TR(BR)-118 : A runoff model for snow dominated catchment in greater Himalayas

Abstract

The catchments located in upper Himalayas have a significant part under permanent snow cover and Glaciers. Modelling runoff becomes difficult with almost no data from these parts. Even in the temporary snow covered zones, the network is generally inadequate. However precipitation characteristics show repetitive patterns and snowline movement elevation wise (as observed from satellite imageries) by and large occurs in the same manner each year, The location of the permanent snowline is also more or less constant. at 4500 M.

A simple runoff model is proposed on a monthly basis to take advantage of above mentioned characteristics, using the degree day approach. The model uses monthly rain, snow (SWE), mean temperature and snowline elevation as primary inputs. Model conceptualisation has been made especially, keeping data constraints in mind.

The model results are encouraging. Runoff simulation also provides a better understanding of snowmelt processes. Further scope for model generalisation and application exists, to several other catchments in Western Himalayas.