Study of trend of desertification trend in Qom province base on remote sensing with emphasis on Landuse changes and water quality and quantity resources

The major part of Qom province areas have involved arid and desert conditions. Immethodical expansion of human acts with no attention to environmental affairs, caused intensifying desertification phenomena. In this paper, trend of desertification was studied with emphasis on land use changes and as well as water quality and quantity resources. For assessment land use changes, satellite data (TM, 1985 and ETM+, 2002) and for evaluation of water quality and quantity resources changes, the hydrometric and climatic data were used. Comparison between land use maps of TM and ETM+, by using visual interpretation method, showed that areas of agriculture lands, rangelands, forest lands, sand dunes and salt lakes, have been decreased in 6.5, 4.14, 70.4, 24.2 and 15.8 percent respectively, whereas, another classes such as saline lands, urban and rural lands have been increased 26.6, 12.78 and 35.6 percent respectively. The output water of 2 main rivers of Qom province (Qomroud and Qarehchay) before establishment of Panzdah-e- Khordad and Saveh dams were 261 million m3, whereas it decreased to 66 million m3 after obstacle foundation. Before construction of Panzdah-e- Khordad dams, The fall of underground water level was 0.5 meter per year in Qom plain, which increased in averages to 1.4 meter per year after establishment of the dam. In addition, balance sheet of underground water, reduced remarkable. Totally, it seems that the human activities and retouching environment by him (especially construction of 2 dams on Qom rivers) are two main factors which have changed (with decreasing plant covering, salinization of major areas et cetera) and reduction of quality and quantity of water resources which could lead to aggravation of desertification in Qom province.