A glossary of hydrological and related terms

There are quite a few good glossaries of hydrological terms already ‘out there’ and ready for you to use. The NIWA one is nicely written but doesn’t cover many terms. Two USGS ones (a, b) look very comprehensive, but don’t cover all the terms in use in the UK. There must be some hydrological vocabulary which is particular to Scotland too.

So here’s my own. Prepared initially in some haste soon after a SEPA training event for flood forecasting staff, I naturally hope this will be of value to students in Dundee and even beyond. It will be even better with your suggestions – so you are very welcome to send in.

annual maximum floodThe largest instantaneous flow in any water year.  The standard water year in the UK is 1 October – 30 September.
antecedent conditionsThe state of catchment wetness prior to a rainfall event and its associated rise in a river.
aquiferA geological unit which holds and releases water – this may be important for sustaining watercourses in dry weather and might also be valuable for a private water supply.
baseflowThe flow of a stream or river which continues well after inputs from rainfall or snowmelt cease.  See also BFI.
BFIBase Flow Index.  Calculated as a fraction of unity: baseflow as a fraction of total flow over an extended period, normally a number of years.
convectionOne of the three main causes of atmospheric uplift which in turn leads to condensation and precipitation.  Convective uplift arises due to localised energy transfer and is associated with localised precipitation (< 5km across at any one time) which tends to be intense (often >20 mm/h) and short-lived – normally the most damaging falls are finished within 1 hour.  Where a convective cell keeps on producing precipitation, it may leave a trail of precipitation accumulations which may extend for 100 km or more.  An example would be the rainfall of 11-12 August 2020 in Scotland.  Convection also may be an important feature of a band of frontal precipitation.
cumecCubic metre per second (m3/s) – abbreviation.  Note 1 cumec is the same as 1000 litres per second.
cusecCubic foot per second. Rarely used in UK hydrology, but still commonly in use in the US.
dischargeThe rate of flow of a watercourse.  Think of the volume of water passing every second under a tape measure across a river.  Means the same as flow.  Normally measured in cumecs.
evaporationLoss of water from catchment surfaces (leaves, ground) to the atmosphere.  Requires energy, water at the surface and unsaturated air to occur.  Strictly, transpiration is a special case of evaporation, but hydrologists try to be clear about exactly which losses of water are being referred to.
evapotranspirationThe sum of evaporation + transpiration.
field capacityThe state of water stored in a catchment after rapid drainage has ceased.
flowSee discharge.
frontal precipitationPrecipitation caused by uplift at a weather front.  Fronts occur within a depression of cyclonic weather system.  Cold, warm and occluded types are recognised, each giving rise to precipitation in its own situation.  Frontal precipitation is normally more widespread than convective, but in Scotland rarely produces precipitation intensities of more than 5 mm/h.  A frontal system will normally take several days to form, intensify and then dissolve, during which time it may travel 1000s of km, most often tracking ENE from the Atlantic across NW Europe.  Frontal precipitation is required to produce extreme floods in large Scottish catchments (say >1000 km2), whereas extreme floods in small catchments (say < 10 km2) will always require localised intense rainfall as arises from convection.
gauging stationA site at which equipment has been installed to monitor water levels.  At many sites, a rating has been established by empirical means to convert water level to flow.  At a minimum, a gauging station may be formed of only a a post or other marker against which the water level may be read and recorded by an observer.  Some of Scotland’s longst-running gauging stations started life as daily-read post gauges.
groundwaterWater held in storage in solid or drift geology.  This water drains slowly into watercourses to provide baseflow.
hydrological modelA representation of a catchment system.
hydrologyThe study of water, particularly the storage and movement  of water across the earth’s surface.
hydrometryThe measurement of water in all its forms through the hydrological cycle.
hypsometric curveLet’s do that one another day ūüôā
interceptionThe means by which some water is caught above the ground surface by falling onto leaves or other surfaces.  Trees provide the greatest interception capacities.  It’s the first precipitation falling onto a dry canopy which will provide the most noticetable interception loss.  Catchment-wide, such losses will rarely exceed 5 mm, and will be small compared with the total amount of precipitation causing a major flood.
lagThe delay between precipitation and a river flow peak.  A variety of methods have been proposed, either requiring hydrograph separation (with a hydrological model) or not.
mixed phase precipitationPrecipitation incorporating solid and liquid precipitation, e.g. snow which has begun to melt as it descends towards ground level, or precipitation which has formed as hail or snow at high altitude and is then supplemented by rain which has formed at lower altitudes.
orographic enhancementRefers to enhancement of the precipitation rate arising from uplift over a topographic barrier – i.e. if there is frontal rainfall of typically 2 mm/hr as a weather system makes landfall over the west coast, the additional cooling caused by uplift over a range of hills may cause the rainfall to reach 4 mm/hr on the highest ground.
overland flowSee surface runoff
precipitationWater falling in any form from the sky groundwards – including hail, snow, drizzle, sleet, rain.
QMEDMedian flood – the median value in a series of annual maxima.
ratingA site-specific calibration used to relate water levels to flow at a gauging station.
runoffThe water draining out of a catchment area via a stream or river.  Runoff depth (in mm) refers to the volume of water which leaves a catchment over a period of time (day/month/year) divided by the catchment area.  Make sure you get your voulme in m3 and your catchment area in m2 before you start (area in m2 = area in km2 x 1 000 000), the convert into mm depth afterwards.
saturationCatchment state when voids within soils, drift or solid geology are full – i.e. there is no more capacity for water storage below ground.  The water table is the surface which separates saturated conditions from unsaturated.
SMDSoil Moisture Deficit, measured in mm.  This is a measure of how much storage is available in the catchment, caused by evaporative lossses and drainage.
snowmeltLike it says on the tin – the melt of snow!  But think carefully – the snow pack must first have become isothermal (0 C through the whole depth profile), then must become ripe (with some surface melt having drained through the profile and likely refrozen at depth); snowmelt will only begin to be noticeable at the catchment outlet once the snowpack can no longer hold any more liquid, guaranteeing that any further melt at the surface does translate to runoff from the areas of melt.
spateThe only Scots word in this glossary so far? Some of us think that a spate is a significant rise in the level and flow of a watercourse, but may fall short of a flood.
staff gaugeA water level gauge, normally graduated in 1m, 10 cm and 1 cm graduations.  Some hydrologists will try to read the water level by careful observation to the nearest 1 mm.
stageHydrologist-speak for water level, measured above a local arbitrary datum.  Good practice is to survey the gauge zero in the Ordnance Datum, which becomes very important in the case of damage to/loss of gauging equipment.
stage boardSee staff gauge.
stochasticConcerned with or relating to chance.
storageWater held in a catchment.  This is so important in hydrology – it’s the functioning of all these storages *together* which causes patterns of river flow to be different from the patterns of precipitation as catchment input.  The 5 storages are on vegetation, on the ground surface, in the soil, the groundwater and in the channel network (the rivers, strams and all other waterbodies which drain the water from the catchment).
surface runoffWater which flows over the ground surface to the nearest watercourse.  This is the quick component of catchment runoff.  Normally caused by come combination of saturation, heavy rainfall and snowmelt, this is the water which is going to be responsible for a flood, if one is going to occur.  How fast it flows, over what area and for how long all combine to control the rate of flow in the drainage network.
timeWe all know what time is, but it’s important to note that in many hydrometric organisations, official protocol is to always record hydrological observations to UTC (which is the same as GMT) – this applies to data loggers as well as field observations – with the intention of avoiding confusion between British Summer Time and GMT readings.  We should always be careful to record the time consistently, stating the unit of time measurement (e.g. GMT) just like we should always record measurements of length in metres/mm/km and units of mass in grams or kg, as appropriate.
time to peakThe time taken for a river to rise from its pre-spate condition to a peak. Time to peak is rarely the same between one event and the next, not least due to differences in antecedent conditions and event rainfall. Quite how we measure the time to peak is also important, but unimodal peaks (those with just a single peak) are normally recommended.
transpirationLoss of water by the internal processes of plants of all kinds – from grasses through to trees.  Are lichens plants?  I suppose they use water too.  Plants lose surplus water through microscopic openings on the under-sides of their leaves after it has been used for the basic functioning of the plant.  Tissue building of the plant also counts as a use of water included within transpiration losses.
water tableThe upper surface of saturation – below or at the ground surface.

Natural flood management, lag time and catchment scale: Results from our Eddleston Water empirical nested catchment study

Delayed flow: calibration gaugings were undertaken today in the Eddleston Water catchment following 40 mm of rainfall over the past 24 hours. Here, a swan takes advantage of some still water in a re-meandered section at Cringletie. Photo: Finlay Leask.

Delighted to see our first Eddleston Water surface water empirical results paper published today in the Journal of Flood Risk Management.  To avoid dependency on uncertain flow calibrations in high flow conditions, our paper focuses on hydrological lag as a measure of change.  We find that in the upper Eddleston Water and its tributaries, lag times have increased by 2+ hours in catchments with areas up to 26 km2 which have been subject to natural flood management (NFM) using flow restrictors (leaky barriers), ponds and riparian planting and fencing.  This extends the range of catchment scales in which NFM may be effective. Meanwhile a further tributary catchment subject to riparian planting and fencing showed no significant change in lag times.

The Eddleston Water Project is a 10-year long, whole catchment project to demonstrate the effectiveness of NFM in the real world – underpinned with empirical evidence. Publication of these results is a key milestone in the project. The combination of record lengths and gauging density makes Eddleston one of the UK’s premier sites for the study of NFM in terms of surface water hydrological change, as well as many other related aspects, including groundwater, channel morphology, ecology and ecosystem services. Our monitoring and analysis are ongoing, with support from the Scottish Government, Tweed Forum, Scottish Environment Protection Agency, Scottish Borders Council, British Geological Survey, Forest Research, Forestry & Land Scotland and research partners. Many thanks to all collaborators past and present for your contributions – this has been a huge team effort!

Read the paper here (Open Access): https://doi.org/10.1111/jfr3.12717

Find out more about the Eddleston Water Project here

Employment opportunities for graduating geographers and environmental scientists

It being the end of the academic year, I’ve pulled together this list of jobs and careers sites to help people looking for employment.¬† Inevitably, this cannot be exhaustive; nor does it attempt to be.¬† Please regard this as a work in progress.

While I list a selection of major jobs portals below, I encourage you to think about your career strategy carefully before you start applying for jobs.  What are your greatest strengths?  What is most important to you?  What does your ideal career look like? Where to start?  Our award-winning Careers Service offer resources on-line to help you with these considerations, and will also support you in the years after graduation as you review your options and develop your career.  Check back to the resources they have brought to your attention in careers sessions through your years of study.

What do geographers (and environmental scientists) do?¬† Remember that your career may be based on the skills you’ve gained over the course of your degree studies, and may not necessarily look like a geographical career on first inspection, in terms of the knowledge you have gained.¬† Check out the range of resources (inc. videos) offered by the Royal Geographical Society.

Graduate opportunities

This is not an exahustive list, but a few that I found.¬† The point here is these are graduate employment opportunities, typically from larger employers.¬† Many offer an explicit training element within the opportunities they advertise.¬† Many will be in careers not directly linked to your geographical knowledge (general management schemes – good pay, responsibility, prospects and opportunities for travel; accountancy, HR, some IT roles, market research…), but in which your skills (research, analysis, synthesis, critical evaluation, GIS, numerical & statistical analysis skills, writing and presentation skills, teamwork, independent working, etc….) may put you at a useful advantage.

Prospects: this is the careers portal for the UK careers services.¬† “We guide millions of students to make the right choice. Match your skills and personality to 400+ job profiles.”¬† Maybe just what you have been looking for.¬† Listings of jobs and work experience opportunities.

Guardian Jobs  More than 1000 graduate positions Рwaiting for your application?

Teaching – Would you like to inspire the next generation of young people?¬† Several jobs sites are available, but remember you will almost certainly need a postgraduate teaching qualification first.¬† Planning for a teaching career needs to start early.¬† The Careers Service can help you get the additional experience that you will need to gain during the course of your undergraduate studies.¬† Teaching jobs sites: TES, MyJobScotland, EducationJobs … there are many more too.

I have no particular knowledge of these others, but they may be worth a look:


GIS jobs

Academic jobs list: you need to sign up to: https://www.jiscmail.ac.uk/cgi-bin/webadmin?A0=GIS-JOBS

ESRI – you should know who they are!


Jobs portals: general, including graduate careers

s1jobs.com – major Scottish jobs site, offering 000s of vacancies, with good search tools for location and “core skills” which look like main employment sectors.

indeed.co.uk – major national site (“millions” of jobs internationally), including GIS jobs or social science graduate jobs – search for whatever your thing might be – “policy officer”, “conservation”, “water” ….

targetjobs – refine your search and set up alerts

Civil Service jobs – Find jobs in the Civil Service and central government organisations

My Job Scotland – portal for all public and third-sector employers in Scotland

jobs.ac.uk – jobs in academic & research institutions – main categories for academic and professional/managerial/support services; also offers career guides (such info is also available through our Careers Service)

ENDSjobsearch – environment and energy focus (links to ENDS report which is worth reading for environment news – could help in your job application/interview)

NHS jobs

If you would like to make suggestions for additions, please get in touch and I will add.

Looking for further ideas?  Look at the careers and employers our graduates have gone into via our Dundee Geog & ES LinkedIn group (which you are encouraged to join).  Our graduates post job opportunities and details of internships here too, so it really does benefit you to sign up. 

Further study

FindaPhD.com Рprobably a large majority of the opportunities advertised here are funded.  2.1 or 1st class degree normally required.  Masters often advantageous.

FindaMasters.com – key resource for finding Masters courses everywhere, including details of funding opportunities (highly competitive)

Note also Dundee masters courses led or taught by Geography staff:


Environment & Water employers

Scottish Water – see also their work placements and internships scheme.

Scottish Environment Protection Agency (SEPA) (note, it’s not the Scottish EnvironmentAL Protection Agency) – look out in particular for their annual graduate trainee scheme (applications to 2019 scheme closed in March).

www.environmentjob.co.uk : UK-wide and international jobs, and volunteering opportunities

Consultants (including renewable energy sector) – some of these may state a preference/requirement for MSc graduates:

  • https://www.jacobs.com
  • https://www.mottmac.com
  • https://www.aecom.com
  • http://www.fairhurst.co.uk
  • http://jbaconsulting.com
  • https://jobs.innogy.com
  • https://www.arup.com
  • http://www.rabconsultants.co.uk
  • http://recruit.net

See also:

  • http://nature.scot (Scottish Natural Heritage)
  • http://ceh.ac.uk (Centre for Ecology & Hydrology)


Space and sanity around Glen Feshie

How to respond to the terrible news of the atrocities in Sri Lanka and its connection to Glenfeshie?  Today I want to share a few photos from my time in Feshie, as some sort of a response to those acts and losses which never should have been.  In the cradle of the Wildland vision we find space, peace and abundant natural beauty; perhaps an escape from a crowded planet for those who want or need it, and have the privilege to visit.

A time to immerse ourselves in nature has to be good for all our souls. Time in Feshie, where I’ve been visiting for 20 years now, is a time to breathe clean air, feel the chill on the face, hear the wind and the birdsong, drink from the sparkling waters, meet and talk with new acquaintances, work out and be glad of it, and enjoy nature in all her glories – the vibrant mosses, the purple heather in autumn, the lichens, the young trees creeping up the hillsides, the majestic landscapes of mountain and moor beyond, and just knowing that there are people who are trying to make this corner of our world a better place.

Let’s remember those who have done so much to help protect and enhance nature in this part of Scotland, and all those who, this week, tragically have lost so much.

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‚Äôs Centre for Environmental Change and Human Resilience (CECHR ‚Äď 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: a.z.black@dundee.ac.uk

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 Рpotentially 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 Рthe 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?