THE ROLE OF GEOLOGICAL STRUCTURES AND RELICT CHANNELS IN THE DEVELOPMENT OF DRYLAND SALINITY IN THE WHEAT-BELT OF WESTERN-AUSTRALIA

Aerial photogeological interpretation techniques have been used to map the geology, delineate the geological structures and identify the relict channels of three representative dryland salinized catchments in the wheatbelt of Western Australia. Much of the variation in groundwater salinity is explained by the distribution of geological structures (dykes, veins and basement highs) in relation to the alluvial systems and relict channels and their effect in modifying groundwater flow. Salinities in the relict channels are generally higher than in other areas of the catchment. Salinity also increases in the direction of groundwater flow along the relict channel. Salinity in groundwaters upstream of geological structures is without exception higher than in other parts of the catchment. The relict channels are found to have an important role in the storage and redistribution of salt in the landscape.