12 Soil Erosion
Jerry C. Ritchie
USDA-ARS Hydrology Laboratory, BARe-West, Bldg-007, Beltsville, MD 20705 USA
12.1 Introduction
Soil erosion is a natural procds caused by water, wind, and ice that has affected the
earth's surface since the beginning of time. Soil erosion and its off-site, downstream
damages are major concerns around the world (Lal 1994b) causing losses in soil
productivity and degradation oflandscape (Walling 1983). Many of man's activities
have accelerated soil erosion (Sombroek 1995; Walling 1983). Oldeman (1994) has
estimated that human-induced soil degradation has affected 15% of the world's arable
land surface. Estimates of global soil erosion rates range from 0.088 rom yr-l (Walling
1987) to 0.30 rom yr-l (Fournier 1960). These values led to estimates of 17.4 to 58.1
x 10 9 Mg of soil loss from the land surface (Walling 1990) which is carried downstream into lakes, reservoirs and estuaries where it reduces storage capacity and
affects water quality, navigation, and biological productivity. On the land surface, soil
erosion decreases organic matter, fme grained soil particles, water holding capacity,
and rooting depth leading to loss of soil productivity and quality. The economic
consequences from soil erosion on loss of productivity, land degradation, and off-site,
downstream damages from eroded soil particles on water quality are a major concern.
Pimentel et al. (1995) estimated the economic cost of soil erosion and subsequent
sediment deposition to be $400 billion per year worldwide. While this economic
estimate of the cost of erosion has been questioned (Sombroek 1995), concerns about
soil loss and the estimated cost point to the need for new and improved methodologies
and techniques for monitoring and quantifYing soil erosion effectively and efficiently
across the landscape so that effective land management practices can be applied to the
land surface to control and reduce soil erosion.
Determining spatially distributed soil erosion on the landscape using classical soil
erosion measurement techniques is difficult, time consuming, and expensive (Brakensiek et al. 1979; LalI994a). These techniques involve field studies with experimental
plots to establish basic principles and measure rates of erosion. Small unit-source
catchments are used for relating these plot studies to larger areas (Mutchler et al.
1994). These types of studies involve continuous measurements of soil and water
movement from plots/catchments and require long time periods (years) of data
collection to provide statistically significant results. Such studies are limited to
establishing information about processes and rates and can seldom be used to
G. A. Schultz et al. (eds.), Remote Sensing in Hydrology and Water Management
© Springer-Verlag Berlin Heidelberg 2000
Jerry C. Ritchie
USDA-ARS Hydrology Laboratory, BARe-West, Bldg-007, Beltsville, MD 20705 USA
12.1 Introduction
Soil erosion is a natural procds caused by water, wind, and ice that has affected the
earth's surface since the beginning of time. Soil erosion and its off-site, downstream
damages are major concerns around the world (Lal 1994b) causing losses in soil
productivity and degradation oflandscape (Walling 1983). Many of man's activities
have accelerated soil erosion (Sombroek 1995; Walling 1983). Oldeman (1994) has
estimated that human-induced soil degradation has affected 15% of the world's arable
land surface. Estimates of global soil erosion rates range from 0.088 rom yr-l (Walling
1987) to 0.30 rom yr-l (Fournier 1960). These values led to estimates of 17.4 to 58.1
x 10 9 Mg of soil loss from the land surface (Walling 1990) which is carried downstream into lakes, reservoirs and estuaries where it reduces storage capacity and
affects water quality, navigation, and biological productivity. On the land surface, soil
erosion decreases organic matter, fme grained soil particles, water holding capacity,
and rooting depth leading to loss of soil productivity and quality. The economic
consequences from soil erosion on loss of productivity, land degradation, and off-site,
downstream damages from eroded soil particles on water quality are a major concern.
Pimentel et al. (1995) estimated the economic cost of soil erosion and subsequent
sediment deposition to be $400 billion per year worldwide. While this economic
estimate of the cost of erosion has been questioned (Sombroek 1995), concerns about
soil loss and the estimated cost point to the need for new and improved methodologies
and techniques for monitoring and quantifYing soil erosion effectively and efficiently
across the landscape so that effective land management practices can be applied to the
land surface to control and reduce soil erosion.
Determining spatially distributed soil erosion on the landscape using classical soil
erosion measurement techniques is difficult, time consuming, and expensive (Brakensiek et al. 1979; LalI994a). These techniques involve field studies with experimental
plots to establish basic principles and measure rates of erosion. Small unit-source
catchments are used for relating these plot studies to larger areas (Mutchler et al.
1994). These types of studies involve continuous measurements of soil and water
movement from plots/catchments and require long time periods (years) of data
collection to provide statistically significant results. Such studies are limited to
establishing information about processes and rates and can seldom be used to
G. A. Schultz et al. (eds.), Remote Sensing in Hydrology and Water Management
© Springer-Verlag Berlin Heidelberg 2000