Detection of Climate Change Signals in the Historical Climate Datasets for Chambal basin in Madhya Pradesh

Abstract

Water resources management in the arid and semi-arid areas is a quite a challenging task owing to the large number of hydrologic, environmental and management factors. The climate change has opened up a new spectrum of challenges viz., higher occurrences of extreme events like droughts, floods and heat waves alongwith increased variability of rainfall and uncertain water availability scenario in the future. Investigations have been carried out to detect the climate change signals in the historical climate datasets for the Chambal basin in Madhya Pradesh. The average annual rainfall has decreased from 1038.5 mm during 1931-60 to 951.40 mm during 1961-90 and 925.10 mm during 2001-2015. The average annual rainfall varies spatially, with decreasing rainfall from east to west (districts bordering Rajasthan) viz., 800-900 mm in the districts of Neemuch, Mandsaur, Ratlam and parts of Ujjain and Dhar districts, 900 – 1000 mm in the districts of Agar, Indore, major parts of Ujjain and parts of Dhar, Dewas, Shajapur and Rajgarh districts, 1000 – 1100 mm) at Guna, parts of Rajgarh, Shajapur, Dewas, Vidisha and Sehore districts and > 1100 mm in the eastern parts falling partly in the districts of Bhopal, Rajgarh, Shajapur and Sehore. The comparison of the number of rainy days between the baseline period (1961-90) and present period (1991-2015) indicates considerable decrease in the number of rainy days in 47 out of the 53 blocks in the study area. The extreme rainfall (P>200 mm/day) and very heavy rainfall (P>100 mm/day) has also increased in most parts of the study area whereas a mixed trend has been observed for heavy rainfall (P>50 mm/day). The 1-day maximum temperature (1-day MaxT) has shown a significant rising trend at 5% significance level. The very hot days (MaxT>40oC) and hot days (MaxT>35oC) have also increased significantly. The trends detected in these indices suggest towards an increased scenario of water stress in the basin at present as compared to the baseline period and investigations are necessary to understand the impact of climate change on the future drought, desertification and water stress under the challenge of climate change related impacts.