Aquifer hydraulic parameters estimation based on hydrogeophysical methods in West Nile Delta, Egypt

Abstract

Water scarcity is becoming a major constraint not only to the reclamation and cultivation of new areas, but also to the irrigation of already reclaimed areas, which could lead to global desertification. Groundwater exploration is one of the solutions to overcome the water resource shortage crisis in Egypt, especially after the building of the Ethiopian Renaissance Dam and its effects with unfavorable consequences for the water supply. The West Nile Delta region (WND) has been chosen by the Egyptian government in the past 30 years to develop several agricultural programs that rely mainly on groundwater for different aquifers. Vertical Electrical Sounding (VES) is the main method for determining the depths to groundwater, aquifer thicknesses, salinity and possibly hydrophysical parameters (transverse resistance and average transverse resistivity). The hydraulic parameters of aquifer and their important role in estimating the safe yields from production wells are essential for agriculture water management. To estimate of main aquifer parameters using geoelectric measurements, which are of great importance in selecting the suitable wells locations and in maintaining the sustainable management of groundwater, hydrogeological data are collected for 32 drilled wells and the Schlumberger array was used to implement 22 VES at specific sites in the study area. Some VES are performed alongside the already drilled wells that have lithology and pumping test data and others are carried out in well-free places especially in the northern and southern parts. Using the partial-curve matching technique, 22 VES data are interpreted to obtain the different geoelectric parameters (e.g., transverse resistance and average transverse resistivity). The constructed relationships between transmissivity—transverse resistance, hydraulic conductivity—average transverse resistivity, and salinity—average transverse resistivity showed well correlation between these parameters, where R2 equal 0.86, 0.7 and 0.8, respectively. Based on these relationships and the data of 22 VES, the predicted values of transmissivity range between 396.4 and 8830.7 m2/day, hydraulic conductivity range from 107.6 to 7.6 m/day and the TDS vary from 413.2 to 1991.6 mg/l. These results showed that VES is a useful method for exploring the groundwater aquifer and predicting its hydraulic parameters (for example, transmissivity and hydraulic conductivity) and salinity, which can be used as a primary data for drilling groundwater wells and further agricultural irrigation in the West Nile Delta, Egypt.