Improvement of Applicability of Snow Hydrological Model by Introducing Snow Correction Factor in the Gilgit Basin

Sohail B. Cheema, M. Afzaal, T Koike, M Rasmy


In order to estimate spatial and temporal distribution of snow cover and associated discharge in Gilgit basin, a physical based snow hydrological model (WEB-DHM-S) version 0.9.7 was developed for study area. The influence of several forcing data against snow thawing and freezing process investigated and correction method was developed for these data sets. The simulated results were assessed by introducing renowned efficiency tests such as Nash Sutcliffe Efficiency (NSE), Relative Volume Error (RVE) and Root Mean Square Error (RMSE). A grid to grid comparison was also made using Kuipers Skill Score and False Alarm Rate (FAR) by two contingency table. The deficiency of Japan Reanalysis-55 (JRA) gridded temperature data was overcome by introducing observed data with adjustment of temperature lapse rate for each model grid. Most of the rainfall gauges were located at lower latitude of the basin except Yasin station. Precipitation was corrected with respect to elevation by considering the fact that high elevation experiences more precipitation and snowfall. Even though precipitation correction provided better results, but simulated snowmelt process was still delayed. This issue was solved by changing fresh snow albedo from 0.90 to 0.80, resulting good correlation with observed data and justify by statistical analysis. antalya escort bayan The model was developed only for snow dynamics but glacier contribution is necessary for accurate discharge.

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