Hillslope erosion improvement targets: Towards sustainable land management across New South Wales, Australia

Abstract

Hillslope erosion, including sheet and rill erosion, is the dominant form of erosion in Australia and many parts of the world. Hillslope erosion improvement (HEI) targets are necessary for the evaluation of natural resource condition and sustainable land use and land management practices. The tolerable soil loss concept has been widely applied to agricultural lands for setting soil erosion targets. It is a static target that is difficult to apply to diverse land uses and soil conditions. In this study, we developed a new approach for setting HEI resource condition targets by considering seasonal erosion levels over a large climate gradient and range of land management practices across New South Wales (NSW), Australia. A 20-year fractional vegetation cover and rainfall erosivity time-series have been used to estimate hillslope erosion rates and assign monthly and annual HEI targets across NSW. To assist with land management action target, monthly vegetation cover levels have been set to meet the HEI targets on a pixel-by-pixel (100 m) basis. We further assessed the HEI targets against land and soil capability classes and their spatial and temporal variation across local land service regions. The findings can help identify the locations and periods of time with hillslope erosion exceeding a desirable threshold level and indicate management actions that might be required to improve the soil condition over areas of concern. The processes are fully automated in a geographic information system (GIS) environment, thus providing a useful tool to determine HEI targets for sustainable soil and land management at any location and period. The methods are globally portable as the input datasets are widely available.