20/06/2005 - After seven
years of hard work, the Environment Agency
has today announced the completion of the
current phase of the Lower Thames Flood Risk
Mapping project – resulting in the most detailed
flood risk maps ever produced for the area.
Initiated in response to the long history
of flooding in the Lower Thames area, the
maps have been generated using highly specialised
models to reflect flooding in the region.
A large amount of detailed information has
been fed into the model to ensure the most
accurate picture possible.
The map has been generated using the latest
technology, including Light Detection
And Ranging (LIDAR) and hydrological and hydraulic
modelling (see notes below).
Data was also used from flood events as recent
as January 2003 to ensure the most up to date
information was used to give the greatest
level of accuracy possible.
All of this data was then fed into the model
which represented the Lower Thames
area to test the behaviour of the River Thames
and the surrounding area during a
range of flood events.
These comprehensive maps will enable the
Environment Agency to make informed recommendations
to Local Authorities regarding developments
in the flood plain. They will also enable
Local Authorities, who will be using the maps
from today, to make educated decisions with
regard to planning permission – helping to
avoid inappropriate development in the flood
plain.
The information from the Lower Thames Flood
Risk Map will also be incorporated into the
Environment Agency’s online flood map later
in Autumn this year – enabling residents to
find out if they are in the flood plain, and
if so – to take action to manage their risk.
South East Thames area manager, Peter Quarmby,
said: “These maps are the most comprehensive
ever produced for this area – drawing on a
high level of detail and using a huge amount
of information. This means that the Lower
Thames Flood Risk Map will show a more accurate,
detailed image of the floodplain – helping
to avoid inappropriate development in the
flood plain and enabling those living and
working within it to be prepared”.
Notes
- LIDAR involves a plane flying over the
rivers and flood plain – sending out a radar
pulse which enables the height of the ground
to be measured.
- Hydrological modelling is the process of
assessing how a catchment and it's watercourse's
respond to a given rainfall event. Factors
which effect the amount of water entering
the river from the surrounding land include
soil wetness, rainfall depth and duration,
soils and geology, land cover, catchment area
and drainage characteristics.
- Hydraulic modelling is used to represent
a river system in a simplified way. It uses
hydrological data (flows, water levels, rainfall,
etc) to predict the flow and level of water
down the river for a specific flood. Water
levels are then combined with survey of the
land surface to produce a flood outline.
