SPATIO-TEMPORAL ANALYSIS OF THE GROMBALIA AQUIFER DYNAMICS--NORTHERN EAST OF TUNISIA

Aquifer maps are key tools for water resources management, and allow to characterize a water table distribution and variability. The Grombalia plain in the northeast part of Tunisia was studied to identify the origin of groundwater recharge and to specify the type of recharge in the whole study area. It aims to investigate the impact of recharge schemes on the piezometric evolution of the water table. Furthermore, the purpose is to investigate the origin and dominant factor of the recharge. The methodology of this work includes two methods of analysis of the dynamics of the piezometric heads of this aquifer, namely the interpretation of piezometric maps for an evaluation of the spatial evolution and the study of piezometric sections. Both methods allow to distinguish between the different types of recharge, show which recharge sources is the most important in supplying the groundwater. In addition, they permit to analyze in detail the piezometric evolution and the impact of the various hydraulic structures on the piezometry. Without forgetting the naturel recharge coming directly from the soil surface and depending on the permeability, there is another natural recharge which comes from flooding areas. In Grombalia groundwater, this natural recharge occurs mainly at Wadi Ejjorf, Wadi Sidi Toumi and Wadi Ejdida sites. This recharge is accented for rainy years and mainly after flooding events. This study shows the picks at all the recharge sites between 1999 and 2009. However, an overexploitation of the aquifer was observed in Soliman-Fondok Jedid, Boucharray, Bou Argoub, which presented local depression zones. The used methodologies are very important tool to choose the best recharge site and allow to adjust the hydrodynamic models. In fact, there is an urgent need for assessing various aspects of ground water resources through a process of systematic data collection, analysis and synthesis.