Meteorological Drought Trends and Patterns in the Gundar River Basin Using the Standardized Precipitation Index (SPI)

Abstract

This study investigates the spatio-temporal patterns of meteorological drought in the Gundar River Basin, Tamil Nadu, using the Standardized Precipitation Index (SPI) at a 3-month scale (SPI‑3). Monthly rainfall data from 1988 to 2023 were obtained from the CHIRPS dataset and analyzed across 20 monitoring stations. The SPI‑3 was computed to identify seasonal drought events, and key drought metrics—onset, offset, duration, magnitude, intensity, and frequency—were derived. Results reveal frequent moderate droughts with significant spatial variability. Sub-basins such as Vembar and Therkkar experienced more prolonged and severe events, while others showed fewer occurrences. Although droughts were recurrent, their intensity remained within the moderate range across the basin. The study highlights the effectiveness of SPI‑3 and geospatial tools for localized drought assessment and emphasizes the need for adaptive water resource management in semi-arid regions.