Adelaide

The value reported in the water accounting statement (112,481 ML) represents runoff into surface water features, such as rivers and reservoirs, in the Adelaide region.

Data source

Bureau of Meteorology: National Climate Centre daily climate grids (rainfall, temperature and solar radiation) and Australian Hydrological Geospatial Fabric (AHGF) waterbody feature class.

Commonwealth Scientific and Industrial Research Organisation (CSIRO): WaterDyn and AWRA-L model parameters, and monthly climatological average radiation grid data.

Geoscience Australia: human-made water body feature class.

South Australian Department for Water: Geographic Information System (GIS) layers.

Data provider

Bureau of Meteorology.

Method

Rainfall runoff into rivers was estimated based on the average of the WaterDyn discharge and the AWRA-L streamflow model outputs.

Using climate grid data for the Adelaide region (including precipitation, temperature and solar radiation data), WaterDyn and AWRA-L were used to estimate the runoff depth at each grid-point within the region. Only runoff from the landscape is considered; therefore, the surface areas of the major reservoirs and the local catchment reservoirs were excluded from the analysis.

Runoff from the landscape is divided into two components: runoff into the connected surface water store (major reservoirs, rivers and drains) and runoff into local catchment reservoirs (farm dams). Only runoff into the connected surface water store is considered here.

The average runoff depth from the landscape into the connected surface water store was determined as the unweighted arithmetic mean of the relevant Australian Water Availability Project grid-points within the region boundary. Mean runoff depth was converted to a runoff volume by multiplying runoff depth by the total area of the region (excluding local catchment reservoirs). Finally, the runoff into local catchment reservoirs (estimated using the STEDI model; see SKM 2010) is subtracted from the total modelled runoff into the connected surface water store to establish the rainfall runoff into storages and rivers only.

Uncertainty

Ungraded.

Assumptions, approximations and caveats/limitations

• The runoff estimates were modelled only and were not verified by real-time analysis of streamflow records. The reported value was an estimate of water that was likely to have entered the connected water store from the landscape.
• The runoff estimates were subject to the assumptions of the WaterDyn model detailed in Raupach et al. (2008) and the AWRA-L model detailed in van Dijk (2010).
• Where the volume of water intercepted by the off-channel private water store (farm dams) has been calculated, the runoff estimates inherit the approximations, assumptions and caveats of the local catchment reservoir model (STEDI) and parameters used.
• The calculation of the landscape runoff assigned each grid-point an equal contribution despite less than 100% of some grid-cells having a portion within/outside the reporting region boundaries. This had a limited influence because the average is then multiplied by the catchment area, which is not calculated based on the spatial dimensions of the Australian Water Availability Project grid-cells.