MODELLING OF SNOW MELT RUNOFF

Abstract

The present study involves development and calibration of a snow melt runoff model. The melt water is estimated by the temperature index method employing time variant melt rate, assuming linear increment of degree day factor with cumulative degree days. The snow covered area is assumed to deplete linearly with accumulated snow melt. The time lag between the generation of water on the catchment (i.e., snow melt and liquid precipitation) and its subsequent availability as stream flow is accounted for by conceptualizing the catchment as two sets of linear.: reservoirs. Thus, •the snow covered and the bare areas with in the catchment are assumed to comprise respectively of n and. nb linear reservoir with respective storage coefficients ks and kb. The precipitation .'-is-`assumed to be in liquid form if the mean daily temperature exceeds a Critical temperature. The excess water produced from snow covered area is computed by multiplying the melt water and liquid precipitation volumes by c, the runoff coefficient of snow covered area. Similarly, the excess water produced from bare area due to liquid precipitation volume is computed by multiplying it with cb the runoff coefficient of bare area. The runoff produced from snow covered area is routed through n reservoirs with storage coefficient ks. Similarly the runoff produced from bare area is routed separately through 'nb reservoirs with storage coefficient kb. The routed runoffs are added to estimate the runoff at the outlet point.