How do we Measure That…

It was 9:55am and, scrolling through my emails, one particular message from Dr Andrew Black caught my attention: ‘Fieldwork Help Required Today’. It didn’t take me long to hit reply…

>1 m standing waves dowstream of Pony Bridge.

Two hours later Finlay and I were driving north on the A9 as quickly as legally possible in our tiny rental car, an ADCP (Acoustic Doppler Current Profiler) jammed in the back seats. The aim of our mission was to quantify the exceptionally high flows occurring on the River Feshie, caused by rapid melt of the snowpack (~40 mm rainfall equivalent) which fell 3 days earlier during Storm Deirdre. We followed the Spey into the Cairngorms. In some places its swirling water had overtopped the banks and here and there a couple of sheep could be seen standing marooned by floodwaters.

SEPA had estimated peak flows of 107 cumecs at their Feshie Bridge gauging station and, as we drove up into Glen Feshie, it became apparent that, if anything, their estimation was conservative. Murky water roared down the glen, tugging at vegetation and cutting into the river banks. We stood uneasily on the Pony Bridge, the standing waves downstream over a metre high! Upstream, fresh erosion could be seen on the high outside banks of the meander and, as we tied ropes to the ADCP, a tree shot past, borne along by the floodwaters.  Neither Finlay or I had ever attempted to gauge flows in conditions quite like this and soon found out first hand just how much power water has.

Big boat, little car.
Preparing the ADCP for launch.

The ADCP emits sound waves and utilises the doppler effect to capture the flow velocities throughout the water column and generate a profile of the river bed. The device must be dragged across the width of the river to obtain a reading and, equipped with several lengths of orange rope, we stationed ourselves on opposite banks. However, with the ADCP in the water, it very quickly became apparent that pulling it across in such high flows was going to be difficult and we hauled it in before it could be swept downstream. Slightly upstream, we found a wider section of river with lower flow velocities.

Ropes at the ready.

However, keeping the long ropes out of the water proved impossible and, once the river had hold of them, it wouldn’t let go! No matter how hard we pulled, the ropes stayed put and gradually slipped through our hands and further downstream! Eventually Finlay waved his arms… it was no use. I let go and, with a snap, the rope leapt from the bank and vanished downstream (it was thankfully tied to a tree on the other bank). At this stage we admitted defeat and packed up our kit. The SEPA gauge downstream at Feshie Bridge had recorded a peak flow of 141 cumecs.

High water under the bridge.


It was an opportunity missed and, in hindsight, there may have been other ways to get the data we were after. Although significantly less high tech, we could have played Poohsticks with twigs, timing their journey down a measured section of river to estimate water velocities across the channel. A river bed profile could then have been obtained another day in more benign conditions. However, now that river levels have fallen again, debris lines left behind by the flood could perhaps be mapped to reconstruct what was going on in the river that afternoon.

Communicating risk in uncertain predictions: focusing on the individual

We’re often surrounded by risks in our daily lives:

  • Is it safe for me to cross the road now?
  • Is the food at this burger van safe to eat?
  • Is this web site safe to use?

The risk of flooding which might affect our homes or our lives often isn’t one of our highest priorities.  We might know it’s been there as a possibility since we moved to our current address.  We might know that we’ve seen rain or storms before; we might also have an optimistic outlook on all these risks.  We don’t want to be pre-occupied by them, do we?  And if we even went looking to find out about risks, would they be applicable to us anyway, and how certain would the assessments of risk be?

Today we publish the results of a pilot project arising from a collaboration between RAB Consultants and University of Dundee researchers.  Through the use of focus group research, it explores attitudes to communicating the risk of flooding on an individual basis, and considers how uncertainties can be expressed in ways which are locally specific and easy to understand.

The research was made possible through an incubator grant from the University of Dundee’s Centre for Environmental Change and Human Resilience (CECHR – now part of the Institute for Social Science Research).

Download: Communicating Flood Risk with Uncertain Predictions

Full citation: Cranston, M, Cuthill, F, Smith, F, Black, A and Malcolm, J (2018) Communicating Risk in Uncertain Predictions.  University of Dundee, 8p.

Time to take down the rain-out shelters

We’re going to be taking down the rain-out shelters in the Eden catchment in reading week, w/c 15 October 2018.  Student volunteers sought to lend a hand, do something different and see some new places on the Lomond ridge above Falkland and at a farm near Dairsie, Fife.  Students see email from Jenny Eades, or please contact me direct.

Andrew Black:

Rapid rise on the Feshie

We’re monitoring water levels on the upper River Feshie, and at two other sites lower downstream (and on some of the headwater tributaries too)!  This is all nested within the catchment of SEPA’s gauge at Feshie Bridge, and will help provide a better understanding of the hydrology of this dynamic catchment.

Today, we have a hydrograph which has steepened as it travelled downstream, leading to a 400+mm rise at SEPA’s Feshie Bridge gauging station in 30 minutes.  In the upper catchment the rainfall has been steady, rarely exceeding 4 mm/hr, leading to a fairly gradual rise.

We’ve seen the opposite situation earlier in the summer: steep hydrographs in the headwaters attenuating downstream, notably a 150 mm rise in 3 minutes which was barely noticeable once it made its way downstream to Feshie Bridge.  I’m going to say nothing today about causes, but just mention in-channel friction, rainfall patterns, and gradients.  Some hydrographs below to illustrate.  More evidence to gather first.

Hydrographs from upper and lower Feshie gauges
The same peak as monitored by SEPA, showing data over the past 3.5 days


For comparison, the upper Feshie peak of 25 August: 15 cm rise in 3 mins, but barely detectable at Feshie Bridge.

Data at the upper Feshie (Eidart confluence) site are recorded every minute, providing a high level of detail, which is useful when examining rapid rises.  Hydrologists working in the river, and walkers crossing the river on foot (there are no bridges on the upper river) need to be aware of the risk of rapid rises like these.  Sometimes we hear stories of absolute walls of water – potentially lethal.


End of semester field visit – the re-watered River Garry (Perthshire)

The exams are all finished now, so what better than a field visit to revisit some of the key themes of the semester just passed?  More so when there’s the offer of a guided tour from Scottish & Southern Energy’s biologist Dr Alasdair Stephen, and a shining yellow thing in the sky all day long!

Struan Weir photo
Visiting Struan Weir – now mostly removed to once again permit fish to ascend the Garry above its confluence with the Errochty Water.

The focus for our day was the River Garry, which has been dry for most of the past 60 years thanks to a diversion of the upper river to supply water to Loch Errochty, for renewable power generation at Errochty Power station.  SSE concluded an agreement with the Scottish Environment Protection Agency (SEPA) and the Tay District Salmon Fishery Board to allow the new provision of environmental flows, commencing in autumn 2017.  We spent some time in class talking about in-stream habitat and ecosystems: the role of water depths, velocities and wetted perimeter.  The works allow SSE to put the demands of the Water Framework Directive into practice.

Calvine Falls Photo
Falls below Calvine. If you were a salmon, would you be able to jump that? At least now the fish get the chance – and observations show that salmon are indeed migrating beyond this natural barrier.

But the trip soon revealed that a lot more was required than ‘just’ hydraulic and ecological modelling.  Our discussion turned to questions of scientific evidence, stakeholder benefits, partnership working, people as much as policy, and balancing acts – how best to protect the local freshwater environment without causing unnecessary losses of generation water?

River Garry sediment downstream of intake
Heavily Modified! Sediment in the foreground has been excavated from the headpond above the Garry Intake, and is deposited adjacent to the river to allow sediment to be entrained in spates – providing a source of suitable bed sediment downstream.

A few photos here give a flavour of the day.  Many thanks, Alasdair, for sharing your knowledge, many experiences and insights.

Loch Garry Weir
Dry river bed at the outlet (east end) of Loch Garry. This is the next phase of the Garry restoration project, to provide a continuous environmental flow here.
Loch Garry inflow - east end
The flow of the Allt Coire Luidhearnaidh joins the Allt Dubhaig and normally flows west into Loch Garry. These watercourses will provide the water planned to re-water the upper Garry.
Sediment traps
Sediment traps on the Allt Coire Luidhearnaidh. Why?

Read more about the Garry re-watering here from:

Garry below Calvine: photo
River Garry downstream of Calvine. The bed is dominated by bedrock. Has it always been like that, or do we see here a result of sediment starvation?

Remembering the Great Tay Flood of January 1993

25 years ago, on 17 January 1993, a peak river flow of 2268 m3/s was recorded at Ballathie gauging station on the River Tay – the highest rate ever recorded in the UK.  At the time, I had only just started work for the National River Flow Archive at the NERC Institute of Hydrology.  The flood left hundreds of people with devastated homes and many lasting impacts: the memory is perhaps best forgotten for many of them.  For me, it was a key moment at the start of a hydrological career in Scotland, and there’s been no lack of interesting projects to investigate since.

Reflecting on the Great Tay Flood, it’s worth taking a moment to think about how much has changed since then.  Many of these changes may be partly attributable to that fateful event in Perthshire: it changed how we thought about flood risk in Scotland at least.  Here are some quick personal reflections:

Climate change was much more of a contentious issue back then – could human agency really be changing the climate?  There was a sense that this was a flood (reckoned to be the biggest in almost 200 years) that shouldn’t have happened: something must have gone wrong to cause such a disaster.  Some looked to climate change as “the reason”.  I remain uncomfortable with the idea of attributing a single large flood solely to climate change, but I think the vast majority of hydrologists would see it as being of critical importance to flood risk assessment in general.  It’s one of the key hydrological challenges for the future.

Sodden house contents after the flood

Flood forecasting and warning were in their infancy then.  Certainly, the hydrologists of the day were using all the information at their disposal; it was clear to them that something very big was about to happen, and that information was shared with the authorities who needed the best information available.  Telemetry monitoring systems, the science behind flood forecasting and the methods of issuing warning messages and preparing recipients have been transformed in the years since – see the Scottish Flood Forecasting Service. and Scottish Flood Forum.  I’m not sure if community resilience had entered many people’s vocabularies back then…?

Washed-out railway embankment at Dalguise in the Tay valley

Perth got its flood defences, completed in 2001, at a cost of £25 million – the most costly scheme in Scotland at the time.  At 8km long, the design allowed for subsequent raising if the need were to arise: a recognition of the uncertainty of risk estimation and the possible effects of climate change.  The defences incorporated more than 80 gates, to address local needs for access, and relying for their operation on the growing capabilities of flood warning.  The scheme provides structural protection for many hundreds of homes and businesses, and a good deal of peace of mind for those at risk.

Perth flood defences under construction, Tay Street

It’s worth thinking about the role played by the flood marks on Smeaton’s Bridge.  The marks showed that 1993 was the highest flood since the bridge was built in the 1770s – excluding the 1814 ‘ice jam’ flood.  And that was an outlier – we don’t get ice jam floods any more: nobody was arguing that we should allow for that scenario in future.  So the historic record provided a context for the flood: it gave some certainty that this flood really was something unprecedented.

Also since 1993, legislation has seen the responsibilities for flood risk management overhauled, most recently in the 2009 Flood Risk Management (Scotland) Act, with the roles of local authorities and SEPA (formed in 1996) in particular clarified, extended and better coordinated.

What else has changed or happened? Scottish devolution, the economic downturn of 2008, ubiquitous smartphones!  These are just a few thoughts as we pass this anniversary.  Maybe you’d like to share your thoughts?

Reaching out in NE Fife – drought risk, climate change, agriculture and YOU!

Drought Risk and You – talking about drought, climate change and farming in Freuchie, Saturday 20th January 2018.

Registration link here.

Programme available here: Jan 2018 Eden DRY event v4

Scotland is considered by many as a wet country but over the past years we have seen some prolonged dry periods – for example, 2003 in Tayside, 2008 in the Hebrides and 2010 in SW Scotland. 2017 saw a dry spring in central Scotland.

The DRY project, funded by UK Research Councils, is investigating drought and water scarcity in the Eden catchment alongside 6 other river basins elsewhere around Great Britain. We are collecting digital narratives from local people, while also undertaking experimental crop and grassland research, and computer-based hydrological modelling. We want to discuss with you:

  • What were the impacts of past droughts like 1976 and 1984 in Fife?
  • What could future drought look like in Fife?
  • What might the impacts of future droughts be on agriculture – on food and fodder crops?
  • How might grassland – a common land cover in lawns, golf courses and pasture – be affected?
  • What research is being undertaken in Fife and the UK to investigate these impacts?

Come and join an action-packed morning where we share some of the science that has been generated though the DRY Project. You have the opportunity to share your stories about past, present and future drought impacts and possible adaptations to drought and water scarcity in Fife and Scotland.

At this event, we aim to engage particularly with the agricultural sector and local people. Members of the research team are keen to capture your thoughts on the day in audio/video formats, with a view to sharing your experiences and insights as part of the wider project . Contributors from the DRY project team participating on the day will be:

  • Professor Lindsey McEwen (University of the West of England) – team leader, Drought Risk and You
  • Dr Ivan Grove (Harper Adams University) – Presenting results of crop research experiments at Harper Adams University. Drought experiments have been conducted on Wheat, Barley, Triticale, Durum Wheat, Quinoa,
    Perennial Rye Grass and Lucerne.
  • Dr Andrew Black (Dundee University) – local coordination for Eden (Fife) catchment, leading site visit to “rain-out” (drought simulation) grassland experimental site on the slopes of East Lomond.
  • Members of the digital storytelling team from the School of the Arts, English and Drama at Loughborough University.

To assist with the collection of digital stories, the organisers are interested to arrange opportunities to audio/video record your experiences and insights about drought risk in the Eden catchment. We’ll follow up all registrations with a follow-up email asking (without any obligation) if you would like to make yourself available for this.

Sometimes, environmental monitoring just has to be a team effort

Upgrading of the power supply required a field visit last Friday, in the interests of maintaining data completeness.  Fortunately, Wildland as site owners have the logistical capabilities to deliver results.

SBS500 recording rain gauge

Visiting during wintry conditions allows processes to be observed at first hand: the icing on the equipment will surely affect recorded precipitation amounts when melt occurs (24.4 mm recorded over 3 hours on Sunday 17th); it was also an opportunity to clear the sensors.  Impressively, the R M Young wind speed & direction sensor was still operating correctly!

When only serious logistics will do!

Many thanks to Sam and Ivan for invaluable help on the day.

Chilly for flow gauging

It was minus 10 C when our Eddleston field hydrometrist Boyd set off for his work this morning – but the work must go on!  Indeed some flow meters might not cope with such temperatures, but our Flow Tracker – and Boyd – seem able to cope with the conditions.  Low temperature gaugings let us keep check on ratings when ice/snow build-up may affect channel conditions and water levels.

Extreme conditions often produce the most memorable photos – so glad there was some added benefit arising from your determined efforts, Boyd!  I am happy to confirm it was very warm in my office this morning 🙂

Storm Caroline brings in the changes to Glen Feshie

Maximum wind speeds at the Wildland Mountain Observatory reached 70.5 mph this morning (31.49 m/s) as Storm Caroline brought high winds and property damage to many parts of northern Britain. Temperatures at 900 m OD fell from a balmy 7.0 C at 0130 GMT to -0.8 C three hours later, and down to -4.8 C at 2045 GMT.  This brought to an end 3+ days of continuous snowmelt from all elevations across the catchment: a 10 mm rainfall at high altitude caused a brief further rise in the river, followed by a fall to levels quickly below the snowmelt levels of the past few days.  Heavy snow is now forecast for all levels, so the river looks set to continue falling for some days.  Disdrometer data from Druim nam Bo show snowflake diameters in excess of 8 mm.

Feshie Bridge hydrograph 4-7 Dec 2017. Source: SEPA

Note for comparison: the Cairngorm AWS recorded a maximum gust speed in the order of 120 mph at an altitude of 1245 m OD.  The ridge location of the Druim nam Bo AWS may limit wind speeds there in comparison to the smoother, broader Cairngorm summit.