Cyclone Nivar, November 2020 and elevated areas to park their vehicles to avoid partial or complete submergence. As officials from the and Puducherry government are tirelessly working to fasten debris removal, maintain Covid-19 related The Very Severe Cyclonic Storm Nivar (VSCS Nivar) formed as a depression norms in the relief shelters and other relief activities, many areas are between November 21 – 22, 2020 and made landfall near Puducherry on experiencing power failure and lack of access to broadband internet. India's southern coast around midnight of November 26. With wind speeds ANALYSIS AND MAPS up to 120-130 KMPH and pounding rainfall, VSCS Nivar majorly affected everyday life in the following districts: Maximum sustained wind speeds due to the VSCS Nivar (wind speeds as per IMD) is represented in the following map.  Puducherry  Villupuram   Kancheepuram   Tiruvallur At least three people have been victims of the VSCS Nivar mainly due to electrocution or tree-fall. Over 2.3 lakh people have been accommodated in about 3000 relief camps across northern Tamil Nadu. Heavy rainfall mainly in Kancheepuram and Chennai districts led to the filling up of various reservoirs, tanks, and ponds. Low-lying areas were inundated, sometimes exacerbated by improper solid waste management and clogged drains. Heavy rainfall led to the release of water from the , which required the pre-emptive evacuation of people from the areas adjoining the Adyar River within Chennai city. The events were a grim reminder of the 2015 flooding incident. Learning from the previous experience, many residents in and around the low-lying areas, especially near Velachery and Madipakkam, used flyovers Figure 1: Maximum sustained surface winds due to VSCS Nivar

1

RMSI also mapped the majorly impacted areas in Tamil Nadu and Puducherry using RMSI’s proprietary India Flood Model using the observed rainfall on November 26. Figure 2 and Figure 3 exhibit the flood extents for Chennai and Puducherry.

Figure 3: Waterlogged areas in Puducherry district (26th Nov) Figure 2: Waterlogged areas in in Chennai district (26th Nov)

2

From the wind hazard and flood maps, it can be observed that the urban areas of Tamil Nadu and Puducherry have been impacted, primarily by waterlogging due to the rainfall-induced by the VSCS Nivar.

Tamil Nadu and Puducherry are just starting with the north-east monsoon season, and VSCS Nivar has already filled the reservoirs supplying water to Chennai. The residents of Chennai, the capital city of Tamil Nadu, still remember that in June 2019, ‘Day Zero’ was declared by the administration

as all the four major reservoirs supplying water to the city had run dry.

The monsoon's vagaries and the adverse impact of predicted variability in climate will need increased focus on urban water resource management for protection from floods as well as droughts and for safeguarding the ecology of our cities.

DISCLAIMER : This report contains information generated through the analyses, and model predictions based on data provided by IMD and compiled using proprietary computer risk assessment technology of RMSI Pvt. Ltd. The technology and data used in providing this information is based on the scientific data, mathematical and empirical models, and encoded experience of scientists and specialists (including without limitation, earthquake engineers, wind engineers, structural engineers, geologists, seismologists, meteorologists, and geotechnical specialists). As with any model of physical systems, particularly those with low frequencies of occurrence and potentially high severity outcomes, the actual losses from catastrophic events may differ from the results of simulation analyses. RMSI specifically disclaims any and all responsibilities, obligations and liability with respect to any decisions or advice made or given as a result of the information or your use thereof. RMSI specifically disclaims any and all responsibilities, obligations and liability including all warranties, whether expressed or implied, with respect to the report, including but not limited to, warranties of non-infringement, merchantability and fitness for a particular purpose. In no event shall RMSI (Or its subsidiary, or other affiliated companies) be liable for direct, indirect, special, incidental or consequential damages with respect to any decisions or advice made or given as a result of the contents of this information or your use thereof. The material contained in this report is the copyright of RMSI and may be used only for informational purposes only. RMSI makes no representations or warranties with respect to this information. For using any information from this report, you agree to the terms and provisions as outlined in this disclaimer. If you do not agree to them, please do not use this report. 3