Applying newly developed spatial analysis method to help reduce flood risk in Leeds
This project helps urban flood risk managers by allowing them to identify the sources of flood risk (where flood water comes from) and not just the hazard itself (where the water ends up).
An holistic approach is used to consider how connections between storm pathways and other urban systems, such as transport or green spaces, can expand the capacity of the overall urban system to cope with present and future risk of flooding as a result of climate change. By taking an approach that looks at the source of flooding it helps planners to identify whether new of urban development have multiple socio-enviro-economic benefits that include managing excess water.
For example, can a road be used to divert flood water? can an open green space store it temporarily?
SUIM helps compare how different infrastructure systems deal with excess water and identify how they can be integrated to make urban areas more resilient to flooding. Areas contributing to flooding are identified to inform new developments so they store or divert rainfall away from flood prone areas. It aims to identify connections, wider catchment opportunities, and funding partnerships beyond the areas of known flood hazard impacts.
Flood source areas
Rainfall that contributes to a flood can fall a long way from where the flood ultimately occurs. For example, contributing rainfall flows overland, along roads and underground through drainage networks, before reaching the site of the flood.
Another iCASP project developed a system to work out the origins of flood water and the pathways it takes before reaching the flood location. This project used one of the datasets from the Wyke Beck catchment, in the east of Leeds, to show the extent of flood water each area of the sub-catchment contributes. This knowledge can inform interventions to intercept, store and divert the water before it becomes a problem, for example, installing rain gardens. Recent and planned developments will be assessed to see if this new approach would or could lead to more cost effective and flood resilient design which also benefits local communities in other ways e.g. improving health, wellbeing and sustainable transport options. The Wyke Beck case will be the basis for a user-friendly ‘interoperability tool’ for Leeds City Council to use in other parts of the city. It could also be used by councils in other cities too.
The SUIM team concluded that the benefits of a flood source area approach were: a useful tool to provide a more strategic way of prioritising schemes ; it can save time when looking for partnership funding; earlier negotiations of section 106 contributions and growth funding and derestriction of the prescribed approach to option selection.
Along with identifying additional schemes across the catchment, it was identified that this approach supports system flood risk management in line with the latest government guidance on this topic. The next step will be expanding the approach to account for costs and benefits and developing it into a useable tool.
Leeds City Council
David Dawson & Amrie Singh – University of Leeds
Ben Rabb, Tom Willis – iCASP Impact Translation Fellows
David Parish & Jonathan Moxon – Leeds City Council
Luke Williams – Environment Agency
January 2020 – 2021