ESTIMATING SALT LOADS IN HIGH WATER-TABLE AREAS .1. IDENTIFYING PROCESSES

This paper describes the detailed investigation on a 9 ha irrigated si te with high water tables in the Tragowel Plains (Australia) of salt t ransport processes from shallow ground water to surface drainage. An i ntensive field monitoring program was established to record surface ru noff and drain stage, fluctuations in water table levers, changes in t he soil moisture profile, climatic data for estimation of evapotranspi ration, changes in vegetation cover, rainfall and irrigation intensiti es, and field and laboratory measurements of a range of soil propertie s. The distributed, physically based European Hydrological System mode l was used to represent the processes using the field characteristics obtained for input parameters as well as time series flow and level da ta for calibration. Despite several limitations of the model, the sign ificant physical processes occurring, and the range of their relative contributions of salt load to the surface drainage; were identified.