Caerphilly County Borough, covering the area immediately north of Cardiff, is typical of most South Wales valleys, where the significant urban areas and infrastructure are located along the narrow valley floor.
Due to its geographic location, the council area is susceptible to some form of flooding in most years. Typical of the catchment is the close proximity of urban areas to the main river headwaters.
On 5 September 2008, approximately 61 mm of rainfall was recorded falling on the county. This led to significant widespread river and surface water flooding, affecting properties and infrastructure. Residents were evacuated from their homes and some key travel routes, including the main railway line, were closed either by flooding or landslides. Several schools were also closed and a residential home evacuated.
Using simple geographical information systems (GIS) tools, the council’s Emergency Planning team assisted in the coordination of the response to the flooding. Geographic information was used to visualise on screen the relationship between the calls and reports of flooding that were being received. This approach enabled the identification of any potential problem areas and key council infrastructure that may have been at risk, including homes for the elderly, schools, community centres and so on.
To demonstrate how quickly and simply GIS can be used during the floods, the Emergency Planning team received a report from the council’s Education and Leisure Directorate that due to the earlier reported closure of the main route between Caerphilly and Newport, a number of schoolchildren would have difficulty in getting home. It was suggested that a rest centre be opened to look after the children until alternative arrangements for travel could be made. In order to determine the most appropriate rest centre, the main incident map, created using Ordnance Survey digital data, was overlaid with the council’s leisure centre dataset. The council was then able to quickly identify the most appropriate rest centre location and the safest route to that centre. It was also important to select a location that would be most convenient for parents to collect their children.
By integrating Ordnance Survey mapping into their emergency control room, staff at Caerphilly County Borough Council were able to make significant improvements in the speed and accuracy of the decisions made during the floods. Making specific use of Ordnance Survey mapping enabled staff to place multiple reports into a single context, helping to identify patterns in the incident, while ensuring people and assets were moved using the safest possible routes.