Vol18 No.9: 2328-2344
【Title】Effects of soil shrinkage in permanent gullies formation: The case of Benggang erosion in the granite area of southern China
【Author】HUANG Wan-xia1; DENG Yu-song1*; CAI Chong-fa2; JIANG Dai-hua3
【Addresses】1 Forestry College, Guangxi University, Nanning 530004, China; 2 Resources and Environment College, Huazhong Agricultural University, Wuhan 430070, China; 3 Agricultural College, Guangxi University, Nanning 530004, China
【Corresponding author】DENG Yu-song
【Citation】Huang WX, Deng YS, Cai CF, et al. (2021) Effects of soil shrinkage in permanent gullies formation: The case of Benggang erosion in the granite area of southern China. Journal of MountainScience 18(9). https://doi.org/10.1007/s11629-021-6828-x
【Abstract】Soil shrinkage is an important factor in slope destabilization in granitic areas, which is also one of the most important conditions for the formation of permanent gullies. This study explored the effect of soil shrinkage on permanent gullies, and Benggangerosion in granitic areas in southeastern China was used as an example. Three types of Benggang in granitic area were selected to examine the soil shrinkage of three soil layers(the lateritic, transitional and sandylayers) and their effect on the development of Benggang erosion was studied. The results show thatthe maximum values of COLEH and COLEV (coefficient of linear extensibility in horizontal and vertical directions, respectively) are 3.09% and 1.60% in the laterite layers, 2.71% and 2.13% in transition layers, and 1.10% and 1.82% in sandy layers, indicating that the shrinkage potential of the soil layers exhibits the following order, from highest to lowest: the laterite layer, transition layer, and sandy layer.With a decreasing volumetric water content, the linear shrinkage ratio increases gradually and eventually stabilizes, and in the laterite, transition and sandy layers, the average values of the maximum linear shrinkage are 1.50%, 2.09%, and 1.74%, respectively. Axial shrinkage is most obvious in the transition layers, in which the volume change in the form of subsidence is greater than that in other layers. The soil shrinkage curves fit the trilinear model (R2>0.9), and the soil shrinkage characteristic curves were divided into structural,basic, and residual sections.The correlation analysis shows that the soil shrinkage rate is positively correlated with clay and Fe2O3 content and negatively correlated with sand content. Clay and sandcontents are the most important factors influencing soil shrinkage.Soil oxides can influence soil shrinkage by affecting the particle composition of the soil, so soil shrinkage is closely related to soil clay minerals. Our findings can provide a theoretical basis for revealing the mechanism of Benggang erosion and its control.
【Keywords】Soil shrinkage; Permanent gully; Granite; Benggang; Soil layers