As a result, the calculated river loads may differ significantly from continuous sampling, which is very time-consuming and expensive and thus hardly available. Long-term composite samples instead of grab samples are better suited here, as they capture the load in the water body more realistically. įor the estimation of soil erosion by water, the USLE (universal soil-loss equation) developed by Wischmeier and Smith and the ABAG (general soil-erosion equation) derived from it by Schwertmann et al. for central European conditions are often used. In the standard DIN 19708 (2017), the procedure for determining soil erosion according to ABAG for agriculturally used arable soils is detailed on the basis of input data that are predominantly digital and available for large areas. In contrast to more process-based erosion models, such as Erosion 3D or the temporally higher-resolution USLE-M, ABAG does not represent soil erosion due to individual events, but rather the long-term expected average areal soil erosion, due to rainfall. Soil erosion due to snowmelt, on the other hand, is not considered. It should further be noted that the ABAG approach only considers sheet, rill and interrill erosion (DIN 19708 2017). The linear erosion forms of channel or gully erosion remain unrecognized in the quantification at the catchment level and are consequently not accounted for.
The long-term mean soil erosion by water A results as follows (Equation (1)):įor the derivation in SAGA-GIS the methods “field-based”/“Moore and Nieber”/“distance-weighted average catchment area”/“contour length simply as cell size” were chosen, resulting in the highest LS values in comparison. Furthermore, barriers in the landscape are considered, which limit the respective delivery areas (unit contributing areas UCA, ). Calculations are performed field by field, which means that catchment area calculation is restricted to each field’s area.
Studies of selected experimental plots by Hrabalíková and Janeček show that this approach yields slightly lower values compared to the original one-dimensional approach by Wischmeier and Smith considering the erosion-effective slope length.
0 kommentar(er)
