1
Monika Šulc
Říční systémy - současné směry
výzkumu a vybrané případové
studie
Rivers in context of actual problems
Rivers – dynamics natural sytems
TYPICAL FLOODPLAIN TOPOGRAPHY FROM
LiDAR, BOGUE CHITTO RIVER, LOUISIANA
PRESENT STATE OF THE FORMER CHANNELS´ SYSTEM
 WATER SUPPLY: THROUGH THE BARRAGESEASONAL
FLOW VARIATION (43<Q<200 m3/s)
 WEIRS INSIDE THE FORMER CHANNEL SYSTEM
CREATE A CASCADE OF SLOWLY FLOWING WATER
BODIES
AFTER DANUBE DAMMING THE FORMER CHANNEL
SYSTEM HAS BEEN ALMOST FULLY SEPARATED:
©VUVH
Introduction
Overview of research topics
1. MEANDERING RIVER SYSTEMS
• Spatiotemporal evolution of a unique meandering systems SACRAMENTO,
SAJO, MORAVA RIVER
2. RIVER RESTAURATION – RHONE RIVER
3. UAV MAPPING (in collaboration with Palacký university)
4. DELINEATION OF FLOOD EXTENDS BY GIS-TOOL
5. EROSION-SEDIMENTATION MODELLING IN SMALL
CATCHMENTS
---
CHALLENGES: MOUNTAIN STREAMS AND FLUXES OF COARSE
SEDIMENTS (in collaboration with Ostrava University)
2
Projects
• 2013 – 2015: IVF Strategic Grant – Detailed aerial mapping and flood impact
monitoring in the V4 region, Head of the Project
• 2012: IVF Small Grant – Evaluation of a new remote sensing methodology for
detailed international mapping in the V4 region, Head of the Project
• 2003 - 2015 – Rhone River Restauration Project
Case studies
1. Meandering Rivers - Morava case studies
2. UAV mapping
Research on meanders
• Empirical approach includes essentially 3 research
directions including
• (1) reconstructions of planimetric development of
meandering rivers from archival documents such as
maps and aerial images,
• (2) repeated field surveys of meandering reaches
illustrating rates of lateral channel migration, changes in
channel geometry, and formation of oxbow lakes, and
• (3) physical modelling of cutoff process in laboratory
experiments (flume studies).
Floodplain lake
• a floodplain lake is an
area of fluvial
hydrosystem spatial
delimited by an axis of
ancient active channel.
• It is composed from two
parts: humid perifluvial
(aquatic perifluvial zone
with ecoton zone) and
terestric zone presented
by an alluvial plug (Rollet,
Citterio, Piégay, 2004).
3
Aim of study
• to bring a new knowledges about selected
characteristics of floodplain lakes as a part of a fluvial
system.
• It responds to this issue with three specific tasks and
work on different rivers and scales.
• Three main axes:
1. the first one presents a historical spatio-temporal
analysis of the Sacramento River,
2. the second part includes a post-restoration analysis of
the Rhone River
3. the third one brings the results from numerical and
physical modeling of flow dynamics and sediment
transport applied on the Morava River.
Lateral Erosion of the Sacramento River,
California: Human influences and
consequences for floodplain lake habitats
I
Objectives
• Problem statement : on a local scale, causes of fluvial changes are difficult
to determine because the location and time of causal factors not always the
same as the associated changes
• our objective is :
– to work on a reach scale
– to relate the spatial and temporal patterns to causal factors using a
comparative approach and multifactorial analysis
• Why this case-study?
– Long alluvial reach with potential structural and spatial variability (160
km)
– Numerous works have been carried out on local scales and a general
background is needed
– Continuing scientific debate on the factors of change and meandering
process
– A lot of data available of good quality
Shasta
Red Bluff
Colusa
160 km
100 km
Channel slope :
0.0002 – 0.0007 m/m-1
Discharge Butte City (1938-1995) :
1750 (Q1.5); 4110 (Q10) m3/s
Mean Annual Flow : 371 m3/s
Catchment size :
31000 km2 (Red Bluff)
Main annual rainfall (mountains)
500-2500 mm.yr-1
Characteristics of
the study reach
230
River Km
Legende:
1983
1978
1963
1978
1975
1964
Colusa Weir,1933
Moulton Weir, 1932
Goose Lake FRS, RM 179
3 B's FRS, RM 186.5
M&T FRS, RM 190
1850-1940
360
350
340
330
320
310
300
290
280
270
260
250
240
230
0 5 102,5
Kilometers
River levees
1964
Date of levees
construction
230
River Km
Legende:
1983
1978
1963
1978
1975
1964
Colusa Weir,1933
Moulton Weir, 1932
Goose Lake FRS, RM 179
3 B's FRS, RM 186.5
M&T FRS, RM 190
1850-1940
360
350
340
330
320
310
300
290
280
270
260
250
240
230
0 5 102,5
Kilometers
River levees
1964
Date of levees
construction
Material & methods
• Select and rectify aerial photos
• Describe relevant geomorphological units (GIS mapping
and measurements)
• Main channel (low flow + unvegetated bars)
• Floodplain lakes
• Compare multiple components over space and time to
identify differences among them and to order them on
longitudinal and temporal gradients (creation of GIS
attribute tables, statistical analysis)
• Literature review and analysis of existing data to identify
the potential causal factors (hydrological signal,
geological settings, history of infrastructures…)
19991985
Similar discharge : Q=300-330m3/s
S. Greco. Univ. of Davis
1962
We also sought to space the photo sets at
similar time intervals of approximately
two decades. We scanned (400 dpi, full
colour) and rectified the photos using the
image of 14 June 1999 (scale 1: 7200) as
reference.
1942
4
Rektifikácia leteckých snímok
(a)
(a)
(b)
(c)
(d) /2/
/3/
/4/
(a)
(c)
(d)
/5/
/5/
/3/
/2/
/4/
(a)
(b)
1) 2)
/1/ downstream distance between downstream
edge of active channel and the edge of
floodplain lake
/2/ intermediary distance between the outline
of first water body edge and the floodlain lake
end
/3/ upstream distance between the edge
channel and active channel
/1/+/2/+/3/ total distance of the mesured unit
/4/ direct distance between the scar lake
edges
/5/ channel center line distance
(a) Water body of connected floodplain lake l
(b) Helophytes and aquatic vegetation
(c) Aluvial plug
(d) Water body of the principal channel
a
3)
1962
1999
age of
floodplain
lake
Active
channel
by segments
Floodplain
lakes
To study the longitudinal organisation and character of the different features, we
created a coverage of elementary segments of 250 m in length from which we extracted the
active channel area, the low flow channel length and the area and eroded floodplain area.
Using channel centrelines mapped for a total of 19 dates from historical maps and aerial
photographs dates 1896 to 1997, we dated historical cutoffs to within 5 years (within 3 years
for more recent years.
• Four distinct reaches were then distinguished statistically:
• the first one downstream of km 272 did not undergo any change in
tendency of cumulative bank retreat whatever the period,
• the second one between km 272 and km 315 is characterised by an
important increase in bank erosion during the period 1962-1985),
• the third section between km 315 and 330 with significant bank
erosion period 1942-1962 (average bank retreat respectively 7.01,
5.41 and 3.63 m/yr).
• the fourth section presents showed two local peaks km 346 and km
358 during the most recent period and underwent from 1942 to 1999
a constant
Evolution of bank erosion by 250m length segments of active channel
Evolution of the characteristics of floodplain lakes
• The size of newly-created
lakes decreased from
1870 to 1940, reaching a
minimum in the 1950’s
and increasing slightly
from 1962-1985.
1999 1985 1962 1942
Appeared since 1985 37
Observed in 1985 31 39
Observed in 1962 10 13 33
Observed in 1942 20 24 35 96
Total 98 76 68 96
Longitudinal Evolutions of Floodplain Lakes
• many lakes downstream
disappeared from 1942 to
1962, but were partly
compensated for by creation
of new lakes over the entire
period through 1999
• In upstream reaches (km 300
to 360), many new lakes
appeared from 1962-1985 and
from 1985-1999. The
longitudinal distribution of
lakes did not change
(regardless of lake type), but
the cumulative values differed
from one photo set to another.
42
62
85
99
-nPCA analysis test the
geometrical differences
between floodplain lakes
according to their inter-date
evolution (new, stable,
disappeared) and the dates of
observation
- F1 axis distinguished the
permanent floodplain lakes
channels whatever the years of
observation
- The lakes “42-62” have the
highest surface areas, axial
length, sinuosity rate, but also
downstream and plug lengths
-The new lakes have a very
short downstream plug, overall
axial length and sinuosity
85-99
42-62
(a)
(a)
(b)
(c)
(d) /2/
/3/
/4/
(a)
(c)
(d)
/5/
/5/
/3/
/2/
/4/
(a)
(b)
/1/ downstream distance between downstream edge of active channel and
the edge of floodplain lake
/2/ intermediary distance between the outline of first water body edge and
the floodplain lake end
/3/ upstream distance betweenthe edge channel and active channel
/1/+/2/+/3/ total distance of the mesured unit
/4/ direct distance between the scarlake edges
/5/ channel centerline distance
5
Shasta dam : 1945
River regulation has reduced the magnitude and frequency of
high-flow events and has increased low-flow discharges during
the summer and autumn irrigation seasons. At Red Bluff, records
from the longest-running streamflow gauge show 2 and 10-year
flood peaks reduced from 3310 and 5840 m3/s respectively predam
to 2170 and 3790 m3/s post-dam.
Effects on peak flow
Summary and interpretation
The history showed that the floodplain habitats of the
Sacramento underwent significant changes during the
20th century:
i) channel narrowing induced a longitudinal simplification
of the aquatic channel and gravel bar habitats,
providing new riparian pioneer habitats upstream
ii) large oxbow lakes have not been created since the late
20th century.
More active bank erosion upstream of km 260 from
1962-1985, increased the rate of new lake creation, but
these new lakes were smaller and less sinuous and
straighter, reflecting their creation by chute cutoff rather
than by neck cutoff.
Conclusions
• Major impacts of bank protection on channel erosion and
floodplain lake formation and geometry
• Change in peak flow as a result of the construction of
Shasta Dam would have induced greater changes in
bank erosion and lake formation if the bank protection
measures have not been in place.
• Artificial bank protection has affected the distribution and
character of floodplain lakes and the floodplain
ecosystem.
• Shasta Dam and other influences have served to
homogenise the channel geometry along the entire
140-km reach, reducing the active channel width.
Feedbacks on Restored Floodplain
Lakes Sedimentation of Upper Rhône
River
II
Rhone River
6
• The floodplain lakes are located
along the River Rhône, France.
• The French Rhône drains the
south-eastern part of France from
Lac of Geneva to the
Mediterranean Sea.
• The river crosses different climatic
zones (continental, oceanic,
mountain and Mediterranean
climates) and is linked by the
Rhodanian alluvial corridor.
• The Rhône is one of the largest
European rivers (812 km,
watershed area = 95 500 km2,
mean annual discharge at the
mouth = 1710 m3/s).
• The hydrologic regime is
characterised by high discharges in
spring and summer.
Objectives
The objectives of study is to:
i) to evaluate the variability in habitat
conditions inside of floodplain lakes from
inter-lake comparison,
ii) to advise the time evolution of habitat
conditions.
Methodology
• From methodological point of
view, we used the methodology
of sediment survey established
recently by Citterio & Piégay,
2008.
• Two steps were considered:
i) the measurement of the
sedimentation rates based on
the ratio between the mean
sediment thickness and the date
of the revitalisation;
ii) the statistical analysis of the
relationships and inter-lake
analysis (the characterisation of
connexion frequency and to
define the life expectancy of
former channels).
237,8
238,3
238,8
239,3
239,8
240,3
240,8
241,3
241,8
242,3
242,8
0 200 400 600 800 1000 1200 1400 1600 1800 2000
altitude(m)
discharge (m3
/s)
real data inflow PK 141.500
real data outflow PK 140.500
calculated data PK 140.830
flood of September 2008
flood of September 2008
flood of March 2006
flood of March 2007
MALOURDIE
Sondes DIVER
and hydrologic data of discharge (source: CNR)
LUISETTES_R
228
228,5
229
229,5
230
230,5
231
231,5
232
232,5
1/1/07
0:00
11
/1/07 10
:00
21
/1/07 20
:00
1/2/07
6:00
11
/2/07 16
:00
22
/2/07 2:00
4/3/07
12:00
14
/3/07 22
:00
25
/3/07 8:00
4/4/07
18:00
15
/4/07 4:00
25
/4/07 14
:00
6/5/07
0:00
16
/5/07 10
:00
26
/5/07 20
:00
6/6/07
6:00
16
/6/07 16
:00
27
/6/07 2:00
7/7/07
12:00
17
/7/07 22
:00
28
/7/07 8:00
7/8/07
18:00
18
/8/07 4:00
28
/8/07 14
:00
8/9/07
0:00
18
/9/07 10
:00
28
/9/07 20
:00
9/10
/07 6:00
19
/10/07 16:00
30
/10/07 2:00
9/11
/07 12
:00
0
200
400
600
800
1000
1200
altitude (m NGF)
discharge (m 3
/s)
MALOURDIE
237
237,5
238
238,5
239
239,5
240
240,5
241
241,5
1/1/07
0:00
11
/1/07 10
:00
21
/1/07 20
:00
1/2/07
6:00
11
/2/07 16
:00
22
/2/07 2:00
4/3/07
12:00
14
/3/07 22
:00
25
/3/07 8:00
4/4/07
18:00
15
/4/07 4:00
25
/4/07 14
:00
6/5/07
0:00
16
/5/07 10
:00
26
/5/07 20
:00
6/6/07
6:00
16
/6/07 16
:00
27
/6/07 2:00
7/7/07
12:00
17
/7/07 22
:00
28
/7/07 8:00
7/8/07
18:00
18
/8/07 4:00
28
/8/07 14
:00
8/9/07
0:00
18
/9/07 10
:00
28
/9/07 20
:00
9/10/07 6:00
19/10/07 16:00
0
200
400
600
800
1000
1200
1400
altitude (m NGF)
discharge (m
3
/s)
BROTALET
233
234
235
236
237
238
239
1/1/07
0:00
11/1/07 10:00
21/1/07 20:00
1/2/07
6:00
11/2/07 16:00
22/2/07
2:00
4/3/07 12:00
14/3/07 22:00
25/3/07
8:00
4/4/07 18:00
15/4/07
4:00
25/4/07 14:00
6/5/07
0:00
16/5/07 10:00
26/5/07 20:00
6/6/07
6:00
16/6/07 16:00
27/6/07
2:00
7/7/07 12:00
17/7/07 22:00
28/7/07
8:00
7/8/07 18:00
18/8/07
4:00
28/8/07 14:00
8/9/07
0:00
18/9/07 10:00
28/9/07 20:00
9/10/07
6:00
19
/10/07 16:00
0
200
400
600
800
1000
1200
1400
1600
altitude (m NGF)
discharge (m
3
/s)
Measurements « HE+ES » and
granulometry
Courbe granulométrique
sur la fraction
0.040 mm - 2000 mm
0
10
20
30
40
50
60
70
80
90
100
0,01 0,10 1,00 10,00 100,00 1000,00 10000,00
diamètre en microns
%
CERISIER N°1 - 24/11/05 - Monika MICHALKOVA
argile silt sable
7
Water depth and sedimentation
Annual mean sedimentation rate(cm/year) Mean water level (cm)
Chautagne T T+1 T+2 T+3 T T+1 T+2 T+3
MAL 29,93 14,62 11,47 7,7 74,4 106,02 96,42 121,6
BRO 15,47 5,57 6,06 6,56 104,6 161,28 93,34 104,6
Belley T-1 T T+1 T+2 T-1 T T+1 T+2
LUI 0 0 0 0 110 102,5 98 113
MOI 1,22 11 11,12 6,27 67,2 115,46 110,59 108,67
FOU 0 0 0,83 0 61,67 125,2 96 89,83
BEA 0,7 1,75 1,87 0,12 7,3 76,02 56,1 48,8
LUC 0 0 0,95 0,42 98,8 112,4 92,3 89,7
YEN 0 0 0 0 3,75 119,25 101,88 97,75
CHA ND 2 ND ND ND 151,6 ND ND
Bregnier-Cordon T-1 T T+1 T+2 T-1 T T+1 T+2
GRA 0 2,32 0 in 2008 0 129,2 136,5 in 2008
VAC 0 0 0 in 2008 96,7 96,4 97,7 in 2008
CER 0,27 9,16 7,08 in 2008 65,4 76,48 68,48 in 2008
MAT 0,76 6,4 en 2007 in 2008 22,4 85,8 en 2007 in 2008
MOL 2,26 27,7 17,34 in 2008 54,8 145,2 148,54 in 2008
PLA 5,05 33,9 18,77 in 2008 55,1 165,2 182,75 in 2008
Sedimentationratesinfloodplainlakes
T-1(before),T(rest.year),T+1(after)
0
5
10
15
20
25
30
35
40
45
50
-5
0
5
10
15
20
25
30
35
40
45
-5
0
5
10
15
20
25
30
35
40
-1
0
1
2
3
4
5
6
-2
0
2
4
6
8
10
12
sedimentationrate(cm/year)
Malourdie (n=10) Brotalet (n=10)
Moiroud (n=10) Fournier (n=6)
Béard (n=10)
2004 feb 2006 oct 2006 oct 2007 2004 feb 2006 oct 2006 oct 2007
2004 feb 2006 oct 2006 oct 2007 2004 feb 2006 oct 2006 oct 2007
2004 feb 2006 oct 2006 oct 2007
-10
0
10
20
30
40
50
60
70
oct 2007oct 20062004
Mollotes (n=10)
sedimentationrate(cm/year)sedimentationrate(cm/year)sedimentationrate(cm/year)
sedimentationrate(cm/year)sedimentationrate(cm/year)
Mapa akvatickej vegetácie
(traitements d’images)
Monitoring « lône de la Malourdie » - Vegetalizácia koryta
Iniciálny stav (20/04/2006)
 Kolonizovaná rozloha : 29%
 Nemožná rekonštrucia batymetrie
Monitoring « lône de Brotalet »
Počiatočný stav (20/04/2006)
 Nemožné rekonštrukcia korytových fácií
 príliš veľa plavenín. Prečo ?
- Otázka lokality
- Absencia freatického prísunu
• 2e état des lieux réalisé fin 2006
Conclusions
• The unique methodology of floodplain lake monitoring
has been presented. The annual measurements have
been done.
• The first feedbacks permit to visualise the lake types.
Also the connecting discharges and the shear stress
have been calculated.
• The duration of the post-restoration period concerning
the floodplain lakes of Brégnier-Cordon and Belley is
relatively short and so the comparison between pre- and
post-restoration state is only just possible.
Morphodynamics of the Exit of a Cut-off
Meander: Experimental Findings from
Field and Laboratory
Studies
III
8
Objective
• The main goal of this study is to investigate the flow and
erosion/deposition processes taking place in the exit of
an floodplain lake.
• Such a situation is common during ordinary floods, as
the inundation frequency is usually much higher at the
exit than at the entrance.
• This kind of ‘backflow’ into the downstream part of the
abandoned channel is a key-process for the infilling of
oxbow-lakes (Shields and Abt, 1989).
• Experiments were conducted on a 8.60m × 19m physical model built within the
VUVH hydraulic facility (Bratislava, Slovakia).
• The model simulates a 2400m-long reach of the lower Morava river, which
forms the boundary between Slovakia and Austria. This originally freemeandering
tributary of the Danube was heavily regulated and channelized in
the mid XXth century.
• The physical model was used to study
several reopening scenarios for two
disconnected meanders, as part of a
European Phare project (Holubova et al.,
1999).
• The main channel and the floodplain,
including disconnected meanders, were
reproduced from bathymetry surveys and
aerial photographs. The floodplain (coarse
sand) and the channel banks and
substratum (concrete) were inerodible.
• In this study, the entrance of the main
meander was closed. Observations were
focused on the downstream exit, which
was directly open to the main channel.
Measurements
• For two different simulation runs, contrasting shapes
were given to the downstream corner of the exit. Run 1
was conducted with a smooth corner (flow incidence
angle roughly 60◦), whereas run 2 was conducted with a
sharp corner and a reduced mouth (flow incidence angle
roughly 90◦).
• During run 1 (smooth corner, a), a 2-gyre system developed, as
observed in spanwise elongated open-channel side cavities.
• The gyre at the mouth of the channel had a mean surface velocity
magnitude that was roughly 3 cm/s in the inflow and less than 2
cm/s in the outflow.
• The velocities measured near the downstream corner suggested a
highly 3D flow structure, confirmed by visual observation of liquid
particles traced by dye injection.
Results
• Topography surveys for both experimental runs yielded similar
erosion/deposition spatial patterns in the meander exit and in the
main channel.
• Some elongated deposits developed in the vicinity of the
downstream side of the exit.
• In run 1, this effect was less visible because 3D currents were not as
strong because of the smoother shape of the downstream corner.
Visual observation indicated an movement of particles inward.
Consistency of Local
Morphodynamical Processes
• Erosion and deposition areas appear to be associated with
acceleration (outflow) and deceleration (inflow) trends, and also with
3D currents induced by the solid boundaries.
• In contrast, sand and silt are deposited in the cavity wherever the
velocity magnitude.
9
Conclusion
• In agreement with previous studies on open-channel
side-cavity flows, a main recirculating flow always
develops in the entrance.
• In the laboratory case, a change in the shape of the
downstream corner of the cavity induced a two-gyre
system instead.
• In the field case, three regimes of complex flow patterns
were distinguished according to the discharge in the
main channel.
• In both cases, a simple analogy - in rectangular cavities
was used to explain the observations.
General Conclusion
• Floodplain lakes have mostly been studied by ecologists,
because their evaluation of river habitats. But the essential
element to know is the structure and functioning of this part of
a fluvial hydrosystem.
• The factor of anthropic pressure cannot be excluded from
analyses of the functioning of floodplain lakes.
• The examples studied in our work join the hydrological
processes and morphological consequences on a fluvial
system.
• The scientific monitoring was the response to different
projects developed by river managers. This can help with the
construction of the coordinated management of a fluvial
system, where the evolution of different parts (such as floodplain
lakes) is included.