Exploring extreme flood events of a western state of India during monsoon season of 2019 from space

Abstract

Maharashtra experienced a series of calamitous flood events during July and September months of monsoon season of 2019 affecting millions of people. Mumbai, Palghar, Thane, Raigad, Satara, Sangli, Pune and Kolhapaur were most affected districts of Maharashtra. Near real time satellite observations from space have been used in this study to monitor these events. Availability of accurate precipitation information at very fine resolution of 5 km (half hourly) from a rainfall model that integrates observations from multi-spectral satellite sensors offers an excellent opportunity to monitor flood events effectively. Utility of this model was tested by investigating flood events of Kedarnath in 2013, Jammu and Kashmir in 2014 and Tamil Nadu in 2015. This model was also used to explore recent flood events of Kerala and Assam in 2019.         Mumbai, Palghar, Thane, Raigad, Satara, Sangli, Pune and Kolhapaur districts received very heavy rainfall from multiple rain episodes during first, third and last week of July, and second and last week of September that resulted in heavy flooding over these districts. Results reveal that few of these districts received cumulative rainfall in excess of 2000 mm from multiple heavy rainy events during July to September. Mumbai, Palghar, Thane and Raigad received a cumulative rainfall in excess of 1700 mm during July and September. Sangali district received an excess of about 200% rainfall than average monthly rain during July 2019. Heavy cumulative rainfall from multiple rain spells resulted in heavy flooding over various districts of Maharashtra. Results reported in this study highlight the importance of mitigation and adaptation strategies against flood disasters.