Climate Trend Analysis and Implications for Water Management in the Upper Bhavani Region, Coimbatore (1995-2021)

This study tried to point out the trends of climate in the Upper Bhavani Region of Coimbatore, India, from 1995 to 2021. Mann-Kendall tests have been applied to the trends of some key climate variables. Our analysis returned significant changes for climate parameters during 26-year period. As such, rainfall trends were mixed, although only that for December revealed a significant increasing trend: Z = 2.251466, p < 0.05, Several months of the groundwater level time series showed significant increasing trends, most of which occurred in the second half of the year. The largest increases occurred in November, Z = 3.043649, p < 0.05, and in May, Z = 2.918567, p < 0.05. Wind speeds showed a decreasing trend, especially the minimum wind speeds. There were significant decreases in all months except October and December with p < 0.05, while in April, there was a maximum wind speed decrease statistically (Z = -2.043, p < 0.05). The highly increasing trends of minimum temperatures were indicated in several months, with the largest increases in November, with Z = 3.127036 and p < 0.05, and December, yielding Z = 3.001955 and p < 0.05. Maximum temperatures showed no significant trends. Results for relative humidity and soil moisture did not show any significant trend in the observed period, thus underlining the real complexity of relationships occurring within the local climatic system. The findings indicate that the Upper Bhavani Region is undergoing process of climatic change characterized by warmer nights, increased groundwater levels, and reduced wind speeds.