Optimizing dam release rules to meet environmental flow targets

Linking environmental flow dam release rules to environmental variables has potential to link the flow variability of a regulated stream to the environmental forces acting on the catchment. A technique is developed to examine a range of release rules related to gauged tributary inflows and optimize these with respect to total water release volumes and other criteria. A model is created consisting of three parts: (1) a Dam Release Event Generator, which generates dam releases according to a set of rules, (2) a simple routing model using linear transforms and derived time-series for ungauged tributary inflows, (3) an algorithm to analyse the output time-series and produce statistics on the environmental flows. This model is run for a range of rule parameters within a parameter space. The results showed that multiple strategies might be capable of achieving the required targets but that some of these may be more robust in the face of climate variability than others. Significant water savings can result from the use of the technique. However. the results also highlight the limitations of the way environmental flows are currently stipulated and point towards a new generation of environmental flows. The technique is applied to environmental flow targets in the Thomson River catchment, Victoria, Australia. Copyright (c) 2005 John Wiley L Sons, Ltd.