Analysis of process controls on streamflow response in an Australian tropical catchment

This study investigates the main processes that may be responsible for the observed streamflow response in Seventeen Mile Creek basin, Northern Territory of Australia. Due to the limited available hydrological information in the area, the present study develops a methodology that can be applied to scarcely gauged basins. To this aim a hydrological model is used, whose appropriate complexity is chosen using a downward approach. Starting from a simple model implementation, the results are tested against signatures of observed runoff variability and using a goodness of fit index. Then, further model features are added if deemed necessary. The results show that the catchment soils have a high storage capacity, which originates a significant delayed runoff, while the saturation excess overland flow occurs only after heavy rainfall events during the wet season. Furthermore, a sensitivity analysis is conducted to determine the effects of soil depth and rainfall variability on the runoff regime.