Theme-IV-6-Estimation of run-off components from a high altitude rivers, Indian Himalayas using stable isotope tracers.

Abstract

Punjab state is drained by five rivers namely Beas, Sutluj, Ravi, Chenab and Jhelum of the Himalayan origin. Discharge of these rivers vary seasonally due to varying contributing discharge components viz., glacial melt, direct rainfall, run-off, base flow etc. Identification of individual contributing components and their magnitude is important in river water management (as these are the major sources for irrigation and power generation). Isotope composition of river water varies seasonally depending upon magnitude of the contributing sources in the total discharge; therefore, isotopic investigations are effective in modelling the seasonal discharge. In the present study, this has been demonstrated successfully using the case study investigated on river "Parbati", a tributary of "Beas river", Himachal Pradesh (HP) of India. About 150 samples were collected from head waters of Parbati river during the period 2002-2005 to study seasonal variations of isotopic composition and to estimate run-off components. By using lean period data, a constant runoff component of sub glacial spring water from bed rock of the glaciers in the region is estimated to be 35 m3 /sec. The runoff components during summer months are estimated and show a increasing trend from March to May from snow / surface ice melting to Parbati river. The contribution from local spring water dominates during lean period compared to the year. Similar investigations can be extended to rivers of Punjab to decipher the runoff components.