We have had the first CCN workshop! In this case for the Flood Risk focus area (one for Water Quality is coming up in Lancaster on Dec 8th). It was held at Sheffield Cathedral and brought together some of the CCN and FRMRC2 team with practitioners from the Environment Agency, several Consultants, local authority staff, and some graduate students. The aim was to make the first steps towards a Guidance document for good practice in incorporating uncertainty into flood risk mapping. The workshop was illustrated with some uncertain flood risk maps for the River Dearne north of Mexborough prepared within the FRMRC2 project.
It proved to be an interesting day, with lots of discussion about the sources of uncertainty, how we might characterise them, how best to communicate assumptions and uncertainties, how they might be interpreted in different contexts, and how different products might be needed for different purposes (the discussions also overlapped into uncertainty in predicting inundation depths for real-time forecasting and incident management).
There is clearly a lot of wariness about uncertainty estimation of flood outlines, particularly in respect of how it might affect the planning process. Under PPS 25, the boundaries of the flood risk zones are crisp lines. Making those lines uncertain would raise many issues, and some people at the workshop thought that this might be counter productive. Others felt it might be advantageous, in that we know the uncertainties are there and there would be real advantages of openness and transparency (and in being less likely to be wrong) in trying to estimate the uncertainties. This will be become more and more important as mapping moves down towards individual property levels.
One strong recommendation from the discussions was to make sure we talk about degrees of confidence in predictions rather than uncertainty or likelihood. Another issue was starting from the needs of different users but with the question of how far we should assume that practitioners and professional partners will understand uncertainty concepts given the necessary future training, even if this does mean assessing probabilities of probabilities, rather than “dumbing down” the concepts. The “small print” of any guidance will be important in ensuring that the concepts involved are properly understood.
So a really interesting day – though we only really touched on uncertainty in estimating flood hazard rather than the consequences or vulnerability components of flood risk. The next steps will be to produce a full report on the workshop discussions – which will be posted on both CCN and FRMRC2 sites – and then a draft guidance document to form the basis for further discussion and consultations over the next year.
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