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Soft engineering case study:River quaggy


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GCSE geography

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Soft engineering case study:River quaggy

  1. 1. Soft engineering: River Quaggy restoration scheme Location: The River Quaggy is an urban river, 17 km in length, passing through the south-east London boroughs of Bromley, Greenwich and Lewisham. It rises from two sources near Farnborough Hospital at Locksbottom and is a tributary of the River Ravensbourne which it flows into near Lewisham station in Lewisham. Causes of management: Since the 1960s the river has been heavily managed and artificial channels and culverts were built to divert it beneath the ground as it passed through Greenwich. As a result of increased flood risk due to continued urban development in Lewisham, more was needed to protect the area from flooding. The Environment Agency had to make a decision about if the river should be channelised to make it more efficient or choose a soft engineering approach in order to protect the river. Why soft engineering? This method of management was proposed by the local residents who formed the Quaggy Waterways Action Group to campaign for a sustainable approach which would improve the local environment. It was thought that a soft engineering approach was both environmentally friendly and cheaper to use than hard engineering. The local habitats of many animals in the area, such as Water voles and Stag beetles, would also be left unaffected by the restoration scheme. Schemes employed to prevent flooding:  The plan was to bring the river back above the ground once again, cutting a new channel for it through Sutcliffe Park, and creating a multifunctional open space. In this way flood management and the quality of the park would be improved. Although a culvert remained to take some water underground during flood conditions, a new lake was created to take over when this became full.  The park itself was lowered and shaped to create a floodplain where water could collect naturally instead of rushing downstream through artificial channels to flood Lewisham town centre. The park’s flood storage capacity
  2. 2. of 85,000m3 of water, equivalent to 35 olympic swimming pools, has reduced the risk of flooding for 600 homes and businesses in Greenwich and Lewisham, and has created a diverse environment for wildlife. By redirecting the river to a more natural course and including a flood storage area, the scheme has created a wetland environment with reedbeds, wild flower meadows and tree. The scheme won the Natural Environment category in the 2007 Waterways Renaissance Awards and the Living Wetlands Award, run jointly by the RSPB and the Chartered Institution of Water and Environmental Management. This is a photograph of the River Quaggy going through Sutcliffe Park. Now the Quaggy flows through the park in a reconstruction of the original route. In storm conditions, the water enters the old trough but then discharges into the park to form a temporary lake. The restored Quaggy has been planted with waterside plants and a small permanent lake has been formed, so the park provides a wildlife reserve and a fun place to play. The Quaggy is being closely monitored to see how it changes its course and how the wildlife develops. What is learnt here will be used in other flood-control schemes. The reeds that have been planted in order to support the bank and to lessen he effects of erosion. These reeds also are the new homes of some new aquatic animals. The reconstruction of the wetland environment has brought some new animals to the area including Kingfishers.