Estuaries

The Estuaries datasets contain the water boundary of each estuary in NSW up to its tidal limits and includes areas vegetated with the macrophytes seagrass, mangrove, and saltmarsh. A survey of the tidal limits was carried out between 1996 and 2005 by Manly Hydraulics Laboratory on behalf of the former Department of Natural Resources. Coordinates of the tidal limits were mapped, tributary waterway areas extended up to the surveyed tidal limits, and a boundary digitised between the upper (fluvial) catchment draining directly to the river system above the tidal limits and the lower (estuarine) catchment draining directly to the estuary and its tributaries. The catchment area draining into each estuary has been defined as two GIS spatial layers - EstuaryDrainageCatchmentBdy (line feature) and EstuaryDrainageCatchment (polygon feature) - based on the digitising of catchments for the NSW Stressed Rivers Assessments conducted for the water sharing plan process. ; ; A nine stage method was used to create the Estuaries(Macrophytes) dataset and details how existing spatial data were combined from a number of agencies and projects and developed through consultation with the existing knowledge base of individuals and reports. Two datasets with polygon features were created, one including the extent of the three different macrophyte types, the other merging macrophyte extent with the estuary water surface (this dataset). These layers were required for calculating basic physical characteristics of each estuary such as area, depth, volume, dilution and flushing; modelling of catchment runoff; development of a new chlorophyll response-based classification system for NSW estuaries and normalising pressures for valid comparisons between estuaries. Separate fluvial and estuary catchments were required for future investigation of causal relationships between catchment pressures above or below the tidal limits and estuary health.