12 Soil Erosion
273
and quantifying soil erosion rates and patterns and the need for techniques that can
identify potential as well as actual source areas of soil erosion on the landscape.
Soil erosion causes both physical (i.e., gullies, rills) and visible (i.e., exposure of
different colored soil layers) changes in the surface properties of soils on the landscape. Such changes can be measured both spatially and temporally using remote
sensing techniques with a variety of sensors and sensor platforms. Remote sensing
techniques can measure qualitative and quantitative information on changes in the soil
surface roughness and on visible features. Remote sensing techniques to measure
eroded material once it leaves the land surface and enters a stream or a water body are
discussed in Chap. 13 of this book.
12.2 Basis for using Remote Sensing
Cihlar (1987) concluded that assessing and monitoring soil erosion occurs in two
dimensions that he called stage and time. He uses stage to refer to the type of soil
erosion (i.e., sheet, rill, or gully) and time to refer to actual or potential soil erosion.
It is important to evaluate both the stage and time dimension if we are to develop
management plans to reduce or control soil erosion. Both the stage and time of
erosion can affect the physical and spectral properties of soil surfaces. Since remote
sensing techniques measure spectral and physical properties, we can use remote
sensing to provide information on these changes in surface properties of the soil
caused by erosion. Remote sensing techniques can provide spatial and temporal data
on these properties that will allow us to develop better management plans for large
areas to reduce soil erosion.
Remote sensing techniques that measure the spectral properties of the landscape are
most commonly applied to study soil erosion patterns and rates. Ground-based and
aerial photographs are still the most popular remote sensing technique used to study
and map soil erosion using either photo interpretation or photogrammetric techniques.
These techniques provide information on spectral differences in the soil surface and
are interpreted to delineate areas affected by soil erosion. Photointerpretation of
images made from digital radiance data from satellite sensors (Landsat, SPOT, IRS,
A VHRR, etc.) is also widely used to map areas of soil degradation. Photographs and
digital imagery have been used for mapping actual/potential soil erosion areas, for
determining spectral patterns and differences in the surface soils related to soil
erosion, and for determining land cover and conservation practices for input to soil
erosion models.
Photogrammetric techniques are used with stereo photographs to measure physical
changes (i.e., roughness) in soil surface elevation. Sequential photographs can be used
to determine changes in areas of erosion or deposition over time. Ground-based and
airborne lasers are also used to measure landscape surface roughness and topography.
These laser systems can measure physical changes in the soil surface to within a few
millimeters from ground platforms and within a few centimeters,from aerial platforms
allowing estimates of soil loss or estimates of surface roughness that allow us to better
understand soil erosion. Synthetic aperture radar (SAR) also has been used to measure
273
and quantifying soil erosion rates and patterns and the need for techniques that can
identify potential as well as actual source areas of soil erosion on the landscape.
Soil erosion causes both physical (i.e., gullies, rills) and visible (i.e., exposure of
different colored soil layers) changes in the surface properties of soils on the landscape. Such changes can be measured both spatially and temporally using remote
sensing techniques with a variety of sensors and sensor platforms. Remote sensing
techniques can measure qualitative and quantitative information on changes in the soil
surface roughness and on visible features. Remote sensing techniques to measure
eroded material once it leaves the land surface and enters a stream or a water body are
discussed in Chap. 13 of this book.
12.2 Basis for using Remote Sensing
Cihlar (1987) concluded that assessing and monitoring soil erosion occurs in two
dimensions that he called stage and time. He uses stage to refer to the type of soil
erosion (i.e., sheet, rill, or gully) and time to refer to actual or potential soil erosion.
It is important to evaluate both the stage and time dimension if we are to develop
management plans to reduce or control soil erosion. Both the stage and time of
erosion can affect the physical and spectral properties of soil surfaces. Since remote
sensing techniques measure spectral and physical properties, we can use remote
sensing to provide information on these changes in surface properties of the soil
caused by erosion. Remote sensing techniques can provide spatial and temporal data
on these properties that will allow us to develop better management plans for large
areas to reduce soil erosion.
Remote sensing techniques that measure the spectral properties of the landscape are
most commonly applied to study soil erosion patterns and rates. Ground-based and
aerial photographs are still the most popular remote sensing technique used to study
and map soil erosion using either photo interpretation or photogrammetric techniques.
These techniques provide information on spectral differences in the soil surface and
are interpreted to delineate areas affected by soil erosion. Photointerpretation of
images made from digital radiance data from satellite sensors (Landsat, SPOT, IRS,
A VHRR, etc.) is also widely used to map areas of soil degradation. Photographs and
digital imagery have been used for mapping actual/potential soil erosion areas, for
determining spectral patterns and differences in the surface soils related to soil
erosion, and for determining land cover and conservation practices for input to soil
erosion models.
Photogrammetric techniques are used with stereo photographs to measure physical
changes (i.e., roughness) in soil surface elevation. Sequential photographs can be used
to determine changes in areas of erosion or deposition over time. Ground-based and
airborne lasers are also used to measure landscape surface roughness and topography.
These laser systems can measure physical changes in the soil surface to within a few
millimeters from ground platforms and within a few centimeters,from aerial platforms
allowing estimates of soil loss or estimates of surface roughness that allow us to better
understand soil erosion. Synthetic aperture radar (SAR) also has been used to measure