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Perspective

Making lives safe from floods: Four steps for an effective flood warning system

Over the last two decades in Asia, floods impacted nearly 1.6 billion people and killed nearly a hundred thousand people, write Uttam Ghimire in an op-ed in the Himalayan Times.

Floods also damaged tangible economy worth 436 billion USD and caused massive inconvenience to the lives of billions. These numbers may very well increase in future, as continued global warming leads to more intense and erratic rainfall and increasing exposure and vulnerability to floods.

Uttam Ghimire / Published on 10 August 2023
Perspective contact

Rajesh Daniel / rajesh.daniel@sei.org

Residential buildings by the Ciliwung River in Jakarta, Indonesia.

Residential buildings by the Ciliwung River in Jakarta, Indonesia.

Photo: Dimas Ardian / Bloomberg / Getty Images

What can be done to manage flood vulnerability and reduce these losses? Can we control nature and change rainfall patterns? No. Could we work to improve our resilience against floods?

Losses of property and lives due to floods can be reduced through two pathways: move the floods away from people and where they live and/or move the people and their livelihoods away from floods.

The first way involves taming the intensity of the floods. In other words, we keep the flood waters locked till it is safe enough to be released. Many natural water systems provide this service of flood retention, such as the Tonle Sap of Cambodia, which stores floodwater from the Mekong River during its high flows and releases it throughout the year.

In the absence of such natural systems, humans have constructed large dams, which require a significant economic investment and are also controversial for displacing or resettling people and destroying forest ecosystems.

The timely and effective evacuation of people and properties from flood-prone areas is a viable approach to reducing flood risks. But core to this approach is making available an effective early warning system coupled with flood forecasting measures.

Four steps to make flood warnings as effective as possible

  1. Improve the accuracy of warnings: The accuracy of flood warnings depends on the robust scientific integration of weather, topography, land use, man-made structures, and human actions into a decision support system. Such systems need rigorous testing on historical flood events and at least a few ongoing events before use for day-to-day operation. The forecaster must be aware of continuous improvements in weather and water resources models in the international research community and must test whether such developments can improve the accuracy of their decision support systems.
  2. Effective and timely deployment of warnings: There is always uncertainty with the future, so the earlier one predicts a flood, the more uncertain the knowledge about the potential impacts. However, one cannot wait till the very last minute to confirm the coming of a flood; then, people and authorities will not get any time to respond.The flood forecaster needs to monitor every potential flood occurrence in an area and track their progress based on their severity and certainty of happening. Before disseminating this information to the public, this information must be sent to a workforce committee that includes relevant groups like disaster managers, civil protection agencies, local administrative offices, and media. Once the potential flood crosses a threshold of certainty and severity, the warnings must be deployed to the public.
  3. Improve the understandability of warnings: The forecasters should refrain from disseminating technical jargon to the public but simplify their language as much as possible. Also, warnings need to be very specific about the impacts. For example, if a river is about to inundate a particular stretch of a highway, rather than just advising people that there might be a flood tomorrow, the forecaster should communicate that: “The road stretch between location A and B is likely to be flooded tomorrow between 10-4 pm. Drivers are recommended to avoid this stretch of highway”. Radio can be an effective channel, as in Nepal, where Radio Nepal had an audio program called “Mausam Chautari,” where forecasters interacted with local people to explain the possible implications of the weather forecast for the next few days or weeks.
  4. Carry out relevant pre-disaster activities: The workforce committee should have a standard operating procedure once flood warnings have been issued. Each person, group, or agency must know their specific roles and when to act. Flood evacuation shelters, evacuation resources, including personnel, food and water rations, emergency medical services, and safe drinking water should be ready. Following the dissemination of warnings through TV and radio, sirens and alarms can be activated, and people can be evacuated. For the entire operation to work in a real flood disaster, drill exercises must be carried out now and then.Using large and expensive structures like dams and embankments to control floods has been a dominant approach for a long time. This approach gave a false sense of security, but many incidents have proved otherwise. It is time to approach flood safety by preparing effective and coordinated responses, as this can serve us better in an increasingly uncertain climate future.

This perspective was originally published by the Himalayan Times.

The author Uttam Ghimire is a water resources modeler at SEI Asia. Ghimire has developed decision support systems for end-to-end flood forecasting across Nepal, Myanmar, Bhutan, and the Philippines and is recently investigating the best practices of impact-based alerting in Nepal and Bhutan.

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