Inland NSW Fish Passage

Australian Fish Passage Services commissioned WMS to quantify the hydraulic impacts to water volumes at a proposed fish passage in inland NSW. A steel plate baffled fish passage has been proposed to replace an existing low flow pipe at the site.

The Run 4 plate design was found to be the preferred option to reduce impacts on water volumes. It was estimated a change in volume of approximately +/- 1 ML/day would occur compared to the base case for 179 days of the year.

The methodology adopted to assess the impacts of the proposed fish passage involved the development of a FLOW-3D (CFD) model of the existing case including the low flow pipe and validating the flow behaviour using a HEC-RAS 1D model. Four CFD models were then set up for the proposed fish passage to test various baffle options. The low flow pipe was removed in these scenarios. Following the completion of the modelling, rating curves were compared for each scenario and the likely impacts (volume changes) were quantified.