‘Tolerable’ Hillslope Erosion Targets To Maintain Sustainable Land Management Across New South Wales, Australia

Abstract

Hillslope erosion is the dominant form of erosion in Australia and many parts of the world. ‘Tolerable’ hillslope erosion or tolerable soil loss (TSL) targets needs to be established considering the inherent physical capacity of the land to sustain specific land uses and management practices without degradation to soil, land, air and water resources. The existing methods on TSL estimation vary greatly over different regions and applications, and few practical and dynamic methods are available. In this study, we explored a dynamic approach to set TSL and vegetation cover targets across the state of New South Wales (NSW), Australia considering the prevailing hillslope erosion and the sustainable erosion level. Over 20-year fractional vegetation cover and rainfall erosivity time-series have been used to determine the hillslope erosion and the TSL targets monthly and the 50 th percentile was set as the target. Consequently, the monthly vegetation cover levels have been set to sustain the TSL targets on a pixel-by-pixel (100 m) basis. We further assessed the TSL targets against the land and soil capability classes and their spatial and temporal variation across NSW Local Land Services regions. The findings help to identify the locations and times with hillslope erosion exceeding a tolerable threshold value across NSW. This approach is practical, semi-quantitative and portable as the input datasets are widely available, thus providing a useful tool to determine varying TSL values for sustainable soil and land management at any location and period.