There is a need to understand how farm dams distributed around a catchment impact on streamflow and the options that can be implemented to improve flows. A project was undertaken in the Seven Creeks catchment that involved scenario modelling under a range of climate change scenarios to determine the most effective management strategy to maximise autumn and summer low flows, by reducing the impact of farm dams. The outcomes of the work provided further knowledge for consideration in the management of farm dams on flow stress.
A model of the Seven Creeks catchment, which represents the water balance for each of the 5,000 individual farm dams, was developed using a modelling platform called eWater Source. By individually representing each farm dam, management strategies such as decommissioning or bypassing farm dams were able to target key farm dams in order to improve low flow compliance.
The decommissioning of farm dams with the greater volumes were able to provide the greater improvement in low flow compliance, including when impacted by climate change. Scenarios that were optimised to decommission farm dams with large contributing catchment area or volume along the same flow pathway were similarly able to improve low flows during the summer and autumn.
The use of water resources models to show the impact of farm dams on environmental flow compliance is the first step in determining the feasibility of rolling out farm dam management strategies across Victoria for environmental flow provision.