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 rel ict channels of three representative dryland salinized catchments in t he wheatbelt of Western Australia. Much of the variation in groundwate r salinity is explained by the distribution of geological structures ( dykes, veins and basement highs) in relation to the alluvial systems a nd relict channels and their effect in modifying groundwater flow. Sal inities in the relict channels are generally higher than in other area s of the catchment. Salinity also increases in the direction of ground water flow along the relict channel. Salinity in groundwaters upstream of geological structures is without exception higher than in other pa rts of the catchment. The relict channels are found to have an importa nt role in the storage and redistribution of salt in the landscape.