Sustainable Water Resources Management, Plantation Forestry and a Method for the Provision of Environmental Flows to Wetland Ecosystems

摘要

Water resources in the Mount Lofty Ranges are critically important to South Australians. The area provides sixty percent of Adelaide's water supply in ah average year, supports more than 25,000 hectares of irrigated agriculture and contains a number of water dependent ecosystems of national conservation significance. The region has recently been placed under a moratorium on water use due to a risk to the region's water resources while a water allocation plan is developed. Hardwood plantation forestry is an industry that has recently targeted the Mount Lofty Ranges as an area for significant development. South Australia is a signatory to the National Water Initiative. Within this framework it is recognised that some activities, including plantation forestry, have the potential to intercept significant volumes of water. The Department of Water, Land and Biodiversity Conservation (DWLBC) is assessing the significance of such activities based on an understanding of the total water cycle, to protect user access to a sustainable water resource and the achievement of environmental objectives. Twenty-five percent of median annual adjusted catchment yield is used in South Australia as an indicator of the sustainable use limit of catchment surface water resources. DWLBC has developed an assessment procedure that integrates the assessment of conventional water affecting activities with the water requirements of nationally important wetlands and the expected impacts of plantation forestry. The requirements of prospective water users are estimated using available information. Wetland requirements are estimated using the Fleurieu Swamp water balance model, while the impacts of plantation forestry on surface water yield are based on gauged streamflow data from the Mount Lofty Ranges. The procedure ensures that the water requirements of downstream users, including wetlands are met, while determining the maximum area of plantation forestry that can be sustainably developed within a well-defined consumptive pool. Once a maximum area of plantation is determined the development should be designed according to guidelines that address specific water resources issues in addition to industry guidelines, which address conventional land management issues.