Index of Estuarine Condition Estuarine Catchments

Areas of catchments that drain directly to Victorian estuaries - i.e. not via major freshwater tributaries. This data updates the previous EST_CATCH (Deakin) layer for use in the 2021 Index of Estuarine Condition. Boundaries were determined from a digital elevation model (DEM) and were compared with DELWP boundaries for some estuaries (where DELWP data existed (i.e. in the estuary fluvial catchment layer [WATER_EST_FLUV_VSDL] available on the Victorian Spatial Data Library [January 2020]). On steep land (the Otways, east Gippsland etc) the boundaries align well. On the flatter areas there are some discrepancies between the DEM derived boundary and the DELWP derived boundary. For some catchments the DELWP boundaries are more accurate, but for others the DEM derived boundary is more accurate. Final catchment boundaries were determined by adopting the DEM derived boundary where there was good alignment with the DELWP layer and then adjusting just the contested boundaries to choose the one that appeared most accurate based on the rationale specified for each estuary below.