On 17 and 18 June 2020 the EPA held its National Water Event as an online conference. This year's theme was 'Restoring our waters'. This years event was free to attend. It was the EPA's largest water event ever, with over 1250 attending. To everyone who joined us: thanks for attending; thanks for your probing questions; thanks for your passion; thanks for caring about our waters. We can achieve more working together. Special thanks to all our presenters and the team who worked behind the scenes to make sure this years conference happened. For science and stories about water quality in Ireland, check out www.catchments.ie

1. Insert
Main Title
Insert Subtitle
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Presenter #1
Presenter #2
Restoring Rivers: Working with River Processes
(but within site constraints)
Hamish Moir
cbec eco-engineering UK Ltd
Rivers and Lochs Institute, University of the Highlands and Islands
EPA National Water Event 2020, Restoring Our Waters, Online Conference, 18 June 2020

2. EPA National Water Event 2020, Restoring Our Waters, June 2020
PROCESS RESTORATION
• Over-arching philosophy: restore catchment-scale
river processes as much as possible.
o Largest feasible spatial scales.
o Restore process not local-scale design.
o Longer temporal scales – not ‘quick fix’.
o Sustainable– let the river do the work!
• HOWEVER, constraints exist:
o Land-use pressures.
o Fragmented land-ownership.
o Lack of catchment scale management plans.
o Inappropriate timescales.

3. GIVEN GEOMORPHIC REGIME AND IMPACTS, WHAT IS REQUIRED?
Process Restoration in Practice Dec 2015
Potential for geomorphic work
(Perceived)degreeofrisk
‘DO
NOTHING’
EPA National Water Event 2020, Restoring Our Waters, June 2020

4. ~1750
‘DO NOTHING’ - White Esk, Dumfries and Galloway
Natural Recovery
1858
EPA National Water Event 2020, Restoring Our Waters, June 2020

5. GIVEN GEOMORPHIC REGIME AND IMPACTS, WHAT IS REQUIRED?
Process Restoration in Practice Dec 2015
Potential for geomorphic work
(Perceived)degreeofrisk
‘DO
NOTHING’
‘ASSISTED
RECOVERY’
‘INITIAL
CONDITIONS
DESIGN’
‘FUNCTIONAL
DESIGN’
EPA National Water Event 2020, Restoring Our Waters, June 2020

6. GIVEN GEOMORPHIC REGIME AND IMPACTS, WHAT IS REQUIRED?
Process Restoration in Practice Dec 2015
Potential for geomorphic work
(Perceived)degreeofrisk
‘ASSISTED
RECOVERY’
(‘Stage 0’)
Allt Lorgy
‘INITIAL
CONDITIONS
DESIGN’
Eddleston Water
‘FUNCTIONAL
DESIGN’
Mains of Dyce
EPA National Water Event 2020, Restoring Our Waters, June 2020
‘ASSISTED
RECOVERY’
River Nairn at
Aberarder

7. Process Restoration in Practice Dec 2015
Case Study 1: Allt Lorgy – Assisted Recovery
• Unusually ‘constraint free’ restoration site
• Very simple land-ownership of area.
• Very little infrastructure ‘at risk’.
‘EVERYTHING ON THE TABLE!’
EPA National Water Event 2020, Restoring Our Waters, June 2020
‘Stage 0’?

8. EPA National Water Event 2020, Restoring Our Waters, June 2020
Case Study 1: Allt Lorgy – Assisted Recovery (‘Stage 0’)
• Let the river do most of the work after constraints to physical
process removed – kick-start dynamic geomorphic activity

9. Assisting channel evolution: Allt Lorgy
9

10. EPA National Water Event 2020, Restoring Our Waters, June 2020
Allt Lorgy: Pre- and Post- Restoration Implementation
2012201420162019

11. Allt Lorgy: spawning habitat
2011-13 = 0 redds
2014 = 5 redds
2015 = 11 redds
2016 = 14 redds
2017 = 31 redds
2018 = 29 redds
Pre-design to post-flood
REDDS
REDD
REDD
REDD
2011 (pre-design)
~5 years for spawning
habitat to evolve?

12. Case Study 2: River Nairn at Aberarder –
Assisted Recovery
12
Greater risks than Allt
Lorgy – slightly more
constrained design
Approximate extents of
wetland/ pond areas areas.
Large wood
structures

13. Case Study 2: River Nairn at Aberarder –
Assisted Recovery

14. Channel evolution 20th – 25th Sept. 2017
Case Study 2: River Nairn at Aberarder –
Assisted Recovery

15. Case Study 2: River Nairn at Aberarder –
Assisted Recovery

16. Case Study 2: River Nairn at
Aberarder – Assisted Recovery

17. Approximate extents of
wetland/ pond areas areas.
~28,200m2 of online
wetland habitat created
Case Study 2: River Nairn at
Aberarder – Assisted Recovery

18. Case Study 2: River Nairn at
Aberarder – Assisted Recovery

19. wood placement
A
A
239
239.2
239.4
239.6
239.8
240
0 5 10 15 20 25 30
Level[m]
Cross chainage SECTION A-A [m]
0
0.05
0.1
0.15
January
February
March
April
May
June
July
August
September
October
November
December
Q95Discharge[m3/s]
RESTORED (POOL)UN-RESTORED
Q95 water depths
Hydraulic model output

20. 0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5
Velocity[m/s]
Depth [m]
Restored reach
Un-restored reach
Fr 0.1
Fr 0.7
Distribution of
depth and
velocity at Q95
Hydraulic model output

21. Habitat utilisation: spawning

22. EPA National Water Event 2020, Restoring Our Waters, June 2020
What is (has been) more typical…
• More significant constraints to design
• Unlikely to be working in relatively un-impacted
system
‘Initial Conditions Design’
• Design initial physical ‘template’ for river
processes to adjust
• But must be based on systematic, science-based
design methodology!

23. Case study 3 – Eddleston Water - Initial Condition Design
Anthropogenic and natural
constraints:
– relatively low energy
– infrastructure/ services
– agriculture
– flood risk
EPA National Water Event 2020, Restoring Our Waters, June 2020

24. Case study 3 – Eddleston Water - Initial Condition
Design
EPA National Water Event 2020, Restoring Our Waters, June 2020
• Imposed Q and slope
• Determine if new channel
alignment is appropriate for
modern controlling physical
variables
• Determine general channel
geometry (width, depth) –
threshold/ regime equations,
‘extremal hypothesis’ relationships,
analogue sites
• Iterative 2D modelling – design
adjustments, progressive
introduction of complexity
• Final design is ‘initial condition’
w = aQb
w = aQbSc
w = aQbScMd
etc

25. PBA Water Summit, Oct. 2018
Project Example (UK) – Eddleston Water

26. Case study 4 – Mains of Dyce – ‘Functional Design’
EPA National Water Event 2020, Restoring Our Waters, June 2020
• Small culverted tributary
flowing to the south of the
River Don in Aberdeen city
• Catchment highly industrial
and urban
• Course of channel tightly
controlled by housing
development – unnaturally
high channel slope
• Initial construction good
example of lack of
consideration of appropriate
geomorphic design

27. ‘Stable’ Channel Design (high gradient)
Practical River Works, Inverness, 23-24 Sept. 2019
• Reproduce natural morphology of ‘step-pool’ type
channels, given high imposed slope (> ~3%)
41.000
41.500
42.000
42.500
43.000
43.500
44.000
44.500
45.000
45.500
46.000
0 50 100 150 200
Elevation(m)
River station (m)
Step-pool profile
Basal bed profile
Design
conditions
(Q = 3.0 m3s-1)
(H/L) × S = C
C = 1 to 2

28. Case study 4 – Mains of Dyce - Functional Design
EPA National Water Event 2020, Restoring Our Waters, June 2020

29. Conclusions and take home points
• Understanding of physical river process key to
successful river management design
• Reproducing natural river form is the most
effective and sustainable design strategy
• Different types of approach are required in
different environments
• Some reproduction of natural process possible,
regardless of constraints and scale
• BUT design methodology needs to be
theoretically/ evidence based may require
detailed assessment (e.g. hydraulic modelling)
• Rivers change – this must be considered in the
design process
MANAGEMENTOFRISK
MANAGEMENTOFRISK
EPA National Water Event 2020, Restoring Our Waters, June 2020

30. Any questions?
SSE Workshop, Inverness, 3rd Sept. 2019
h.moir@cbecoeng.co.uk
01463 667318

31. CASE STUDIES
Process Restoration in Practice Dec 2015
Full catchment
scale process
restoration
1. Allt Lorgy – Assisted Recovery (‘Stage 0’)
2. River Nairn at Aberarder – Assisted
Recovery (initial conditions?)
3. Eddleston Water – Initial Conditions
Design
4. Mains of Dyce – Functional Design
Increasingdesignconstraints,
decreasingpotentialfor
geomorphicwork
EPA National Water Event 2020, Restoring Our Waters, June 2020

32. Process Restoration in Ideal and Practice May 2014EPA National Water Event 2020, Restoring Our Waters, June 2020
Conclusions
Explicit consideration of physical process in restoration design is
essential:
• Ensures that some reproduction of natural process,
regardless of constraints and scale
• Better understanding of risk to design if controlling
processes (and related uncertainties) are understood
• BUT design methodology needs to be systematic and
theoretically/ evidence based
Further development needed on:
• Further research needed to assess the assumption that
instream ecology responds to natural physical process
• MORE carefully designed monitoring – feedback into
design methodology and biophysical linkages

33. Case study 3 – Eddleston Water - Initial Condition Design
EPA National Water Event 2020, Restoring Our Waters, June 2020

34. Case Study 2: River Nairn at
Aberarder – Assisted Recovery

35. Case Study 2: River Nairn at
Aberarder – Assisted Recovery

36. Habitat utilisation: spawning
POT
POT
TAIL
TAIL
HABITAT UTILISATION BY
SPAWNING SALMON
WITHIN 3 WEEKS OF
PROJECT COMPLETION

37. EPA National Water Event 2020, Restoring Our Waters, June 2020
Acknowledgements
Liz Henderson,
Duncan Ferguson
Julie Tuck,
Alasdair
Matheson
Will Boyd-Wallis
Anne Elliott
Luke Comins, Hugh
Chalmers, Chris Spray

38. Controls on channel morphology
Process Restoration in Practice Sept 2014
WANDERING
POOL-
RIFFLE
STEP-POOL
CASCADE
PLANE
BED
Transport capacity
DYNAMIC
POOL-
RIFFLE
‘Supply-limited’
channel
morphologies