CM2 The Process
Nine people participated in the Otley Community Modelling group – two academics (Nick and Matilda) and seven people from Otley. Two of the participants worked for the Yorkshire Dales Rivers Trust which is also involved with flood modelling further upstream in the River Wharfe catchment. The group met four times, with each session lasting two to two and a half hours, in the Otley Town Council’s meeting room.
The first session drew on information gathered in interviews done by Matilda, summarising people’s perceptions of local flooding and potential solutions. Nick, the scientific modelling expert, explained the difference and application of hydraulic and hydrological models in the context of basic hydro-geomorphology to enable the group to decide what processes to model and what type of model to use. The group opted for HEC-RAS, a hydraulic model that is free to use, to consider flooding in the affected area within Otley. All group members were encouraged to download the software for themselves and use it in between meetings.
In the second session Nick introduced a basic version of the model set up for a river like the Wharfe. This session was an opportunity to try out the HEC-RAS user interface, and to understand the different ways in which local flooding could be modelled. In the session group members got to use the HEC-RAS software on laptops to draw their own river channel transects.
For session three Nick had developed a prototype representation of the area to show to the group. He explained how the model represented the local landscape and how different flows generated inundation zones, depths and velocities.
The fourth session summarised the progress made. This included confirming the total volume of flood water calculated to be moving through different channels, and from that information discuss which management solutions might be the most effective and feasible. Some final modelling was done at the end of the session showing how different flow channels were integrated into one model, and how it might be used to represent the management options. Group members found that the model appeared to accurately simulate the December 26 flood event in 2015.
Videos about the CM2 Process