Hydrodynamic Characteristics of the Continental Intercalaire and Continental Hamadien Aquifer Systems in the Iullemeden Basin of Tahoua Region Republic of Niger

Abstract

This study was conducted in the region of Tahoua the northeastern part of the Southern Illulemeden sedimentary basin. In this region the transboundary aquifer system of Continental Intercalaire (CI) and the Continental Hamadien (CH) are potentially rich in underground water especially in free and captive aquifers. More, this water is the main source of drinking water for the populations, the animals and for agriculture and extractive industries. However, the population growth, the agricultural development, and the climate change have a real impact on the dynamics of groundwater and the exploitation of these resources. Hence, this study aims at analyzing the behavior of aquifers and assessing the impact of various natural and anthropogenic factors. Especially it matters to analyze the drilling parameters and cuttings, logging data and pumping test of nine new boreholes. The results reveal that the depths equipped with boreholes catching the CI/CH complex vary from 70 to 800 meters from East to West while the average thickness of the reservoir CH is 50 meters and it mainly consists of coarse sandstone. Drilling penetrated more than 100 meters into the CI without reaching the base. The CI tank is composed of several layers of gravel and clay whilst the CI/CH aquifers flow rates range from 0.2 to 22.8 m 3 /h/m. So this is cause of great variability of the water potential within this aquifer. Lastly, the transmissivity coefficients are more important in the CH than in the CI, and the water flow average rates range respectively from 29 m/year to 7 m/year.