Groundwater Modeling in Agricultural Arid Area under Different Scenarios, East Nile Delta, Egypt

Abstract The East Nile Delta represents the natural extension of the Nile Delta that recently showed significant changes in groundwater system related to both agricultural and urbanization land development. The current study presents a GIS-based 3D groundwater flow model to outline a safe framework for pumping stress management to the upper 100 m of Quaternary aquifer located North of Ismaelia Canal. Model construction comprised 93 borehole data to model a 19-layer grid of the fluvial Quaternary deposits. The finite difference MODFLOW 2000 accomplished simulation to predict groundwater head distribution across the aquifer system in both steady and transient states. Steady state model is calibrated to the 1991-groundwater hydrogeological map of Egypt, and subsequently provided the initial conditions for the 1991–2005 transient simulation. The transient model is considered calibrated as the calculated head matches the field observations of 2004–2005. Using severe aquifer stress strategy, three scenarios are proposed to manage the reported local rise in groundwater head and evaluate the potential aquifer production during drought. This involved using several infiltration rates from irrigation return and pumping stress to model predictions extending to the year 2030. Results showed pumping controls to the rising groundwater head especially towards the North where confinement conditions prevail with two subregions, northern and southern, requiring different schemes of management. Optimum pumping and infiltration rate are determined for these subregions and for the unconfined parts of the Quaternary aquifer. During drought, a maximum of 500 million m3/yr are producible from the unconfined aquifer with standard discharge of 5000 m3/d that may induce drawdown less than 0.5 m. The water budget of modeled aquifer indicated that pumping stress is predominantly balanced by seepage from Ismaelia canal and Damietta branch with slight contributions from irrigation canals and drains. Details of water budget and changes in groundwater head to pumping stresses across the modeled area are presented and discussed in detail. The model results provide a scientific platform to delineate efficient and sustainable management to the East Nile Delta Quaternary aquifer associating active dynamic land development.