Forecasting bathing water quality UK Beach managers conference 14 th May 2014 Ian Dunhill Tidal water quality team Environment Agency
Day 1: Sample taken Day 2: Analysis starts Day 5: Analysis Complete Day 7: Results at beach
1400 1200 1000 Cfu/100ml 800 600 400 200 0 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 E.Coli Intestinal Enterococci
Sources of FIOs 10% 90%
Effect of discounting (152 sites) Change 2013 Good Excellent 40 Sufficient Excellent 3 Sufficient Good 17 Poor Good 7 Poor Sufficient 19 Sites out of Poor 26 Other sites improved 60 If a site is classed as ‘Poor’ STP can’t be used But the first classification won’t take place until 2015 . Therefore STP can be used in 2014 and 2015 to avoid it becoming ‘Poor’
Defra responsibilities Legislation – implementation of the rBWD into the BW Regs Set policy Designate sites Controllers Signage Electronic signage Reporting
LA responsibilities Fixed signage Permanent signage requirements Number of previous year’s warnings Reactive Signage Check BW explorer or text messages daily Ensure sign(s) up by 10am
EA responsibilities Determine suitable system – ‘developing system’ Determine suitable sites Make forecasts Post on BW explorer Send SMS text messages Sampling and analysis
Site selection The water quality many sites is too good to have effective forecasts Some sites not predictable using rainfall, other factors affect water quality such as groundwater contamination Sites need to be affected by rainfall to be suitable for pollution risk forecasting (at present) Forecasts will be made at all suitable sites Only those sites with active signage will qualify for STP As the method develops existing sites will come out of the scheme and new ones may be added Note: We can’t guarantee that all sites currently in scheme will continue to be included
Terminology Pollution risk forecasting Pollution risk warning Short term pollution: - requires management measures
STP Management measures Signs must be displayed in the vicinity of the bathing water when a pollution risk warning is issued The Environment Agency sampler must see an appropriately dated warning sign (or electronic sign) A sample has to be taken by the Environment Agency after the STP event to confirm the end of the event. If these conditions are met then up to 15% (3 in 20) of samples may be disregarded from classification. In many cases this will improve the classification of the site by not counting the periods when advice against bathing was issued.
How accurate are weather forecasts? 73.3% of three hourly weather is correctly forecast as 'rain 94% of three hourly temperatures are accurate to within +/- 2 ° C 78.4% of three- hourly weather is correctly forecast as 'sun’ Source: http://www.metoffice.gov.uk/about-us/who/accuracy/forecasts
How accurate are pollution risk forecasts? EC 300 10000 IE 180 1000 FIO (cfu/100ml) 100 10 1 08/09/2013 06:00 08/09/2013 18:00 09/09/2013 06:00 09/09/2013 18:00 10/09/2013 06:00 10/09/2013 18:00 Axis Title EC IE Data collected by the Centre for Research into Environment and Health, University of Aberystwyth, as part of the Cloud to Coast Project, Reference: NE/I008306/1, funded by the Natural Environment Research Council, Medical Research Council, Economic and Social Research Council, Department of Environment, Food and Rural Affairs through the Environmental Exposures & Health Initiative (EEHI). '
Beach samples Quality distribution, daily sampling 350 300 250 200 Count 150 100 50 0 5 10 50 100 200 500 800 1000 1500 2000 More cfu/100ml E-coli Intestinal enterococci
Warnings
Daily procedure 5 th May to 30 th September Web page will be updated by 9am with the day’s forecasts. These will then also be sent as a text message to registered mobile phone numbers and electronic signs By 10am warnings will have to be displayed at bathing waters The sampling programme will continue without alteration, 20 times per season
Additional samples for STP Most of the time warnings won’t require any additional samples. When we have issued a warning and this coincides with a statutory sample and a sign is present additional samples will be required. The directive requires us to take a sample to “confirm the pollution has ended”, the confirmation sample. The directive also specifies that “If necessary to replace a disregarded sample, an additional sample is to be taken seven days after the end of the short- term pollution” the replacement sample: this year only. Once a year’s classification has been made samples can’t be added or removed at a later date from that year’s data
Signage requirements Fixed: [In an easily accessible place in the vicinity of the bathing water] Notification that the bathing water is subject to short-term pollution, An indication of the number of days on which bathing was prohibited or advised against during the preceding bathing season because of such pollution. Conditions likely to lead to short-term pollution, — the likelihood of such pollution and its likely duration, the causes of the pollution and measures taken with a view to preventing bathers' exposure to pollution and to tackle its causes. Reactive: A warning whenever such pollution is predicted or present “A sign visible to the public, which states that there is an increased risk of pollution, expressed in those or other words and that sign is dated for the day on which you are sampling. “ Note: We won’t be able to be disregard samples taken during STP events without the sampler observing the appropriate warning sign (fixed and reactive)
Signage
Warning messages No water quality warning issued Risk of reduced water quality due to heavy rain (or whatever else) No water quality forecast available Electronic signs 25/07/2014: NO WATER QUALITY WARNING ISSUED 25/07/2014: RISK OF REDUCED WATER QUALITY DUE TO HEAVY RAIN (or whatever else) NO WATER QUALITY FORECAST AVAILABLE
Pollution risk forecasting Not predicting actual water quality Predicting an increased risk of encountering reduced water quality There is always a risk of unfavourable water quality, but after rainfall this risk increases In most cases warnings not linked to discounting Project in it’s early stages, it will evolve over time Hope eventually to combine warnings from CSO alerts into system
rBWD: Percentile cBWD: Fixed limits evaluation
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