estimating the distribution of snow melt equivalent at the peak of snow accumulation, through degree – day model

estimating snow melt water equivalent is one of the most important challenges in determining the hydrological regime in mountainous basins. there are some problematic obstacles in field observations, due to inaccessibility as well due to difficulties in snow sampling at snow covered peaks making researchers try to find indirect approaches. one of these methods in use is degree- day model that is simple and used in snow melt estimations. in this study the model is applied along with modis images for predicting snow water equivalent at times of peak snow accumulation. for this purpose, following a determination of the time of snow accumulation peak, the degree-days needed for the snow to be completely melted is computed and then, the snow water equivalent at any point calculated by reversing degree-day equation. the results show that there is 13 percent difference between the observed and estimated data. this indicates that modis data and degree-day model can acceptably estimate snow water equivalent in not easily accessible areas. therefore, the degree-day model would be helpful in hydrological monitoring programs in not easily accessible mountainous basins.