Identification of areas vulnerable to soil erosion and risk assessment of phosphorus transport in a typical watershed in the Loess Plateau

Abstract

Soil erosion is an increasingly serious eco-environmental problem and an important driver of phosphorus loss, which not only reduces soil productivity but also decreases water availability. The integration of the universal soil loss equation (USLE) and the geographic information system (GIS) technique is globally popular for erosion prediction and assessment. The Fen River basin is located in the east of the Loess Plateau and has eco-environmental problems of soil erosion and eutrophication because of excess phosphorus content. This study attempted to use the USLE model to evaluate soil erosion and the transport of the resulting particulate phosphorus in the Fen River basin under a GIS framework. The results showed that soil erosion in 15.8% of the study area exceeded 8000 t/(km2·a) and was mainly distributed in the upper Fen River basin. Soil erosion was greatest in the bareland area, with an average of approximately 1.22 × 104 t/(km2·a), followed by that in grassland. Soil erosion in the study area is most sensitive to the rainfall erodibility (R), followed by the soil erodibility (K), topographic factors including slope steepness (S) and slope length (L), the soil and water conservation factor (P), and the vegetation cover and management factor (C). Similar to soil erosion, the high-risk areas of particulate phosphorus transport were mainly concentrated in the upper reaches of the basin. The study also pointed out that the combined use of available data sources with the USLE model and GIS technique is a viable option to calculate soil erosion and assess the risk of particulate phosphorus transport, which could provide a scientific basis for reducing soil erosion and controlling phosphorus migration.