42.5 Releases from storages
|Releases from storages||Volume 2010–11 (ML)|
|42.5 – Releases for hydro-electricity and subsequent downstream users||
|42.5b – Releases for the purposes of the environment (Spillway Creek)||
|42.5c – Releases from the irrigation valves||
|42.5d – Licensed abstraction||
42.5d comprises abstractions of Argyle Diamond Mine (192 ML) and Lake Argyle Village (28 ML).
a. Releases for hydro-electricity and subsequent downstream users
The volume of water released from Lake Argyle for hydro-electricty was estimated using the power output of the power station, measured at the terminals of the station's generators. The volume is calculated using the difference in pressure between the inlet and outlet of the power station, and the flow rates through the power station.
b. Releases for the purpose of the environment (Spillway Creek)
The volume of water released from Lake Argyle to Spillway Creek was calculated based on the water level of Lake Argyle, and stream gauging in Spillway Creek.
c. Releases from the irrigation valves (used for recreation)
The volume of water released from Lake Argyle through the irrigation valves was calculated using hydraulic rating tables, and valve opening settings recorded by the dam operators.
d. Licenced abstraction
Direct abstraction under licence from Lake Argyle is metered.
Assumptions, Limitations, Caveats and Approximations
- Calculation of flow rates through the power station includes allowances for head losses in the tunnels, pipe work and turbines of the power station.
- Storage–volume curves represent specifically surveyed parts of the water storage, and may not reflect the storage–volume relationship across the entire storage.
- Water storages are subject to sedimentation and other physical changes over time, which, in turn, affects the accuracy of the storage–volume curves.
The uncertainty estimate was not quantified.