Historical Trend Analysis of Climate Variables using Mann-Kendal Trend Test to Assess the Local Climate Change over Bhima Basin

Abstract

Climate change is taking a toll on India’s agricultural productivity and farmers’ incomes as said by Economic Survey 2018. Climate plays an important role in the lives and livelihoods of the people and has greater impact on socioeconomic development as a whole. Annual temperatures are expected to rise by 1-2 per cent over three decades. The report admits that, climate change could cost India 2.8 per cent of GDP, and lower living standards of nearly half of its population by 2050. The aim of the present study is to analyse historical trend analysis of rainfall and temperature (maximum and minimum) and detecting potential trends for assessing their significance over the four meteorological sub-divisions in particular and Bhima basin a whole. The assessment of changes in aforementioned climate variables during the historical period provides a valuable evidence to the future in assessing the impacts of climate change. Historical trend analysis is an important exercise which gives an idea of historical changes over a period of time in the basin. The trend in climate variables is examined using Mann-Kendal (M-K) trend test. 149 numbers of IMD grids (0.250x0.250, spatial resolution) have been considered in this study to show the changes in historical trend as well as future projection of all the climate variables. Based on the trends in the historical data of rainfall (1901-2016) it is observed that approximately 0.024% decrease of the annual value of rainfall. Likewise, temperature (maximum and minimum) (1969- 2005) shows a very steep increasing trend about 0.04% and 0.09% respectively. The rainfall in the downstream stream shows considerable declination thus, these area are more vulnerable to occurrence of drought. The upper stream (Western Ghats) region of the basin depict an alarming signs of increasing trends of temperature (positive trend) is an evidences for the global warming.