Geoscience Reference
In-Depth Information
10.5.7.2
Selection of Input Observed Data
•
Environment Agency regional telemetry systems feed in measured rainfall, river
level, river fl ow and gate positions amongst other data sources.
•
The Met Offi ce provides 'observed' intensity and accumulations of rainfall,
'measured' from their radar network.
•
The National Tidal and Sea Level Facility send measurements of sea level at key
ports.
10.5.7.3
Selection of Input Forecast Data
• The Met Offi ce use their expertise and systems to provide grids of forecast rain-
fall, tide level, surge level, wind speed and direction and wave height and direc-
tion four times a day, for the forthcoming 48 h.
• Longer term forecast data sets are also used, including astronomical tide levels
and evaporation profi les.
Imported data is automatically processed within NFFS, to appropriate spatial
and temporal scales, accuracies and formats. All the data are then fed into the vari-
ous modelling platforms on a regular, scheduled, basis to produce outputs at speci-
fi ed locations. Where the input data is a forecast, the computed outputs also look
into the future. Some outputs then also use mathematical formulae to 'error correct',
and improve the results. Combining the outputs with understanding of at what level
fl ooding will occur produces, in effect, a fl ood forecast.
River fl ood forecasts use rainfall forecasts as inputs, with models generating
forecast river fl ows and levels. Tidal fl ood forecasts use meteorological forecast
inputs to adjust the tide levels from the 'normal' level predicted by the interaction
and movement of the sun and the moon.
Users can interact with and assess the data put into and being generated by
NFFS (Fig .
10.10
). They can run the required models more frequently than sched-
uled and can also create customisable 'what if' scenarios to know the magnitude
and characteristics of the anticipated fl ood. 'What if' runs allow users to modify
inputs to represent a range of scenarios. The resulting predictions allow users to
understand the bounds of the forecasts and how sensitive forecasts are to change-
able inputs.
Forecasts that are approved, either automatically or manually, are shared with the
wider fl ood response teams within the Environment Agency, via a set of customis-
able HTML reports displaying snapshots of the forecast information, packaged and
exported by the NFFS (Fig.
10.11
). Based on the results, fl ood warnings may be
issued.
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