نوع مقاله : مقاله پژوهشی
نویسندگان
گروه مهندسی آب، دانشکده فناوری کشاورزی ابوریحان، دانشگاه تهران، تهران، ایران.
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
In many regions, snow cover in mountainous areas are the main source of surface and ground water supply. Thus, it’s very important to estimate the snow melt runoff in these areas. To achieve this objective, it’s necessary to estimate the basin snow cover area and its variations for a complete water year. Considering that measuring of ground snow can’t be done daily, Satellite images give a suitable information. In this study, the snow cover area as the most important hydrological variable can be extracted using TERRA- MODIS satellite images with a spatial resolution of 500 meters on daily basis. Thus, to calculate watershed snow melt runoff, the Snowmelt Runoff Model (SRM) was used. This model produces snow melt runoff using the data pertaining to meteorological parameters, hydrology and watershed characteristics. In this study, the necessary data for model application were extracted on daily basis for the years 2002-2003 and 2003-2004. Snowmelt runoff model has been calibrated using the data during 2002-2003 year. The results show that the square of correlation coefficient (R2) between the simulated and observed daily runoff is 0.93 and the difference between the simulated and observed annual runoff volume is 4.74 percent. The SRM has been performed using the 2003-2004 data. The results show that the difference between the simulated and observed annual runoff volume is 2.15 percent and the square of correlation coefficient (R2) between the simulated and observed daily runoff is 0.84. The above values show accuracy of used images in the estimation of snow melt runoff which is the sign of ability and quality of this model and MODIS images to use for other watershed regions. Estimating runoff from snowmelt in mountains is of great importance. To achieve this goal, it is necessary to accurately and reliably estimate the snow cover of the basin and its changes throughout the year. Given that ground-based snow measurements are not performed daily in our country, satellite images provide the necessary information with good accuracy. In this study, the level of snow cover in the basin, as the most important hydrological variable, was obtained daily using TERRA_ MODIS satellite images with a spatial resolution of 500 meters. Then, the snowmelt model (SRM) was used to calculate snow runoff in the basin. This model calculates snowmelt runoff using meteorological, hydrological, and basin characteristics parameters and presents it graphically and numerically along with observed runoff. In the present study, the necessary data for running the model daily and for the water years 2001-2002 and 2003-2004 were extracted. Data from 2001-02 were used to calibrate the SRM model. The model simulated annual runoff volume with a 4.47% difference and daily flow rate with a coefficient of determination of 0.93. Data from 2002-03 were used to evaluate the model. The model estimated annual runoff volume with a 2.15% difference and daily flow rate with a coefficient of determination of 0.84. The above values indicate the high accuracy of the images used and the model in estimating snowmelt runoff for the aforementioned basin, which indicates the capability and ability of the model and MODIS images to be applied to other basins in the region.
کلیدواژهها [English]
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