Delineating desert domains using geomorphoclimatological factors

KHOSROSHAHI, Mohammad
Research Institute of Forests and Rangelands.P.O Box 13185-116 Tehran, IranEmail: khosro@rifr-ac.ir

ABSTRACT
Desert and desertification is one of the climate change and human activities causes. however;desert areas are increasing yearly duo to these two factors, but currently the extent of desert areas has not been recognition based on a proper and scientific criteria. Usually some natural factors (like climatology, geomorphology, geology, hydrology, vegetation cover and soil) are effective in determination of domain desert areas. In this paper we conducted to identify desert regions from nonedesert based on some suitable climatology and geomorphologic parameters in Tehran province
First, informational layers of each criterion were determined. For example, related to climatology factor, annual precipitation, coefficient of variation, irregularity factor of precipitation, daily mean intensity, range of absolute monthly and yearly temperature, evaporation were considered. For geomorphology indicators such as; pediment, salt lake, sand dunes, nebkha, reg, badland, yardang and….were determined. These indices for all factors were assessed as description of research methodology. Supply of numeral maps in GIS for each factor showed, there are different area from 9.3, and 16.1% for climatology and geomorphology factors respectively in Tehran province. Overlaying factors showed that; there are different areas of desert from each factor. Meant the region that one of factors introduces it as desert, The other didn’t know it as desert. Thus for Delineating and separating of desert and non-desert areas we can't use only one factor. We must use all of factors for separating desert area. The regions have more desert factor have more bio- environment difficulty.
Key word: desert, climatology, geomorphology, GIS, Tehran province.