عنوان مقاله [English]
نویسندگان [English]چکیده [English]
The study and measure of snow level changes as one of the main sources of water supply, is so important. Due to the harsh physical conditions of mountainous environment, it is not possible to conduct the earth measuring continuously to estimate the snow water resources and forming the database. So, using satellite images to identify snowy areas and assess its changes has a great importance.
The data used in this study are TERRA/ MODIS sensing satellite images of Iran’s North West region related to years 2000 up to 2009. The method used in this study is NDSI index, and Supervised and Unsupervised classifications, after comparing between the methods, the Supervised classification was selected as the appropriate method. Review of the maps related to changes of snow cover in April showed that during the study period , the lowest amount of snow is related to year 2008 with an area of about 1040.01square kilometer and the highest area is for year 2007 with about 10471.78 square kilometer.
This represents a 1000 percent changes in snow cover during one decade at the north west of Iran and shows vulnerable of water resources depending on melting snow. Also the results showed that in the years which the average of cold season temperature is lower, the area covered by snow is more than the other years, so that in year 2007, it had the lowest amount of snow coverage during the last 10 years (2.6 c◦) while the highest amount of snow cover during the last ten years is related to this year.(10471.78 km2)