Flood Modelling

When are Flood Models Required?

Flood models are required when there is a need to understand and predict the potential impacts of flooding in a specific area. This could be for various reasons, such as:

1. Flood mapping and flood risk management: flood models are required on a national scale to help identify areas at risk of flooding. This is vital for various reasons, include the safety of inhabitants, alongside the allocation of funding for flood risk management, and such floodplain storage is maintained so that the risk elsewhere is not exacerbated. The mapping can also be used to determine what management measures can be implemented, and whether this will have an impact on the surrounding areas upstream or downstream of the proposed defence. The models can also be used to assess the effectiveness of different risk management methods within the catchment. The U.K is fortunate to have extensive flood mapping freely available for river flooding, surface water flooding and reservoir flooding. National Flood Maps are produced by the relevant agency, such as the Environment Agency, Natural Resources Wales, or Scottish Environment Protection Agency. 
2. Planning and development: models are often required for planning applications to assess the flood risk associated with proposed developments and to ensure the safety of developments and those who use them. A model may also be required to ensure that the flood risk is not exacerbated elsewhere through the development. This may include the construction of a new site or aspects such as re-aligning a river bank. A bespoke model may be required if existing flood models are not detailed enough to make a judgement on whether or not the site can be developed safely.
3. Climate change stress testing and adaptation: as the climate changes, flood models are utilised to understand how flood risk may change in the future. This may be due to changing storm events, or sea level rise. The model will be required to help inform decisions on how to manage the risks, developments, and how to adapt to changes. 
4. Assisting Emergency Response plans: detailed flood risk information is usually required to assist with Flood Warning & Evacuation Plans, and flood risk management. Flood models can be used to determine which areas are at risk, and who should be evacuated. The modelling can assist with emergency planning and flood forecasting.

Overall, flood models are used whenever there is a need to understand the potential impacts of flooding, and to enable informed decisions about flood risk management and mitigation to be made.