Soil Erosion by Water

Authors: McCool, Donald; Williams, John

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 10/5/2007
Publication Date: 8/24/2008
Citation: McCool, D.K., Williams, J.D. 2008. Soil Erosion by Water. In Sven Erik Jorgensen & Brian D. Fath, (Editor-in-Chief), Ecological Processes. Vol. [4] of Encyclopedia of Ecology, 1st Edition, Elsevier B.V., 5 vols. pp. [3284-3290] Oxford.

Interpretive Summary: Soil erosion by water, the wearing away of the earth's surface by the forces of water and gravity, consists of particle dislodgement, entrainment, transport, and deposition. This sequence of events occurs over a wide range of temporal and spatial scales, from raindrop splash moving particles a few millimeters in milliseconds to suspended sediment and bed-load in rivers continuously moving an estimated 15.5 billion metric tonnes per year to the oceans of the world. As a matter of course, soil erosion begins in the uplands where soil is dislodged and moved down-slope, progressing from splash saltation, to entrainment in micro-channels, to collection in rills, concentrated flow channels, gullies, streams and river channels, and ultimately deposition in a closed basin or the ocean. Deposition and re-entrainment occurs continuously from ridge top to delta. Erosion is a natural geological process, wearing down rugged mountain ranges and creating smoothed ridges, flood plains, and deltas. The progression from dislodgement and entrainment to deposition can be accelerated or retarded through human manipulation of the soil resource, plant cover, animal use, or structural measures. In this chapter we examine how soil erosion in uplands is influenced by rainfall, climate, topography, soil characteristics, and most importantly, human activities.

Technical Abstract: Soil erosion by water, the wearing away of the earth's surface by the forces of water and gravity, consists of rock or soil particle dislodgement, entrainment, transport, and deposition. This sequence of events occurs over a wide range of temporal and spatial scales, from raindrop splash moving particles millimeters in milliseconds to suspended sediment and bed-load in rivers continuously moving an estimated 15.5 billion metric tonnes per year to the oceans of the world. As a matter of course, soil erosion begins in the uplands where soil is dislodged and moved down-slope, progressing from splash saltation, to entrainment in micro-channels, to collection in rills, concentrated flow channels, gullies, streams and river channels, and ultimately a closed basin or the ocean. Deposition and re-entrainment occurs continuously from ridge top to delta. Geologic erosion, also commonly referred to as natural erosion, results from processes not affected by humans. The uneven loss and accumulation (or development) of soil across a landscape is a primary factor in the shifting mosaic of ecological communities. The progression from dislodgement and entrainment to deposition can be accelerated or retarded through human manipulation of the soil resource, plant cover, animal use, or structural measures. In this chapter we examine how soil erosion in uplands is influenced by rainfall, climate, topography, soil characteristics, and most importantly, human activities.