Linking Hydrology, Plant
Ecology and Fluvial
Geomorphology
Angela Gurnell
Colleagues
g
on Current Research Grants
Walter Bertoldi,, Tom Liffen,,
Judith O’Hare
Queen Mary, University of London
M tti O’H
Matti
O’Hare
Centre for Ecology and Hydrology
Natasha Bankhead
Bankhead, Andrew Simon
USDA, Agricultural Research Service
C rrent F
Current
Funding
nding
NERC Grant NE/F014597/1
Leverhulme Trust Grant F/07 040/AP
The Leverhulme Trust
The climate-catchment-reach cascade
The important
p
role of engineering
g
gp
plants
Interactions between plants
plants, fluvial
disturbance and sediment supply
The role of plants in rivers of differing
energy
Region
Catchment
Sector /
Junction
Process
domains
Reach
H d l i l
Hydrological
Discharge
Di
h
connectivity
Regime
Longitudinal
Extremes
Floodplain
Power
Alluvial aquifer
Transport
thresholds
Channel
Rock type River network Riparian &
mobility
Structure
Aquatic
Solid
Confinement
Vegetation
Superficial
Resistance
Aquifers
Biostabilisation
Retention
Channel &
Sediment
Topography Lithographic
floodplain
–topographic
supply
style
units
it
M h i
Mechanisms
Quantity
Calibre
Cli
Climate
L d cover
Land
Landform /
Patch /
Habitat
T
Types
Turnover
Mosaic
Sector /
THE (BIO)HYDROGEOMORPHOLOGICAL
CASCADE
Landform /
Junction
Patch /
Region Catchment
Reach
Process
Habitat
domains
H d l i l
Hydrological
T
Types
Discharge
Di
h
connectivity
Regime
WATER,
Longitudinal
Extremes
SEDIMENT
SEDIMENT,
Floodplain
Power
EROSION
EROSION,
DISCHARGE
VEGETATION
WATER BALANCE
Alluvial aquifer
Transport
DEPOSITION,
regime
&
extremes
DYNAMICS
regime & extremes
thresholds
BIOChannel mobility STABILISATION
Turnover
Rock type
River network
Riparian &
VEGETATION
CHANNEL
HYDROLOGICAL
Solid
Structure
Aquatic
PROPAGULE
DIMENSIONS,
PATHWAYS
Superficial
Confinement
Vegetation
LANDFORM
dispersal
MIGRATION,
Overland
flow,
subsurface
Aquifers
Resistance
DEVELOPMENT
INCISION
flow
Biostabilisation
& TURNOVER
SEDIMENT
Channel &
Retention
MOBILISATION & FLOODPLAIN
ROCK
TYPE,
EXPOSURE,
Mosaic &
p
style
y
Topography
Lithographic –
Sediment supply floodplain
CHANNEL
TRANSPORT
(ALLUVIAL
ERODIBItopographic
ERODIBILITY
ITY
Mechanisms
FLOODPLAIN
regime & extremes
AQUIFER)
sediment availability
units
Quantity
HABITAT
DEVELOPMENT
Calibre
MOSAIC
VEGETATION COVER
propagule pool
Climate
Cli
t
L d cover
Land
RAINFALL
regime & extremes
Dispersal / Hydrochory
Gurnell etal. (2009) J. Ecol.
The climate-catchment-reach cascade
The important
p
role of engineering
g
gp
plants
Interactions between plants
plants, fluvial
disturbance and sediment supply
The role of plants in rivers of differing
energy
Vegetation Obstacles:
The Key to Riparian
Engineering by Plants
COLE: Obstacle = Rooted Clod
Flow direction
Stoss
Obstacle
clast
FROME: Obstacle = Emergents
Wake
TAGLIAMENTO: Obstacle = Sprouting Tree
•
•
•
•
•
Sediment and propagule trapping
Bioprotection, reinforcement,
aggradation
Habitat creation
Creation of perched soil moisture
system?
Reduction of flood disturbance
The climate-catchment-reach cascade
The important
p
role of engineering
g
gp
plants
Interactions between plants
plants, fluvial
disturbance and sediment supply
The role of plants in rivers of differing
energy
Interactions between plants,
fluvial disturbance and sediment
supply:
National scale assessment of
the importance of river energy
1
2
Sand and finer
Fine gravel (granules)
Pebble
10-1
3
Cobble and coarser
4
1
5
braided gravel bed channels
wandering and braided gravel bed
channels, sand bed braided
channels
wandering gravel channels, braided
sand bed channels
meandering and low sinuosity sand
bed channels
meandering sand bed channels
2
slope
10-2
upper limit
limit, single
thread gravel
channels
3
lower limit, braided
gravel channels
10-3
upper limit
limit, sand
channels with
sinuosity > 1.25
4
10-4
467 British river reaches
100
101
5
Qmed
lower limit, braided
sand bed channels
102
103
based on Church (2002)
Distribution of aquatic plant morphotypes in Britain
i: some mosses but low abundance of all groups
10-11
ii: high abundance patch submerged, some mosses
iii: high abundance branched emergents
iv: high abundance linear submerged, some linear
e e ge ts
emergents
v: high abundance linear emergents
vi: high abundance linear and patch submerged and
linear emergents
slop
pe
10-2
10-3
Plants eroded?
Landform building?
10-4
100
Channel choked?
101
102
Qmed
103
Interactions between plants,
fluvial disturbance and sediment
supply:
Reach scale assessment of the
importance of plant growth
rates
Rapid growth
plant growth rates
and channel
pattern
Tree
e growtth
Intermediate
growth
Slow growth
Time
Time periods between
uprooting floods for rapid growth
Time p
periods between
uprooting floods for slow growth
Braided – Occasional islands
Occasional islands - Island braided
Island braided - Wandering
Braided – Occasional islands
O
Occasional
i
l iislands
l d - Island
I l db
braided
id d
Island braided - Wandering
Example tree growth trajectories under different growth conditions and in the
absence of uprooting
p
g floods
Growth stages along the growth trajectories
Range in time periods between uprooting floods across the different growth
trajectories to prevent transition from the first to second channel planform style
2001
2008
Interactions between plants,
fluvial disturbance and sediment
supply:
Patch scale assessment of the
importance of plant
biomechanical properties
Manning’s n for narrow, low gradient,
heavily vegetated channels at
baseflow
reach 1
upstream
t
0.25
A
reach 2
reach 3
downstream
d
t
C
02
0.2
B
0.15
A
n
0.1
B
0.05
March
October
0
90
126
164
209
day number
C
246
287
A
B
F
C
A
D
B
C
C
D
F
Gurnell et al (2006) River Research
and Applications.
The climate-catchment-reach cascade
The important
p
role of engineering
g
gp
plants
Interactions between plants
plants, fluvial
disturbance and sediment supply
The role of plants in rivers of differing
energy
Low energy
energy, Single Thread
Thread,
Lowland Rivers
High energy, multi-thread rivers
Bankfull
stage
400
Fre
ee water surface
e level ((cm)
350
Most islands
turn over
Surface flow inundates
entire active tract
300
250
200
150
Floodplain avulsion
Large trees uproot & disperse
Surface water reaches major islands
Complex morphological changes
around vegetated patches
Surface water reaches many vegetated patches
All surface water bodies connect at surface
High open bar surfaces start to inundate
Ponds connect at surface to flowing channels
Low bars inundate, sediment turnover commences
100
50
Number
N
b off fl
flowing
i
channel
h
l segments
t rapidly
idl
increases
Surface flow predominantly
in a single channel
0
0.1
1
Bertoldi, W. et al. (2009) River Research and Applications
10
Return period (yrs)
100
Inc
creasing vegetattion influ
uence
Channel change
commences
in main channel
(i)
Resprouting Trees and Islands on
River Bars
(i)
(ii)
(iii)
(ii)
(iii)
Gurnell et al, 2005
Gurnell, Tockner., Petts, Edwards (2005) Frontiers in Ecology and
Environment
Time Periods / Rivers of
Varying Energy