Finding needles in haystacks using satellites

Soil and nutrients washing off agricultural land is the single most common reason for our rivers and streams not being as healthy as they should be. Across England it accounts for a quarter of the reasons for waterbodies not achieving good status under Water Framework Directive classifications. In Herefordshire where soils are very light and agricultural practices intensive the figure is a worrying 48%.


Tackling the problem obviously involves finding out where the polluting runoff is coming from. This sounds simple but isn’t! River and stream catchments (the area of land that drains into them) are large. Often the runoff originates quite a distance from the polluted river or stream, finding its way by gravity via roads, paths, ditches and other fields. Also agriculture is a highly mobile industry. 


What is a bare arable field one year might be pasture the next, so the locations of high risk move around.

To help us find the needles in the haystack we’ve turned to modern technology. And it’s working.

Fields of bare soil with no growing crops or grass covering them are clearly much more likely to lose their soil. We can now identify where they are by using the excellent images from the Sentinel 2 satellite which was launched in 2015. 


It crosses the UK every few days so gives us an almost real time picture of land use, although we do have to have clear skies!


We can then overlay other useful information over the top of the satellite imagery which further narrows our search.

Environment Agency LIDAR data provides incredibly accurate information on the height and levels of land. For our search we identify all land that has a slope of more than 6%. This is because soil runoff is much more likely to happen when there is a steep slope.


The next step is to overlay a highly detailed map of the river network. This includes tiny ditches and streams as well as larger rivers and gives a good idea of how soil and nutrients running off the land might find their way into the main river network.


Finally we put on details of soil types. Light, sandy soils are much more likely to be washed off than heavy clays.

By doing all this we can massively reduce the area of the catchment we target for visits by our Environment Officers. 

Our first trial over a whole catchment was carried out on the River Lugg in Herefordshire. Its catchment has a total area of 170 square kilometres. Where to start?!


By selecting areas of bare soil from satellite data we reduced 170km to 30. A lot better but still a massive area to walk over!

By overlaying data layers of steep slopes and soil types we got down to 6.5km and 50 discrete fields. That’s less than 4% of the total catchment area. Much more like it!

Following some typical winter rainfall in early February we mounted an operation to send officers to visit each of the identified 50 locations. They were equipped with iPads (other tablets are available!) with pre-loaded maps and a specially designed app to upload details of what they found. This can include text, photos and video footage. A network connection allows details to be uploaded in real time, although if there’s no reception (fairly common in Herefordshire) data is stored and uploaded as soon as a connection is found.

 
Data and images can been collated immediately and activity coordinated by the operation manager back at the office and also viewed, in real time, by other teams of officers at different locations.


Initial results have been very encouraging. Of the 50 locations visited, 13 were assessed as presenting a high risk of causing immediate pollution problems. 5 were actually causing pollution at the time of the visit despite only relatively small amounts of rainfall.


During the period of the operation no high risk fields were found that hadn’t been highlighted by our targeting system.

We will be contacting all the owners of the 13 high risk locations soon.

Perhaps the most encouraging aspect of the technology (in addition to its accuracy) has been the reaction of our staff who are using it, several remarking it’s revolutionising the way they’re working and making their job far more productive and rewarding.

This is just the start of our journey in using data and technology together in the field to more accurately target our agriculture inspection and regulatory work. It should bring benefits both to the environment and the industry.

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Keeping Herefordshire’s soil where it belongs

Soil washing off fields is an increasingly common problem across the UK. Not only is it a waste of a precious, non renewable (at least in sensible timescales) resource, it causes serious pollution in rivers and streams and dangers to road users. More intense rainfall and increased intensification of agriculture appear to be making matters worse.

Herefordshire is especially vulnerable. The fine red soils which give the County much of its landscape character, are easily mobilised by heavy rain and the undulating terrain means it can move quickly and over long distances.


On 15 June, a number of heavy but localised showers and thunderstorms in Herefordshire resulted in tonnes of soil being washed from many field onto roads, then into ditches and streams. This resulted in some of the larger watercourses, like the River Lugg becoming discoloured through increased turbidity. Levels of nutrients, for example phosphate would also have been raised significantly.


The main areas of concern are where steeply sloping fields have been cultivated next to watercourses, especially potatoes, maize and soft fruits grown under plastic. Here the risk of soil erosion is much higher. We have identified many of these locations using Light Detection and Ranging (LiDAR) information, aerial photography and field surveys. Because agriculture is so dynamic we need to keep reviewing this information. What is a high risk maize field one year might be low risk pasture land the next.

These higher risk sites were shown to be washing significant quantities of soil during Wednesday 15 and Thursday 16 June with significant impacts to roads and watercourses.

It is not just the Environment Agency that is concerned about soil washing off. Local Authority Highways are particularly concerned about this issue.


 Putting aside the obvious road safety issues associated with mud on highways, the cleanup costs from soil on roads can be very significant for Local Authorities, who will seek to recover these costs from landowners wherever possible. 


Increased runoff from fields also increases the risk of flooding to local properties with floodwater depositing large quantities of sediment onto private land .

As Regulators, we have been working to identify high risk sites, where soil run off is likely to be most significant and where risk to local watercourses is greatest.


 After rainfall events we gather evidence and information that we use for future enforcement and prosecution action and to refer sites to the Rural Payments Agency, where a breach of the soil standards in England have been identified under cross compliance.    

Farm HEREfordshire has been set up in the last year in an attempt to raise awareness of soil erosion and pollution while promoting sustainable and profitable farming. It is possible to achieve both! It’s a partnership supported by industry, voluntary organisations and statutory bodies like us. See more about its work and some nice little videos here http://www.wyecatchment.org/farm-herefordshire/
If you see large amounts of soil washing off into local streams please report it on our 24 hour incident hotline 0800 80 70 60. 

River Teme fish rescue

The River Teme is one of England’s finest lowland rivers. It rises near Newtown in Wales, meanders through Shropshire and Worcestershire before joining the mighty River Severn just below Worcester. It is a Site of Special Scientific Interest for its entire length.

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Despite its size, however, sections of its upper reaches are prone to drying out during periods of dry weather. This is a fairly frequent occurrence, happening, on average, around once every three years. The stretch most at risk is from Knighton to the confluence with the River Clun at Leintwardine.

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Drying out happens very quickly with low flows changing to a completely dry river bed within a day or two.

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Because the upper parts of the Teme rely on catchment runoff (rather than groundwater) for its flow, an extended period of dry weather quickly translates into low flows and then drying out. That is what has happened this year. The record-wet year of 2012 topped up our reservoirs and groundwater reserves very nicely but the lack of rainfall runoff for the last month (combined with high temperatures and evaporation) has resulted in the upper Teme (and other similar rivers) starting to dry out.

Fishy haven

The Teme is an excellent fishery and is home to a wide range of game and coarse fish. It is very popular with anglers who travel great distances to sample its challenges. The upper Teme is an especially valuable spawning ground for salmon and trout.

You may have thought that a drying river wouldn’t cause too many issues as the fish (being sensible creatures) would just move downstream as things dried out. The problem is that as the flows reduce , large, deep pools of water get cut off as the main river bed becomes dry. The fish tend to seek these pools out as they are deeper and cooler and tend to contain cover (weeds and fallen trees).

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The sun then gets to work on these pools, warming them quickly and oxygen levels in the water fall quickly. Obviously, in time, the pools themselves will dry out.

Launch the rescue team

We monitor high risk river areas like the upper Teme on a regular basis during dry weather. Our fishery officers have years of experience of where and when to look.

Once we know fish are becoming stranded and rescue is possible we scramble our rescue teams from Shrewsbury, Kidderminster and Tewkesbury (depending who’s closest).

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We use electrofishing to catch the fish in the pools. A small electric current is passed through the water which is sufficient to momentarily stun fish. There is quite an art in knowing where to look for the fish and how to efficiently get the optimum charge to the right spot!

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Members of the rescue team scoop them up in nets as they come to the surface and put them into buckets of water.

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The fish are then transferred to a large aerated tank of water towed by a landrover. This keeps them safe and happy until the rescue is complete. They are then taken downstream to a location where flows will be maintained and released.

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Teme haul

During the morning of 18th July we rescued around a hundred large fish from a dozen or so pools. Sadly the small fish and fry cannot be rescued. Some beautiful brown trout were saved as well as salmon parr, stone loach and bullheads.

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In addition we scooped up lots of brook lamprey and returned them to a safer place.

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Work like this is made possible by the money we receive from rod licence sales. We hope that anglers agree that it is important work in safeguarding the natural fish stocks in our rivers.

If you see and dead fish or fish in distress please call our incident hotline 0800 80 70 60

Crayfish carnage in Worcestershire

On the 6th July we electric fished the Suckley Brook at Longley Green, Worcestershire as part of our routine sampling programme. 

  

Sadly the results were abysmal, we caught 2 x 3 spined stickleback and 1 large eel in 100m stretch. 

   
 
The reason? Signal crayfish, large and small. Every time we tuned the current on there they were. We caught and dispatched what we could but they appear to have decimated the watercourse as they’ve eaten much of the insect life and the fish fry leaving a very barren stretch. 

  

This non-native species was first introduced to Britain in the 1970s and has spread to many of our rivers and streams. It out-competes our native white-clawed crayfish and, as our survey shows, can have serious impacts on the local freshwater ecology.

Unfortunately, the problems caused by signal crayfish were compounded at the survey location by overshading and heavy sedimentation caused by run-off from farmland within the catchment (both also common issues on lowland watercourses)

  
 It was a sad sight to be hold. We’d hoped trout would be hiding under all the large woody debris but alas nothing. 

Bug sorting

A guest blog by Libby

The Spring ecology sampling season began at the beginning of March and our Sampling and Collection team are out and about, busy collecting invertebrate samples. On 5th March a macro-invertebrate sample was collected by Laura (see previous blog post) on the Piddle Brook and brought back to the Analysis and Reporting Team’s laboratory in Tewkesbury to be preserved. The sample is now ready for me to begin the invertebrate analysis process.

I begin the analysis by washing the sample through a very fine meshed sieve to remove all of the preservative. I have to be careful to make sure no tiny invertebrates are washed away down the sink! I then put a small amount of the sample into a white tray.

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The trays are divided into squares and I work through each square, pulling out all of the invertebrates present using small forceps. It can be difficult to spot them all in the trays, especially some of the very tiny ones! Can you spot the invertebrates in the picture of the tray below?

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Once I am happy I have removed all the invertebrates from the tray I will wash the sorted section into a sieve. I then continue to take out all the invertebrates from the rest of the sample. This process usually takes me a whole day, a lot of patience is required for this job!

After I have removed all the invertebrates from the entire sample I then move onto counting and identifying all the specimens. I have to identify them to species level, which I do using a high powered microscope, lots of identification keys and some very fine forceps!

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Species identification often involves looking at small features, such as tiny hairs, and dissection, such as mouthparts and gills. The picture below shows the mouthparts of a mayfly larva, Baetidae, which sometimes require dissection to identify to species level. To do this I need a very steady hand!

mouthparts

After I have identified all the invertebrates I enter the list of species onto our ecology database, Biosys, and check to see whether the sample will be put through our Analytical Quality Control (AQC) system.  To make sure my, identification and sorting remains at a consistently high standard, 1 in 10 samples are analysed again by AQC analysts. This can be a nerve wracking process but keeps us on our toes! Luckily my sample has not been selected for AQC, if it had been I wouldn’t have been allowed to exceed either  2 invertebrate family gains and/or misses in a sample.

In order to keep my skills up to scratch, I also have to complete 4 species ring tests and at least 1 reverse ring test each year. The species ring test involves identifying a set of invertebrate samples to species level and successfully meeting the pass mark. If I’m selected for a reverse ring test I will put together a vial of all the species present in the sample which will be identified again by an experienced analyst. This may seem like a tough and thorough process but it is essential to ensure the data we collect is of the highest quality.

The invertebrate species present in the sample can give me a lot of information about the quality of the site because each invertebrate species has varying habitat preferences to different pressures. To help me do this there are a number of analysis tools and indices available. For example, the Proportion Sediment sensitive Invertebrates (PSI) index combines each species’ tolerance to sediment levels to create an overall score which indicates whether a site is impacted by sediment pressures. We use the Walley Hawkes Paisley Trigg (WHPT) index to analyse an invertebrate communities tolerance to organic pollution, which incorporates deteriorations associated with changes to taxa abundances. There are also tools available to analyse invertebrate community’s to see if they are impacted by flow, habitat and pesticides.

As I’m analysing the Piddle Brook sample I notice it contains relatively high numbers of snails and small numbers of multi-gilled cased caddis and mayfly larvae. The picture below shows some of the snails and a cased caddis that I have found in the sample. These invertebrates favour habitats with sluggish flows and indicates to me that slower flows are experienced at the site. I haven’t found any highly sensitive taxa in the sample but there were a number of moderately sensitive taxa present, such as the caseless caddis Hydropsychidae and cased caddis Limnephilidae. The overall scores for the site are consistent with previous years’ data, indicating there has been no deterioration in quality at the site.

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The results from the sample will be used to classify the Piddle Brook for the Water Framework Directive (WFD) next year. The aim of the WFD is for all waterbodies to achieve Good status by 2027. To classify the invertebrates I identified for WFD the data will be combined with a sample collected in the autumn from the site and the results analysed using a tool called the River Invertebrate Classification Tool (RICT). The tool will compare the results from the site (the observed scores) to an un-impacted reference condition site (the expected scores for a site of this type) to create an Environmental Quality Ratio (EQR). The EQR will fall between 0 and 1, a score closer to 1 indicates a site which is less impacted. The EQR determines which of the 5 WFD classification groups (Bad through to High) the invertebrate site will be classified as.

At the end of the day I thoroughly wash the sieves and trays that I used so they are ready for me to use tomorrow to sort the next sample.

The 2015 river monitoring season gets underway

A guest blog post by Laura

 

This week marks the start of the ‘spring’ ecology sampling season for my team.  Today I was out collecting invertebrates in Upton, Pershore, Evesham and Broadway, in Worcestershire. I catch the creatures using a method called kick sampling. 

In a nutshell I kick around in the substrate and search under stones to look for invertebrates, they are collected in the net then transferred to a tray.

I pick out all the leaves, sticks and stones, checking none contain invertebrates.  The sample is then tipped back through the net, the water drained off and placed in the container.  


Data is then collected on substrate type, surrounding vegetation, width, depth, plant growth etc.  All this has an impact on the site and can affect the biological water quality and hence the type of creatures present.  Data is automatically uploaded onto a database. 


Once back at the lab the sample is preserved in methylated spirit so the it doesn’t degrade.


Each invertebrate has a score; 1 reflects poor (low) water quality and 10 is excellent (high) water quality.   The photo below shows leeches, molluscs and shrimp (I won’t bore you with the Latin names) from Mere Brook. This initially tells me the water quality is average as these species can tolerate heavy sedimentation and low water quality.  

However, the picture below shows a high scoring cased caddis crawling along the container, its case is made from tiny sand grains.

Cased caddis out of its case

Its’ presence shows the watercourse must be good quality.  Just from poking through the sample in the tray I can see lots of species that indicate good water quality.  Once under the microscope our experts can pick out the smaller species, the scores are added up and this gives the site an overall score for biological quality.

 

In the photo below can you spot the difference between the 2 inverts and the sticks? That is what samplers are trained to do.  You need attention to detail in this job!

In Piddle Brook at Pinvin and Seaford there were more high scoring inverts present, mostly different types of cased caddis fly larvae.  In photo below you can see the cased caddis fly larvae has crawled out of its case which is made from sand grains.  Some make a case out of tiny sticks and leaves.


The caddis fly larvae places 2 stones on either side of their case when constructing it that create ballast so it can crawl along the riverbed.  It is able to retreat into its case to prevent fish from eating it.  If it didn’t have ballast it would get swept away into the water column. 

 

I finished the day in Broadway kick sampling the Badsey Brook. Once back at the office, all 3 pairs of waders, trays, nets and gloves were disinfected and hung up to dry.  


This is what we call biosecurity. We take is very seriously as it can prevent the accidental transfer of diseases and invasive species from one waterbody to another.

They’ll be used in the Sud Brook at Gloucester tomorrow when the monitoring programme continues!

Nothing bore-ing about the Severn Estuary

Big tides go in cycles depending on the alignment of the moon and earth, and, to a lesser extent, all the other planets in the solar system. If you want the detail have a look here https://metofficenews.wordpress.com/2015/02/20/super-tides-the-weather-and-coastal-flood-risk/

The cycle is about 18 years and February 2015 saw some of the biggest tides in that cycle. This is big news on the Severn Estuary where the tidal range (the difference in water levels between high and low tide) is huge – up to 15 metres at Avonmouth.

The Severn Estuary is like a huge funnel. Tidal sea water pushes up the Bristol Channel and gets increasingly contrained by the narrowing channel, raising levels dramatically. The bigger the tide, the greater the rise.

The most spectacular result of high tides on the estuary is the world famous Severn Bore.  Large tidal bores (which is what the Severn bore is) are actually very unusual and only happen at a handful of locations across the world where there is a large tidal range. The Severn Estuary has the third largest tidal range in the world (behind the Bay of Fundy in North America and Ungava Bay in Canada).

Bores happen when the front edge of the advancing tide becomes contrained by the sides of the estuary, forcing the water up into a wave. It is pushed along by the millions of tonnes of water in the advancing tide behind.

The Severn Bore can usually be seen between Sharpness and Maisemore Weir in Gloucester, a distance of around 20 miles. It travels at a speed of 8-13 miles an hour.

The height of the wave can be anything from a few inches to over six feet. This is largely dependent on the size of the tide but is also influenced by wind, weather systems over the Atlantic and the amount of fresh water coming down the river. Bore forecasts are available well in advance and give them a star rating, the the best (biggest) being five star bores. You can find the forecasts here: http://www.thesevernbore.co.uk/timetable/4586702434

Watching the bore is a great experience. It makes an amazing rumbling sound which you can hear well before you see the wave. The wave itself and the boiling, tumultuous water pushing it seem completely alien on an estuary that is usually fairly calm and placid.

Not surprisingly the spectacle attracts thousands of sightseers and also large numbers of surfers who travel great distances to ride the wave (with varying degrees of success!). Keen surfers try to catch the wave three times during a single pass (usually at Newnham, then Minsterworth and finally Gloucester).

At the Environment Agency we’re more interested in the hour after the bore has passed. This is the time when water levels rise dramatically and very quickly. The rise can be 15 metres at Avonmouth, 10 metres at Sharpness and 6 metres at Minsterworth. This rise is just as spectacular as the bore itself, although the majority of bore watchers do not stay to see it.The impact of the tide is felt much higher up the river than Gloucester. Amazingly, during the February high tides the river at Upton in Worcestershire (about 60 miles from the estuary) was pushed into reverse twice a day. The graph below shows how normal flows of about 100 tonnes of water per second travelling downstream changed to an upstream flow of up to 40 tonnes per second in a matter of minutes. There was also an accompanying rapid rise in water levels of over half a metre. Incredible!

We have miles of flood defences along the length of the Severn Estuary which protect over a thousand homes and businesses. Few people notice most of them as they look like natural grass banks. However, if they weren’t there high tides would routinely cause extensive flooding across the estuary. When high tides are imminent we check all our defences to ensure they are in good working order. This is no small task given the extent of the defences and the remote nature of parts of the estuary.

After the high tides and storms of 2014 some of our defences were damaged. We spent the autumn and early winter carrying out Over £3 million of repairs so they would be ready for the huge tides of 2015. In February they received a good test (like Minsterworth here) and performed perfectly.

There are more very big tides in 2015 (especially in March and September). We’re ready for them.

Why not get out yourself and experience a truly world class natural phenomenon.

Video courtesy @theocair