Soil Physical Properties of Collapsing Hill and Gully and Their Indications for Soil Erosion: An Example of Liantanggang Collapsing Hill and Gully in Wuhua County of Guangdong
详细信息
- 责任者：Liu Xilin (School of Geography and Planning ; Sun Yat-Sen University ; Guangzhou 510275 ; China) ; Zhang Dalin
- 刊名：Advances in Earth Science
- 出版年：2013
- 卷期：28(7)
- 关键词：泥石流 ; debris flows ; 水土流失 ; soil erosion ; 土体结构 ; soil mass structure
- 页码：p.802-811
- 图表：8 illus., 3 tables, 25 refs.
- 分类号：1800
- issnNo：ISSN1001-8166
- isbnNo：CN62-1091/P
摘要
Collapsing hills and gullies concentrating in 7 provinces(autonomous regions) of southeast China,mainly in Guangdong and Fujian with a total area of approximate 50 000 km2,are the most serious area of soil erosion in southeast China.Collapsing hill and gully is resulted from the hydraulic-gravity compound erosion,and is the result of gully erosion.In southeast China,Collapsing hills and gullies mainly generate on the thick layer of weathering crust of granite.High viscous clay and low coarse gravel are the main feature of the collapsing soil.The average median grain size of the collapsing soils from top to toe shows a change from coarseness to fine,reflecting the erosion and transportation processes of running water on slope.The soil of collapsing hill and gully is easily erodible.The erodible factor K value averagely is about 0.26,more than 0.03 to 0.05 compared with the K value of red soil in southeast China.The K value of the collapsing soils is greater in slope foot than that on the top,indicating the erosion at the slope toe is greater than that on the top,which provides a new interpretation for the mechanism of the collapse hill and gully processes.The collapsing wall and colluvial deposits have 10.53% clay content,more than 5% of the necessary requirement for debris flow initiation.When steep collapsing hill and gully terrains are coupled with the appropriate rainfalls,may be transformed into "debris flow",but the debris flow’s grain size is much smaller(only about 1/12) than that of the conventional debris flow,and gravel content is only a quarter of the debris flow.Therefore,the collapsing hill and gully transformed into debris flow(namely the collapsing hill transformed into debris flow) is not the conventional sense of debris flow,and it is a new debris flow subtype: Clay sand flow.