IEEE Public Safety Technology Initiative IEEE Public Safety Technology Initiative

Guide to Flood Forecasting: Technology and Connectivity Are Key for Reducing Flood Danger

Flood forecasting, along with forecasting for other natural disasters like earthquakes, is essential technology that can save lives. Floods occur throughout the world due to a variety of factors. As a result, leaders need to be prepared with sensing technology in many areas to predict flood risks. Using tools like drones, thermal cameras, and satellite imagery, forecasters have advanced sensing technologies that can reliably predict flood risks and allow forecasters to send out an early warning.

In this guide to flood forecasting, you will learn about the current technology for flood forecasting, how leaders communicate about flood risks, and the future of flood forecasting. For effective flood forecasting, leaders must proactively monitor for potential flood risks and continue improving connectivity so that they can alert affected residents in advance and support digital communication during disasters.

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How Flood Forecasting Works

A flood occurs when water pools in an area that is typically dry. Floods can vary in severity from a few inches of standing water to several feet. There can be many contributing factors that lead to flooding, but the following are the most common causes of a flood:

  • Heavy rain
  • Sudden melting of snow
  • Broken dams
  • Storm surges in the ocean

Certain locations can be more susceptible to flooding as well. For example, the following areas are at higher risk for floods:

  • Urban areas with tightly packed buildings can flood because rooftops channel water to paved streets that can’t absorb rain.
  • Areas surrounding rivers can flood when the water level rises too quickly and overflows to surrounding areas.
  • Areas near mountains can flood as rain or snowmelt runs quickly to lower surrounding areas.

To accurately predict floods, forecasters must consider many different factors. Even if a storm won’t bring much rain, an area could flood if there was a lot of rain recently and the soil is heavily saturated already. Forecasters must understand these nuances to accurately predict when a flood could occur.

Flood Forecasting System Process

The flood forecasting process works by applying collected data to models to anticipate floods. Forecasters collect data like the recent amount and location of rainfall, the current water levels of rivers and reservoirs, and the temperature forecasts to factor in snowmelt. Then they use hydrologic modeling to estimate the amount of runoff that will occur based on the forecast precipitation.

Flood Forecasting Alerts

The goal of flood forecasting is to be able to alert people so that they can prepare to evacuate if needed. Complex flood forecasting models can predict whether a flood might occur as well as the expected severity of it. With this information, forecasters can notify affected populations using technology like text alerts and Google notifications.

A Google flood forecasting alert is one example of a way that residents can learn about an impending flood hazard. Google issues an alert if water in a river is expected to be higher than a predetermined warning level. This water level warning is typically set by a local government agency based on previous flood events in the area.

What Methods and Systems Are Available for Flood Forecasting

To predict floods, forecasters need data about existing conditions, forecasts about future conditions, and models to estimate how those data points will combine to create potential flood hazards. In the United States, the National Severe Storms Laboratory primarily uses radar, gauges, and satellite tools as the methods and systems for flood forecasting.

Radar

The National Weather Service operates a network of Doppler weather radars called Next-Generation Radar (NEXRAD). This network of radars detects precipitation and displays its movement on a map. Using this map, forecasters can watch how storm cells begin or intensify, allowing them to predict if flooding will occur.

Rain and Stream Gauges

Rain gauges measure the amount of precipitation at a particular geographic location in real time. Because rain gauges measure actual precipitation amounts, forecasters can use this data to accurately predict flood risks. However, this data is available only in areas where rain gauges are installed.

Stream gauges measure the amount of water flowing in a river or stream or the amount of water discharged. Forecasters use these measurements to determine the flow and height of a body of water. Because this data is collected frequently and transmitted through a satellite, forecasters can see when water levels are rising quickly and can issue warnings in time.

Satellite

Satellite estimates of rainfall are less accurate than estimates from radar or gauges. However, satellite data is available in more locations, such as over oceans or in mountainous or remote areas. Satellite data offers high resolution views that help flood forecasters identify developing floods in these less-monitored areas.

Communication Systems

In addition to technology for detecting precipitation and water levels, forecasters need a warning system to communicate flood risks to affected populations. If researchers know about a threat ahead of time but can’t warn the affected people, the knowledge of the threat doesn’t help. The affected population needs to have reliable, increased access to internet connections, and 5G networks offer promising solutions to achieve that. In particular, 5G promises reliable, low-latency communication and support for enormous volumes of machine to machine communication, such as real-time data from large sensor networks. This could be key to effective early warning systems (EWS) and is an area being studied by the World Health Organization. Before making this technology more widely available, though, policymakers need to overcome the 5G deployment challenge first.

How to Communicate and Warn about Floods

All of these methods and systems available for flood forecasting can help with the estimation of how high floodwaters will reach. For example, the United States Geological Survey is a government agency that monitors the height and flow of streams and rivers around the country using gauges. The agency uses data from these gauges along with precipitation forecasts to estimate how high floodwaters will reach. After a flood, they also use this data to identify a flood’s peak height. As artificial intelligence, or AI, becomes more widespread, it is also becoming a tool for use in warning and forecast systems.

However, a flood forecast isn’t complete by simply identifying a flood danger. Another component of flood forecasting is communication. When forecasters predict that a flood will occur, they use a flood warning system to notify people in the affected area. This early warning system is essential, giving residents time to evacuate if needed.

Flood Watch and Flood Warning Communication

The National Weather Service issues two types of notifications related to flood risks: flood watches and flood warnings. A flood watch means that the conditions could result in a flood in the near future. Residents receive a notification on their cell phones indicating that they should stay alert and monitor the news for information. A flood warning means that flooding will occur if it hasn’t already. Residents should move to higher ground or evacuate the area.

These alerts help communicate flood risks to the affected area, but you can help communicate and warn about floods in your community as well. Before a flood occurs, agree on a safety plan with loved ones and the other members of your household. When a flood happens, you may be separated from each other, and cell phone systems may be unreliable. To combat these challenges, agree on an emergency meeting place ahead of time where you can reunite with loved ones. Make sure you have emergency numbers memorized or written down in case cell phones aren’t available.

If authorities recommend evacuation, check in with your neighbors to offer assistance and make sure they know about the risk. Elderly neighbors or people without access to technology may not be informed yet. Until 5G deployment is complete and access to devices is universal, you can save lives by helping to spread information about flood warnings as well. 

Guide to Flood Forecasting Safety Tips

People under a flood watch or flood warning must stay informed about the developing situation and follow any instructions from public safety officials. Local news stations and the National Oceanic and Atmospheric Administration weather radio provide relevant information about flood risks in real time.

To safely deal with a flood, follow these tips:

  • Evacuate immediately if told to do so by public safety officials. Take only essential items to evacuate in a timely manner.
  • Do not walk through fast-moving water or drive through flooded roads. According to Ready, a national public service campaign, you can be swept off your feet in only six inches of water. Cars can be swept away in only a foot of flood water.
  • Stay in your vehicle if you are trapped in fast-moving water, and climb to the roof if the water level is rising in the vehicle.
  • Stay away from bridges because they can wash away unexpectedly.
  • Move to the highest level of a building as water levels rise. If necessary, move to the roof and signal for help.

After a flood, you should only return home when safety officials declare it safe to return. Avoid downed utility wires that could cause electrocution and damaged buildings that may no longer be structurally sound. Consider using professional cleaning services to clean and disinfect flood-damaged buildings after water levels recede.

What Is the Future of Flood Forecasting

According to the National Severe Storms Laboratory, flood forecasting methods are largely accurate and reliable. Forecasters’ predictions usually identify when conditions could cause flash flooding. They can often predict the flooding of large rivers several days in advance. However, to save lives and better prepare for flash floods, the agency is working on strategies to transmit a flash flood warning with more advance notice.

The consequences of floods can be significant, causing lost lives, damaged property, and destroyed infrastructure. Consider some of these examples that illustrate the consequences of flooding:

  • According to the National Weather Service, there were 145 flood fatalities in 2021.
  • According to the National Flood Insurance Program, one inch of floodwater in a building can cost up to $25,000 in damage.
  • According to the United States Environmental Protection Agency, items can develop mold that can make you sick if they stay wet for more than twenty-four to forty-eight hours. Flood waters can also be contaminated with raw sewage or other hazardous waste, which can spread disease.

Because of these significant costs, governments must continue improving flood forecasts and remediation to better prevent, predict, and respond to flooding disasters. In some cases, governments may save money by purchasing and demolishing flood-damaged buildings located in places that repeatedly flood. Families could then relocate to homes without as high of a risk for flooding.

Another way to reduce the impact of flooding is through improving technology. Researchers are exploring remote sensing technology that uses satellite data but requires fewer computing resources. Researchers are also working to increase global connectivity to digital tools, such as reliable first responder networks.

First responders need digital connectivity to successfully communicate during rescue operations. Residents also need digital connectivity to monitor flooding levels and call for help. However, if electricity access is cut, which is common during a flood, people can’t make calls or communicate effectively. The future of flood forecasting includes working on new solutions like pop-up networks that can support connectivity during a flood even if the electrical grid is down. Technology like drone-based and satellite-based connectivity would save lives by helping people make calls to family, friends, and emergency services during a disaster.

How Improving Connectivity Can Save Lives

In this guide to flood forecasting, you’ve learned about the technology used to identify flood risks and communicate flood warnings. The key to improving flood forecasting is increasing connectivity to support all the components of public safety, including areas of prevention, rescue operations, and analytics. Technical professionals at the Institute of Electrical and Electronics Engineers are working together to improve connectivity around the globe. Together, this community is working to help save lives in disaster situations like floods.

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