2.7. Soil erosion modeling
For this study a model-based approach was used to assess soil erosion risk. The well-known Universal Soil Loss Equation (USLE) (Wischmeier and Smith, 1978) was used because it is one of the least data demanding erosion models that have been developed and it has been applied widely at different scales. The model is designed to estimate long-term annual erosion rates of agricultural fields. The USLE model as described in Equation 1 was used to predict erosion of each 100 m2 cells in this study.
A=RxKxLSxCxP [1]
Where A, Annual soil loss (in ton ha-1year-1); R is the rainfall erosivity factor (MJ mm ha-1 h-1); K is the soil erodibility factor (t ha h ha-1 MJ-1 mm-1); LS is the slope steepness and length factor …show more content…
Although agricultural land use had 44.56% within the basin, it produces 88.44% of total soil losses. 56.00% of these are under 11.2 t ha-1y-1, which was accepted as a maximum value for soil loss tolerance by many researchers such as Smith and Stamey (1964), Stamey et al. (1964), Wishmeier and Smith (1978), McCormack et al. (1981), Mannering (1981), Skidmore (1982), Schertz (1983), Pierce et al. (1984), Jones et al. (1985), Johnson (1987), Pretorius and Cooks (1989) for sustainability and soil productivity. If we accept this value of sustainability, about 8.32% of agricultural areas, which produce 44.00% of the total soil loss. That means, these areas should be protected via cultural applications such as contour farming, strip cropping; physical structures such as terracing; or land use changing and converting the natural land use.
Brush land use, 2.38% of total basin area, had 9.00% of total soil losses. Soil losses within this land use are changing 0 and 13.20 t ha-1y-1. These areas generally on steep slope (Figure 4 and 8). Soil depths of the brush land generally are not deep profile, which is about 20-50 cm. Soil loss tolerance of these depths is 4.5 and 2.3 t ha-1y-1 for renewable and nonrenewable soils,
For this study a model-based approach was used to assess soil erosion risk. The well-known Universal Soil Loss Equation (USLE) (Wischmeier and Smith, 1978) was used because it is one of the least data demanding erosion models that have been developed and it has been applied widely at different scales. The model is designed to estimate long-term annual erosion rates of agricultural fields. The USLE model as described in Equation 1 was used to predict erosion of each 100 m2 cells in this study.
A=RxKxLSxCxP [1]
Where A, Annual soil loss (in ton ha-1year-1); R is the rainfall erosivity factor (MJ mm ha-1 h-1); K is the soil erodibility factor (t ha h ha-1 MJ-1 mm-1); LS is the slope steepness and length factor …show more content…
Although agricultural land use had 44.56% within the basin, it produces 88.44% of total soil losses. 56.00% of these are under 11.2 t ha-1y-1, which was accepted as a maximum value for soil loss tolerance by many researchers such as Smith and Stamey (1964), Stamey et al. (1964), Wishmeier and Smith (1978), McCormack et al. (1981), Mannering (1981), Skidmore (1982), Schertz (1983), Pierce et al. (1984), Jones et al. (1985), Johnson (1987), Pretorius and Cooks (1989) for sustainability and soil productivity. If we accept this value of sustainability, about 8.32% of agricultural areas, which produce 44.00% of the total soil loss. That means, these areas should be protected via cultural applications such as contour farming, strip cropping; physical structures such as terracing; or land use changing and converting the natural land use.
Brush land use, 2.38% of total basin area, had 9.00% of total soil losses. Soil losses within this land use are changing 0 and 13.20 t ha-1y-1. These areas generally on steep slope (Figure 4 and 8). Soil depths of the brush land generally are not deep profile, which is about 20-50 cm. Soil loss tolerance of these depths is 4.5 and 2.3 t ha-1y-1 for renewable and nonrenewable soils,