IMPACT - WP4 Dam-break induced floods and sediment movement Progress report

Mo-i-Rana - September 2002

Dam-break floods and sediment movement

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IMPACT - WP4IMPACT - WP4

Dam-break inducedDam-break induced floodsfloodsand sediment movementand sediment movement

Progress report

Université catholique de Louvain

Yves Zech, Benoit Spinewine and Sandra Soares Frazão



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Aims and objectivesAims and objectives

Improve the prediction

of the motion of sediments

in association with catastrophic floods



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MotivationMotivation

• Dike breaching

BitterfeldRiver ElbeGermanyAugust 2002



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• Dike-breaching wave

GlashütteMüglitzGermanyAugust 2002



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• Debris flow

WeisensteinRiver ElbeGermanyAugust 2002



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Issues of IMPACT WP4 researchIssues of IMPACT WP4 research

• Extreme flows

intense erosion and solid transport

• Intense sediment transport

affects flood-wave prediction– Arrival time– Maximum water level– Morphological changes



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Scope of the researchScope of the research

• Near-field – Uniform debris flow– Severe transient debris flow

• Far-field – Intense transport– Bank erosion and geomorphic changes



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Near field : problems to be solvedNear field : problems to be solved

• Initiation of movement– Acting forces– Vertical effects– Inertial effects– Sediments bulking

• Propagation– Intense scouring– Debris-flow front



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Debris flow : research programmeDebris flow : research programme

• Experiments : acting forces (UDT)– Uniform material

• Months 1-18

– Graded material• Months 18-32

BM UDT ?



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Debris flow : research reportDebris flow : research report

• Uniform material experiments– Tilting flume (L = 6 m, S0 = 0° to 23°)

– Uniform cylindrical PVC particles• Equivalent spherical D = 3.5 mm• Density = 1540 kg/m³



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• Mature debris flow: collisional + frictional

• Rigid-bed debris flowcollisional



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• Mature debris flow



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• Mathematical description (collisional)– Normal stress local equilibrium

• Submerged weight overlying grains• Inter-granular collisional contacts

(pressure related to granular temperature)

– Tangential stress local equilibrium• Relation between external

and internal tangentialstress

• Effect of added mass



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• Rigid bed debris flow– Concentration

– Velocity profile

0.000

0.005

0.010

0.015

0.020

0.025

0.030

0.035

0.000 0.100 0.200 0.300 0.400 0.500 0.600 0.700 0.800

c [-]

z [

m]

c-theoreticalprofile

c-exsperimentalprofile

0.000

0.005

0.010

0.015

0.020

0.025

0.030

0.035

0.000 0.500 1.000 1.500 2.000

u [m /s]

z [

m]

u-theoreticalprofile

u-exsperimentalprofile



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Near-field dam break : programmeNear-field dam break : programme

• Experiments: uniform material (UCL)– Same bed levels

• Months 1-9

– Initial step in bed levels• Months 1-9

BM UCL 2

BM UCL 1



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Near-field dam break : research reportNear-field dam break : research report

• Experiments: uniform material (UCL)– Same bed levels



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Near-field dam break : programmeNear-field dam break : programme

• Mathematical modelling (UCL)– 1D model: months 1-6

– 2D-V model: months 21-32BM UCL 3



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• Mathematical modelling (UCL)– 1D model:

• Velocity distribution• (Concentration distribution)

Near-field dam break : research reportNear-field dam break : research report

pure water

mixture

u

z



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Near-field : research programmeNear-field : research programme

• Validation of codes (UDT, UCL, Cem)– Uniform debris flow (to be clarified)

• Months 11-12

BM UDT ?



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Near-field : research programmeNear-field : research programme

• Validation of codes (UDT, UCL, Cem)– 1D dam-break flow in the near field

• Months 11-12

– 2D-V dam-break flow• Months 34-35

BM UCL 2BM UCL 1

BM UCL 3



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Far field : problems to be solvedFar field : problems to be solved

• Transition from near-field to far-field• Geomorphic changes

– Bank erosion and failure• Tractive forces applied

• Failure mechanism

– Channel widening

– Deposition of material• De-bulking• Distribution of sediments• Formation of secondary dams



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Far field : research programmeFar field : research programme

• Laboratory experiments– Dam-break in an initially prismatic valley

(UCL)• Uniform material• Graded material

• Months 13-20

BM UCL 4



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• Laboratory experiments– Large-scale model (Châtelet)

• Prismatic valley• Enlargement

• Months 24-31

BM Chat



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• Field experiments– Norwegian dam (SG)

• Geomorphic survey (to be checked)

• Months 9-12 and 19-21

BM Norway



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• Numerical modelling– Extension of 2D-H model (UCL)

• Bank erosion

• Months 12-20 50°

37°

85°

Vbank



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• Validation (UCL, UDT, Cemagref, IST)– Laboratory tests

• Prismatic valley (UCL)• Enlargement (Châtelet)

BM UCL 4 BM Chat



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• Validation (UCL, UDT, Cemagref, IST)– Field tests

• WP2 Norwegian dam ?• Lake Ha!Ha!

• Months 33-35

BM Ha!Ha!

BM Norway

Brooks and Lawrence1999



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Benchmark summaryBenchmark summary

• Near field

• Far field

BM Ha!Ha!

BM Norway

BM UCL 4

BM Chat

BM UCL 3BM UCL 2BM UCL 1

BM UDT ?



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IMPACT - WP4IMPACT - WP4

Dam-break inducedDam-break induced floodsfloodsand sediment movementand sediment movement

Progress report

Université catholique de Louvain

Yves Zech, Benoit Spinewine and Sandra Soares Frazão

Documents

IMPACT - WP4 Dam-break induced floods and sediment movement Progress report