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Snow melt runoff simulation and seasonal snow melt volume forecast using Remote Sensing and Geographic Information System
A.Jeyaram, Y.V.N. Krishna Murthy, D.S. Pandit, S.Adiga*
Regional Remote Sensing Service Centre, ISRO
Department of Space, Amravati road, Nagpur - 440 010
* RRSSC-NNRMS, ISRO Headquarters, Bangalore
Abstract
The Martinec - Rango snowmelt runoff model has been successfully used in the United States, Japan, Poland and French Alps. In addition to snow cover data, the model requires hydro-meteorological parameters in the higher altitudes of watershed. But these parameters are not available in the higher altitudes of Himalayan catchments. Precipitation and temperature data are generally measured in the lower altitudes of the Himalayan catchments. In view of the above fact, the model has been modified wherever necessary, to suite the Himalayan watershed conditions. Beas catchment above Manali, Himachal pradesh has been taken for the present investigation. A package, SRM-GIS has been developed using C - language and AML programming in GIS environments for daily snowmelt simulation and seasonal snowmelt volume estimation. SRM-GIS is semi-automated package and performs snow cover estimation using satellite data, calculation of coefficients, degree - day factor, recession coefficients, snow/rain separation, orographic increase in precipitation, model calibration, regression models, goodness of fit and plotting of hydrographs, mass curves etc. The model has been successfully applied in Beas watershed above Manali for six years period. The capability of the model has been demonstrated through the package SRM-GIS to provide reasonable simulation of snowmelt hydrograph and runoff volume estimation.
Introduction
A vast amount of snow is deposited on the Himalayan slopes during the winter months forming biggest water resources in the northern parts of India which continuously melt and feed the north Indian rivers thus making them perennial. The estimation of snowmelt runoff and resulting stream flow from Himalayan catchments is of considerable use in planning and operation of river valley projects. Different models have been developed in various parts of the world and the temperature index model is among the notable ones developed by Martinec & Rango (1979) and is used by various organizations in many parts of the world. The snowmelt process is influenced by a number of factors and taking all the factors into consideration is practically impossible. In temperature index degree - day approach, maximum atmospheric temperature is taken as an index which is the representative of all the melting factors. The degree day for melt computation is normally the positive departure of the maximum temperature above base temperature of 0 0C. Thus, this is a empirical measure of the amount of energy available to melt snow based on atmospheric temperature alone. The data in most of the Himalayan catchments are available only in the lower altitudes thus making them unrepresentative in the higher altitudes. The suitable adjustments are made to suite the Himalayan catchments and snowmelt runoff volume has been calculated with reasonable accuracy.
Experimental Watershed
Beas watershed above Manali covers an area of about 344.09 sq. km and lies in Himachal pradesh of North India.. The altitude ranges from 1900 m to 5932 m above msl (HANUMAN TIBBA) which is representative of a typical high rise Himalayan basin and there for has been considered suitable for developing and testing methodologies appropriate to the Himalayas. The watershed experience heavy snowfall covering 80-90 percent of the area during winter and with minimum temperature if the order of -12 C at base station Manali and about 90 percent of the are is snow free during summer. The hydrometeorological data on routine observation are being carried out by Bakra-Beas Management Board (BBMB), Mountaineering Institute and snow and Avalanche Study Establishment (SASE) for their own purpose. The catchment is divided into 20 elevation zones each of 200m attitude. The study indicates thick vegetation in the lower altitudes of the watershed and bushes in higher altitude.
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