Future Irrigation Projects Hydrological Analysis
Yield analysis for development of proposed irrigation schemes
The Tasmanian Future Irrigation Project will build on Tasmanian Irrigation’s Tranche 1 and Tranche 2 schemes. As a result of consultation and investigation, Tasmanian Irrigation identified eight concepts for potential irrigation schemes across Tasmania. Four of these schemes, Detention River, Fingal Valley, Flowerdale, and Pipers River, were the subject of this study.
Tasmanian Irrigation carried out a preliminary scheme design and water availability analysis for each of the four schemes. To ensure that water availability will not impact the viability of the schemes, a more detailed assessment of the volume of water available at 95% reliability under future climate was required, with consideration of existing irrigation rights and environmental water requirements.
The proposed irrigation schemes included off-stream and in-stream storages, with pumping into the storages from larger rivers. WMWwater developed models to estimate the flow at each damsite and pump location, under a future climate scenario. These models developed a flow record of 92 years of data, which was used to assess yields at each site. The modelled runoff was compared to gauged flow data from nearby sites, and was adjusted if required. The available yield, at each inflow point for the concept schemes, was calculated taking into account environmental flows and water entitlements in the catchments. At the pump sites, the accessible yield was assessed based on a range of conceptual pump capacities.
The yield analysis has enabled Tasmanian Irrigation to prioritise the concept schemes for further investigation and scheme design.