A Hierarchical Approach for Groundwater Modeling

Abstract

In Egypt, there has been a major effort to improve the water supply and also sanitation services although there are still major deficits in rural areas. Remaining a major challenge on the national level, rural drinking water supply is projected to become increasing inadequate with population growth. A part of the water supply comes from the Nile system and the other part comes from groundwater sources mainly by using wells. Typical applications of numerical models to field scale problems generally require large grids that can seldom accommodate cells as small as the actual well diameter. Several methods have been used to simulate a more accurate head at the well scale. The three primary methods are local grid refinement, local analytical correction and local numerical correction. However, all these methods have limitations, especially for applications that involve the development of numerical models for large scale hydrogeologic systems with multiple pumping wells. The paper presents a hierarchical approach for groundwater modeling and especially for predicting head at the well scale. The hierarchical approach enables converting a large, complex problem into a network of hierarchically nested and dynamically coupled models that can be easily solved. The study aimed to demonstrate that the hierarchical modeling approach and provide an accurate representation of head and groundwater velocities in a well field in large scale hydrogeologic systems.