soil and water assessment tool model, swat, uses different layers of watershed data which out of soil layer is the important one. soil layer data should be extracted from detailed soil maps. in most developing countries including iran, these detailed maps are not available except for irrigation districts and rarely for dry land farming areas and also for some strategic places of development pur...

In many places in the world, soil information is difficult to obtain and can be non-existent. When no detailed map or soil observation is available in a region of interest, we have to extrapolate from other parts of the world. This chapter will discuss the Homosoil method, which assumes homology of soil-forming factors between a reference area and the region of interest. This includes: climate,...

desertification in arid, semi-arid and dry sub-humid regions is a global environmental problem. considering theincreasing importance of desertification and its complexity, the necessity of giving attention to desertification criteria andindices is essential. models and methods such as medalus, unep-fao, and others have been proposed on local andnational scales. in this research, imdpa was selec...

Desertification in arid, semi-arid and dry sub-humid regions is a global environmental problem. Considering theincreasing importance of desertification and its complexity, the necessity of giving attention to desertification criteria andindices is essential. Models and methods such as MEDALUS, UNEP-FAO, and others have been proposed on local andnational scales. In this research, IMDPA was selec...

Soil type maps at the scale of 1..1 000 000 are used extensively to provide soil spatial distribution information for soil erosion assessment and watershed management models in China. However, the soil property maps produced through conventional direct linking method usually suffer low accuracy as well as the lack of spatial details within a soil type polygon. This paper presents an effective m...

  Application of gepraphic information system and image processing in evaluation of surface runoff of a watershed in recent years has increased greatly. In the study , the runoff curve number map was prepared using geographic information system (GIS)and Landsat Sattelite Images (ETM+)for two watersheds of Mansourabad in southern Khorasan province and Navroud in Gilan province based on the facto...

The IRS-1D LISS III false colour composite (FCC) decoded imagery belonging to Kosi river watershed of Almora district of Uttaranchal under warm humid Lesser Himalayan agro-ecological region was interpreted and surveyed for soil resource mapping. On the basis of image interpretation and ground truth study ten physiographic units were identified. Soil physiography relationship was established on ...