Electrical Resistivity, Geochemical and Hydrogeological Properties of Wadi Deposits,Western Saudi Arabia

Abstract

Six main wadi systems within the Arabian Shield. filled with a heterogeneous. strongly anisotropic assemblage of alluvial deposits. were investigated with Schlumberger resistivity soundings . Aquifer electric resistiv ities were determined for 39 vertical electrical soundings at these wadies where pumping and recovery tests were also performed. The hydrogeophysical properties of the wadi deposit exhibit a wide range in all its individual characters. The hydraulic conductivity varies from 3 to 166 m1day, the aquifer resistivity is between 1.4 and 176n m, the transmissivity values are 40:-5800 m2/day, the apparent formation factor is 0.17-26, and the electrical conductivity of the groundwater varies from 610 to 19000 J.l Slcm. The major ionic composition shows a wide variation in the hydrochemical properties of the groundwater of the wadi deposits . The results of this study also indicate that electric resistivities determined from soundings and aquifer properties have a relation of the type : Y= aJ(J. The comparison of the results of the present study with previous published work (largely from temperate zones) has shown that wadi deposits have different hydrogeological propert ies.