The spatial distribution of Benggang and the factors that influence it

Benggang, a fragmented landform induced by the overall collapse of soils on slopes, is one of the most serious land erosion problems in Southern China. The reasons for the concentrated development of Benggang and the major influencing factors are still unclear. The key driving factors for Benggang development in Fujian and Jiangxi Provinces were investigated by ArcGIS spatial analysis of the effects of rainfall, lithology, elevation, and geomorphology. It was found that Benggang density increases first and then decreases with annual average rainfall, elevation, and hypsometric integral value (HI) and that the regions with a density of greater than 0.2 Benggang km(-2) are characterized with an average annual rainfall of 1,395-1,645 mm,an elevation of 200-400 m,and an HI of 0.14-0.30. Lithology and weathering crust exhibit an important influence on the development of Benggang, with the formation of 41.94% of Benggangs in 25.88% of the granite area. HI shows a significant positive correlation with elevation in the 1,680 watershed areas (r = .83, p < .01). In different HI value ranges, the annual average rainfall presents an opposite trend to the development density of Benggang. The HI values are consistent with the maximal number of Benggangs associated with granite, tuff, conglomerate, and sandstone, indicating a close relationship of the regional Benggang development with the stage of geomorphical development. The underlying surface conditions created by geomorphological development are the direct causes for Benggang, whereas human activities only accelerate or delay its occurrence.