pump.At Yelbouga drinking water is currently being fetched from a number of very busy water points in thevillage. During the dry season water for cattle is also fetched from these wells, making them evenmore busy. The repairs of the dam at Yelbouga will therefore have an indirect effect on the wateravailability since it will reduce the stress on the water points in the village. If the repairs of the damare combined with the construction of shallow drinking water wells the dam will have a directlypositive effect on drinking water availability. Since this site was not among the proposed dam sites, itwas only paid a short visit and the geology wasn’t inspected. So it is not sure whether any shallow wellcan provide enough water to serve as drinking water wells.The site of Kayérobo is very suitable for the construction of a micro-dam. If the construction of themicro-dam is combined with the construction of shallow drinking water wells with a (hand) pump thedam will have a positive effect on drinking water availability.At the sites of Onliassan and Tékoura there was still surface water present in natural depressions ofthe riverbed. This surface water was only used for cattle and washing. No agriculture or brick makingwas being carried out. It remains unclear why. The construction of a micro-dam will increase thewater availability at these sites, but since the water isn’t being used intensively it is uncertain whetherthis increased amount of water will be used.At Onliassan people currently rely on boreholes and an old deep open well for drinking water. Theboreholes and well have water all year round, so for drinking water it is not necessary to construct amicro-dam. The construction of a micro-dam combined with the shallow drinking water wells couldcreate new drinking water points, but it is uncertain whether this is necessary. It is probably a betterinvestment to make the old open drinking water well in the village micro-biologically safe by coveringthe well and placing a (hand) pump.At Tékoura there is only one old open deep well where people get their drinking water from. Last yearCREDO constructed a borehole, but it doesn’t function properly. CREDO is still discussing with theconstructor to get it fixed. The construction of a micro-dam combine with the shallow drinking waterwells can create new drinking water point, but it is uncertain whether this is necessary. It is probably abetter investment to make the old open drinking water well in the village micro-biologically safe bycovering the well and placing a (hand) pump and to keep putting effort in fixing the borehole properly.33
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Page 39: Appendix 1Topographic map
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Page 49 and 50: Sander de Haas02-03-2010Waterlevel
Page 51 and 52: If the waterlevel in the reservoir
Page 53: If there is water near the dam, mea
Page 57: Wednesday February 10 2010Flight to

Hydrogeology and siting of micro-dams around Léo Burkina Faso

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