Characterization of the Hydrogeological Functioning of Fissured Aquifers in a Mining Context: The Case Study of the Yaoure Gold Project (Central-West Ivory Coast)

摘要

Mining is a major concern for the availability of groundwater resources due to the continual pumping out for pit dewatering. The objective of the study is to assess the impact of mining on the functioning of the aquifer system of the Yaoure Gold Project area. The methodology adopted was to first caracterize the aquifer system by producing the fracturing map from remote sensing. Endeed, the water level in the aquifer system was determined by the Castany method. The piezometry was studied in low and high water in order to determine the recharge and discharge zones and to follow the behaviour of the water in the aquifer system. Finally, the analysis of pumping test sheets was used to determine the hydrodynamic characteristics of the aquifer. The results obtained show 170 lineaments oriented in the N-S, NE-SW and NW-SE directions. The recharge of the aquifer is 46.5 mm/year with discharge zones observed in the north-east and south sectors and a recharge zone in the north of the study area. Water level variations in some boreholes and the determined transmissivity values varying between 1.85.10~(-6) and 3.5.10~(-4) m~2/s (average of 2.47.10~(-5) m~2/s), indicate a probable influence of pumping on the water level in the aquifer. Groundwater flows preferentially in a west-east direction and could generally discharge into the Bandama River. The hydraulic conductivities vary between 1.23.10~(-7) and 1.32.10~(-5) m/s with an average of 3.3710~(-6) m/s. The specific flow rates vary between 0.05 and 3.6 m~3/h/m and the average value is 0.61 m~3/h/m.