Field parameterization to determine trigger mechanisms of streamflow generation in an ephemeral-intermittent system, South Australia

For non-perennial streams (intermittent and ephemeral streams) the processes that control streamflow generation remain poorly understood and represent one of the greatest challenges to better understand the dynamic behavior from one of earth's most widespread water systems. This study examines an intermittent-ephemeral catchment in South Australia where little is scientifically known about the relative contributions of overland flow, soil saturation, and groundwater inflow to creek flow, although there are many well-developed hypotheses among the local vineyard owners. Detailed field data were used to characterize the hydrologic links between precipitation, antecedent soil moisture, groundwater levels, and resulting streamflow to identify triggers at the threshold to flow in the creek. A previous study in the catchment documented a complex interaction between the creek and the shallow aquifer outlining the spatially and temporally variability between losing and gaining conditions along the creek. Monitoring sites were distributed across the catchment to capture the hydrologic processes under gaining, losing and variably loosing-gaining stream conditions. Results from this study will provide of a better understanding on the controlling mechanisms of stream flow generation on non-perennial streams under varying stream conditions. Furthermore, the results are expected to be used for the development of an analytical equation to predict streamflow that will be used in development of an integrated surface water-groundwater model of the basin.