Meeting Environmental Outcomes – A Planning Framework - Water and Agriculture: Sustainability, Markets and Policies - page 207

Discussion
The environmental objectives considered here, while set in a context of flow
conditions on the Murrumbidgee River, are still hypothetical. Nevertheless, the exercise
raises a wide range of conceptual and applied issues.
One advantage of adopting a formal decision framework is that it does link river
hydrology to environmental objectives and the demand for water resources to meet those
objectives. It places a strong focus on the hydrological aspects of an event that are
important to achieving a desired or at least improved outcome. The adverse impact of
attenuation on achieving the flow target in the solved example offers a good example. If
maintaining constant flows is important to delivering the environmental outcome, then it
might be necessary to increase the targeted flow rate, increasing both the resource
requirements and cost of the strategy. If the underlying objective is to initially fill and to
eventually flush the billabongs and lagoons, then it might be better to reconsider the
definition of a successful event.
One potential disadvantage of this type of planning framework is that it can reduce
the ability of an environmental manager to respond to unanticipated opportunities to
achieve a desired environmental outcome. Hence, a release strategy should not fully
preclude the discretion of the environmental manager. Further, while not a limitation, it is
important to acknowledge that a planning framework will embody qualitative value
judgments regarding, for example, the desired characteristics of a high flow event, as well
as non-market values such as the cost of failing to meet an environmental objective.
The linking of the decision framework to a hydrological model such as IQQM allows
environmental managers to more systematically explore how alternative environmental
objectives and release strategies impact on the river system, not only at the point of
reference but throughout the system. It allows the consideration of how targeted releases
will affect subsequent storage levels, spills and end-of-system flows.
The cost of the example strategy is large when compared with current government
commitments to increase environmental flows. This is largely an artefact of the design of
the example, reflecting the high level of reliability imposed on the strategy and the cost of
holding high security water at the dam wall. More importantly, the integration of the cost
minimisation framework with river hydrology allows the costs of alternative strategies to
be compared and options to reduce those costs to be explored. For example, rather than
holding a high security entitlement, a general security entitlement or options contract, as
discussed in Hafi et al. (2005) and Heaney et al. (2005), can substantially reduce costs,
albeit at a lower level of reliability. Improved forecasting of river flows, and hence
release requirements, is another avenue to reduce costs. These are all areas of ongoing
research.
ACKNOWLEDGEMENT
Funding support from the Natural Resource Management Division, Australian
Government Department of Agriculture, Fisheries and Forestry is gratefully
acknowledged.