Regional Groundwater Modelling for Determining Adaptation Strategies in the Nile Delta Aquifer

Climate change, as predicted by several global climate models, is very likely to have severe future impacts, including sea-level rise. At the same time, population increase and development imperatives create additional pressure on available water resources. These changes are particularly problematic for the Mediterranean coastal areas, and especially the Nile Delta coast, causing increased salinity levels in groundwater. Particular focus of this study is on salinization of groundwater resources in the Nile Delta Aquifer (NDA) due to seawater intrusion. Groundwater quality in this area may significantly deteriorate in future, due to the impacts of sea level rise combined with excessive increase of groundwater extraction. To assess current conditions and develop future adaptation strategies for the NDA, a three-dimensional model simulating regional variable-density groundwater flow and coupled salt transport was constructed, using the SEAWAT code. For identifying the representative model for the seawater intrusion and salinity conditions in the NDA in the year 2010, a methodology of ‘evolving’ the conditions from completely fresh to salinized conditions using different simulation periods was used. This model was then applied to test the NDA conditions under several pre-defined scenarios of sea-level rise and groundwater extraction. Three different adaptation measures and their impacts in the Sharkeya Nile Delta governorate were initially tested, indicating that changing crops and irrigation practices to water saving options seems to be a promising measure, compared to artificial recharge with injection wells or extraction and usage of brackish groundwater after desalination. Studies with combinations of measures are further needed.