Sustainable Diversion Limit (SDL) Catchment Baseflows

The Sustainable Diversion Limit (SDL) project focused on developing a means to rapidly estimate the winterfill diversion potential of unregulated and typically ungauged streams. The SDL project divided Victoria into 1,584 catchments, 1,419 of which were not gauged. For the 165 gauged catchments baseflow separation occurred enabling interpretation of streamflow and baseflow specifically for that catchment. For the 1,419 ungauged catchments, each was assigned an indicator gauge as part of the SDL project based on a method that considered hydrological similarity. The hydrological indicators selected to define the streamflow regime in gauged catchments were; base flow index, mean annual flow and median summer flow. The characteristics that were correlated to these hydrological indicators in ungauged catchments were: soil permeability, vegetation cover, stream frequency and annual rainfall. Information generated through the SDL project assisted in the interrogation of the relative magnitude of annual and seasonal baseflows to groundwater use, on an SDL catchment scale.