Identification Et Cartographie Des Zones Potentielles De Recharge Des Eaux Dans La RÃ©gion De Dosso (Sud-Ouest, Niger) Par Analyse MulticritÃ¨re
Authors: Ali Ibrahim Abdou , KonatÃ© Moussa 
Published: July 2020

Les eaux souterraines constituent la principale sourcedâ€™approvisionnement en eau des populations de la rÃ©gion de Dosso, situÃ©e dansle Sud-Ouest du bassin des Iullemmeden. En dÃ©pit du climat aride Ã semi-aridequi caractÃ©rise cette rÃ©gion, le renouvellement des eaux des nappessouterraines sâ€™effectue Ã travers les pluies. Cette recharge des eaux, quiconstitue un Ã©lÃ©ment essentiel dans le cycle hydrologique, se faitprÃ©fÃ©rentiellement selon des zones qui peuvent aussi Ãªtre des zonesvulnÃ©rables Ã la pollution des nappes. Lâ€™objectif principal de cette Ã©tudeconsiste Ã identifier puis Ã cartographier les zones potentielles de recharge deseaux. La dÃ©marche mÃ©thodologique utilisÃ©e dans le cadre de ce travail anÃ©cessitÃ© lâ€™utilisation de lâ€™analyse multicritÃ¨re combinant le SystÃ¨medâ€™Information GÃ©ographique (SIG) et la tÃ©lÃ©dÃ©tection. AprÃ¨s le traitement desimages Landsat de Dosso, tous les paramÃ¨tres influenÃ§ant les processus derecharge des eaux ont Ã©tÃ© intÃ©grÃ©s au SIG. Il sâ€™agit : des types de sol, delâ€™occupation du sol, des densitÃ©s des fractures et du drainage, de la lithologiede la zone non saturÃ©e et de la pente du terrain. La carte des zones potentiellesde recharge des eaux montre que la majoritÃ© de la zone Ã©tudiÃ©e prÃ©sente unpotentiel rÃ©el dâ€™infiltration des eaux liÃ© Ã : la nature sableuse des sols, laprÃ©sence des zones de cultures pluviales, la prÃ©sence de fractures et la densitÃ©du rÃ©seau hydrographique. Cette carte a aussi permis de confirmer que leszones Ã potentiel Ã©levÃ© de recharge se situent dans les lits des mares et des"dallols" (larges vallÃ©es sÃ¨ches), qui deviennent ainsi des zones plusvulnÃ©rables. Ce support cartographique constitue de ce fait un outil dâ€™aide Ã ladÃ©cision.
Groundwater is the main source of water supply in the Dosso regionwhich is located in the southwestern part of the Iullemmeden Basin. Despitethe arid to semi-arid climate that characterizes this region, groundwaterrecharge is occuring mainly through rainfall. This recharge of water which isan essential element in the hydrological cycle is prefentially done accordingto zones which can also be vulnerable to groundwater pollution. The mainobjective of this study is to identify and mapped the potential recharge areas.A methodology based on a multicriteria analysis integrating GIS and remotesensing was used to map the potential recharge areas. After processing theLandsat satellite images of Dosso region, all the parameters influencing thehydrological recharge processes were obtained and integrated into GIS. Theseparameters are: soil types, land cover, fracture density, drainage density,lithology and slope. The map of potential recharge areas obtained shows thatthe majority of the study areas has great recharge potential. According to thisstudy, this great potentiality could be linked to: the sandy nature of the soil,the cultivable areas, the presence of fractures and density of hydrographicnetwork. This map also confirmed that areas with high recharge potential arelocated in the beds of ponds and "dallols" (wide dry valleys), which thusbecome more vulnerable areas. This map of potential recharge areasconstitutes therefore a tool for decision makers.