State and trends of hillslope erosion across New South Wales, Australia

Hillslope erosion is a widespread natural hazard which often causes land and water quality degradation. Consistent and continuous erosion monitoring will help identify the impact of land management practices and improve soil condition. This paper presents an improved modeling approach for monitoring and predicting hillslope erosion on monthly basis over New South Wales (NSW), Australia by using the most recent time-series fractional vegetation cover data, regional climate projections and the Revised Universal Soil Loss Equation. The time-series estimation was used to analyze the state and trends of hillslope erosion, identifying the places and times of greatest erosion hazard. The average hillslope erosion rate for the current period (2000-2017) was estimated at 0.85 Mg ha(-1) yr(-1) over NSW. The areas with high erosion risk was the North Coast, Hunter and Greater Sydney regions with erosion rates of 4.04, 3.74 and 3.06 Mg ha(-1) yr(-1) respectively. The Western region had the lowest hillslope erosion risk (0.11 Mg ha(-1) yr(-1)) due to its flat terrain. Hillslope erosion in NSW was generally decreasing over the past 18 years, with a reduction of 16% in the recent three years (2015-2017) compared to the previous 15-year (2000-14). However, the future hillslope erosion is predicted to increase about 7-21% in the next 60 years due to the likely increase in extreme rainfall events and decrease in groundcover. The methodology and datasets used in this study are general, thus they have the potential to be applied elsewhere.