Participants in PhD student Shaun Maskreyâ€™s second Flood Risk Modelling Workshop in July worked hard to draft networks showing how flood risks work in Hebden Bridge.

John Woods of the Environment Agency helped Shaun to facilitate the workshop and Christina Hooley at Treesponsibility did the catering.

Shaun’s first workshop introduced the idea of using Bayesian networks to cope with uncertainties about how different variables affect flooding. After this bracing start, participants had worked in two groups to identify actions, or “interventions” that could reduce flood risk in Hebden Bridge.

The second workshop was about taking the list of interventions from the first workshop, and trying to work out a network that showed the interrelationships between these variables and their effects on flood risk.

Shaun’s presentation explained how to construct a network from a set of inter-related variables. He outlined the different kinds of variables. These are shown and colour coded in the general network structure on the left in the following diagram, and in the worked example on the right of the diagram.

(To enlarge the diagrams and graphics in this post, just click on them.)

Following the presentation, Shaun gave each group a set of variable cards which were colour coded as per the diagram. Groups then organised the variables, or subsets of the variables, into the general network structure. They recorded this by taking photographs of the network/s.

After the meeting, Shaun organised the groups’ post it notes and photos into the following networks, one from the yellow group and one from the green group.

All of the arrows in the network diagrams flow from cause to effect. Shaun has asked participants to let him know if they think any arrows or variables are out of place, or missing. He will try to take any comments fully on board before the third workshop, and redesign the networks to accommodate any changes.

These initial networks will form the basis of discussion at the opening of the third workshop, where we will fine tune the networks, simplify them where possible and set the states for each variable.

The next workshop will take place on **Tuesday 17****th ****September **in **The Terrace Room, Hebden Bridge Town Hall. **Refreshments from **6:45pm for a 7:00pm start. **

It would be good to know if Calderdale Council and the Environment Agency will incorporate the Hebden Bridge participatory flood risk model into their plans for reducing the impact of flooding in the Upper Calder Valley. I’ll try and find out.