Monitoring of extreme rainfall events and drought severity using drought indices in the southeast semi-arid areas of Karnataka state, India

Abstract

Over the past few decades, precipitation changed in duration and intensity due to climate change. The Karnataka economy and water resources are severely impacted regularly by droughts and floods. Drought indices are used to evaluate the drought conditions in the state of Karnataka. This study examines the Modified China Z-Index (MCZI), Decile Index (DI), Rainfall Departure (RD), and Percent of Normal Index (PN) to determine which measure is most appropriate for Karnataka the state's regions that experience both dry and wet climate. The total mean rainfall in the study area from 1951 to 2019 was 672.83 mm, with an average deviation of 208.10 mm. The stations in the Kolar district grid stations receive more rainfall than the Chikkaballapura district grid station. The PN along with the DI drought indices correlation in the station Bangarapete shows the highest positive correlation a value roughly R² = 0.6876. During contrasted to other indices, the RD (Rainfall Deviation) index is the easiest to compute and has the best statistics for determining dry and wet years. 1959 (-70.8 %) and 1995 (-68.4 %) were two drought years that this index could easily identify. In 1965, Bangarapete indicated an extreme drought with a 65.2 % rainfall deviation rate. Two particularly dry years have been detected in Gudibande 1981 (-72.5 %) and 1983 (-87.0 %). The study's findings will assist the state in better organizing and enhancing its approaches to managing water resources, agriculture, floods, and drought.