SR-17 : Global climate change and its effects on regional and global hydrology

Abstract

Concentrations of several gases viz. carbon dioxide, methane, Nitrous oxide, chlorofluorocarbons in the atmosphere have significantly increased since the dawn of the industrial era. The observed built up of the gaseous pollutants has enhanced the so called greenhouse effect and hence increased the radioactive heating of the globe. The global warming is expected to have profound imp act on meteorological parameters as absolute humidity and precipitation , annual rainfall regime, and net terrestrial and global solar radiations etc. This, in turn ,would also have profound impact on various hydrological parameters ,viz runoff, evapotranspiration ,soil moisture, ground water etc.The direct assessments of impacts and realistic evaluations of the climate sensitivities of water resource systems, specially on a regional scale are a matter of concern and need considerable study.

Various methodological approaches as the coupled general circulation -hydrologic models ,analysis of long term variations in runoff and meteorological elements over the past years ,use of water balance methods over a long period of time and use of deterministic hydrological models have been used to study the hydrologic consequences of future climatic changes by different research groups in the recent years .Inspite of enormous work being done in the subject area there still exist gaps in the knowledge of expected changes in future water resources

In the present status report a review has been carried out on changes in meteorological parameters due to increasing concentrations of greenhouse gases and the hydrological impacts of global climate change .The status of studies in the subject area has been presented for the world 'with special emphasis on Indian context and the need of future studies has been emphasized.