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Catchment Area Management the Only Way to Manage Flood Risks Properly

Flooding on the Severn River

In the wake of the disastrous floods that have swamped much of lowland Britain since Christmas, a group of leading experts has echoed the opinions of experts on Sustainable Cities Collective's webinar on extreme weather preparedness a few days ago in calling for complete catchment area management of water flows as the only sustainable way to deal with the threat of flooding.

The Landscape Institute has joined together with 12 professional organisations, who regularly work together on projects designed to manage water, prevent flooding and increase resilience, to demand that the UK government put in place proper long-term planning to avoid further flooding devastation in the UK.

The group includes the Chartered Institute of Water and Environmental Management, The Institution of Environmental Sciences, Royal Institution of Chartered Surveyors and Energy Institute.

Floods in Fowey, CornwallIn a letter, they call for a complete re-think to the way the country manages, stores and distributes its water, and how it plans both the natural environment, and the built environment of towns and cities to make them more resilient.

The letter clearly states that a comprehensive range of water management techniques could have helped prevent the effect of water through villages, towns and over surrounding land seen recently, and it warns against dredging (as on the Somerset Levels) as a universal panacea for the problems as it may increase flooding to towns downstream. 

It calls for proper exploration of the larger catchment management issues, and how forestry, land management and soft engineered flood alleviation schemes can hold back water in the upper reaches of rivers, and work alongside a dredging programme in the lower reaches.

In town and cities the group advises that the planning of all new developments and regeneration schemes include a wide range of flood alleviation and protection measures.  It wants all new housing in flood plains to be resilient from the moment they are built and for Sustainable Drainage Systems (SuDs) to be comprehensively retro-fitted, and for SuDs to be a compulsory requirement for all new buildings.

The group call for an immediate cross-departmental conference with the Department for Energy and Climate Change (DECC),the Department for the Environment, Farming and Rural Affairs (DEFRA), the Department for Communities and Local Government (DCLG), the Environment Agency and National Resources Wales (NRW), in a similar manner to that which was convened to address the problem of ash-dieback (a disease affecting ash trees across the country).

Speaking about the letter, Sue Illman, President of the Landscape Institute said: "Why do we keep spending money putting homes and lives back together when we could spend it more effectively preventing the problem?

"The Landscape Institute has long been campaigning for Water Sensitive Planning - that considers the entire water cycle - for a comprehensive programme of retrofitting SuDS in our towns and cities, and the full implementation of schedule 3 of the Floods and Water Management Act. We need hard and soft engineering to work together to manage water, protect people and their livelihoods, whilst improving the natural and built environment for all." 

The letter was also sent to the Secretary of State for the Environments, Owen Paterson, Anne McIntosh, Conservative Chairman of a cross-party Select Committee on Environment, Farming and Rural Affairs (which is conducting an enquiry on the best way to deal with flooding), and Lord Smith, chairman of the Environment Agency.

Meanwhile, many voices, such as Greenpeace, are calling for Prime Minister David Cameron to remove Owen Paterson from his position as Environment Secretary because he does not believe in climate change. Greenpeace's petition has reached 55,000 signatures, a separate petition launched by 38 Degrees has reached almost 10,000 votes, a further UK Government managed epetition has reached nearly 5000 votes, and a Facebook page has over 2000 likes.

The cures for flooding

Here are the remedies for flooding, according to the expertise of the Landscape Institute:

  • It's time to look beyond the idea that a pipe in the ground is the best option for getting rid of rain water – this is an obsolete 19th-century solution to a growing 21st-century problem;
  • We need to start prioritising all elements of the water cycle when designing and developing new places;
  • We need to better understand the economics that allow soft planted (bioengineered) drainage schemes to cost less whilst increasing property values;
  • When planning outdoor space, we must consider 'whole life costs' and recognise the multiple benefits which arise from sustainable design: attractive liveable spaces, increased biodiversity, better air and water quality, improved public health and enhanced land values.

Sustainable Drainage Systems (SuDS) – better resilience against flooding

  • SuDS are an increasingly important part of our green infrastructure;
  • Through the creation of ponds, wetlands, swales and basins, which mimic natural drainage by absorbing or attenuating water into permeable surfaces and vegetated surfaces, we can slow down water and help to prevent surface flooding.
  • SuDS are a cost-effective way to reduce flood risk and damage.
  • SuDS are being embraced elsewhere in the world. Investment is accepted as an economical and sustainable way of protecting against the costs of flooding. 

International examples of SuDS:

  • Since 2001 in Augustenborg, a highly populated inner-city suburb of Malmö, Sweden stormwater has been dealt with via a complex arrangement of green roofs, channels, ponds and small wetlands. Green roofs are effective at lowering total runoff, and the ponds successfully attenuate storm peak flows for even 10-year rainfall;
  • In Portland, Oregon a long-established (10 years) downspout disconnection programme protects more than 42,000 homeowners and has removed more than 1.3 billion gallons of stormwater per year from the combined sewer system;
  • In 1980 Tokyo installed an 'Experimental Sewer System' (ESS) in about 249 ha of the city, which included permeable pavements, porous concrete blocks, infiltration trenches on housing sites, streets, school grounds and public gardens and water storage tanks to provide water for toilets, sprinkling, car wash and a recreational pond. So successful was the control of stormwater runoff that the Tokyo Metropolitan Government has since built the ESS over an area of more than 1,423 ha with 33,294 infiltration pits, 285 km of infiltration trenches and 484,000 m2 of permeable pavement. Water Sensitive Urban Design (WSUD) – an integrated solution to flooding, droughts and water quality;

Water Sensitive Urban Design:

  • means thinking about water supply, waste water, surface water and flooding when planning and designing new places – rather than as an after-thought. 
  • improves the quality of water entering the waterways, allows for storm water and grey water harvesting and reuse, and delivers significant reductions in potable water needs;
  • reduces pressure in existing infrastructure, directs flood waters away from homes and businesses and reduces the amount of water entering the sewers Landscape Institute recommendations;

The Landscape Institute also calls upon the UK government to:

  • implement in full the UK's Flood and Water Management Act, which would ensure the use of SuDS on all new developments in the UK;
  • remove the 'un-economic cost' get-out in the Draft National Standards unless exceptional circumstances exist (with 'exceptional' being defined);
  • Consider soft options first, to obtain multi-functional benefits of green infrastructure;
  • Adoption of water sensitive urban design policies in every Local Plan;
  • Embark on a comprehensive programme of retrofitting SuDS alongside larger water catchment management programmes and flood defence programmes.