1. Basin or catchment area of Himalayan Rivers is extensive and spread over thousands of kilometres. The catchment area of Indus river 115 lakh sq. kms and catchment area of Ganges 9 lakh sq. kms, whereas the catchment area of peninsular rivers is comparatively lesser.2. Himalayan rivers do not cut the high Himalayas to make rivers. These rivers are older than the Himalayas itself and have been constantly flowing in all stages of formation of Himalayas. The Himalayas have been rising gradually and these rivers have kept their flow perennial by the eroding base layer.