Yr12 Rivers: Soft management strategies (Case Study)
Definition: This focuses on flood abatement (reducing the scale of the flooding rather than necessarily preventing flooding,
which hard strategies attempt to do; and particularly better in built-up urban environments). However, soft strategies such
as conservation and river restoration are now taken seriously by water managers (e.g. Environment Agency); as they balance
the need for flood protection with those of improving the environment through limited interference with the natural river
system; and are considered more affordable than hard strategies, though still provide costs as well as benefits. For
instance, afforestation increases interception & potential evapotranspiration, reduces surface run-off and increases the lag
time to the river channel. However, time is needed for trees to mature from planting and needs to be on a large enough
scale to influence a noticeable reduction in discharge levels.
Case study: River Quaggy River Restoration Scheme, UK
Where: River Quaggy, south-east London
When: Quaggy Waterways Action Group (QWAG) established in 1990 by local residents.
Why:
Since the 1960s it has been heavily managed and artificial channels and culverts
(drains) were built to divert it beneath the ground as it passed through Greenwich.
This, together with the increased urban development of Lewisham and Greenwich
meant the flood risk became far greater, were the Environment Agency felt that
hard engineering such as channelisation would not be adequate protection,
economically or environmentally in the long-term
What was proposed?:
 Return the river above ground, cutting a new channel for it through Sutcliffe
Park.
 A culvert remained to take water underground during flood conditions.
 Flood storage capacity increased to 85,000m3 of water; as the park was
lowered and shaped to create a floodplain where water could collect naturally
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Yr12 Rivers: Soft management strategies (Case Study)
How successful is the scheme?
 Reduced the flood risk for 600 homes and businesses in
Greenwich and Lewisham with the creation of a new
lake.
 Created a multi-functional open space which improved
flood management by avoiding increased, rapid
discharge through artificial channels to Lewisham town
centre.
 It also created a diverse wetland environment for
wildlife with reedbeds, wildflower meadows and trees,
which won the Living Wetlands Award in 2007; run by
the RSPB.
Disadvantages?:
As the map shows, this scheme is possible due to the
availability of green spaces; which may not be possible in areas
which have very high housing densities.
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