Abstract
The Khulais plain lies within a typical arid area in western Saudi Arabia. Groundwater occurs within two aquifers in the area: the alluvium of the wadi system, and the sandy layers of the Cretaceous-Tertiary sedimentary succession. Detailed field investigations and laboratory analysis helped in determining the aquifer properties for each of the water-bearing units. Groundwater movement has been thoroughly studied, and distribution maps prepared to explain the variations in transmissivity, permeability, porosity and specific yield. An attempt has been made to estimate volumes of groundwater flow towards the plain. This study presents a first attempt towards determining groundwater availability in the Cretaceous-Tertiary succession of this part of the world.