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191220 | Hayle flooding: what did we know, when did we know it, and what are we going to do about it?

EXCLUSIVE – Hayle flooding: what did we know, when did we know it, and what are we going to do about it?

Posted By theboss on 20th December 2019

By Graham Smith

As the inquest into yesterday’s (Thursday’s) flooding of Hayle and St Erth gets underway, it is clear that it could not have come as a surprise. The area has such a long and detailed history of flooding that emergency services even have an evacuation plan ready to move residents to safety.

Cornwall Council’s Community Flood Risk profile for the Hayle area warns that hundreds of properties are constantly at risk.

While heavy rain on Wednesday night undoubtedly led to a rapid rise in the level of the Hayle River, some local residents believe that the development of hundreds of new properties over the past 10 years diminished the potential for natural drainage.

The area also has a vast underground network of industrial watercourses, associated with former mining activity. Contemporary knowledge of these heritage watercourses is incomplete.

The Hayle River is so well known for flooding that the government maintains an online real-time warning system. At 8.15am this morning the warning was still advising that “minor flooding is possible.”

Official documents describe Hayle as a “Critical Drainage Area” where the construction of new homes should have been accompanied by a positive reduction in the flood risk. The cost-benefit of such preventive measures is always controversial, and developers are keen to resist them.

The latest “Flood Risk Management Investment Profile” is currently described as “TBC” and “under review.” The document is prepared by Cornwall Council and the Environment Agency.

It says the “main challenges” facing the area include

  • Implementing the changes required in the Shoreline Management Plan will require a review of community development
  • Balancing the needs of the residential and commercial property owners to ensure that continued growth does not create additional risk Opportunities for Flood Risk Management in Hayle
  • The Hayle River corridor would benefit from realignment of the flood banks to create habitat and reduce flood risk
  • Along the Mellanear Stream; flood wall and embankment raising would provide an improved standard of protection
  • There may be potential to allow more flooding of the Marsh Lane County Wildlife Site area to reduce flood risk elsewhere through ecosystem services and reduce the need for pumping on the Angarrack Stream
  • Area would benefit from a Surface Water Management Plan to reduce the problems around Foundry Square and the area between Copperhouse Pool, Loggans Mill and Marsh Lane
  • Target channel maintenance and review current drainage system infrastructure capacity to reduce incidents of blockage and flooding.

A Brief History of Flooding in Hayle

- In 1970 there was flooding in the Commercial Road area from the Angarrack Stream

- In 1971 the War Memorial flooded, presumably from surface water runoff

- In 1974 Foundry Square, Loggan’s Cross, Marsh Lane, Penmare Hotel and Golden Sands Caravan Park flooded from the Angarrack Stream and Loggan’s Mill Leat

- In 1978 Penmare Hotel flooded, from assumed fluvial sources

 

- In 1979 Foundry Square and Loggan’s Cross area flooded from the Angarrack Stream and Loggan’s Mill Leat

- In 1981 Foundry Square and adjacent residential areas were flooded due to a combined fluvial and tidal event

- In 1983 Marsh Lane flooded due to unauthorised operation of a sluice

- In 1985 Foundry Square flooded when water rose through the culverts

- In 1988 Marsh Lane flooded due to surface water drains being locked by high river levels

- In 2004 the Cornish Arms, Wheal Alfred Road and Commercial Road due to surface water runoff

- In 2006 there was small scale flooding due to spring tides

- In 2008 there was flooding on road and car park following high spring tides, strong winds and storm surge


via https://cornwallreports.co.uk/exclusive-hayle-flooding-what-did-we-know-when-did-we-know-it-and-what-are-we-going-to-do-about-it/