Forecasting bathing water quality
UK Beach
managers
conference
Ian Dunhill Tidal water quality team
Environment Agency
14th May 2014
Day 1: Sample taken Day 2: Analysis starts
Day 5: Analysis Complete Day 7: Results at beach
0
200
400
600
800
1000
1200
1400
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
Cfu
/10
0m
l
E.Coli Intestinal Enterococci
Sources of FIOs
90%
10%
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
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
Site selection
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.
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 weather forecasts?
1
10
100
1000
10000
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
FIO
(cf
u/1
00
ml)
Axis Title
EC IE
EC 300 IE 180
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). '
How accurate are pollution risk forecasts?
Beach samples
Quality distribution, daily sampling
0
50
100
150
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300
350
5 10 50 100 200 500 800 1000 1500 2000 More
cfu/100ml
Co
un
t
E-coli Intestinal enterococci
Warnings
Daily procedure
5th May to 30th 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
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
Electronic signs
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
cBWD: Fixed limits rBWD: Percentile evaluation