Detection of abrupt change in trends of rainfall and rainy day’s pattern of Uttarakhand

Abstract

Due to climate change, variations in rainfall and rainy days have signifcant efects on the hydrological cycle and these changes are important for planning and management of food, drought, and water resources. The study aimed to determine spatio-temporal change in annual rainfall and rainy days for thirteen districts of Uttarakhand, India, located at the foothill of the Himalayan region. The temporal trend in data was determined using the Mann–Kendall (MK) test and the modifed Mann–Kendall (MMK) test at a 10% level of signifcance after investigating autocorrelation in the data set using the student’s t-test at a 10% level of signifcance. Theil’s-Sen slope estimator test was used to evaluate the slope of rainfall and percentage change in rainfall over Uttarakhand. Furthermore, the sequential Mann-Kendal test (SMK) has been applied to determine the abrupt change in rainfall and rainy-day time-series. Results of the study show that six districts have an increasing trend from which two districts show a signifcant increasing trend and seven districts show a decreasing trend from which one district has a signifcantly decreasing trend at a 10% level of signifcance. In the case of rainy days, four districts have an increasing trend from which two districts show a signifcant increasing trend and nine districts show a decreasing trend from which no district show a signifcant decrease at a 10% level of signifcance. Based on the SMK test, Uttarkashi District shows a maximum of six change point years, whereas Rudraprayag District has no change point year in annual rainfall. For rainy days, Uttarkashi and U. S. Nagar Districts have a maximum of seven change point years, whereas Bageshwar, Haridwar, and Rudraprayag Districts have no change point years. Spatial distribution in annual rainfall and rainy days interpolated by inverse distance weighted (IDW) method in QGIS 3.14. The spatial map might be very helpful for local farmers, water managers, and stockholders to assailability and risk of climate change in their region. The result of the study also could be very precious for agriculture planning, water management, and soil and water conservation for Uttarakhand.