An international team of mathematicians and civil engineers has developed a method for enhancing the Top: FEV expressed as a square 2 m deep lake of side length 216 km. Bottom: the FEV lake, shallow relative to its side length, viewed from the top. Source: Onno Bokhove et al.accessibility and comprehension of flood mitigation policy options and technologies by stakeholders. The method relies on visualization rather than equations and scientific language to convey information on complex flood protection schemes.

The method was demonstrated using data from the Boxing Day 2015 flood of the River Aire in Leeds, U.K., to illustrate the concept of flood-excess volume (FEV), which is the volume of the total river discharge causing flooding above a certain threshold river level. Around 9.34 million cubic meters of water flooded from the River Aire during this event, which is visualized as a 2 m deep square lake with sides of 2.16 km in length.

Hypothetical flood-mitigation schemes for FEV reduction are proposed and assessed graphically, with scenarios based on natural flood management, flood defense walls and other mitigation options. Graphics are overlaid with the options necessary to hold back or to capture the flood waters, and how much each will cost. The cost-effectiveness analysis was deemed to provide a rational way to compare and select between flood-mitigation scenarios in an understandable and quantitative manner.

Researchers from the University of Leeds and Université Grenoble Alpes (France) contributed to this study, which is published in Water.