عنوان مقاله [English]
نویسندگان [English]چکیده [English]
In mountainous area of the northwest of Iran, snowfall could be regarded as an important climatic element particularly during cold seasons. Snow cover and snow depth, in turn, could influence the other hydrological components such as: stream flow charge, ground water reservoir, flood occurrence and vegetative canopy, by means of significant interconnected reflections throughout a water basin.
The current research was accordingly introduced to provide some snow cover maps using MODIS imageries in the Agi-Chay basin which is located in the east of the Orumiyyeh Lake, with two high mountains namely: Sahand and Sabalan in the catchments. First, to design the snow cover map, different image processing algorithms were progressively applied to the same time series imageries (provided for year 2005) and available ground-based data by applying an ERDAS Imagine software. Then, using ArcGIS software some required spatial analysis such as: transforming of existing analogue topographic maps to digital format, designing of a DEM model, extracting of watershed divides and generating of Thiesen polygons have been subsequently completed. At the last stage, an overlaying operation was applied to estimate the rate of snow water equivalent (nearly about sixty nine billions m3 for year 2005)in the study area referencing to the ground observation data.
Final results reveal the importance of models which have been provided by processing of MODIS images because of its spatial and temporal resolutions and the great number of bands. By examining snowmap algorithm, it was found that this function could be regarded as a precise method in the analyzing of imageries at a regional scale. Easy calculations, simplicity, high accuracy and automated operations are the most implications of a methodology which was introduced in the current investigation.