Piezometric and Hydrochemical Dynamics of Alluvial Aquifer in Timia Valley, Aïr Mountains, Semi-Arid Region (Agadez, Niger)

The alluvial aquifer of the Timia valley provide the supply of water to the population, but also the need for irrigation water. This important aquifer is highly dependent on precipitations and sometimes it dries out before the return of rainy season leading to drought. Also, the increase of agricultural activities has led to the deterioration of water quality in places but also to the depletion of this alluvial aquifer. The objective of this study is to contribute to understanding the quantitative and qualitative dynamics of this limited extension aquifer. A methodological approach based on piezometric and hydrochemical methods has revealed that the alluvial aquifer is renewed from the arrival of first floods of Timia valley and the main flow directions that are globally NE-SW. It show too an increase concentration of cations Ca 2+ , Mg 2+ , Na + and stability of K + during the rainy season. However, for anions a low increase of HCO 3-, Cl - , SO 42-and NO 3-during the dry season is observed.