Evaporation and potential evapotranspiration in India under conditions of recent and future climate change

Long-term changes in evaporation and potential evapotranspiration can have profound implications for hydrologic processes as well as for agricultural crop performance. This paper analyses evaporation time series data for different stations in India, and for the country as a whole, for different seasons on both a short-term (15 years) and long-term (32 years) basis for pan evaporation and on a short-term basis alone for potential evapotranspiration. The analysis shows that both pan evaporation and potential evapotranspiration have decreased during recent years in India. The likely causative meteorological parameters for such changes are identified. Future scenarios of potential evapotranspiration, and its component energy and aerodynamic terms, for India based on results from six global climate model climate change experiments are also calculated and intercompared. Future warming seems likely to lead in general to increased potential evapotranspiration over India, although this increase will be unequal between regions and seasons. Such changes could have marked implications for economic and environmental welfare in the country, especially if the increases in evaporation are not compensated by adequate increases in rainfall. (C) 1997 Elsevier Science B.V.