According to the UK Met Office, 2012 was the second wettest year since records began, and whilst the effects of climate change on rainfall are still unclear, it is likely that the UK will experience more frequent extreme weather events including the prolonged and intense rainfall that results in flooding.
Flood warnings in England and Wales are issued by the Environment Agency (EA) which records rainfall and operates a network of monitoring stations that measure river and sea levels. Data from this network are used to generate flood warnings and the EA aims to issue these at least 2 hours in advance of flooding.
Over 5 million people in England and Wales live and work in properties that are at risk of flooding from rivers or the sea, and the cost of flooding in 2012 has been estimated at £1billion which is almost double the annual investment in England and Wales for building and maintaining flood defences.
The problem in Oxton
Oxton village has a long history of flood-related problemscaused in large part by the local geography which during times of high rainfall, funnels land, road surface and lake water into a stream (known locally as the Oxton Dumble) which passes through the village and eventually flows into the Dover Beck. The construction of a flood relief channel in 1984 was designed to take much of this excess water around the village perimeter and whilst this has undoubtedly been beneficial, the channel needs to be regularly maintained and kept clear of bushes, trees and other debris if it is to be given a chance to cope with the more extreme rainfall events.
Subscription to the EA’s flood warning system can provide timely alerts to those in flood-susceptible areas. Occasionally and for various reasons, however, even the flood relief channel in Oxton cannot cope and in both 2007 and 2009, flooding caused devastation to a number of residents’ homes and local businesses; 14 homes were damaged in 2007. Even as recently as December 2012 and January 2013, properties narrowly escaped flooding although roads in the village became impassable and water was brought up to doorsteps.
Flooding in Oxton is therefore related to the river levels and rainfall that are recorded by the EA, but because of local conditions, flooding can occur in Oxton when the EA has not issued a warning.
Recognising a need to be able to monitor water level in the village stream with an ability to raise an alarm when certain conditions arise, Oxton’sParish Council obtained a monitor from OTT Hydrometry known as an ‘Orpheus Mini’which has been installed in the water course and now monitors and logs water temperature and level continuously. An alarm level has been set and when this is reached, the instrument automatically issues an alarm text message tomembers of Oxton’svolunteer emergency response flood team and to those residents whose properties are most susceptible to flooding. After receiving an alert, the flood team assembles at itsresilience store to begin the deployment and building of temporary flood defences,including Aqua-Sacs, to prevent the rising waters from reaching residents’ homes.
In December last year, thelevel monitor raised the alarm three times, which initiated the successful deployment of the village flood plan and prevented any significant damage.
Explaining the advantages of Oxton’s early flood warning system, Dr. Kilpatricksays, “As a result of recent events, the residents of Oxton are more sensitive to water levels than most. However, we cannot watch the stream every day of the year and certainly not at night, so a continuous automatic monitor is the ideal solution.
“Theinstrument has raised several flood alerts since its installation in July 2012 and thereby helped us to prevent similar disasters to those experienced in 2009, 2007 and earlier.”
Clearly, Oxton’s flooding potential is affected by a number of local conditions. However, OTT Hydrometry’sManaging Director, Simon Wills, believes that many more communities suffer from a similar susceptibility and would therefore benefit from this technology. “Both sensor and telemetry technology have advanced considerably in recent years, so we are now able to supply low cost, easy to use, ‘off the shelf’ equipment that can provide residents with vital advance notice of local flood conditions,”he says, adding: “This does not in any way replace the flood warnings that are issued by the Environment Agency, but it does enable local people to build a reliable low-cost warning system that is dedicated to their specific needs.”