The coupling of hillslope- and gully-erosion increases their controlling efforts: A case study in Liaoning Province, China

Abstract

The widespread hillslope- and gully-erosion in Liaoning Province of Northeast China, pose serious challenges to the local agricultural production. Hillslope- and gully-erosion have typically been studied separately; however, there has been little investigation on the relationship of these two types of erosion. In this study, the coupling relationship of the hillslope- and gully-erosion from the perspectives of erosion intensity and land use, as well as the slope gradient, aspect, and shape, was analysed. The study employed remote sensing and geographic information system techniques, and the universal soil loss equation and kriging were used to perform a macroscopic analysis. The results showed that gully-erosion was more severe compared with hillslope-erosion in the study area. The cultivated land has the highest level of human activities, therefore, the most intense hillslope- and gully-erosion. The threshold slope gradients for the hillslope- and gully-erosion are 14° and 6°, respectively. Above the threshold of 6°, the slope gradient is no longer the primary factor affecting the gully-erosion. Sunny slopes have observably more hillslope-erosion than shady slopes, and the highest hillslope-erosion is observed on the south-southeast-facing slopes. The effect of the slope aspect on the gully-erosion should not be ignored, as evidenced by the considerable gully density of the east-northeast-facing slopes which is obviously higher than for slopes with other slope aspects. The highest hillslope-erosion amount and gully density occur on concave slopes, followed by convex and straight slopes, and straight slopes have little effect on the hillslope-erosion, but have a marked impact on the gully-erosion. The results of this work may serve as a scientific reference for the comprehensive control of soil erosion across a slope-gully system in Northeast China.