Regional modulating behavior of Indian summer monsoon rainfall in context of spatio-temporal variation of drought and flood events

Abstract

In this paper, daily modulating behaviors of Indian summer monsoon rainfall (ISMR) has been evaluated over eight important sub-zones of India viz Northwest India (NWI); Northcentral India (NCI); West Peninsular India (WPI); Eastern Peninsular India (EPI); Southern Peninsular India (SoPI); Central India (CI), Northeast India (NEI) and Western Ghat (WG) using latest SA-CORDEX simulated climate data during 1981–2015. The climate extreme indices, standardized precipitation index (SPI) and empirical orthogonal function (EOF) have been utilized to uncover substantial regional spatial patterns and temporal variability of monsoon precipitation over India and its sub regions to understand the regional modulation of these events based on duration, frequency and severity. The comprehensive assessment of ISMR modulated characteristics (intensity, spell, and frequency) were showing significant decreasing trend over NEI and NCI which can be leading factors for demarcating major hotspots for land degradation, effective management and adaptation towards water resources and hazards related to the flood/drought events. India has received flood events (1983, 1988, 1994, 2005, 2011, 2013) and drought event (1982, 1987, 2002, 2004 and 2009) during 1981–2015, which have been verified with SA-CORDEX RCMs (RegCM4.7, COSMO & REMO2015) using SPI. The first mode of EOF(IMD), explained 17% of the total SPI variability on the interannual scale, shows anomalous large positive values concentrated over the western peninsular region and extending towards central India as well as the NWI region of India. On the other hand, high anomalous negative values dominated over the NEI and eastern parts of the Indo-Gangetic Plain. Therefore, this study underscores the importance to uncover the prevalent dynamics and climate change variability on changing trend variability of the precipitation indices, drought and flood characteristics. As moderate to severe drought variability portrays a diversity over regional scale viz northwest India, north central India, eastern ghat of the southern peninsular region and northeast India while the occurrence of moderate to severe flood are dominated towards Himalaya region (26°N-35°N; 70°E-80°E), western peninsular region and western ghat.