Geophysical methods integration for deep aquifer reservoir characterization and modeling (Sidi Bouzid basin, central Tunisia)

Abstract

Groundwater resources of the Sidi Bouzid basin (central Tunisia) are hydrogeologically and economically important. This importance is restrained by the complex and poorly understood subsurface geometry of the main basin, the overexploitation of its near-surface aquifers and the lack of deep hydrogeological wells in the study area. To overcome these issues a multidisciplinary study was conducted integrating geological, geophysical, and hydrogeological methods. As the regional structural tendency of the study area is predominated by Atlassic NE-SW trends, gravity anomalies could be defectively interpreted. Thus, different gravity treatments and filters were processed. A residual gravity response of Sidi Bouzid basin was rationally isolated, the main structural features were then outlined and depths of rooted sources were detected. The obtained results are in a good conformity revealing a newly detected sub-horizontal geophysical lineament that seems to be a high zone which may act as a hydrogeological barrier within the investigated basin.Forward gravity modeling supported by 2D seismic reflection data over geological and geophysical methods integration, highlighted the Sidi Bouzid basin subsurface extent. It also defined its thick Tertiary complex substratum and the unknown total thickness and arrangement of its subsurface series. The used approaches provided a depth to basement modeling of the siliciclastic Tertiary complex estimating its depth and disclosing its subsurface configuration and its internal preferential water flow directions. A geophysical basement topography mapping enhancing the subsurface overview was also yielded.