The increased amount of surface water drained from developed
areas is having a huge impact on Britain's river catchments.
As development intensifies, less water can filter through the
soil, which leads to increased flows and risk of flooding, and also
a threat to water quality and the environment. This will worsen as
the climate changes.
This has put drainage and water management firmly under the
legislative spotlight. For example, you now need planning
permission to lay an impermeable driveway or parking area that
measures over five square metres. The Code for Sustainable Homes
also imposes minimum standards for surface water management.
With a conventional drainage system, rainwater is carried away
as quickly as possible from where it has fallen. This can lead to a
number of problems:
- Water run-off from impermeable paving can cause flooding
- Run-off water rapidly picks up contaminants such as oil,
organic matter and toxins resulting in poorer water quality in
rivers and groundwater.
- The redirection of rainfall into piped systems means a
reduction in the amount in water seeping directly into the ground
and this results in reduced flows during dry weather periods.
However, there are now more sustainable drainage options
available - either by using materials that have less impact on the
environment or by managing surface water runoff more effectively
you can avoid the problems outlined above.