The migration of native fish throughout the Murray Darling Basin relies on the performance of River Murray Vertical Slot Fishways to provide effective fish passage around infrastructure barriers. The fishways are typically designed to operate at normal weir pool levels, therefore their performance can be impacted during elevated or reduced weir pool levels due to unregulated river events or planned weir pool manipulations which target other environmental objectives in the River system.
A project to improve the understanding of fishway performance under various hydraulic scenarios was undertaken by GHD for SA Water to develop a new fishway hydraulic model and provide a dashboard enabling the simulation of fishway performance at 13 existing or proposed fishway sites. The key model inputs used to compute performance are related to fishway attraction, fishway energy and size constraints.
The dashboard user is simply required to enter fishway upstream and downstream water levels with the key model output being an interactive map visually displaying colour coded fishway performance across all sites. Other model outputs include graphs for each available fishway exit presenting the combined performance metric relative to fish size with an output range of 0 (no function) through to 1 (full function). The hydraulic data calculated at each fishway slot or pool is also presented.
The modelling tool enables efficient evaluation of weir pool manipulations and river flow scenarios on fishway performance. As an important element of river health, it is hoped that the performance of fishways will be optimised through the use of this model in alignment with other river management requirements and constraints.