Numerical groundwater flow modeling for managing the Gabes Jeffara aquifer system (Tunisia) in relation with oasis ecosystems

Abstract

8The Gabes Jeffara aquifer system, in southeastern Tunisia, is essentially recharged by rainfall infiltration 9 and by groundwater inflow from the Intercalary Continental aquifer in the northwest. The increase in 10 groundwater pumping for irrigation in recent decades has induced a serious decrease in groundwater levels, 11 depletion of springs and degradation of oasis ecosystems. A multidisciplinary study was carried out to better 12 understand the behavior of oasis ecosystems and aquifer systems and to provide tools and recommendations 13 for water resources management. An important part of the study was devoted to developing a hydrodynamic 14 flow model of the Jeffara aquifer system, which can be used as a future groundwater management tool 15 considering different recharge or exploitation scenarios. This model was built with Processing Modflow, 16 gathering data on geology, hydrogeology, hydrology, rainfall, piezometry, withdrawals and spring flow 17 rates. The model was calibrated in steady state with reference to the piezometric levels measured in 1970 18 and in transient state for the period 1972-2014, using records from more than 200 wells and piezometers. 19 The analysis of current and future water consumption was carried out with existing data, processed satellite 20 images and farmer surveys. This analysis was used to define water demand scenarios combined with 21 scenarios of decreased groundwater withdrawal, reinforced groundwater recharge and use of alternative 22 water resources. The scenarios tested with the model show that the situation will be critical in less than 25 23 years without radical measures to reduce groundwater withdrawals by at least 60 MCM/y. 24 25

Coastal aquifer recharge and groundwater–seawater exchanges using downscaled GRACE data: case study of the Djeffara plain (Libya–Tunisia)

“…However, Chulli et al [2007] estimated the SGD in the gulf of Gabès at 0.2 m 3 •s −1 (0.1 m 3 •s −1 for half of the coast length) using Darcy's calculations for the Upper aquifer. This relatively low value also obtained in a recent modeling study by Vernoux et al [2020] justifies maintaining the grid resolution as adopted here.…”

Application of a Linked Hydrodynamic–Groundwater Model for Accurate Groundwater Simulation in Floodplain Areas: A Case Study of Irtysh River, China

“…An additional improvement to the coupled model involves enhancing the efficiency of flood inundation simulation. Considering the lengthy timescale of GW evolution, GW prediction periods typically span several decades [26,[62][63][64][65]. In capturing the influence of long-term changes in flood inundation characteristics on GW, the coupling model developed in this study proves to be effective.…”