Geologically related variations in saturated hydraulic conductivity in the regolith of the western wheatbelt of Western Australia and its implications for the development of dryland salinity

Abstract

This is the first systematic study of geology-related saturated hydraulic conductivity differences in the regolith of the wheatbelt of Western Australia. Except for 2 rock types studied, much lower permeability in the pallid zone than in the underlying aquifer, is substantiated. Higher permeability in major faults than in the surrounding granite is confirmed, and this extends into the pallid zone. Mafic dykes have no significant differences in permeability to granite in the saprolite aquifer but it is arguable that the permeability of dykes in the pallid zone is greater than granite. Permeability of the Tertiary valley filling sandstone aquifer is higher than of the underlying granite and much higher than of the overlying claystone aquiclude. The results presented in this paper provide a basis for groundwater models to take into account differences in permeability between major faults and granite and within Tertiary sediments, which is necessary in order to improve predictions of salinity extent and treatment effectiveness.