forum david hetherington

Fluvial Geomorphology –From Theory to PracticeFrom Theory to PracticeDr David Hetherington

Ove Arup and Partners, Newcastle upon Tyne, UK.

Friday 4th June 2010, Sustainable Cities Forum

Universidad Javeriana Bogota ColombiaUniversidad Javeriana, Bogota, Colombia

Personal Profile – David Hetherington

• BSc Geography

• MSc Catchment Dynamics and Management

• PhD Remote Sensing and Fluvial Geomorphology

• Have worked in Fluvial Geomorphology for 10 years.Have worked in Fluvial Geomorphology for 10 years.

• Employed for Over Arup and Partners (“ARUP”) for 5 years.y

• My work relates to River Restoration, Geomorphological Assessment, Flood Risk Management and Geomatics.

• I operate the Arup “Geomorphology” and “Remote S i ” C iti ( 80 t ff)Sensing” Communities (appx 80 staff).

Research Profile

• Geomorphological Evolution

U f T t i l LiDAR (Li ht D t ti d• Use of Terrestrial LiDAR (Light Detection and Ranging) in Rivers

• Use of Terrestrial LiDAR in Engineering• Use of Terrestrial LiDAR in Engineering

• Fish Habitat

• Hydromorphology and Hydraulics

• The use of Urban Models for Flood Risk M tManagement

• Fluvial Geomorphology and River Restoration

Ove Arup and Partners (“ARUP”)

• An international multi disciplinary consultancy firm of engineers,

i ti t d d i ( 10 000 t ff)scientists and designers (>10,000 staff)

• Founded in 1946 by Ove Arup Sydney Opera House was anSydney Opera House was an early project.

• Ove was an engineer and philosopher (he died in 1988)• Ove was an engineer and philosopher (he died in 1988)

• Recent large projects including much of the Beijing Olympics.Olympics.

• Independent and staff owned (trust).

• Please visit www arup com• Please visit www.arup.com

The Key Speech

• Ove Arup made the key speech in 1970 to remind Arup staff of how they should operate: key pointsstaff of how they should operate: key points…

• Work should be interesting and rewarding and be of the best quality possibleq y p

• All work should have a humanitarian attitude

• Work should be honourable with a social conscience• Work should be honourable with a social conscience

• Money is not the main aim

• We should be a force of good, and help to shape a better world….

10565 520

35130

35

GLOBAL WATER SKILLS NETWORK

March 2009

Fluvial Geomorphology – What is it?

• A river is something of unimaginable wonder• A river is something of unimaginable wonder . . .


• An understanding of river behaviour• An understanding of river behaviour . . . .


• A complex earth science using elements of Hydraulics, Geology and Physics.

• “the study of sediment sources, fluxes and storage within the river catchment and channel over short, medium and longer timescales and of the resultantmedium and longer timescales and of the resultant channel and floodplain morphology” (Newson and Sear 1993).

• The study of river form-process interactions and feedbacks over many scales, from the single grain up to the entire catchmentup to the entire catchment.

• In Short: An well-qualified Fluvial Geomorphologistunderstands how rivers behave, and can use this ,knowledge to manage them appropriately . . .

Fluvial Geomorphology – Catchment Processes

Fluvial Geomorphology – Catchment Controls

• Catchment nature ultimately determines habitat in natural conditions

( )• Diract (local) and Indirect (Catchment) Anthropogenic changes p g gdisrupt natural reactions and responses

• Taken from Brierley and Fryirs, 2007 – River stylesstyles

Fluvial Geomorphology – Small Scale

Fluvial Geomorphology – Why do we need it? (1)

• Rivers are the arteries of the landscapeRivers are the arteries of the landscape . . .

• Freshwater rivers are valuable and only cover around 0.0001% of the Earth’s Surface. (0.0002% of (total volume of water) – NASA estimate

• Natural rivers are physically diverse over short distances supporting unique assemblages

• Healthy river systems typically offer better fish stocks, and better quality water to local communities.


• Healthy meandering systems can help to maintain y g y paggracultural water table levels.

• Upland meandering systems can provide upstream flood storage (reducing flood risk downstream).

• Designing with natural geomorphological processes is k if i i h b i blkey if new engineering schemes are to be sustainable and environmentally sensitive.

Rivers are important community features and• Rivers are important community features and boundaries


• Rivers are hydraulically and morphologically dynamic inRivers are hydraulically and morphologically dynamic in time, making then unique spaces.

• Support varied and sometimes rare flora and fauna pp(which has evolved to natural systems)

• Damage needs repair

• As with most habitats, the quality of the physical space plays a major role in promoting healthy ecology

N t l d t d i l k b tt d k l• Natural and restored rivers look better and make people happy!

Ecology - Fisheries

Fluvial Geomorphology and good quality riverse s

Geomorphology What is considered as being a good quality i ?

gyand

Hydromorphologyriver?

1) Suitable physical habitat for native species

2) Suitable water quality to support sensitive

Ecology Water quality

to support sensitive native species

3) Availibility / introduction of native species

Fluvial Geomorphology and good quality riverse s

Geomorphology What is considered as being a good quality i ?

gyand

Hydromorphologyriver?

1) Suitable physical habitat for native species

2) Suitable water quality to support sensitive

Ecology Water quality

to support sensitive native species

3) Availability / introduction of native species

Fluvial Geomorphology in the UK

Fluvial Geomorphologists

• It is a specialist subject that usually requires outside contractors to supply the necessary levelsoutside contractors to supply the necessary levels of expertise. From the outset it is important to make clear that like any science, a broad understanding of principles only gets you so far and a littleprinciples only gets you so far, and a little knowledge can be a very dangerous thing.

Source: (DEFRA) R&D TECHNICAL REPORT FD1914Source: (DEFRA), R&D TECHNICAL REPORT FD1914, Applied Fluvial Geomorphology.

• It is a profession, and a job of responsibility

Expertise Levels in the UK

DEFRA R&D TECHNICAL REPORT FD1914

Legislation and Authorities

The Water Framework Directive - Legislation

•To protect, and where necessary, restore the structure and function of the aquatic ecosystemthe aquatic ecosystem

•An obligation to return our rivers to their natural hydromorphologicalstate

•The aim of achieving “good ecological status”

The UK Environment Agency

•The UK statutory body responsible for caring for the environment

•Powers to prosecute in response to damage to river systems

•Promote restoration and habitat creation wherever possible

H bli h d t id Ri W k•Have published recent guidance on River Works

The Department for Environment, Food, and Rural Affairs (DEFRA)

• Government Department

• Conduct research of a national interest• Conduct research of a national interest

• Produce Guidance

C• With the Environment Agency - Commissioned a “Guidebook of Applied Fluvial Geomorphology” (R&D Technical Report FD1914) in 2003 ( p )

• By D Sear, M Newson and C Thorne.

• Freely Available on line• Freely Available on line.

• Sets national standards and raised the profile and requirement for Fluvial Geomorphology.requirement for Fluvial Geomorphology.

The River Restoration Centre (RRC)

• “A national information and advisory centre on all aspects of river restoration and enhancement, and sustainable river management”sustainable river management

• The RRC and an Non-Profit organisation based in Nottingham, UK.Nottingham, UK.

• A hub for best-practice and knowledge sharing

• Keep databases of projects and outcomes• Keep databases of projects and outcomes

• Offer consultancy services (checking and review)

• Work with rivers trusts and local fisheries

• Offer promotion and training on River Restoration.

Drivers for Geomorphological Studies and work

• Ecology

• FishingFishing

• Social (Recreation / Community)

Landscape Improvement• Landscape Improvement

• Stability (Land Erosion)

• Understanding of impacts of river change

• Engineering (allowing for natural processes)

• Flood Risk Management

• Sediment Managementg

From Assessment to Enhancement . . .

1) Asses – Measure/Map/Log evidence of the system

2) Understand – Analyse the Data2) Understand – Analyse the Data

3) Identify problems – Reveal key information of quality

4) Prioritise Use information to plan rehabilitation4) Prioritise – Use information to plan rehabilitation

5) Restore – Propose sensible, sensitive and sustainable solutions that consider many environmental and social factors.

Geomorphological Assessment

• 3 broad levels of approaching investigation and Assessment

Small Immediate

• Site Specific Local scale• E g geomorphological impacts of weir removal or

Small - Immediate

E.g. geomorphological impacts of weir removal or channelisation

• Reach ScaleReach Scale• Restoration plans, rivers with special status,

sediment management plans, water level management plans, fisheries improvements.g p , p

• Catchment scale• Catchment Audits and Management PlansCatchment Audits and Management Plans

Large – Long Term

Desk Study Information

• Old photographs

Ai b h t h• Airborne photographs

• Old Mapping

• Anecdotal evidence

• Flow Records

• Topographic information

• Agency / Government recordsg y

• Geological information

Empirical vs Rational Approaches

• Empirical understanding based upon spatial measurements (quantitative)

• Requires skills in selecting the correct measurementRequires skills in selecting the correct measurement techniques, methodologies and Processing and analytical methods.

• Rational understanding based upon experience-based observations (qualitative)

• Requires “hands-on” experience in various river systems to q p yunderstand how they operate under different conditions, and react to catchment changes.

• Most studies use a combination of Empirical and• Most studies use a combination of Empirical and Rational Geomorphological work.

Empirical Tools – Field mapping

• Locating features onto maps or direct into GIS

• Handheld GIS has built in GPS technology (How long until we can install GIS on our I-phones?)

Empirical Tools – Surveying and Terrestrial LiDAR

Rational Tools - Experience

• Field proforma allowing descriptions and mapping of:of:

• Types of erosion and deposition• Types of sediment Bar Features

Severity of Erosion• Severity of Erosion• Severity of Deposition• Evidence of active and dormant processes• Evidence of Morphological features (Riffles, pools etc)• Hydromorphological units (runs, cascades, riffles, ponded

flow etc))• Anthropogenic influences (farming, dumping, livestock

etc)

Rational Tools - Proforma

Geomorphological Patchiness and Diversity

• Patchiness is an expression of the number of different key geomorphological featuresdifferent key geomorphological features identified within an individual reach.

Di it i d t f t hi th t t l• Diversity is a product of patchiness - the total number of all features within a reach, multiplied by the number of different feature types presentby the number of different feature types present within the reach (i.e. patchiness). It is thus a measure of the frequency at which key features q y yoccur along a reach.

Assessment of Geomorphological quality

• Scales and criteria can be manipulated to suit the pcatchment, and to reflect absence or presence of key project features.

GIS analysis

Restoration options

Restoration projects – in channel options

Back water channel Log v weirs

Flow deflectors/ D’s Flow deflectors/groynesFlow deflectors/ D s Flow deflectors/groynes

Catchment Scale – Geomorphological mapping

Geomorphological Standard Diversity V.low

low

Mod

High

V hi hV.high

Catchment Scale – Ecological mapping

V.low

low

Mod

High

V hi hV.high

Standard diversity for salmonids, lampreys and bullheads (EA technical manual - Hendry & Cragg-Hine, 1997)

Geomorphological – Ecological linksGeo Eco Com

30.00

40.00

vers

ity

R-Sq = 7.8%; P = 0.037

20.00gy

Sta

ndar

d D

iv

0.00

10.00

0 00 5 00 10 00 15 00 20 00 25 00 30 00 35 00 40 00

Ecol

og

0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00

Geomorphology Standard Diversity

Geomorphological – Ecological linksGeo Eco Com

R-Sq = 7.8%; P = 0.037

Target for restorationGood Qualityy

Judgement required

Project Example – River Mease• A Site Specific – Geomorphological Impact

assessment of removing a weir

Project Example – River Mease

River Mease - Considerations

• Important habitat for Bullhead

• Important habitat for Spined Loach

• Local regime will change

• Local sediment transport potential will changeLocal sediment transport potential will change

• Local hydraulic diversity will change

• Upstream impacts?• Upstream impacts?

• Downstream Impacts?

• Flood Risk?

• Stability

River Mease – Existing Conditions

River Mease – Restoration/mitigation Proposals

River Mease – Anticipated hydraulic habitat

River Mease - Outcomes

• Impact assessment reveals opportunities!

• Habitat for key species promoted in new layouty p p y

• Opportunities found to relocate vegetation

• Improved local floodplain connectivity• Improved local floodplain connectivity

• Upstream hydraulic diversity improved as backwaters are removedbackwaters are removed

• Improved aesthetics

• Reduced livestock access• Reduced livestock access

• Land-owners appeased

Project Example – Beam Parklands

• A reach based assessment to inform landscape improvement for community use

Beam Parklands – Landscape Vision

Beam Parklands - Considerations

• No access for fish (downstream sluice)

• Urban – high population area, community park

• Very Low Morphological or Hydraulic Diversity

• Heavily modified systemHeavily modified system

• Currently inaccessible

• Very low gradient• Very low gradient

• Invasive plants

• Polluted site

• No key species present

Beam Parklands – Restoration Plan

Beam Parklands - Outcomes

• Accessible park landscape promoting community involvement and natural playinvolvement and natural play

• Two restored rivers with dramatically improved geomorphological hydraulic and ecologicalgeomorphological, hydraulic and ecological diversity.

• Pool riffle sequence mimicking natural conditionsPool riffle sequence mimicking natural conditions

• Wetland areas

• Improved flood storage• Improved flood storage

Hydromorphology and Hydraulic Diversity

• Definition:

“The physical characteristics of the shape, the boundaries and the content of a water body” Water Framework Directive Definition

A k t f thi “ t t” i ti t l• A key part of this “content” is spatio-temporal hydraulic diversity.

• Fish plant and invertebrate species undertake• Fish, plant and invertebrate species undertake different parts of their life cycles and daily routines in different hydraulic units (Biotopes) – Diversity is key.

• It is possible to map these flow unit habitats (Bi t ) i ll b t thi ith(Biotopes) visually, but this comes with many problems.

Biotope TypesBiotopes (hydraulic habitats)

Mapping Hydraliuc Diversity using terrestrial lidar

•The local standard deviation of the data were computed using a 0 2 m radius•The local standard deviation of the data were computed using a 0.2 m radius moving window•Data were gridded at 0.04 m so as to capture the smallest biotope unit seen at the study sites•Local standard deviation values at each of the measured biotope locations were then extracted from the grids using the residual function in SURFER™ •Local standard deviation values interrogated at each known biotope location•Statistical properties of each biotope determinedStatistical properties of each biotope determined

Biotope signals

Results: Typology validation

Unit descriptorfrequency biotope successfully

classified frequency amalgamated biotope successfully classified

Run 0.00 0.90

Glid 0 14 0 75Glide 0.14 0.75

Chute 0.20 0.59

Rapid 0.38 1.00

Riffle 0.25 0.55

D d t 0 71 0 71Deadwater 0.71 0.71

Pool 1.00 1.00

Research outcomes

• Different features offer similar surface structure (suggesting similar hydraulics).

• Current system for classifying hydraulic units are over-complex.

• Rivers present a continuum of hydraulics, rather than defined units (fuzzy boundaries in time and space).space).

• Potential for analysing exiting LiDAR data on larger river systems.y

• Methods limited to local and reach scales of investigation (quantifying betterment).

Terrestrial lidar and design

Conclusions – Fluvial Geomorphology

• Diagnosing the problems and causes is key to management.

• The scale that processes are operating at should determine the scale of the study, and the response.

S ll l / bl L l t di• Small scale processes/problems = Local studies

• Catchment scale processes/problems = Large studiesstudies

• Consideration of this early on makes schemes sustainable and adds value (in many ways)sustainable, and adds value (in many ways).

• It is a serious and complex subject and expertise is required.q

Conclusions – River Restoration• We need to learn from, and correct historical

mistakes.

M h i ti id d j t i• Much existing guidance and project experience.

• Should be based on a sound understanding of the River SystemRiver System.

• Needs to be focused on the drivers.

• What conditions to key species require?

• Provides multiple direct benefits (and residual b fit t lit )benefits e.g. water quality).

• Often a far more cost effective solution than hard engineeringengineering.

River Restoration: Costs• Hard to generalise in terms of economics (projects

so diverse!)

S ft V H d (S ft i t l 25 50% h t• Soft Vs Hard (Soft approximately 25-50% cheaper at initial outlay)

• Cost per m <50% for soft• Cost per m <50% for soft

• Engineers vs Bio-engineers (bioengineering groups small with low overheads - 50% in some cases)small with low overheads 50% in some cases)

• Soft then requires monitoring, and maintenance• But has a longer design life because of thisg g

• Restoration should be part of other schemes.• Additional cost – but great additional benefit

• Cost does not reflect “value”

River Restoration: Limitations

• A river can never be fully “restored” back to its i i l t toriginal state.

• Sometimes difficult to design for extreme flood eventsevents.

• Sometimes restoration has to be done within constraintsconstraints

• Huge potential benefits make the limitations worth working withworking with

Acknowledgements

• The project organisers in Bogota!

• Arup for supporting my involvementArup for supporting my involvement

• The below Arup people for contributing and/ helping in various ways towards my attendance and y ypresentation at this forum:

Patrick Kuhn, Amit Dutta, Dr Sally German, David Wilkes, Prof Mark Fletcher Daniel Newton Daniel House Jane SaulMark Fletcher, Daniel Newton, Daniel House, Jane Saul.

• Dr David Bradley – APEM aquatic scientists

• Research Colleagues• Dr George Heritage – Salford University, UK• Dr David Milan – University of Gloucestershire, UK

Questions?Questions?

[email protected]

(Please stay in touch!)

Useful Additional Background Information . .

• DEFRA: www.defra.gov.uk (search for “fluvial geomorphology”)g ( g p gy )

• EA fluvial design guide: http://evidence.environment-agency.gov.uk/FCERM/en/FluvialDesignGuide.aspx

• River Restoration Centre: www.therrc.co.uk

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