Incorporating the concept of equivalent freshwater head in successive horizontal simulations of seawater intrusion in the Nile Delta aquifer, Egypt

Intensively exploited Mediterranean aquifers: resilience to seawater intrusion and proximity to critical thresholds

“…These aquifers have also been studied previously by several scientists using variable-density models such as 2D-FED: NDA (Sherif and Singh, 1999), FEFLOW: NDA (Sherif et al, 2012), ICA (Yechieli et al, 2010), SUTRA: CAA (Prieto, 2005;Prieto et al, 2006). However, the present study is the first that addresses their vulnerability in direct relation to the high non-linearity of the seawater intrusion process with associated tipping points for complete aquifer intrusion (Mazi et al, 2013), in conjunction with consideration of critical seawater intrusion to different possible groundwater pumping locations (Koussis et al, 2010a, b), and comparatively so across the different aquifers.…”

“…An accurate balance for the Nile Delta cannot be calculated, due to unreliable or missing data (Mikhailova, 2001), and only a few components can be estimated with some certainty. Sherif et al (2012) report that, today, seawater intrusion has reached 100 km from the coast.…”

“…The hydraulic conductivities of the two sections were found by interpolating the curves in Fig. 7a, b of Sherif et al (2012); for the mNDA profile section K = 100 m d −1 , and for the eNDA profile section K = 120 m d −1 . The slope of the aquifer base and the aquifer depth at the coast were determined for the mNDA profile-section as 0.3 % and 740 m, respectively, and for the eNDA profile-section as 0.4 % and 910 m, respectively (Fig.…”

“…In their recent paper, Sherif et al (2012) performed simulations with FEFLOW for five horizontal layers (areal sections) of the NDA, reaching to a depth of 400 m; without explicitly reporting the aquifer recharge, they report the seawater intrusion to exceed 100 km (1000 ppm TDS) from the coast. As no information is openly available for the NDA recharge, and in order to use the latest published data on the Nile Delta seawater intrusion, we have used the present analytical model to calculate the likely current location of the interface toe, l T , by calibrating the net aquifer recharge, r n , in the definition of submarine groundwater discharge q SD .…”

“…Through this calibration, the sharp interface toe for the mNDA was positioned at l T = 100 km, according to the intersection of the constant slope aquifer base with the 50 % salinity line of profile 1 in Fig. 10 of Sherif et al (2012) (the 50 % salinity line was interpolated from the 1000 and 35 000 ppm lines in the salinity transition zone). The thus calibrated net recharge value r n was found to be about 10 mm yr −1 , incorporating the aquifer recharge from all possible (natural and artificial) sources minus the known magnitude of groundwater extractions from the mNDA.…”