Modeling predictive assessment of soil erosion related hazards at the Uva province in Sri Lanka

Abstract

At present, soil erosion is one of the most prominent environmental and socio-economic concerns in Sri Lanka and identification of soil erosion hazard zones is crucial for applying effective soil and water conservation measures. Thus, the study assessed the soil erosion and generated soil erosion hazard zonation map for the Uva province in Sri Lanka by means of the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) Sediment Delivery Ratio (SDR) model, which was developed as part of the Natural Capital Project, a partnership between Stanford University-USA, the Nature Conservancy (TNC), and the World Wildlife Fund (WWF), working with many other institutions. The estimated mean soil erosion rate of Uva province was 25.6 t ha−1 year−1 and which is ~ 3 times greater than the soil loss tolerance in Sri Lanka. However, the soil erosion rates of the major basins in the province ranged between 0.9 and 117.8 t ha−1 year−1. Based on this study, province was classified into five soil erosion hazard classes viz. low (0–5 t ha−1 year−1), moderate (5–12 t ha−1 year−1), high (12–25 t ha−1 year−1), very high (25–60 t ha−1 year−1), and extremely high (60 < t ha−1 year−1) and the study revealed that under the existing land use scenario, 73.5% of the land area falls into low soil erosion hazard category while 11.7%, 2.1%, 1.6% and 11.10% of the areas falls into moderate, high, very high and extremely high soil erosion hazard categories respectively. Moreover, the soil erosion hazard status of the Uva province clearly indicates that the soil erosion occurring in the province are related to the improper land use practices and resulted in copious environmental and socio-economics problems. Hence, the findings of the study suggest that the implementation of sustainable watershed management options is crucial to mitigate present soil erosion and to enhance the quality of the watershed.