Early warnings will reduce disruption and
damageA dramatic increase in severe summer and winter
floods in the UK since 1998, such as those at Boscastle, Lewes,
Northampton, Carlisle, York, Conwy, and in north-west Scotland,
have led the Department for Environment, Food and Rural Affairs
(Defra), the Environment Agency and the Scottish Environmental
Protection Agency (SEPA), to adopt risk based flood management
strategies, based not only on flood defences but increasingly on
new innovative improved flood detection, early warning and
forecasting systems such as the National Flood Forecasting System
(NFFS).
Mott MacDonald has delivered real-time forecasting models to the
NFFS for the Rivers Darent, Medway and Great Stour in Kent and the
River Cam in Cambridgeshire. These state-of-the-art continuous
river flow simulation models receive real-time and forecast
rainfall from telemetry raingauges and weather radar to forecast
river levels and flows in key flood risk areas up to 36 hours
ahead.
Now large flood-prone towns, such as Tonbridge, Maidstone, Ashford,
Canterbury and Cambridge, and villages on the flood plains, receive
sufficient advance warning to give emergency services, businesses
and householders time to activate official flood response plans,
prepare public defences and protect private property.
At least 6 hours' flood warning is required to
deploy the stopboards that will prevent these houses flooding
againMott MacDonald has developed the key skills necessary
to construct operationally robust, accurate, fast-running flood
forecasting models that are tolerant to telemetry failures due to
storm damage, that remain computationally stable over a wide range
of flows, and that forecast river levels with an accuracy of 200mm
and the times of onset of flooding within two hours.
Mott MacDonald’s successful approach the development of real-time
flood forecasting models demands careful mathematical
representation of natural river channels, flood plains, and the
man-made structures and features that influence river levels. It
demands thorough quality control of the historic data used to
calibrate and test the models and demands detailed study of the
location, frequency and impact of previous flooding. This rigour
has given Mott MacDonald a strong proven track record in the
development and delivery of flood forecasting models to NFFS.
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