Rainfall trend, variability and changes over the state of Punjab, India 1981–2020: A geospatial approach

Abstract

India is in the tropical monsoon zone receives most of the rainfall during the South West Monsoon (SWM) season, which lasts from June to September (JJAS). The SWM rainfall exhibits high spatial and temporal variability over the Indian subcontinent. There have been significant changes in SWM mean rainfall pattern and variability as a result of climate change. Moreover, the climate change has impacted the intensity and frequency of extreme rainfall events. In this study we used the Climate Hazards Group InfraRed Precipitation with Station data (CHIRPS) is more than 30 years quasi-global rainfall dataset from 1981 to 2020 for carrying out annual and SWM rainfall spatial and temporal variability over a total of 78 sub-districts (Tehsils) from 22 districts of Punjab state with a spatial resolution of 0.05°.This study analyzed Tehsils' level rainfall using statistical non-parametric tests – the modified Mann-Kendall (MMK) test and Sen's slope which revealed an increasing trend in annual and southwest monsoon rainfall over all the tehsils except Dhar Kalan Tehsil in the Pathankot district where as the decreasing trend in post-monsoon seasonal rain. The statistically significant increasing trend is observed over annual and monsoon rainfall over Punjab from the World Meteorological Organisation (WMO) standard period of 1981–2010 to 1991–2020. The annual precipitation has increased by 5.67%, i.e., 32.18 mm, and monsoon rainfall has increased by 6.39%, i.e., 27.45 mm over the state of Punjab from WMO standard period of 1981–2010 to 1991–2020.