黄土丘陵沟壑区典型小流域沟道类型和坡面组成对重力侵蚀的影响

Influence of gully type and slope composition on the gravity erosion of typical small basins in the hilly and gully areas of the Loess Plateau

重力侵蚀是黄土丘陵沟壑区小流域发生水土流失和地质灾害的重要原因之一,但对其存在和发生环境的研究仍不充分。为探究沟道形态和坡面组成对重力侵蚀的影响,基于无人机摄影测量、遥感解译、现场调查等方法,系统研究山西省吕梁市王家沟流域内78处滑坡、26处崩塌和108处泻溜的空间分布、侵蚀数量特征及与沟坡的关系。结果表明:1)沟道类型影响重力侵蚀危害程度。沟道分类有助于识别重力侵蚀活跃区域,冲沟和干沟的重力侵蚀量及面积分别占研究区总量的88.5%和81.4%。2)重力侵蚀与沟道坡度存在紧密关系,在不同类型沟道中的表现差异显著。坡度30°~60°区域分别是切沟和冲沟中重力侵蚀最严重区域,发生率约是其他区域的2.57倍和1.19倍;干沟和河沟的重力侵蚀主要发生在坡度0~30°区域。3)坡面组成方式对重力侵蚀危害程度和发生类型存在显著影响,土壤类型及其空间分布特征是重要影响因素。该研究可为黄土丘陵沟壑区重力侵蚀精准防治提供理论依据。

[Background]Gravity erosion is one of the prevalent types of soil erosion in the hilly-gully region of Loess Plateau,which causes a large amount of soil erosion and serious harm.Gravity erosion inducing factors are very numerous and have complex interrelationships,which makes it difficult to study.Figuring out the environment in which gravity erosion exists and occurs,so as to construct more scientific and effective prevention and control methods,is an issue that needs to be solved urgently in the current research on soil erosion in hilly and gully areas of the Loess Plateau.[Methods]We systematically studied the spatial distribution of 78 landslides,26 collapses,and 108 slumps,the quantitative characteristics of erosion,and the relationship between erosion and gully in Wangjiagou watershed of Lüliang city,Shanxi province,by using unmanned aerial vehicle(UAV)measurements,remote sensing interpretation,and field surveys.[Results]1)Gully types had an impact on the extent of gravity erosion hazards.The classification of gully types was helpful in identifying areas where gravity erosion was active,with head-water gullies and valley-side gullies accounting for 88.5%and 81.4%of the corresponding number of gullies in the study area in terms of gravity erosion weight and area,respectively.2)There was a correlation between gravity erosion and gully slope,and it showed significant variability in different types of gullies.The region of slope 30°-60°was the most serious area of gravity erosion in the hill-side gullies and head-water gullies,respectively,with approximately 2.57 and 1.19 times higher occurrence rate than the other regions.Gravity erosion in valley-side gullies and head-water gullies mainly occurred in the region of slope 0-30°.3)The level of damage and type of occurrence of gravity erosion varied significantly across slope composition types,which may be directly related to the types of soils that make up the slope and the spatial distribution of soils.[Conclusions]This study revealed the main areas and environments where gravity erosion exists and occurs in the loess hilly gully area,and by classifying the gully and slope refinement,the degree of influence of the gully-slope system on gravity erosion could be further quantified,which may provide a theoretical basis for the prevention and management of gravity erosion in the hilly-gully region of Loess Plateau.