ANALYSIS OF RAINFALL TREND USING NON PARAMETRIC METHODS FOR WATERSHEDS OF BENGALURU URBAN AREA

Abstract

Rainfall plays a crucial role in the hydrological cycle, and changes in its patterns directly impact water resources. These alterations affect hydrological properties and soil characteristics. Analyzing rainfall trends is essential for understanding the impact of climate change on water availability and food security. Numerous studies have investigated rainfall trends at regional and national levels, providing valuable insights into future changes. This study examines 43 years (1980-2022) of rainfall data in Bangalore Urban using the Mann Kendall (MK) and Sen’s slope estimator tests. These methods detect variations and long-term monotonic trends in rainfall. Analysis was conducted using XLSTAT software at a 95% significance level. Across 12 rain gauge stations, average annual rainfall ranges from 479.22 mm (Krishnarajapura) to 873.15 mm (Anekal). Krishnarajapura exhibits the highest variability in annual rainfall (coefficient variation of 92.77%), while Anekal shows the lowest (coefficient of variation 29.14%). Sen’s slope estimates indicate a positive trend at all stations, suggesting an overall increase in rainfall. However, the Attibele rain gauge station shows a decreasing trend in the pre-monsoon and monsoon periods, and Anekal exhibits a decreasing trend in the monsoon period. The irregular and intensified rainfall patterns, coupled with urban sprawl in Bengaluru Urban, contribute significantly to flooding events.