for suiting the condition in Taiwan, Domestic scholars Huang in 1979
studied R factor for Taiwan area according to geographic characteristics
for local condition. He established average R factor contour map for
whole Taiwan island using nonlinear regression equation and the
relationship between average rainfall and R factor. The reference figure
shows as figure 2.
K — soil erodibility factor—the soil loss rate per erosion index unit for a
specified soil as measure on a unit plot, the reference value shows as
Figure 3.
Figure 2 The K value reference figure Figure 3 The R value reference figure
L —slop length factor—the ratio of soil loss from the field slope length under
the unit plot conditions as above.
S — slope steepness factor—the ratio of soil less from the field slope gradient
under unite-plot conditions.
Slope length and steepness is recorded by soil map unit area on aerial
photographs, and can be interpreted from soil maps for farm planning
purposes to help control erosion. Steeper slopes have greater soil erosion
potential because runoff is more rapid, and longer slopes have more water-
gathering capacity to move larger volumes of sediment. Slopes can be made
shorter and less steep with terraces.
This study produced slope and aspect information from ten meter contour line
and on Figure 5. through digitizing transfer into Vector file and using the GIS to
generate the slop and aspect date.
Table 1. The C & P reference value
C Value P. Value
Forest 0.01 0.01
Betel nut 0.025 0.14
Urban 0.01 ]
Bare ^ Collapsed |l 1
Water 0 0
C—=cover and management factor—the ratio of soil loss from an area with
specified cover and management to that from a unit plot in tilled
continuous fallow. This study extracted land cover factor as shown from
Table 1., which consider classified landcover type and other references.
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International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B7. Vienna 1996