1.2 Unregulated river
The volume reported (402 ML) represents the total volume of water held in surface water weirs within the Adelaide region at 30 June 2013. This volume includes surface water weirs that are operated by SA Water, contribute to the operation of the urban water supply system through diversion to urban water storages, and for which appropriate storage height data was available to estimate total storage volume.
|Surface water weir||Total storage capacity (ML)||Dead storage capacity (ML)||Storage volume at 30 June 2013 (ML)||Storage volume at 30 June 2012 (ML)|
The volume reported above does not include unregulated river channels, including private on-channel storages. These volumes could not be quantified in a way that is complete, neutral and free from material error; therefore, they were not reported in the water accounting statements.
Unregulated rivers include all rivers and tributaries within the major catchments in the Adelaide region. The volume of water held within unregulated rivers is considered to be substantial and will have a material impact on the volume reported for the surface water store; however, its omission is not expected to have a material impact on the surface water balance because annual variation in the volume of water stored in river channels is assumed to be non-material in comparison to annual river flow.
Storage volume was measured using gauged water level height(s) in metres with respect to the Australian height datum for individual storages. The height measurement was converted to a volume using the storage-volume relationship(s) of SA Water. The storage volume of individual surface water storages was aggregated to present the total volume for this line item.
Assumptions, limitations, caveats and approximations
- Storage-volume relationships were derived from surveys of specific parts of the individual storage (weir), and may not reflect the storage-volume relationship across the entire storage.
- Water storages are subject to sedimentation and other physical changes over time that in turn may affect the accuracy of the storage-volume relationships.