Egypt has recently inaugurated a mega development project aiming to alleviate the overpopulation along the Nile River and to meet the looming food gap. Toshka is a promising area where groundwater-dependent activities are being expanded adjacent to Lake Nasser. Thus, it is of utmost importance to provide a sustainable development approach and to assess the resulting environmental implications. Accordingly, a coupled groundwater flow and transport model was invoked. The generated model was successfully calibrated for the observed water levels and salinity. The proposed exploitation regime of 102 wells each pumping 1000 m³/day was simulated for a 100-year test period. The maximum resulting drawdown was about 25 m, compatible with the advocated sustainable restriction limit. Climate change (CC) impacts of reducing the lake’s storage and increasing the crops’ water requirements were investigated. The lake’s water level fluctuations were a key factor in the aquifer hydraulics and flow direction. The drawdown breakthrough considering the CC catastrophic scenario (RCP8.5) has increased by about 20%. The developed solute transport model was utilized to simulate the salinity spatial distribution and the lateral movement of leaking pollutants from the underway activities. Cultivation activities were found feasible up to 80 km away from the lake border where salinity does not exceed 2000 ppm. Yet, a protection strip of not less than 4.8, 6.0, and 7.2 km according to the lake operating condition is inevitable to ensure that pollutants do not intrude into the lake. These findings will assist the decision-makers in scheming environmental impact assessment criteria for sustainable development.

Water scarcity poses major constraints to sustainable rural development, particularly in arid regions. In Egypt, limited freshwater resources are increasingly prioritized for domestic use, compelling proposed large-scale land reclamation projects to rely on brackish groundwater. However, marginal water quality restricts cultivation to salt-tolerant crops, undermining the long-term profitability of ongoing agribusiness activities. This study is the first to evaluate the techno-economic viability of integrating decentralized desalination systems into the Moghra development area. A systematic hydrochemical assessment of 73 wells, using the Irrigation Water Quality Index (IWQI), classified 49 as “Severe Restriction” and 24 as “High Restriction”, confirming widespread concerns about groundwater suitability. A two-stage reverse osmosis (RO) desalination system powered by photovoltaic (PV) energy was designed to achieve a 70% recovery rate. An optimization model identified blending ratios that maximize post-treatment water quality while minimizing the desalinated water volume. Results showed substantial improvements: the average sodium adsorption ratio (SAR) decreased by 66%, and IWQI increased from 34 to 77. Consequently, 68 wells were reclassified as “Low Restriction” and 5 as “Moderate Restriction”, enabling a shift from salt-tolerant olives to higher-value crops (e.g., wheat–maize rotation). A cost–benefit analysis assessed trade-offs between desalination costs and resulting economic returns. Under the abstraction limit, the proposed RO–PV blending strategy yielded a 35% higher net present value (NPV) and a 15.7% internal rate of return (IRR), demonstrating both technical and financial viability. These findings provide actionable insights for policymakers, stakeholders, and investors to enhance water productivity and agricultural sustainability in arid regions.