Morphological challenges: morphological impact resulting from the demands of the individual interests. some Dutch examples

1. Morphological challenges: morphological impact
resulting from the demands of the individual interests.
RESTORE – WORKSHOP
Part 1
Sharing River restoration knowledge and experience in Europe,
Iaşi-ROMANIA, 9-11 May 2012
Hendrik Havinga
1
Dutch Ministry of Infrastructure and Environment
Rijkswaterstaat Oost Nederland

2. River restoration topics
• Goals (increase bio-diversity, WFD)
• River functions
• Current situation (natural river, regulated river, physics)
• Restoration measures problems (challenges..)
• Mitigating measures
• Monitoring
• Maintenance
• Administration processes

3. The river and its user
functions
Primary function
Added functions

4. Regulated
River
The Waal River, NL

5. The Primary function
(safe discharge of
water, ice and
sediment)
Discharge control at Pannerden Weir
1993 flood in Waal River at Kekendom
Bridge upstream city of Kampen, 1996

6. New levee after breach, Dongting Lake , 1998
Sedimentation in branch of Yangtze River in Dongting area

7. Added functions

8. Current situation, Rhine
example
• Historical developments
• Today

9. Rhine River catchment
Istein

10. The Oberrhein in early days...
(at Istein)
Basel

11. View at Istein today..
Restrhein +
Canal d’Alsace

12. The Oberrhein
Regulering regulation

13. River regulation German
Oberrhein
Johan
Gottfried Tulla

14. River training:
also closing of side
channels

15. Dike failure through ice
dams
(may very well start on shoals, at side
channel inlets)

16. River Regulation Measures
Measure Hydromorphological effect
Singular groynes (jetties) Width reduction
Dikes (Levees) “
Normalisation “
Bend cut-off River shortening
Locks and dams Sediment withdrawal
Deforestation Sediment supply

17. The regulated river
levee floodplain fairway
summerdike
groyne
Why this lay-out ?

18. LAY-OUT PREFERENCES
Interest Geography Defenses Hydrology
SAFETY Summer dikes "armoured" guarding max. design water-
AG AINST Winter dikes constructions levels and discharge
FLOODING
Groynes (ice) rock distributions
NAVIGATION summer dikes "armoured" up to 4,0 m waterdepth:
Deep minor bed constructions total discharge through minor
rock bed.
AGRICULTURE summer dikes "armoured" no flooding
polder dikes constructions
grass
no natural
vegetation
ECOLOGY summer dikes with "soft" frequent flooding
inlets and outlets constructions
secondary no rock
channels
Natural vegetation

19. The regulated river
levee floodplain fairway
summerdike
groyne
Impact of levees, dikes and groynes ?

20. Width reduction
top view
Flow direction
l
leve
W ater
longitudinal view
Bed

21. short term effects of width reduction
top view
Flow direction
l
leve
W ater
longitudinal view
Bed

22. Final effects of width reduction
top view
Flow direction
l
leve
W ater
longitudinal view
l
leve
Bed

23. Bend cut-off
top view
n
irectio
F low d
A B
vel
Water le
longitudinal view
Bed
B
A

24. Short term effects of Bend cut-off
top view
n
irectio
F low d
A B W ater
leve
l
longitudinal view Bed
B
B
A

25. Final effects of bend cut-off
top view
n
irectio
F low d
A B W ater
leve
l
longitudinal view Bed le
vel
B
B
A

26. Dam in the river
top view
Flow direction
level
water
longitudinal view
Bed

27. Short term effects of dam in the river
top view
Flow direction
level
Water
longitudinal view
Bed

28. Long term effects of dam in the river
top view
Flow direction
level
water
longitudinal view
el
Bed lev

29. Side-effect of regulation works: increased flood levels
Q
8000
m3/s
Worms
ΔQ = 1820 m3/s
Maxau Δt = - 45 hr
ΔQ = 1100 m3/s
Δt = - 45 hr
Maxau
1882/1883
4000 1995
Worms
1882/1883
1995
2000
Flood wave
Oberrhein
0 t
1 2 3 4 5 6 7 8 9 10

30. • Dutch Rhine

31. Other side-effect: Bed degradation
(Waal River)
Ochten Hulhuizen
IJzendoorn Dodewaard
Haalderen
Tiel
Ben. Leeuwen
Gorinchem Pann. Kop
Herwijnen
Haaften Opijnen Dreumel
Erlecom
Nijmegen
Zaltbommel
St.-Andries
sea
sedimentation
dredging
z: 2 cm/year
turning point
erosion

32. The regulated river
levee floodplain fairway
summerdike
groyne
Regulation led to increase of flood levels and severe bed erosion
Also nature values have been harmed

33. Today’s major river projects
in the Netherlands
• Room for the River Program:
– Lower flood levels
– Some 40 measures to increase flood conveyance (400 km)
– Increase of landscape quality
• Natural vegetation, side channels
– Ready in 2015
– Budget € 2.3 billion
• European Water Framework Directive (WFD):
– Good Ecological Potential
– Only banks and floodplains can help

34. Overview of Room for the River
projectsites

35. Room for the River measures
Measures with ecological potential

36. WFD Project scope for central and eastern NL until 2015
95 ha floodplain lowering
25 km secondary channel 2-sided
IJssel 8 km secondary channel 1-sided
60 km ecological river banks
15 ha shallow reed zones
L. Rhine-Lek 41 fish passages
Waal Budget 130 80 million €
Postponement of measures after
2015

37. Many projects
Example IJssel River
(120 km)

38. Restoration measures

39. Normalised Rivers : hydromorphological
pressures
Groynes narrow main channel and
prevent lateral migration
Main channels
incise
Floodplains aggrade
All large rivers are designated as heavily modified
and can only to a limited part be rehabilitated

40. Types of measures for
ecological improvement
for fish, macrofauna and
waterplants
Theme Measure
Restoration of habitats and natural Ecological banks
dynamics Connecting lakes to rivers
• Shallow areas, low flow velocity Construction of secondary channels
• Protected from waves from ships Lowering of floodplains
• Variation in conditions (substrate, flow
velocity, water depth)
• Sandy banks with a gradual slope
Remove barriers for fish migration Construction of fish passages
• Connect rivers and brooks Rehabilitation of mouth of brooks
• Connect fresh and marine waters
Introduction of seeds of water plants
Clear and clean water
Creation of shelter by e.g. a dam

41. Ecological river bank
Actual
Plan

42. Erosion from ecological
river bank
Sedimentation in
navigation channel
Concern from
navigation sector
Morphological
study

43. Secondary channels Waal channel Amerongse
and Nederrijn-Lek Bovenpolder 5,8 km
Gameren
Maintenance
Vreugdenrijkerwaard - Sedimentation in main
and secondary channel
- Vegetation

44. Fish passage Weirs Nederrijn

45. Restore connection for fish
migration between rivers and
brooks
Pumping station winde
Mouth of
brook
45

46. Assignment
• Group divided in 4 subgroups
– Discuss of your home situation, executed/planned
restoration measures and problems
– Give short outline on flipoverflaps
• Results will be presented tomorrow
• Possible rearrangement of content

47. Results of the assignment

48. Restoration measures problems
(challenges..)
• Free banks
• Side channels

49. Removal of bank defenses and re-
introduction of side channels may
present management problems
River restoration measures
– Natural vegetation
– Free banks
– Side channels

50. Natural vegetation decreases flood protection

51. Example: longitudinal dam in groyne
fields (prevents erosion, increases
fairway)
(Waal River near Opijnen)

52. Side channel through groynes =
fish passage

53. Vegetation Development
Opijnen 1992

54. Vegetation Development
Opijnen 2003

55. Intervention and
Monitoring
???
What is the right moment to intervene ?
Quality: flood protection level, sailing depth, stability, ecological potential,..

56. Historical bank erosion (by cattle and ships)
was reason for bank protection
56

57. Removal of bank protection
(right bank) at Engelse
Werk (Zwolle) dynamic land-
water gradient
• Removal of rip rap, construction of
new groynes
• Sandy banks, tolerated bank erosion
• In time accretion in navigation
channel
IJssel Engelse werk
photo: B. Boekhoven

58. Engelse werk, 13 years later
16 m (16 m in 1995-2001)
28 m (8 m in 1995-2001)
21 m (12 m in 1995-2001)
Original bank
February 2008

59. Increased morphodynamics
sedimentation during flood
Initial outflanking of groynes
bank erosion by wave attack
More various macrofauna communities

60. Side channel in the Klompenwaard (Waal River near bifurcation Pannerden)

61. Bakenhof dike set-back,
Nederrijn River, 2000
near bifurcation Westervoort

62. Impact on low
Plan Westenholte:Lowered flood plains + side channel
water bed
Aggradation of bend
First shoal
Flood shoal Increased flood levels
Hindrance to navigation

63. Morphological effects on
main channel (1/3)
elevation
(m+NAP)
gradual
flow velocity acceleration abrupt
(m/s) deceleration
abrupt
gradual acceleration
decelaration

64. Morphological effects on
main channel (2/3)
gradual
acceleration abrupt
flow velocity
deceleration
(m/s)
abrupt
gradual acceleration
decelaration
sedimentation
front
initial bed level
changes
(m/day) sedimentation
erosion erosion
expansion
wave

65. Morphological effects on
main channel (3/3)
sedimentation
front
initial bed level
changes
sedimentation
(m/day) erosion erosion
expansion
wave
elevation
(m+NAP)

66. Gameren

67. Side channel
(Waal River near Gameren)

68. Aggradation main channel as
planned (2 dm, channel discharges
< 3%).
Local erosion at groyne roots and
transfer zones
undefended/defended banks
West channel East channel
Large channel

69. Computed bed level respons
Gameren
(2 dimensional morphological model
Delft3DMOR, repeated yearly hydrograph)
Deltares (former WL Delft Hydraulics, 2004)

70. Control principles for side
channels
(from) MSc Study of Mr. Bhuban Ghimire
S control (local) student at UNESCO-IHE Delft (2003), titled:
“No-regret” solutions for intakes for side channels
Quantity of
Sediment Entering
Q control (local) Channel
Stability
Sediment Transport
Increasing sediment size Increasing slope
capacity
River X-section control
Waal (whole channel)
Degradation Aggradation
Secondary
Sediment load Water discharge
Channel
Lane’s Balance

71. Control principles..
Sediment distribution
Hydraulic control Sediment control
Sediment Sediment
Transp. Cap.
distribution distribution
ΔS(Qcontrol)
⎛ S sc ⎞ ⎛ S sc ⎞ ΔS (S control)
⎜ ⎟ ⎜ ⎟
⎜ SW ⎟ ⎜S ⎟
⎝ ⎠ ⎝ W⎠
Transport capacity
⎛ Q sc ⎞ ⎛Q ⎞
⎜ ⎟ ⎜ sc ⎟
⎜Q ⎟ Cross-section control ⎜Q ⎟
⎝ W ⎠ Sediment transport capacities ⎝ W ⎠
for different channel sections
Normal
channel
⎛ S sc⎞ Deep
⎜ ⎟ channel
⎜ SW ⎟
⎝ ⎠
Wide channel
⎛ Q sc ⎞
⎜ ⎟
⎜Q ⎟
⎝ W ⎠

72. End of part 1
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