impact - wp4 dam-break induced floods and sediment movement progress report

Louvain-la-Neuve -Nov 2003

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 Nicolas le Grelle

IMPACTInvestigation of extreme flood Processes and uncertainty



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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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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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Near-field : programme & scheduleNear-field : programme & schedule

• Debris flow : acting forces (UDT)

• Dam-break experiments (UCL)

• Dam-break numerical modelling (UCL)

• Validation of codes (UDT, UCL, Cem)



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• Debris flow : acting forces (UDT)– Uniform material

• Months 1-18

– Graded material• Months 19-32




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• Dam-break experiments (UCL)– Same bed levels

• Months 1-9

– Initial step in bed level• Months 1-9 > 1-23

BM UCL 1

BM UCL 2



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• Dam-break numerical modelling (UCL)– 1D model : months 1-6

– 2D-V model : months 21-32



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

BM UCL 1

BM UCL 2



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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• Secondary dams



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Far field : programme & scheduleFar field : programme & schedule

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

(UCL)– Large-scale model (Châtelet)

• Field experiments : Norwegian dam (SG)

• Numerical modelling (UCL)

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



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

(UCL)• Uniform material• Graded material >

probably one test

• Months 13-20

BM UCL 4



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• Laboratory experiments– Large-scale model (Châtelet)

• Months 24-31 > 27-31 • Prismatic valley

– Same bed level (DB)– (Initial step) (DB)– With embankment (BM Chat)

• Enlargement (BM Chat)BM Chat



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• Field experiments– Norwegian dam (SG)

• Geomorphic survey not realised

• Months 9-12 : cancelled

• Months 19-21:

– Downstream survey (DB)



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

• Bank erosion

• Months 12-20

> 12-31

50°

37°

85°

Vbank



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

• Prismatic valley, with embankment

– BM UCL 4 : small scale– BM Chat 1 : large scale

• Enlargement (BM Chat 2)

BM ChatBM UCL 4



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• Validation (UCL, UDT, Cemagref, IST)– Field cases : Lake Ha!Ha!

• Months 33-35 > 24-34

BM Ha!Ha!

Brooks and Lawrence1999



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Benchmark summaryBenchmark summary

• Near field

• Far field

BM UCL 1BM UCL 2

BM UCL 4

BM Ha!Ha! BM Chat



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Progress report





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Decisions / questions / discussionDecisions / questions / discussion

• Experiments– Experiments with an initial step

• new flume available in June 2003• completion postponed till September 2003

> November 2003 (1)

– Extension to graded material• for the forces acting on sediment• near-field experiments : a few bimodal

tests• far-field : probably one test



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• Benchmarks– Benchmark BM UCL2 :

Dam break experiment with initial step • benchmark available in November 2003• results December 2003 > March 2004 ?

(2)

– Benchmark BM UCL3 : 2D-V case• cancelled



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• Benchmarks– Benchmark BM UCL4 :

Dam-break flow in initially prismatic valley, with uniform (and graded) material• form of the benchmark : 2003 tests• launched in September > November ? (3)

– Benchmark BM Chat : Large scale dam-break experiments with uniform material (LRH Châtelet)• form of this benchmark ? (4)



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• Benchmarks– Benchmark BM Norway :

Norway field test• cancelled ? (5)

– Benchmark BM Ha!Ha! : Lake Ha!Ha! dam-break event• feasibility of the schedule• invite a member of the Geological Survey

of Canada• discuss format > launched at LLN meeting



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Progress report



impact - wp4 dam-break induced floods and sediment movement progress report

Documents

sediment movementfar

uncertaintydambreak

cemdambreak floods

sediment movementnear

sediment movementnearfield

sediment movementaims

sediment movementscope

ist1d dambreak flow