Dynamics of the alluvial aquifer in the northern part of the dallol Bosso and assessment of water potential for small-scale irrigation: Departments of Balleyara and Filingué

In the Departments of Balleyara and Filingué in Niger, the development of irrigated agriculture is a key factor in improving food security.  Irrigation is considered as the best way to increase agricultural production and reduce its vulnerability to climate variability. The alluvial  aquifer of the dallol Bosso, easily mobilized because of its shallow depth, is heavily used for this purpose. However, this groundwater  resource is subjected to the effects of anthropogenic actions and climate change. The aims of this study, was to improve knowledge of  the aquifer system and the dynamics of the alluvial aquifer in the context of climate change. The methodology adopted was based on the  analysis of hydro-climatic and hydrodynamic parameters and their processing using various softwares. The results obtained showed a  decrease in precipitation from south to north part in the area, with interannual averages of 440.3 mm in Balleyara and 408.73 mm in  Filingué. The water balance estimated for the year 1952 showed an infiltration rate in the water table of 20.29% for an easily usable  reserve (RFU) of 100 mm and 23.79% for an RFU of 50 mm and the annual recharge of the water table for the year 2018 is estimated at  1.43108 m3 . The dynamics of land use between 1972 and 2014 showed a deterioration of vegetation in favor of bare surfaces. The alluvial  aquifer is mainly made up of sand of alluvial and aeolian origin, with thicknesses varying between 5 m and 27 m. The piezometry  shows a main flow direction from south to north, at the alluvial water table scale. These results showed that the alluvial aquifer is  favorable for irrigation.