Rapidly growing Chennai submerged by rare extreme rainfall event

This factsheet examines the causes and impacts of a rare extreme rainfall event in Chennai, India, on 1 December 2015. It highlights that while human-caused emissions had no measurable effect on the rainfall itself, unplanned urban growth, encroachment on water bodies, and poor infrastructure management significantly increased the city's vulnerability and the resulting devastation.

• An extreme rainfall event on 1 December 2015 in Chennai, India, caused devastating floods that resulted in over 470 deaths and brought the city to a standstill. Analysis indicated that there was no measurable effect of human-caused emissions on this specific one-day rainfall event.
• The floods caused significant damage to housing, agriculture, and infrastructure. Specifically, 4.92 lakh houses were damaged or destroyed, 3.83 lakh hectares of crops were lost, and Chennai Airport was closed for 5 days. Extensive damage also affected roads, drinking water, sewerage, drainage systems, health centres, and educational institutions.
• Human factors and unplanned urban development significantly increased Chennai's vulnerability to flooding. These factors include the encroachment of buildings on the Adyar and Cooum rivers, the loss of natural water bodies, and the construction of approximately 101,000 tenements in low-lying areas. The Parliamentary Standing Committee on Home Affairs specifically cited inadequate flood zone planning and a lack of timely desilting as major contributors to the impact.
• The flooding was exacerbated by the release of water from the Chembarambakkam reservoir into the Adyar and Kosasthalayar rivers to prevent the reservoir from being breached. While this was a necessary engineering decision to avoid a larger disaster, the timing of the release left many residents unexpectedly flooded overnight, and many did not receive or were unprepared for the warnings.

APA

Singh, R., & Arrighi, J. (2017). Rapidly growing Chennai submerged by rare extreme rainfall event. Climate and Development Knowledge Network. https://cdkn.org/sites/default/files/files/Rapidly-growing-Chennai-submerged-by-rare-extreme-rainfall-event.pdf

Chicago

Singh, Roop, and Julie Arrighi. Rapidly growing Chennai submerged by rare extreme rainfall event. Climate and Development Knowledge Network, 2017. https://cdkn.org/sites/default/files/files/Rapidly-growing-Chennai-submerged-by-rare-extreme-rainfall-event.pdf.

Wikipedia

{{cite report |last1=Singh |first1=Roop |last2=Arrighi |first2=Julie |title=Rapidly growing Chennai submerged by rare extreme rainfall event |publisher=Climate and Development Knowledge Network |date=2017 |url=https://cdkn.org/sites/default/files/files/Rapidly-growing-Chennai-submerged-by-rare-extreme-rainfall-event.pdf |access-date=17 August 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{singh2017rapidly, author = {Singh, Roop and Arrighi, Julie}, title = {{Rapidly growing Chennai submerged by rare extreme rainfall event}}, institution = {Climate and Development Knowledge Network}, year = {2017}, url = {https://cdkn.org/sites/default/files/files/Rapidly-growing-Chennai-submerged-by-rare-extreme-rainfall-event.pdf}, urldate = {2026-08-17}, note = {Indexed by Climate Insights Directory} }