Modeling Coastal Aquifer Recovery Trajectories Under Post-Conflict Intervention Scenarios: The Gaza Groundwater Crisis

The Gaza coastal aquifer, serving as the sole natural freshwater source for approximately 2.3 million inhabitants, has experienced catastrophic degradation following decades of chronic overextraction and the acute impacts of the 2023-2025 conflict. With 97% of groundwater already unfit for human consumption prior to the conflict and approximately 80% of water, sanitation, and hygiene (WASH) infrastructure subsequently destroyed, the aquifer's long-term viability is critically uncertain. This dissertation developed spatially-explicit groundwater models to project aquifer recovery trajectories under alternative post-conflict intervention scenarios, addressing a critical gap in reconstruction planning. The research employed MODFLOW-2005 integrated with SEAWAT for variable-density flow simulation, calibrated to 30 years of historical observations (1990-2020) and validated against independent pre-conflict data (2020-2023). Model calibration achieved Nash-Sutcliffe efficiency values exceeding 0.80 for both hydraulic head (NSE = 0.86) and chloride concentration (NSE = 0.81). Results revealed current aquifer conditions of extreme degradation, with average water levels at -11.4 m below mean sea level and mean chloride concentration of 2,847 mg/L—exceeding WHO drinking water guidelines by more than an order of magnitude. Twelve intervention scenarios were simulated over a 25-year projection period. Baseline projections (no intervention) indicated continued catastrophic deterioration, with only 1.1% of the aquifer meeting WHO standards by 2050. Maximum integrated intervention combining wastewater treatment, managed aquifer recharge, desalination expansion, and demand management achieved 58.2% recovery at an estimated investment of $2.4 billion. The research identified critical threshold conditions (chloride >10,000 mg/L, water level <-15 m MSL) beyond which recovery becomes technically infeasible, with 12% of the aquifer currently exceeding these thresholds. Findings support the prioritization of wastewater treatment restoration as the highest-impact early intervention, demonstrating superior cost-effectiveness compared to desalination-focused approaches. Keywords: groundwater modeling, coastal aquifer, seawater intrusion, post-conflict reconstruction, Gaza, WASH, water security