Geostatistical Approach In Determining Slope Length Factor In Soil Erosion Modeling For Managing Natural Hazards

Soil erosion has been one of the environmental problems that have a very significant impact in human life. This model requires a number of parameters such as rainfall erosivity (R), soil erodability (K), slope length and steepness (LS), crop cover (C) and prevention practice (P). With a GIS, such modeling can be accomplished and commonly done using raster technique whereby all the parameters are mapped in the form of grid layers of a specific cell size. The issue is that the appropriate cell size is always ignored or wrongly chosen without a thorough statistical analysis made prior to the analysis for managing natural hazards. This is the focus of this research whereby four cell sizes are selected, i.e. 33m, 13m, 533m and 333m and applied to data of Kuala Yong as a sample test. LS factor has been selected for this comparison where semivariogram models are fitted to the height information (original 03-m contour topographic map) and the best parameters such as nugget, partial sill and sill are derived. Overall results show that with increasing cell size up to 13m, the nugget effect decreases and spatial dependency increases. According to best spatial dependency and high variances and diversity of 13 m cell spacing, the Digital Elevation Model (DEM) of this cell size is found the most appropriate for such dataset. In general, results of this study confirm that geostatistical analysis could and should be applied to select suitable cell spacing in DEM to predict topographical factor in soil erosion modeling.

کلیدواژه ها:

Natural Hazards ، Environmental Problems ، Soil Erosion Modeling ، Slope Length ، GIS