水力侵蚀的自然与人为驱动机制

Mechanisms of nature- and human-driven soil erosion by water

水力侵蚀是一种自然现象,在土壤特性、地形、植被和气候等自然因素的驱动下,在地球表面呈条带状或区域化分布.然而,在人类活动(农业活动、城市建设、工业发展和水利工程建设)引起的地表剧烈变化及全球气候变化的驱动下,水力侵蚀模式会发生转变.本文综述了自然和人类活动共同驱动下的水力侵蚀机制.土壤母质决定了土壤的本质属性,其中包括土壤可蚀性;通常,水力侵蚀速率随着坡度、坡长和降雨强度的增大而升高,而植被因子负反馈调控水力侵蚀过程.自然水力侵蚀过程是缓慢的;然而,在人类活动的强烈干扰下,土壤、地形、植被和气候发生了巨变,极大加速了自然水力侵蚀过程.人类对陆地表面的改造,引起全球土地利用格局的巨大变化,导致植被锐减和全球气候变化;人为的植被破坏成为全球水力侵蚀加剧的主要因素;气候变化,极大地改变了水力侵蚀模式,导致极端水力侵蚀事件频发.可持续的土地管理可降低人类活动和气候变化带来的不利影响;基于流域尺度的水力侵蚀预报模型的建立与应用,有利于水力侵蚀的预报、预警和防治.

Soil erosion by water(water erosion) is a natural phenomenon distributed in band or regionally on the earth′s surface due to natural factors(soil property, topography, vegetation and climate). However, the pattern of water erosion is altered as a result of dramatic change of the earth′s surface arisen from anthropogenic activities(agricultural activities, urbanization, industrialization, and water project construction) and global climate change. This paper summarizes the mechanisms of water erosion driven by both nature and anthropogenic activities. Soil parent material determines the essential properties of soil, including soil erodibility;the rate of water erosion generally increases with the increase of slope angle, slope length and rainfall intensity, whereas vegetation impedes water erosion. Water erosion proceeds slowly in the natural condition, however, soil, topography, vegetation and climate have undergone significant changes under the strong disturbances of human activities, which has greatly accelerated the process of water erosion;land surface changes caused by humans have exerted tremendous impacts on global land use patterns, resulting in sharp declines in vegetation coverage and global climate change;human-induced vegetation destruction is a major factor for global water erosion;climate change has greatly changed the patterns of water erosion, causing frequent extreme water erosion events. Sustainable land management is considered to reduce the adverse effects of human activities and climate change;the establishment and application of water erosion prediction models on a watershed scale are beneficial to the prediction, early warning and prevention of water erosion events.