Managing catchments for multiple objectives: the implications of land use change for salinity, biodiversity and economics

Policy developed for the management of natural resources in agricultural landscapes in recent years has emphasised the need for an integrated approach. Operationally however, natural resource objectives have been pursued independently with little consideration of the link between components of ecosystems and therefore the possibility of trade-offs between components. In the absence of this information, decision makers cannot adequately assess the cost-effectiveness of alternative strategies for improving the condition of the natural resource base. The aim of this study is to assess the extent of trade-offs between multiple catchment objectives viz. biodiversity, stream salinity, stream yield, salt load, sequestration of carbon and farm profit in the Little River Catchment in Central New South Wales. Seven scenarios describing different land use alternatives for the catchment were assessed using spatial datasets of catchment characteristics. A suite of models was used to determine the impact of land use change on these characteristics over a 50-year timeframe. The results of the analysis indicate that changes in farm production methods may deliver small improvements in some indicators of catchment health. However, significant improvements would require the establishment of large areas of woody perennials and this is only likely to occur with significant public investment, given the consequent large reduction in farm profit. Trade-offs between several catchment indicators were identified. Significantly the benefits of reducing stream salinity were outweighed by the losses resulting from reduced stream flow. Generally, the financial benefits of improving the indicators of resource condition were low relative to the investment required. It was concluded therefore that the environmental value of these improvements would need to be substantial to justify the investment.