Spatio-temporal Changes in Rainfall and Temperature of the Bhima River basin (India)

Abstract. The historical spatio-temporal annual variation in rainfall and temperatures of the Bhima river basin was analysed using gridded temperature (minimum, maximum and mean) and rainfall data of 1ºx1º resolution. The presence of significance auto-correlation was tested by Student‘s t-test at 10% significance level. The non-parametric tests; Mann-Kendall/Modified Mann-Kendall tests were applied to non-autocorrelated/autocorrelated series for detection of presence of trend in the series. Theil and Sen‘s slope estimator was used for estimation of magnitude of trend slope. Annual minimum and maximum temperatures showed an increasing trend in the basin. The rainfall data was analysed in two time periods i.e. 1901-2004 and 1961-2004 in order to assess the effects of increased anthropogenic activities in the latter period. The analysis of the data on annual scale shows that the rainfall increased over the last century (15% increases), however there is a decrease in the annual rainfall during 1961-2004 (11% decreases). This disparity is indicative of the effects of anthropogenic climate change. There is considerable spatial variation in the rainfall data over the basin. While the central parts of the basin showed an increase in rainfall (1901-2004) the upper and lower parts showed decreasing trends of rainfall (1961-2004). The changes in the pattern of trends in rainfall is prominent in the two timescales, which gives credibility to the fact that the changing climate is affecting basin scale climatic processes and patterns with the accelerated warming of basin in recent duration.