Managing coastal aquifer salinity under sea level rise using rice cultivation recharge for sustainable land cover

Study region: The coastal aquifer of Nile Delta, Egypt is used to develop the current study. Study focus: Excess water from rice irrigation is a source of incidental recharge to mitigate seawater intrusion. This paper numerically explores the optimal location of rice cultivations by subdividing the delta domain into three distinct recharging regions (north, central and south). Additionally, SEAWAT code was simulated under a combination of rice cultivation relocation and sea level rise (SLR). New hydrological insights for the region: The study findings revealed significant variations in salt volume reduction depending on the location of rice cultivation in the delta. Placing rice culti-vation in the northern region resulted in the highest reduction of salt volume (19 %). In contrast, locating the recharge in the central region yielded a salt volume reduction of 0.50 %, while rice cultivation in the southern region produced a 15 % increase. Considering the projected SLR of 61 cm by 2100, there was an overall salt volume increment of 3 %. However, when accounting for both SLR and rice cultivation recharge in the northern region, a substantial salt volume reduction of 17 % was observed. The results demonstrated that incidental recharge by rice cultivation in coastal aquifers is an effective method for enhancing saltwater intrusion control. Moreover, this study improves our understanding of hydrological processes and expected responses in the delta under future climate scenarios.

Automated summary

The study investigates the optimal location of rice cultivation in the coastal aquifer of Nile Delta, Egypt for mitigating seawater intrusion. Different recharging regions in the delta were subdivided and the SEAWAT code was simulated to understand the effects of rice cultivation relocation and sea level rise (SLR) on salt volume reduction. The findings indicate that rice cultivation in the northern region yields the highest reduction of salt volume (19%), while cultivation in the central and southern regions result in minimal reduction and an increase in salt volume, respectively. Taking into account SLR and rice cultivation in the northern region, a significant salt volume reduction of 17% is observed.