Extreme rainfall and temperature events in Odisha: Trends and vulnerabilities

Abstract

This study examines extreme rainfall and temperature events in Odisha, India, using 32 years of rainfall data (1991–2022) from the Special Relief Commissioner, Government of Odisha, and 23 years of temperature data (2000–2022) from the India Meteorological Department (IMD). The analysis calculates the number of heavy (64.5 to 115.5 mm), very heavy (115.6 to 204.4 mm), and extremely heavy (204.4 mm) rainfall events for annual, monsoon, and non-monsoon periods. It also identifies the occurrence of temperature extremes, such as 40 C, 45 C, and 10 C, for 24 IMD measurement stations. The Mann-Kendall test was applied to detect trends in rainfall and temperature extremes. To assess vulnerability, extreme rainfall and temperature values were normalized. The state as a whole received a total number of 4146 extreme rainfall ( 115.6 mm) events, with Kalahandi district experiencing the most (257) and Deogarh the lowest (42) during the period. The 2nd decade (2001 to 2010) realised the maximum number of extreme rainfall events (1458) followed by 1267 number of events in 1st decade and 1239 in the 3rd decade. Trend analysis indicated a significant increase in the frequency of heavy rainfall events in two districts such as Koraput and Malkangiri; and extremely heavy rainfall events only in Nawarangapur. However, a decreasing trend was noticed for heavy rainfall events in Balasore and Jajpur; very heavy rainfall in Angul, Dhenkanal, Jajpur and Kendrapada; and extremely heavy rainfall in Puri. The one-day Probable Maximum Precipitation (PMP) value was the highest (905 mm) for Kalahandi district and the lowest (318 mm) for Dhenkanal. The Vulnerability analysis of extreme rainfall events (115.6 mm) revealed the districts namely Kalahandi and Puri to be highly vulnerable. The Vulnerability Index analysis, based on contribution of the top seven extreme rainfall events to annual normal rainfall, found that Boudh, Cuttack, Jajpur, Jharsuguda, and Khordha were highly vulnerable, while the remaining 25 districts were moderately vulnerable. Bolangir recorded the highest number of extreme temperature events for both the 40 C and 5 C thresholds, followed by Sambalpur and Hirakud stations.