How the Loddon catchment floods • A summary of our best information and an opportunity to share it with you all. • Reach agreement on what the challenges are. • Discuss ways of working that provide multiple benefits. • Provide a platform for working together on shared solutions. 1. Summary of Catchment Overview of the River Loddon and its tributaries Catchment characteristics: Area, River length Geology, Standard Percentage Runoff (SPR), Landuse and critical infrastructure Flood Alert and warning areas Catchment Response to Rainfall Historic flooding Past experiences The Loddon and it’s tributaries • The Loddon is approx. 45 km long. • It originates from the chalk of the Hampshire Downs at Basingstoke. • It is fed from Groundwater springs. • The major Loddon tributaries are The River Hart, Blackwater, Whitewater and Emm Brook. • It joins the Thames West of Wargrave, downstream of Shiplake Lock. • Flood storage at Cove Brook and some attenuation in the gravel pits in the Blackwater Valley which take runoff from new developments.
Catchment Geology Standard % Run Off (SPR) Urban and Riparian
Reading
Wokingham Bracknell
Crowthorne
Sandhurst
Camberley
Frimley
Farnborough Fleet
Basingstoke Aldershot Critical Infrastructure
Six Flood Alert Areas 15 Flood Warning Areas Rainfall needed to cross threshold for varying SMDs Alert criteria: 10-15mm on a wet catchment; 30mm + on a dry catchment
Warning criteria: 20-60mm on a wet catchment; Rarely exceeds Flood Warning when catchment is dry Sources/types of flooding
Groundwater – e.g. Basingstoke 2000/01 Surface Water – e.g. Winnersh, Wokingham 2007 Fluvial – e.g. Lower Loddon 2013/14
Types of events
• July 2007 – Summer, high intensity storms, relatively short durations. • Winter 2013/14 – Long duration, conveyor belt of active weather systems caused saturated ground. Chineham Chineham, Basingstoke – Upper Loddon – July 2007 Chineham, Basingstoke – Upper Loddon – Winter 2013/14 Chineham, Basingstoke – Upper Loddon July 2007 level = 1.3 mASD, flow = 2.9 m³/s Dec 2013 level = 0.8 mASD, flow = 1.1 m³/s July 2007 event – 54mm in 15hrs Winter 2013/14 – 52mm in 19hrs
• July 2007 was largest on record at this site. • Winter 2013/14 was 4th largest on record.
Tongham Tongham, Aldershot – River Blackwater – July 2007 Tongham, Aldershot – River Blackwater – Winter 2013/14 Tongham, Aldershot – River Blackwater July 2007 level = 1.8mASD, flow = 2.5 m³/s Dec 2013 level = 1.6mASD, flow = 1.9 m³/s July 2007 event – 52mm in 14hrs Winter 2013/14 – 38mm in 20hrs There is a small difference in actual levels between bankfull and property flooding. Lodge Farm Lodge Farm, River Whitewater – July 2007 Lodge Farm, River Whitewater – Winter 2013/14 Lodge Farm, River Whitewater – Winter 2013/14 Lodge Farm, River Whitewater – July 2007 July 2007 level = 0.6mASD, flow = 3.3 m³/s Dec 2013 level = 0.5mASD, flow = 2.2 m³/s July 2007 event – 52mm in 14hrs Winter 2013/14 – approx 370mm over 6 weeks
July 2007 highest on record Winter 2013/14 2nd and 3rd highest on record Lodge Farm, River Whitewater – July 2007 Levels at lodge farm are affected by a sluice gate just upstream, which is operated by the pub owner (used to be a mill). This can result in a surge of flow moving downstream. Basingstoke canal can heavily overtop into the river here at times of high flows
Sindlesham Mill Sindlesham, Lower Loddon – July 2007 Sindlesham, Lower Loddon – Winter 2013/14 Sindlesham, Lower Loddon
July 2007 level = 1.5mASD Feb 2014 level = 1.2mASD July 2007 event – 54mm in 15hrs Winter 2013/14 – 58mm in 46hrs
July 2007 highest on record Winter 2013/14 8th highest on record
Sindlesham Mill Loddon Bridge Park & Ride, Cinema Winnersh Garden Centre and the George Pub (DS) of Sindlesham Mill Wokingham, Emm Brook – July 2007 Wokingham, Emm Brook – Winter 2013/14 Wokingham, Emm Brook
July 2007 level = 2.3mASD, flow = 11 m³/s Feb 2014 level = 1.6mASD, flow = 4 m³/s July 2007 event – 54mm in 15hrs Winter 2013/14 – 122mm over 2 weeks
July 2007 highest on record Winter 2013/14 3rd highest on record Twyford Twyford, Lower Loddon – July 2007 Twyford, Lower Loddon – Winter 2013/14 Twyford, Lower Loddon July 2007 level = 2.8mASD, flow approx (50-70 m³/s) – some bypassing of the gauge at high flows causes uncertainty in estimates Feb 2014 level = 3.1mASD, flow approx (75+ m³/s) July 2007 event – 62mm in 8hrs Winter 2013/14 – approx 300mm over 6 weeks It is also common for high Thames levels to ‘back up’ the River Loddon, delaying its peak to produce even more protracted flood conditions in the lower reaches. Swallowfield – full record back to 1987, one of the longest records we have for the Loddon Historic Flooding Date Details of Flooding
Winter 2013- 6 Reported 2014 July 2007 131 properties
2006 59 properties (10 Farnham, 34 Alderhot, 15 Ash Vale)
January 2003 12 properties flooded in Loddon Drive
November 2000 7 properties unsubstantiated
October 2000 2 properties flooded 17 properties unsubstantiated December 1999 2 properties flooded
1998 2 properties flooded
February 1990 3 properties flooded Gardens of 30 properties
Wokingham
Aldershot Whitewater road run off 2007 (top left) Blackwater Frimley 2007 (top right) Blackwater Eversley 2007 (bottom right) Arborfield 2007 (road photo 2011) 2007 flooding The Emm Brook flooded in July 2007 when approximately 90 properties flooded in Wokingham. A further 100 were surrounded by floodwater. The Blackwater and Cove Brook catchment also flooded in 2007 affecting the areas of Farnborough, Aldershot, Ash, Ash Vale and Cove. Winter 2013-2014 Early Jan 2014 Six reported properties:- -1 in Arborfield -1 at Twyford/Wargrave area, -1 at Aldershot, -1 at Farnborough -2 at Crookham.
-The Winnersh park and ride site was closed for the majority of the flood event (Dec – Feb) -The Winnersh garden centre in the Lower River Loddon alert area flooded on several occasions. -Also looks like Twyford reached its highest recorded level in February!
Progress – the story so far
Owen Peat - 2007 event Lindsey Newton 2009 – legal context Angela Gunnel (QMUL) 2011 – woods in rivers QMUL 2014 – 2 MSc dissertations - Flood risk and work in Blackwater Valley (Farnham Quarry) - Managing fallen trees
Ongoing & completed projects Water Framework Directive & Flood Risk: working together, making space for water, working with natural process
Flood Risk Management Plans
Flood/Hazard Map RBMP Costs and Benefits? Do we need change?
Costs? Are we turning our backs on rivers and coasts? we still flood, the future cost?, 30% topsoil (national), draining land everywhere, >90% river length modified (Thames) and over 80% waters failing ecology, Thames salmon gone = restaurants, B&Bs, tackle shops closed, membership decline, upper Thames not good ecological state, many wildlife impacts, economic benefits of a healthy environment, community cohesion, fertiliser /maintenance costs, somewhere for children to play and visitors enjoy (future), culverting, accessible blue/green infrastructure, unsafe water… This may cost tax payers a very indicative £500k to £3.8million per catchment every few years (2014 Environment Agency national catchment event). Cost £9.5million to £72.2million in the Thames basin every few years. Can we afford not work together, is this estimate right?
Whats to gain? Better soils, sustainable futures, solving problems not symptoms, bridging gap between poor and rich from up-skilling, employment and outreach, we are happier and work together.. Water for life and livelihoods; a better balance between using and protecting the environment. A sense of place toenjoy
Do we want to turn our back on catchments, wetlands, rivers and coasts? (Mersey Basin Campaign following 1981 riots etc) flooding scenarios suggest not.
Get in touch with River Basin Management Plans, Flood Risk Management Plans and catchment delivery to help solve these for you and our future generations in your catchment Flood risk management duties & obligations National Flood & Coastal Erosion Risk Strategy Avoid damaging the environment, wherever possible work with natural processes Always seek to provide environmental benefit, as required by Water Framework Directive
England Biodiversity Strategy 2020 5000ha new habitat 95% SSSIs in favourable condition
WFD FCRM works must not cause deterioration to the ecology of a water body FCRM should try to find opportunities to improve the ecology of water bodies What can we do?
Collaborative advantage
Adopt Catchment Based Approach
Work with natural processes
Develop & promote good practice
Design projects early with multiple benefits
Spatial planning and development solutions
We are all the solution
Right measures in precisely the right place
Aiming for multiple benefits
(Semi Natural) Gravel bed and earth banks
Multi Benefit Aspirational
Single Focus GEP
Highly Modified Channel Culverted or channelised
Practicing working with natural processes Working with natural processes restores habitats and improves flood risk management by design
Thames river basin district: Significant water management issues Solutions: community action, flood management and wider interest turning this...
WFD Directive 2000/60/EC – framework for community action in water policy… AND DELIVERY http://ec.europa.eu/environment/water/water- framework/index_en.html To this: better soils, reducing run off managing flood risk Cotswolds and Upper Thames
Source: D Martyn from Upper Thames visit Managing Thame catchment run off and diffuse pollution
Source: P. Nicolet January 2014 Thames RBD Liaison Panel presentation River of Life – Thames Shillingford
Source: L Stephenson Multiple benefits Hanson Aggregates, Farnham Quarry River Blackwater river and floodplain restoration – phase 2 completed Dec 2013 for improving community asset, working with communities, flood risk management, WFD, biodiversity and fisheries, urban diffuse pollution, adapting to climate change..
Source: D Martyn Via development – before and after, Cornmill Gardens Lewisham, River Ravensbourne
Now? Less crime, a valued and valuable, accessible local asset, sense of place, emotional, hearts, minds And reducing flood risk. Improving health and wellbeing River Quaggy Chinbrook Meadows restoration: flood management, public access, climate change & ecology River Quaggy wetland flood alleviation 2003 means: “...one of the most spectacular wetland sites in Greater London, rich in wildlife and providing a home for a variety of birds, animals and plants.” Royal Borough of Greenwich
UNCLASSIFIED 6 8 Sutcliffe Park – plan
UNCLASSIFIED 6 9 The benefits of ponds & basins • Ponds: - Natural ecosystems - permanent waterbodies - Benefits: - Reduce runoff - Provide excellent wet habitat - Amenity/educational resource • Basins: -Temporary wet features Image source: Construction online, - Capture rainfall and slowly infiltrate 2011. - Benefits: - Reduce runoff - Reduce pollution – solids settle out - Provide habitat - Groundwater recharge
Image source: SuDS Wales, 2013. Lee tunnel – to help reduce CSO pollution (early construction photo) There’s other benefits for us and its not just the ecology. Towards WFD good status and potential?
The River Lambourn in Newbury, Blackwater at Hawley and Carshalton Arm of the Wandle are getting there as are others… Looks good and highly valued?! South East Rivers and Wetlands Community Days Improving rivers and wetlands for people, floods and wildlife
73 Reconnecting people and nature: flood &wildlife bypass channels working with natural process Shift from fixed to moving parts (sediment transport) Trees for refuge and morphology adjustment Fish and wildlife spawning grounds Backwaters solutions: academic partnerships understanding actions to good ecological status and potential while targeting flood risk
Queen Mary University London (R. Ing 2012, C. Orlandi Pinto 75 2013)