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Urban Development

Devising a Flood Early Warning System in Kolkata

  • Project Name: Flood Forecasting and Early Warning System for the City of Kolkata
  • Region/Country: South Asia/India
  • Sector and Themes: Urban Development
  • Year: 2017
  • Project Leaders: Ashwin Hosur Viswanath
Devising a Flood Early Warning System in Kolkata
ADB has been supporting Kolkata to become a more livable city through integrated planning and phased investments for building resilience and improving urban services.

Natural calamities, including heavy rain, can occur any time. This system will reduce economic loss and impacts on livelihood and improve flood awareness and safety at the community level.

—Sovan Chatterjee, mayor, Kolkata City

Development challenge

Kolkata has 4 million people exposed to flooding risks, with 1,800 milliliters of annual rainfall, of which 80% falls during the monsoon. The topography and tidal range (the height difference between high tide and low tide) exacerbate the situation, as does high population density.


ADB sponsored the Kolkata Environment Improvement Investment Program (KEIIP) that assisted the Kolkata Municipal Corporation (KMC) in making a smart and resilient city by modernizing financial, administrative, and asset management systems; reducing urban flood risks; improving land use planning; and developing their capacity to reach citizens through introduction of a flood forecasting and early warning system.

Being a people-centered flood-forecasting tool, the early warning system empowered individuals, communities, and other stakeholders to act quickly and appropriately to reduce flood risks. Predictive modeling, historical flood assessment from remote sensing, and consultation withcitizens and borough engineers helped identify locations for real-time data collection on rainfall and flood risk, which were then verified during the monsoon.

Knowledge products and services delivered

The flood forecasting and early warning system was developed through an ADB TA program supported by the Urban Climate Change Resilience Trust Fund. A team from TARU Leading Edge Pvt. Ltd., PricewaterhouseCoopers, and Antea Group assisted KMC to design and implement the system. The Rockefeller Foundation and the governments of Switzerland and the United Kingdom were the project’s financing partners.

This is the first comprehensive city-level early warning system in India. It provides real-time information from more than 300 Internet of Things-based multifunctional sensors to provide forecasts throughout the city, enabling informed decision making before and during disasters and help reduce loss and damage. It gives updates on multiple types of data and information including flooding, air quality, heat stress, and humidity, accessible via the K-Flood website and through the K-Flood app, which issues mobile phone alerts and has a monitoring system to inform city residents, among others.

The system provides forecasts and real-time updates
The system provides forecasts and real-time updates on rainfall and inundation levels, among other climate and environmental data, thereby strengthening the city’s resilience. .

Impact and results

The city was provided with a comprehensive forecasting system that gives real-time information on inundation, temperature, air quality, and other climate-related data that can help and improve the lives of various stakeholders.

KMC has also been simultaneously improving the city’s urban services and climate resilience under KEIIP. It has been systematically expanding sewerage and drainage network in Kolkata, including peripheral flood-prone areas; increasing sewage treatment capacity; improving water supply through reductions in nonrevenue water; managing solid waste; and increasing operational efficiencies and building capacity to better sustain the services it provides. Flooding has already been reduced in about 4,800 hectares, and KMC expects further flood reduction in more than 6,000 hectares covered under the projects.

This is the first comprehensive city-level early warning system in India
This is the first comprehensive city-level early warning system in India.

Lessons for Replication

Many of the existing pumping stations are old and are not amenable to control and automation. This necessitates capture of pumping data from basic sensors. The pumping stations have corrosive and dark environments, especially within the sumps, which reduces the life of sensors, so they need regular maintenance.

The Kolkata drainage system is a very complex one, involving underground networks and hundreds of pumping stations, and it requires a lot of expertise and information to handle the storms and the big rains. Sometimes there are huge rains but the pumping stations are situated 3–4 kilometers away from that area. This system helps the pump operators plan better as the sensors alert them of any flow that goes over permissible limits.

—Soumya Ganguly, KEIIP, Kolkata Municipal Corporation