Environmental water requirements and management options in Gunbower Forest, Victoria

Abstract

Plans to provide water to floodplain ecosystems are frequently constrained by insufficient ecological and hydrological data. Published ecological studies provide a range of indicator species to assess the impacts and to predict the responses of water management. However, if the a site’s hydrology and ecology is not well known, this information is of little value.This paper presents an approach to apply the known responses of indicator species to an ecosystem where the hydrology is poorly understood. Gunbower Forest, a River Murray floodplain ecosystem in northern Victoria, has experienced reduced flooding as a consequence of river regulation and diversions. This project assessed the ecological impacts of hydrological change and recommended compensatory water provisions.Foresters had previously mapped the spatial distribution of timber quality classes in Gunbower Forest. The known relationship between timber quality and flooding at Barmah Forest was applied to Gunbower Forest to map hydrological classes. The flora and fauna associated with these classes were attributed from known hydrological relationships at Barmah Forest and the wider scientific literature.A key finding of the project was that low flows are important in rehabilitating permanent wetlands in the forest. The current framework for providing environmental flows is inadequate in this respect. Floodplain ecosystems are generally provided with large, infrequent flows from allocations of surplus flows. However, small, frequent inflows require allocations of secure water which are not widely available to the environment.