UK: Aerial laser mapping technology is helping Wiltshire Council investigate flooding in the town of Corsham. Working with engineering consultancy Atkins, the Bluesky LiDAR data is being used to create a hydraulic model of the drainage network and its interaction with the watercourses serving the catchment. This detailed model will allow Council staff to predict the flow of flood water, as a result of rainfall falling directly onto the ground and of flow overtopping river banks or escaping from the drainage network via manholes and gullies.
In September 2014, heavy rainfall caused extensive flooding across Wiltshire. Wiltshire Council and Wessex Water worked alongside the Corsham Town Council, Police, Ministry of Defence and local schools to minimise the impact of flooded roads, including the major A4 trunk road. The same event flooded the railway line, and passengers had to be rescued from a train after it became trapped in flood waters.
Using the Bluesky LiDAR data, captured using aircraft-mounted lasers, a hydraulic model of the drainage network in the Corsham catchment area is being created. A hydraulic model is a mathematical model of a fluid flow system, such as a water, sewer or storm system, and it is used to analyze the system’s hydraulic behavior. Using the Bluesky data, the staff at Atkins created a 2D mesh over the catchment area, which allows them to see the likely flow of water and its potential impact on people, property, and infrastructure.
“Working with Bluesky, we were able to configure the LiDAR survey to meet our requirements,” commented Sophie Slade, Consultant Hydraulic Modeller at Atkins Global. “In fact, Bluesky gave us a choice of resolutions and a range of survey areas to allow us to decide on an appropriate scope for the modeling project. In the end, we were able to secure a higher resolution of data at the same price.”
Daniel Everett, Principal Drainage Engineer at Wiltshire Council, added, “Once the detail of the survey had been agreed, delivery of the data was prompt and we were kept informed at all stages.”
Since 2007, Wiltshire Council has established two Operational Flood Working Groups in order to address the growing threat of flooding. These groups provide a forum for stakeholders, including the Environment Agency, water companies and Town and Parish Councils, to work together to reduce flooding and its impact on communities.