12 Soil Erosion
277
metry, model/GIS inputs, spectral properties, and topographic measurements.
Examples of studies will be used to describe each approach.
12.4.1 PhotointerpretationlPhotogrammetry
Photointerpretation techniques have been used extensively to map soils, vegetation
cover, drainage patterns, soil degradation, and other erosion related factors. Many of
these applications have been used for mapping erosion patterns and estimating erosion
rates. The Food and Agriculture Organization (FAO 1979) routinely uses photointerpretation techniques with aerial photographs and satellite images to assess and map
soil degradation in developing countries around the world. The F AO maps are used
to determine areas of critical erosion and soil degradation in a series of 1 :50000 and
1 : 100000 scale maps for developing countries.
Aerial photographs and satellite images were used to map changes in the shape and
size of the Rosetta promontory in the Nile Delta (EI-Raey et al. 1995). Analyses of
data from 1955 to 1991 found that photographs/satellite imagery could be used to
follow the erosion and deposition patterns and changes in the size of the promontory
that agreed with ground measurements. They concluded that the Rosetta promontory
had been eroding since the building of the Aswan High Dam. They also found that
remote sensing techniques were a more accurate, efficient, and cost effective tool for
monitoring such changes than were ground measurements. Samarakoon et al. (1993)
used Landsat TM images in a similar manner to monitor areas susceptible to landslides and concluded that TM data was a useful tool for monitoring and mapping
potential landslide areas.
Panchromatic and Color Infrared (CIR) aerial photographs (see Color Plate 12.A)
have been used to identify and map rill and gully soil erosion (i.e., Morgan et al.
1978; Frazier and McCool 1981; Stephens and Cihlar 1982; Cihlar 1987). Many
different photographic scales have been used. Frazier et al. (1983) used ground (see
an example of their photography, Color Plate 12.B) and aerial photographs taken with
a 35-mm camera to assess and map rill development and soil erosion patterns in the
steep hills of Palouse area of the western United States. They found that aerial
photographs were the most effective tool to study the development of rill and soil
erosion patterns and to determine the effectiveness of management practice for
erosion control. Aerial photographs allowed them the overview that was necessary for
mapping rill development that was not possible from the ground. Using stereoscopic
photointerpretation techniques, Stephens (Stephens and Cihlar 1982) established an
erosional classification system and mapped erosion patterns for 100 km 2 area in New
Zealand using 1: 10,000 aerial photographs. He found that remote sensing techniques
were more accurate and cost 30% less. Using the same technique in Canada, Stephens
and Cihlar accurately mapped rill and gully erosion cost effectively. Several researchers (Stephens et al. 1982; Cihlar 1987) have used sequential photographs taken over
periods of weeks to years to map and study the changing patterns of rill development
and soil erosion. By comparing maps prepared from these sequential aerial photographs, changes in the pattern of erosion and estimates of rates were determined.
277
metry, model/GIS inputs, spectral properties, and topographic measurements.
Examples of studies will be used to describe each approach.
12.4.1 PhotointerpretationlPhotogrammetry
Photointerpretation techniques have been used extensively to map soils, vegetation
cover, drainage patterns, soil degradation, and other erosion related factors. Many of
these applications have been used for mapping erosion patterns and estimating erosion
rates. The Food and Agriculture Organization (FAO 1979) routinely uses photointerpretation techniques with aerial photographs and satellite images to assess and map
soil degradation in developing countries around the world. The F AO maps are used
to determine areas of critical erosion and soil degradation in a series of 1 :50000 and
1 : 100000 scale maps for developing countries.
Aerial photographs and satellite images were used to map changes in the shape and
size of the Rosetta promontory in the Nile Delta (EI-Raey et al. 1995). Analyses of
data from 1955 to 1991 found that photographs/satellite imagery could be used to
follow the erosion and deposition patterns and changes in the size of the promontory
that agreed with ground measurements. They concluded that the Rosetta promontory
had been eroding since the building of the Aswan High Dam. They also found that
remote sensing techniques were a more accurate, efficient, and cost effective tool for
monitoring such changes than were ground measurements. Samarakoon et al. (1993)
used Landsat TM images in a similar manner to monitor areas susceptible to landslides and concluded that TM data was a useful tool for monitoring and mapping
potential landslide areas.
Panchromatic and Color Infrared (CIR) aerial photographs (see Color Plate 12.A)
have been used to identify and map rill and gully soil erosion (i.e., Morgan et al.
1978; Frazier and McCool 1981; Stephens and Cihlar 1982; Cihlar 1987). Many
different photographic scales have been used. Frazier et al. (1983) used ground (see
an example of their photography, Color Plate 12.B) and aerial photographs taken with
a 35-mm camera to assess and map rill development and soil erosion patterns in the
steep hills of Palouse area of the western United States. They found that aerial
photographs were the most effective tool to study the development of rill and soil
erosion patterns and to determine the effectiveness of management practice for
erosion control. Aerial photographs allowed them the overview that was necessary for
mapping rill development that was not possible from the ground. Using stereoscopic
photointerpretation techniques, Stephens (Stephens and Cihlar 1982) established an
erosional classification system and mapped erosion patterns for 100 km 2 area in New
Zealand using 1: 10,000 aerial photographs. He found that remote sensing techniques
were more accurate and cost 30% less. Using the same technique in Canada, Stephens
and Cihlar accurately mapped rill and gully erosion cost effectively. Several researchers (Stephens et al. 1982; Cihlar 1987) have used sequential photographs taken over
periods of weeks to years to map and study the changing patterns of rill development
and soil erosion. By comparing maps prepared from these sequential aerial photographs, changes in the pattern of erosion and estimates of rates were determined.