Rainfall Variability Trend in Porbandar, Gujarat

Abstract

Rainfall is a principal element of the hydrological cycle and its variability is important from both scientific as well as socioeconomic points of view. This study presents an analysis based on the rainfall variation over 31 years from 1991 to 2021 in Porbandar, Gujarat located in the western region of India. The data were analyzed using fundaments statistical parameters and trends in rainfall were investigated using Mann-Kendall Test and Sen’s method. In Porbandar, the average monsoon rainfall from 1991-2020 for the monsoon months of May to October is about 539.11 mm. Mann-Kendall value Z and Sen’s estimator β show the non-significant but decadal-increasing trend in rainfall. The negative value of Z statistic and Sen’s estimator β for the month of August, September, and October shows a non-significant downward trend while the positive for July month shows a non-significant upward trend. Overall there is a steadily increasing trend of rainfall in Porbandar. These observed changes in rainfall, although most time series are not convincing as they show predominantly no significance, along with the well-reported climatic warming in monsoon and post-monsoon seasons may have implications for human health and water resources management over bio-diversity-rich Porbandar district.