Nick Paling, Westcountry Rivers Trust
We have been exploring the use of the SCIMAP Surface Flow Index, which shows areas of surface flow accumulation and hydrological connectivity, in combination with LIDAR Digital Terrain Model data from the Environment Agency Geomatics Group to identify opportunities for urban surface water management interventions (i.e. SuDS) to be delivered in a number of urban landscapes across the UK (Leicester, Manchester, London and Newton Abbot). Initial findings suggest that this model gives a very useful indication of where surface water is likely to flow and accumulate in urban landscapes (under high rainfall, impermeable land surface or drainage failure scenarios) and hence provides a powerful tool for local delivery groups/practitioners to target water sensitive urban design interventions on the ground.
To examine this further we have compared the performance of this model with the highly complex industry standard Local Authority Surface Water Management Plan (SWMP) models and the Environment Agency’s Surface Water Flood Risk Model (typically derived from the former). This has revealed that the SCIMAP SFI has the potential to provide highly robust and informative insights into surface water management in urban landscapes and can also illustrate some additional evidence of the sources of surface water accumulation in a cost effective and easy to interpret manner. This additional evidence makes it a potential highly useful tool for civil society groups, catchment partnerships and local practitioners attempting to target, design and deliver SuDS in their urban environment.