Effect of Landform's Type on The Results of Geopedology Approach in Soil Mapping of The Damavand Region

Geopedology which is a systematic approach to analyze the influence of the geomorphic levels on soil mapping، makes it possible to generalize the soil survey results in one geomorphic unit to the other similar units of a studied area that resulted in reducing the time and costs of soil survey. The main question، in this regard، is to what extent the soil data generalization can be valid? To answer this question the effect of landform''s kind on the reliability of the geopedology approach was studied in an area of about 1500 ha on the east of Damavand. For this purpose، the geomorphic units were determined by interpreting the 1:55000 scale air-photos of the study area. In the next step، two similar delineations were selected in the piedmont landscape and two similar ones were selected in the hill-land landscape as well. Then، according to semi-detail soil surveys، some pedons were studiedin each of similar delineations. Through the description and sampling of all of pedons and through physical and chemical analyses on all of the pedons’ master horizons، the pedons were classified up to the family level according to Soil Taxonomy system. The results indicated a significant effect of landform''s kind on the results of geopedology approach. Although the kind of map unit for similar landforms was the same; the similarity was lower among the pedons in the hill-land landscape than the piedmont in all levels of Soil Taxonomy system. It was probably due to the more slope variations in the hill-land (compared to piedmont areas)، and as a result، a greater spatial variation of the nature of exist soils on this landscape.