An autonomous community located in the northern part of Spain and the southwestern part of France, Basque Country is known for its diverse culture and landscapes. Like many regions around the world, Basque Country also faces challenges from natural hazards such as flooding, erosion and landslides. Under climate change, these hazards are likely to be exacerbated, resulting in increasing impacts as well.

Owing to the region’s topography and steep relief, this makes the region prone to flash floods during periods of heavy precipitation, and in some cases, the response time can be on the order of less than 1 hour. In recent years, there have been several severe flood events that have caused infrastructural and economic damage in Basque Country, such as the November 2021 floods. Urbanised areas are especially vulnerable owing to the dense urban planning and impact on populations and infrastructures. The Basque Water Agency (URA – Uraren Euskal Agentzia) is responsible for flood mitigation, protection and preparedness within the region, who are also the end users within this project for the Basque Country case study. They focus on four main pillars in their flood management strategy: Prevention, Protection, Preparation and Recovery & Evaluation.

User

Current forecasting infrastructures

Currently, Basque Country has two systems in-place to support timely delivery of actionable information.

SAIH (Automatic Hydrological Information System): A network of meteorological and hydrological data collected from a network of more than 130 measurement stations. Several agencies contribute to this system, resulting in a robust collection of monitoring data.

UHATE (Hydrological Prediction and Alert System): A real-time forecasting information system that provides emergency services with information on the probability of hydrological flows to support rapid decision-making. The hydrological forecast is based on real-time data and meteorological forecast, based on a dense monitoring network of over 220 stations and buoys.

In the event of a flood event, a close collaboration between the Basque Water Agency, Euskalmet (Meteorological office of Basque Country) and Civil Protection collaborate and take part on the emergency committees for disaster preparedness and evacuation.

Contribution to the Disaster Risk Mitigation & Climate Adaptation Use Case

On the 17^th March 2023, the user kick-off workshop was held at the Deltares office in Delft. The main goal of the meeting was to understand the individual users’ needs and to set a draft scope for the individual case study. In the case of Basque Country, decision-making currently relies heavily on expert judgement and much less on models or forecasts. The curiosity remains if higher resolution data made available within Destination Earth could potentially contribute to improved forecasting. In addition, compound flooding was identified to be much less of an issue. Instead, other types of flooding are a concern here, which are namely pluvial and fluvial. Pluvial flooding occurs when when the drainage capacity of the infrastructure in place is not sufficient or when the amount of rainfall exceeds the capacity of water to infiltrate through the ground. Fluvial flooding occurs when rivers overflow from excessive water, resulting in flooding in the immediate area. However, identifying surge components might become more important with sea level rise. The generic model workflow for both hydrological and coastal hydrodynamics modelling can then be applied for this region. When higher resolution meteorological data is made available within Destination Earth, the higher resolution results for both disaster preparedness (forecasting) and climate adaptation can be assessed for its suitability in the region.

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