Rainfall Variability and Drought Characteristics in the Mysuru Region of Karnataka: Implications for Agriculture

Abstract

The study aimed to analyze long-term rainfall variability, drought characteristics, and rainfall trends in the Mysuru region of Karnataka and to understand their implications for agricultural sustainability in a semi-arid environment.A long-term observational and statistical study design was adopted using historical rainfall data and standard drought and trend analysis techniques.The study was conducted for the Mysuru region of Karnataka, India, using 58 years (1968–2025) of observed rainfall data collected from the Weather Observatory of the Agrometeorological Field Unit (AMFU), Organic Farming Research Station (OFRS), Naganahalli, Mysuru. Annual rainfall data were analyzed using descriptive statistics to assess interannual variability. Rainfall anomalies were evaluated using the Rainfall Anomaly Index (RAI), and drought severity was assessed using the Standardized Precipitation Index (SPI-12). Long-term rainfall trends were examined using non-parametric Mann–Kendall test and Sen’s slope estimator. The long-term mean annual rainfall of the region was approximately 730 mm, with annual rainfall ranging from about 244 mm to 1381 mm, indicating high interannual variability. About 30–35% of the years were classified as deficit rainfall years, confirming the drought-prone nature of the region. RAI analysis showed frequent negative anomalies. SPI-12 analysis indicated repeated moderate to severe drought events, with SPI values falling below −1.0 in several years and below −1.5 during severe drought periods. Trend analysis revealed no statistically significant long-term trend, with Sen’s slope indicating a marginal change close to zero.The study concludes that agricultural risk in the Mysuru region is primarily driven by rainfall variability and drought recurrence rather than changes in mean rainfall. Strengthening climate-resilient agricultural practices, drought preparedness, soil and water conservation, and weather-based agro-advisory services is essential for sustainable agriculture in the region.