Flood forecasting to protect what matters most

Highly precise flood impact forecasts are improving emergency responses across Scotland.

“Standing on your carpet as water comes up through the floor, it feels like you are walking on jelly. I’ve never felt anything like it.”

In the early hours of 12 August 2020, Janice Haig’s home was filling with floodwater. It filled the space beneath the ground floor and rose to cover the skirting boards.

Neighbours phoned her at 2am to say they were evacuating under the advice of the local fire brigade. But first they carried Janice’s elderly father upstairs to safety and asked Janice what she’d like to save from the living room.

“I didn’t know what to do,” Janice said. “I kept looking around and I had no idea what to do. I don’t remember much of the night after that.”

Living with the impacts of flooding

Janice spent the next year without carpets or flooring, waiting for tradespeople to become available so she could try to restore normality in her home. Her insurance premiums quadrupled.

She began researching flood resilience and installed air brick covers and water pumps.

She checks the weather forecast every day and receives weather, flooding and lightning alerts from various sources.

The constant flood warnings can be exhausting, especially for families whose homes have flooded before. Janice says: “It doesn’t matter whether it was a few inches or four feet of water. It stays with you.”

Modelling how water flows across landscapes

Householders like Janice rely on flood forecasting, but so do local authorities and first responders.

Having better information about where and when floods might occur, and the potential impact they may have, can help mitigate damage.

UK Research and Innovation (UKRI) supported researchers at the UK Centre for Ecology and Hydrology (UKCEH) to develop the grid-to-grid, or G2G, model with partners.

The model translates rainfall into river flows to predict potential river flooding.

Instead of a static measurement taken at a known hotspot, G2G models how water moves across whole landscapes. Its real-time forecasting considers slopes, soil type, the geology of an area and how those might change as moisture levels evolve.

Better preparedness for floods

It provides the foundation of the Scottish Flood Forecasting Service’s flood forecasting capability, enabling Scottish Environment Protection Agency (SEPA) and the Met Office to deliver coordinated, Scotland-wide warnings.

The service isn’t aimed at the general public, but is used by category one and two responders like:

  • local authorities
  • Police Scotland
  • SEPA
  • NHS Scotland

The complex data is turned into daily bulletins, delivered to the responders daily, which give them access to detailed Scotland-wide flood forecasts with five-day lead times.

The earlier warnings and comprehensive coverage have meant better preparedness for floods.

Predicting impact, Storm Babet and Brechin

G2G changed flood forecasting in Scotland, but its first iteration didn’t consider the impact of a flood.

UKCEH, SEPA and the Met Office worked together to develop a new tool called PREDICTOR, which predicts how much impact a flood could have, as well as how likely it is.

Combined with G2G, it can provide real-time flood risk information for properties and transport systems.

Helping with on-the-ground efforts

In 2023, Scotland was confronted with a number of severe storms. Storm Babet, in October, brought a high level of rainfall across north-east Scotland and caused significant flooding.

The town of Brechin was particularly affected: three people died, hundreds of homes were evacuated and the town suffered significant damage.

It could have been even worse.

During the storm period, G2G provided early warnings of flood risk and the PREDICTOR tool was used for the first time to provide flood impact across the region.

Mike Cranston, Lead Specialist in Flood Forecasting at SEPA, said the operational use of the G2G model helped with on-the-ground efforts in Brechin.

This capability enabled us to accurately assess the flood risk days in advance, and work with responses to ensure they were able to prepare and respond to the severe flooding.

Mike Cranston

Lead Specialist in Flood Forecasting, SEPA

Consider the safety of a whole region

Better forecasting means responders can consider the safety of a whole region. For householders like Janice in Perth, it means knowing whether to start preparing, or simply waiting for the rain to pass.

After her home was flooded a second time in September 2022, Janice set up ​Perth Community Flood Aid, a group that helps local residents prepare for floods.

It has installed a river monitoring system in the Craigie Burn, which runs to the south of their homes.

Its work with the Scottish Flood Forum has led to over 30 residents having flood resilience assessments carried out, and over 1,500 people monitor the group’s Facebook page for alerts.

The group has some funding to help install property flood resilience measures in homes, but Janice believes accurate forecasting is just as important.

Buying time to prepare

Knowing the potential impact of a storm or prolonged rainfall will help responders, homeowners and businesses act earlier, whether that’s delivering sandbags or closing roads.

“Forecasting may not stop the rain, but it gives us time to prepare and action,” said Janice. “If we know earlier what might happen, we have a better chance of staying safe.”

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