Evaluation of district-level rainfall characteristics over Odisha using high-resolution gridded dataset (1901–2013)

Abstract

In the present global warming era, exploring the regional/district-level changes in rainfall patterns/events is highly essential for understanding the diverse characteristics of rainfall, which will be value added for the policy planning for rainfed agricultural-based states like Odisha, a region that is also highly prone to flood and droughts. Since most of the global and continental scale climate studies rarely contribute for such planning of agro-economic states of India like Odisha, there is a colossal necessity for the analysis of rainfall characteristics at regional/district level. In the present study, the rainfall characteristics at district level over Odisha are extensively evaluated for winter (JF), pre-monsoon (MAM), monsoon (JJAS) and post-monsoon (OND) using India Meteorological Department high-resolution gridded rainfall analysis dataset for the period 1901–2013. The El Nino Southern Oscillation (ENSO) influence on the district-level seasonal rainfall during four distinctive seasons has also been studied. The results suggest that the frequency of various categorical rainfall events and associated seasonal rainfall patterns over Odisha is highly heterogeneous and varies from season to season in magnitude and similar statements can be highlighted for inter-annual variability and coefficient of variation. Although the seasonal rainfall time series is significantly persistent in most of the districts during all the seasons, it is manifested to the normal distribution in majority of districts only for JJAS. Statistical analysis infers that most of the districts possess reasonable abrupt changes in seasonal rainfall during mid- and late twentieth century. A significant increasing (decreasing) trend in the frequency of high-intensity (low-intensity and wet days) rainfall events over most parts of Odisha is observed for all the seasons. A notable decreasing trend in seasonal rainfall is perceived over southern districts during MAM (7–21 mm) and OND (23–49 mm), western districts during MAM (2–41 mm) and JJAS (6–309 mm) and most of the districts during JF (6–46 mm), while increasing trend is prominent over coastal and northern Odisha during MAM (7–46 mm), northern coastal Odisha during JJAS (25–175 mm), northern and northern coastal Odisha during OND (2–64 mm). It has been noticed that the ENSO influence on seasonal rainfall is insignificant during summer monsoon, while it is notable during the other seasons. This study is very useful in determining the effects and assists the risk management for various sectors in acclimating innovative technologies for a sustainable future in the present global warming era.