DTM as a Tool for Correction of Alluvial Soils Delineation on Middle- and Small-Scale Maps.
Vit Penizek, Lubos Boruvka, and Josef Kozak. Czech Univerzity of Agriculture in Prague, Kamycka 129, Prague, Czech Republic
Alluvial soils are represented by soil groups of Fluvisols (FL) and Gleysols (GL). Fluvisols represent azonal soils that occur along bigger water courses. Another group are intrazonal Gleysols that occur mainly as narrow strips along smaller water courses or at their beginning. Delineation of these soils at detail scale do not cause serious problems. The problems arise during generalization of the maps to middle and small scales. The principal aim of maps generalization is to maintain important map objects, patterns, and relationships, while suppressing unimportant ones. In this case generalization of detail soil maps into middle and small scales causes that the extent of Fluvisols and Gleysols around small water courses is exaggerated (in our study, the proportion of FL and GL increased from 11.8% at 1:5k map, to 16.7% at 1:50k map, and to 25.7% at 1: 250k map). The exaggeration can cause different problems in exploitation of such maps in environmental modeling. This contribution presents techniques based on soil-landscape relationship modeling using Digital Terrain Model (DTM). Exploitation of terrain attributes as specific catchment area, topographic (wetness) index, relative elevation above watercourse and its combination eliminates exaggeration caused by generalization. Results show that the exploitation of used technique provides reasonable correction of delineation of alluvial soils (FL, GL) around small watercourses at middle and small scale maps. Such treatment of traditional soil maps, which are still an important source of soil information, can increase the quality of spatial soil information.