26. Analysis of Long-Term Rainfall Trends in Rajasthan, India

The climatic variability for an area is referred to the long-term change in precipitation, temperature, humidity, evaporation, wind speed and other meteorological parameters. In order to identify the change, quantification of environmental change is essential that has occurred already and will be further helpful to make forecast for future. This will result into a better awareness for natural disasters. The objective of the study is to examine the rainfall variability in east as well as in west Rajasthan state in India. This will give an understanding about rainfall trends or changes. In this study, trend analysis has been carried out on monthly, seasonal and annual scale for the 33 districts of the arid as well as semiarid east and west Rajasthan state, India. Mann–Kendall test and Sen’s slope estimator (statistical trend analysis techniques) used to detect trends at the 5% significance level on time series data of the east and west Rajasthan state for the time period, 1871–2016. This test was applied to identify the change in magnitude and direction of existing trend over the time. Trend detection of rainfall using techniques over 146 years shows increasing trend in premonsoon, southwest monsoon and annual precipitation in west Rajasthan while in east Rajasthan, it shows increasing trend in premonsoon, postmonsoon and annual precipitation. For proper water resource management and its planning, the analysis of climatic variables like heavy rainfall, temperature and humidity is helpful in adverse climatic conditions.