CLIMATE CHANGE INFLUENCES ON HYDROLOGICAL ELEMENTS

Abstract

Present study is an attempt to identify the influences of climate change on the two most vital hydrological elements i.e. temperature and precipitation in Indian Subcontinent. This study is carried out with the monthly average subdivisional rainfall (1871-2003) and monthly average regional temperature (1901-2003) time series available on IITM, Pune web site. Non parametric Mann Kendall trend test with autocorrelation approach has been adopted for trend analysis of precipitation and temperature time series. The time series have also been analysed for the rate of change per 100 year during the period (1901-2003) and the period (1971-2003). Findings of the study are as under: 1. Punjab and Chhatisgarh, with highest rising and declining trend in annual rainfall (1901-2003) at 1% significance respectively, are identified as two poles with respect to trend in the Indian subcontinent. A phenomenon of perfectly smooth transformation of trend in annual rainfall between these two poles through intermediate subdivisions has been investigated. 2. Recent period of 1971-2003 witnessed sharp rise in the rate of increase in minimum as well as maximum temperatures in all the temperature homogeneous regions compared to the period 1901-2003. 3. Minimum temperature of the subcontinent is found to increase at rate of 2.16 °C (100 year)"lover the period 1971-2003, which is almost 10 times the rate over the period 1901-2003. Western Himalaya followed by North East region witnessing maximum rise of 3.11 °C (100 year)"' and 2.74 °C (100 year)"' respectively in annual minimum temperature during period 1971-2003. 4. Maximum temperature of the subcontinent during 1971-2003 is found to be increasing at the rate of 2.01 °C per 100 year which is almost 3 times the rate over the period 1901-2003. Western Himalaya followed by North West region witnessing maximum rise of 5.26 °C (100 year)-' and 2.84 °C (100 year)-' respectively in annual maximum temperature during 1971-2003.