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Soil-landscape modelling to quantify spatial variability of soil texture

Abstract:

Soil-landscape models were developed to pbkp_redict the spatial distribution of soil texture at the surface horizon across a catchment in southeastern Nigeria. A discretised thin-plate spline technique, in conjunction with a connected drainage-enforcement algorithm supplemented with the incorporation of ridge and stream-line data, was used to ensure proper hydrogeomorphic properties of the output Digital Elevation Model (DEM). Terrain attributes were derived from the resulting DEM. Stepwise multiple-linear regression was performed on the normalised terrain attributes and on the principal components constructed from the normalised terrain attributes to avoid multi-collinearity. The derived soil-landscape models were used to pbkp_redict clay, silt, sand, ironstone and thickness of the surface horizon from the original terrain attributes for the entire study area (R2=0.41 to 0.75). The models were further validated using statistical criteria. Only for the soil variable clay did the soil-landscape model improve after stratification according to geological formation (R2 increased from 0.47 to 0.76). Cell-based algorithms were used to map the soil-landscape models spatially. The resulting spatial patterns correctly showed a significant relationship with the terrain attributes. This relationship is useful when studying patterns of sediment movement. © 2000 Elsevier Science Ltd. All rights reserved.