Summary
Small watercourses, drains and culverts are often where national scale flood maps are least precise. A property can sit outside a broad planning Flood Zone but still face local flood risk from an ordinary watercourse, blocked culvert, undersized drainage structure or steep overland flow path. Local Strategic Flood Risk Assessments and Lead Local Flood Authority records can be more useful than national layers in these cases.
Definition
Small watercourses and culverts are local drainage and watercourse features that may not be fully represented in national flood mapping, especially where channels are minor, hidden underground, privately maintained or affected by blockage risk. Buyers should investigate local SFRAs, Section 19 flood investigation reports, drainage records, water company sewer maps, visible channels, headwalls, trash screens and planning documents where a ditch, culvert or ordinary watercourse is near the property.