Flood Manager Game is an educational game to illustrate the process of selecting optimal packages of flood management measures. Select your flood management options, enter your name and email address and then click the "Enter the competition" button. Selecting or hovering over each option will show you more information about it. The aim is to select options which provide the highest benefit:cost ratio (the 'score').

Upstream storage

Raise defences

Property level

benefit:cost ratio

Thanks for entering!

Today's high score

benefit:cost ratio

Find out more about Flood Manager

© Copyright CH2M HILL 2017. Although the data used in Flood Manager is based on a real location, the flood risk management options, modelling and outputs have been developed to illustrate a hypothetical portfolio of responses, and do not represent real world flood risk in that location.

About Flood Manager


The Flood Manager game is a simplification of the process of decision making for flood management. There are many more options available and the process of selecting the optimal packages is much more complex: there is much more to consider than just the benefit:cost ratio of options. Information about the standard process used in England is provided in Flood and Coastal Erosion Risk Management appraisal guidance.

The Flood Manager game was developed by CH2M – a global engineering and project delivery company partnering with public and private sector clients to tackle the world’s most complex infrastructure and natural resource challenges.

The game illustrates some of the complexities of selecting optimal flood management measures. Even this simplified game involved around 100 simulations using CH2M’s Flood Modeller hydraulic modelling software to generate flood maps (as shown in the image below), together with calculations of costs and benefits for 64 combinations of options.

About the modelling

Flood Manager screenshot

The linked 1D/2D model underlying this tool was developed and simulated using Flood Modeller (download a free version from floodmodeller.com). Different versions of the model were developed for the different flood mitigation options. Although this tool presents a fictional example, the costs of the different schemes described within this tool were broadly estimated using cost estimation documents produced by the Environment Agency.

To represent the raised defence options, the bank tops were raised by 0.3, 0.5 and 1.0 m along the river channel. For the upstream storage options, flood flows were removed from the upstream of the town to represent the effect of the flood storage areas, though it is possible to represent reservoirs and storage areas directly in the model. Simulations were performed in Flood Modeller with each combination of the upstream storage and hard channel engineering measures for flood events with an annual exceedance probability of one in 10, 50, 75, 100, 200 and 500.

The average annual damages for each combination of mitigation measure were then calculated using Damage Calculator, a tool within Flood Modeller. Damage Calculator takes modelled water depths for different flood events and property information and calculates average annual damages using depth damage curves which have been provided by Multi-Coloured Manual Online. Floodplain measures representing different property level protection measures were then incorporated as part of Damage Calculator. These measures alter the depth damage curves used to calculate expected damages and represent how the different measures would be expected to reduce damages at given water depths.

Once the annual average damages have been calculated for each of the flood mitigation strategies, the average annual benefit can be calculated by taking the difference between the annual average damages with and without the flood mitigation measures. The benefit was then increased by a factor to represent additional benefits other than those directly related to property damage. This was then multiplied by 29.68 to calculate a lifetime benefit, enabling comparison to the lifetime costs of the options. This value was then divided by the cost of the selected schemes to calculate a benefit cost ratio.

About the website

Flood Manager screenshot

The website is written using standard web technologies (HTML, JavaScript and CSS) with server-side scripts written in PHP. The visual structure is based on Bootstrap, a framework designed to support the development of responsive websites that work well on different types of device.

The Flood Manager map was built using Mapbox GL JS, a JavaScript library that uses WebGL to render maps. The background mapping has been designed to showcase the flexibility of vector map tiles, which can be dynamically styled and provide a more fluid experience for users. The tiles are provided by Mapbox, which uses OpenStreetMap data. WebGL and vector map tiles are also used by more recent versions of web mapping services like Google Maps.

The map shows upstream storage locations, flood defence alignments and properties at risk. This information is stored as GeoJSON files, an open format for spatial data that is readily compatible with web technologies. The styling of these layers is then changed based on user options - for example extruding the flood defence alignments to represent raised defences.

Outputs from the modelling and damage calculation are stored as tabular data, which is loaded into the website. When someone enters the competition, the relevant data for the combination of options is selected and the benefit:cost ratio is identified and compared with the current high score for the day.

Further reading

Mapbox maps

Mapbox GL JS