TN-77 : Hydrological response of greenhouse effect with emphasis on evaporation and evapotranspiration

Abstract

The scientific community has expressed a great concern in the recent past over the increasing temperature of the earth's surface due to rapidly rising concentrations of various greenhouse gases viz. , carbon dioxide, methane, nitrous oxide, chlorofluorocarbons etc. The greenhouse gases, produced by human activities allow the solar energy to pass through while absorb and re-radiate 'to the earth much of earth's long wave radiation, thus contributing to the ' Greenhouse effect'.

The global warming due to enhanced greenhouse effect is expected to cause major changes in various climate variables 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. Evapotranspiration ,a major component of water cycle would also be affected but in a more complicated manner than generally expected.

The present report gives a review of the recent trends of increase in greenhouse gases, impact of increase in greenhouse gases on meteorological and hydrological parameters and also discusses the status of these aspects for India. The methodologies used by hydrologists to study the hydrological response of enhanced greenhouse effect has also been reviewed. Special emphasis has been given on effect of climatic change on evaporation and evapotranspiration.