The Risk of Flooding from Surface Water (RoFSW) product draws together:
- Environment Agency national-scale surface water flood mapping (carried out to support and on behalf of the Lead Local Flood Authorities – LLFAs – in 2013) and
- locally produced detailed mapping, as provided by the LLFAs.
There are approximately 3.2 million properties at risk of surface water flooding in England, out of a total of 25.7m (NRD 2014). Out of those, approx. 1.8m are within local detailed model extents (7%).
Local detailed models cover an area of 1060 km2, which is just shy of 1% of England. Given that vast majority of local detailed ROFSW models cover urban areas and these constitute 8% of England by area, approximately 10% of all urban areas are covered by local detailed modelling.
With the upcoming Boosting Action on Surface Water models, we will more than double the proportion of local detail modelling coverage for both area and property totals, within the next year.
The ROFSW product is updated with local detailed modelling on approximately annual basis. Most recent update (June 2021) encompasses local detailed modelling outputs for the following areas:
- Barking & Dagenham (Whole Borough)
- Ealing (Greenford, Northfield Avenue, Perivale, Yeading Lane, Beech Avenue, Carr Road)
- East Sussex (Hastings Central, St Leonards Warrior Square)
- Hertfordshire (Baldock, Bengeo, Berkhamsted Kings Road, Bishop’s Stortford West, Bishop’s Stortford East, Broxbourne Chesthunt, Broxbourne Rosedale, Broxbourne Flamstead End, Broxbourne Wormley, Buntingford East, Buntingford West, Hitchin Cambridge Rd, Hitchin Town Centre, Hemel Hempstead Highfield, Kings Langley, Knebworth, North Hoddesdon Rye House)
- Gloucestershire (Whaddon)
- Hammersmith and Fulham (Whole Borough)
- Hounslow (Hounslow Town Centre, Brentford North)
- Oxfordshire (Waterstock)
- Shropshire (Hopstone)
- Warwickshire (Wellesbourne)
- Westminster (Whole Borough)
- Windsor and Maidenhead (Ascot – Woodby Drive)