Présentations Colloques

Oral Presentation
6.03
Session 6.03: Innovative tools to improve understanding of groundwater recharge processes
Nesrine Ghouili
Groundwater recharge assessment of Takelsa multilayer aquifer (Northeastern Tunisia)
Facing to the risk of the imbalance between demand and water supply, the Tunisian water authorities are called to prospect new groundwater resources and enhance aquifer recharge. The Takelsa multilayer aquifer is among the important aquifers in the Northeastern Tunisia. This region is characterized by semi-arid climate and water resources scarcity with groundwater resources largely used in the agriculture sector especially for irrigation. The groundwater recharge of this aquifer is mainly based in the infiltration of the precipitation through the permeable outcrops of sandstone formations of the region. **The aim of the present research work is to evaluate the distribution of the groundwater recharge in order to better assess the groundwater resources of the studied area and improve their management. For this purpose WetSpass model, acronym for Water and Energy Transfer between Soil, Plants and Atmosphere under quasi-Steady State, has been used. It is a physically based model for the estimation of the groundwater recharge, surface runoff and evapotranspiration employing physical and empirical relationships. The model is integrated in GIS ArcView as a raster model. The inputs include grids of land use, groundwater depth, climatic data (precipitation, potential evapotranspiration, wind-speed and temperature), soil, and slope.**The resulting recharge map shows values ranging between 0 and 168 mm year with a mean of 22 mm year and a standard deviation of 32 mm year. The average annual groundwater recharge represents a mean infiltration rate of 4 % of the annual rainfall. **The calculated recharge distribution is introduced in the groundwater flow model developed with Processing Modflow, in order to simulate the hydraulic head distribution. The calculated hydraulic heads matches well with the observed values. The groundwater resources of Takelsa multilayer aquifer estimated by the model, are about 15 Mm3 year+ this value is less than the current pumping volume measured to 18 Mm3 year. The sustainable management of the Takelsa multilayer aquifer is recommended.
Tunisia