Meeting Environmental Outcomes – A Planning Framework - Water and Agriculture: Sustainability, Markets and Policies - page 191

Chapter 14.
Meeting Environmental Outcomes - A Planning Framework

Stephen Beare, 1 Ray Hinde, 1 Terry Hillman, 2 Anna Heaney 1 and Ilan Salbe 3

One of the main river management goals in the Murray Darling Basin is to strengthen the
link between the river and wetland environments by augmenting natural high flow events
with synchronised releases from storages. However, the volume, and timing of release, of
water resources required to meet this goal is highly uncertain. An environmental
planning framework is developed that generates well specified demand for environmental
water and a set of high flow release rules. The framework provides clearly specified
environmental objectives, giving rise to measurable performance, that are met at the
lowest possible resource costs. The problem is specified as a constrained cost
minimisation where the constraints define the characteristics of a successful high flow
event. An optimal water release strategy is determined using a genetic algorithm. The
approach is applied to a case study in the central reaches of the Murrumbidgee River and
linked to a hydrological model of the entire river system. This link allows the systematic
exploration of how alternative environmental objectives and release strategies affect the
river system. The cost minimisation framework allows the costs of alternative strategies
to be compared and options to reduce those costs to be explored.

Introduction

One of the main river management goals in regulated catchments in Australia is to
strengthen the link between the river and wetland environments of the flood plains. The
natural link between these environments was through high flow events, but such events
occur much less frequently in highly regulated river systems. In a regulated system, this
connection can be re-established by creating or augmenting natural high flow events with
synchronised releases from storages. Supplementing existing high flows reduces the
volume of water required to meet the flow objective and reduces the likelihood of failing
to create the event.
Meeting both agricultural and environmental demands will place increased pressure
on water resources. However, it is recognised that the timing of irrigation and
environmental demands are quite different. In relatively dry years the cost of reallocating
1. Australian Bureau of Agricultural and Resource Economics, Canberra.

2. La Trobe University, Melbourne.

3. New South Wales Department of Natural Resources, Sydney, Australia.