Trend analysis in gridded rainfall data using Mann –Kendall and Spearman’s rho tests in Kesinga catchment of Mahanadi river basin, India

Abstract

The article provides a long-term trend analysis of the Kesinga catchment daily gridded rainfall at a (0.25°*0.25°) high spatial resolution from the years 1901 to 2020 (120 years). The trend in seasonal and annual rainfall was therefore detected using nonparametric statistical tests spearman’s rho and Mann-Kendall, smoothing curve, Sen’s slope test, and plot of innovative rend analysis. The results showed that statistically significant trends (SSTs) had a pattern with both positive (increasing) and negative (decreasing) trends, with positive and negative trends evident in the winter and negative trends shown in the monsoon, PREMON, and annual seasons. The middle of the study area revealed the highest negative trend and the lower Kesinga catchment showed the lowest negative annual rainfall trend. The entire Kesinga catchment, the seasonal data and annual rainfall both showed statistically significant and non-significant patterns. Consistently, the MK and SR tests were both conducted at the validated significance level. In various contexts, the massive trend that has occurred with statistical significance were negative (70%). If the current pattern continues in the future, then there will be a scarcity of water and more strain on the control of water resources at the given grids in corresponding temporal scales.