ILKLEY & DISTRICT U3A STUDY DAY
FLOODS – PAST, PRESENT AND FUTURE
Wednesday 29 October 2014 at St Margaret’s Hall, Queen’s Road, Ilkley
The aim of the day was to give U3A members the opportunity to understand some of the causes of flooding, why instances of flooding seem to be occurring more frequently, and what can be done to lower the risk from flooding and prevent serious damage and loss of life.
We were pleased to welcome 6 members from the U3A group in Wetherby, who swelled the numbers attending to 57. The morning session consisted of 3 talks from U3A members covering the historical background to flooding, some basic meteorology and possible links between extreme events and climate change, followed by 2 case studies of recent floods. In the afternoon, two speakers from the Environment Agency talked about flood risk management and funding, and the role of the Environment Agency in managing the River Wharfe. This was followed by two speakers from the Yorkshire Dales Rivers Trust, a registered charity, on natural flood risk management, including projects on two catchment areas (a) Swale, Nidd, Upper Ouse, and (b) Wharfe and lower Ouse. We were delighted that the external speakers were able to join us for the whole day and contributed to discussion in the morning sessions too.
Summary of the talks 1 Jim Butterfield (U3A member) The hydrological cycle and a historical perspective of flooding There are flood legends in many religions and cultures, often involving a wrathful deity. Many examples of flooding in historical records (e.g. in Pepys Diaries in the 1660s, Old Bridge in Ilkley replaced in 1676 after being swept away). Flooding in China in 1931 was world’s biggest natural disaster with about 4 million deaths. The hydrological cycle - constant cycle of evaporation and transpiration, condensation into clouds, precipitation, ground water flow and storage, and plant uptake. Importance of understanding behaviour of ground water – when ground is saturated, rainfall runs away on surface. History of flood defences from first agricultural settlements to present day. Anthropocene age – large dams are being constructed, major rivers diverted, increased ground water extraction, impact of growing population and economic growth. Use of water resources now moved to a much broader base involving multipurpose management.
2 Mike Pilling (U3A member, Emeritus Professor in Physical Chemistry, University of Leeds) Extreme weather events – meteorology and the effects of climate change A combination of extreme weather events in the winter of 2013-14 which led up to the flooding in Somerset and other areas in the south of England. - High rainfall in Dec and Jan (wettest 2 month period since 1910), increasing the ground saturation. - Major storm Jan 5-6 which coincided with exceptionally cold weather in Canada and northern US states. This cold weather was linked to perturbations in the Jet Stream over the Pacific Ocean, North America and the Atlantic Ocean. Some meteorological background on the origin of the Jet Stream and the role of the Rocky Mountain range in splitting and diverting the Jet Stream. The two branches of the North American Jet Stream combine and form the North Atlantic Jet Stream, which normally passes to the north of the UK, but in winter of 2013-14 it swung to the south causing a series of depressions and heavy rain over southern England. Models for forecasting climate and weather and how they are constructed. Increasing sophistication of the models. Summary of the recent IPCC 5th Assessment Report on the effects of climate change. Increasing evidence that extreme daily rainfall is becoming more intense, with a probable contribution from climate change.
3 Jackie Beecham (U3A member) Two case studies: Boscastle (2004) and Barèges (2013) There were common features to the flooding in the two areas. Both places are situated in steep-sided valleys with an underlying geology of impermeable rock. In both cases several events coincided to lead to the flooding and small, low bridges trapped debris and impeded water flow. Boscastle, Cornwall (16 Aug 2004) Very heavy rain (remnants of Hurricane Alex) over 8 hr period falling on already saturated ground from rain over previous 2 weeks. Two rivers (Valency and Jordan) meet in Boscastle and overflowed. Sudden surge of water coincided with high tide. Large trees, cars and buildings formed part of debris trapped by low bridge. Damage estimated at £50 million. Flood defences (none before) now in place include a new large culvert on River Jordan to carry double the amount of water, Valency River widened and deepened, new higher bridge, new tree management and new sewage pumps and stations.
Barèges, High Pyrennes (18 June 2013) Unusually cold spring left deep snow on the ground. Series of avalanches (Feb-May) blocked river channels with snow, rocks and tree debris. Warm southerly wind on June 17 accelerated snow melt. Le Baston river burst its bank, changed course and broke existing flood defences. Some homes and businesses washed away. Bridges washed away, except one which trapped debris. Damage estimated at 30 million euros and several elderly people died because of shock. Improved flood defences, including new style bridges and some areas beside river left blank to allow the water to spread.
4 John Woods (Flood Risk Advisor, Environment Agency) The role of the Environment Agency in flood risk management and funding for schemes In Bradford district, 5606 properties at risk of flooding from rivers (varying from significant to low risk); in addition 18 502 properties at risk from surface water. If you live on a flood plain, your house is more likely to be flooded than to catch fire. Number of properties at risk from flooding in Ilkley is 43, in Addingham is 196. Role of the Environment Agency in reducing risk from flooding - regulations - forecasting and warnings - flood risk mapping and modelling - emergency response - maintenance - investment justification, improvements, new schemes Two proposed schemes in Ilkley (Backstone Beck culvert improvement would benefit 55 houses and Denton Road Flood Alleviation Scheme would benefit 88 houses). Sources of funding include, among others, DEFRA Flood Defence Grants, Local Levies and contributions from developers. Detailed explanation of how funding is allocated. New approach to ways in which projects are assessed and funded (change from previous ‘all or nothing’ approach in which selected projects deemed to deliver best value for money were fully funded, to more flexible system in which a fixed rate of funding per £1 of benefit is offered to all proposed projects and other funding or cost- saving sought to meet the remainder).
5 Mark Fuller (Flood Risk Advisor, Environment Agency) The role of the Environment Agency in carrying out river maintenance and maintaining our structures. Managing the River Wharfe. Environment Agency guide ‘Living on the Edge’ explains the rights and responsibilities of a riparian landowner (owning land adjoining a river) and who is responsible for flood risk management and flood defences, and what that means in practice. Environment Agency has powers to work on main rivers and the sea to manage flood risk, but it does not have to maintain or construct new works. Environment Agency has duties to produce a national strategy (with DEFRA) for flood and coastal erosion risk management, and to promote conservation of the natural water environment. Work on the River Wharfe includes - routine maintenance (grass cutting, vermin control, tree works, structure maintenance etc) - majority of routine maintenance downstream from Tadcaster - project work (floodbank repair, erosion control etc)
6 Dan Turner (Yorkshire Dales Rivers Trust) Natural Flood Risk Management and the River Cover Project Increasing flood risk from effects of climate change, increasing population and urban sprawl, change in land use, intensification of agriculture. Natural flood risk management – a multi-benefit, proactive approach that is resilient to future predicted climate trends, involving - Making space for water (e.g. Moors for the Future, Peak District) - Source to sea (e.g. on National Trust land at Holnicote, Exmoor) - Slowing the flow (e.g. forest research, better land management, Pickering) - Sustainable urban drainage systems (e.g. London) Moors for the Future Project in the Peak District involves restoration and stabilisation of eroded peat areas to slow run off. Upper Derwent is source of water for regular flood events affecting the Derwent and subsequently the Trent. River Cover Project in North Yorkshire aims to study the effect of installing wooden debris in the river (which has been straightened in the past) to slow down the flow. The River Cover rises on the slopes of Buckden Pike and Great Whernside and flows into the River Ure, and eventually into the Ouse. Crowd source funding – raising monetary contributions from a large number of people, typically via the internet.
7 Rita Mercer (Senior Project Officer, Yorkshire Dales Rivers Trust) Dales to Vale Rivers Network In 2013, the Yorkshire Dales Rivers Trust secured a DEFRA grant to host 2 catchment partnerships (a) Swale, Nidd, Upper Ouse, and (b) Wharfe and Lower Ouse. Using a catchment-based approach, develop a plan based on observational data and evidence rather than anecdotes. Monitor the resulting outcomes and improve the plan. Aim is to produce a shared overarching vision for each catchment area, drawing together key stakeholder organisations into a cohesive Project Partners Group. Keen to attract and train volunteers.
Organisers: Mike Pilling Jim Butterfield Jackie Beecham Angie Grain Alan Kay
Report prepared by Gwen Pilling