MRC Preliminary Design Guidance

Mekong Forum on Water, Food and Energy7-9 Dec 2011, Phnom Penh , Cambodia

MRC Initiative on Sustainable Hydropower

Dec 2011

MRC Initiative on Sustainable Hydropower

Dec 2011

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MRC Preliminary Design Guidance


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Meetings to disseminate the content of the MRC Preliminary Design Guidance


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Design guidance document

Based on 5 basic principles

• Avoidance of impacts where possible

• Precautionary principle (esp avoid biodiversity loss)

• User pays• Adaptive management• International good practice


Guidance for navigation lock design and operations

Guidance for navigation lock design and operations

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MRC AGREEMENT

Article 9:Freedom of Navigation“ The Mekong river shall be kept free from obstructions, measures, conduct and actions that might directly or indirectly impair navigability, …


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Preliminary Recommendations for Lock Dimensions on the Mekong River

Future doubling of the locks if traffic increases in parallel set-up to a width of 24m.

These specifications are based on international standards, recommendations by the International Inland Navigation Association (PIANC), and assessments of Chinese waterway classifications in the case of rivers associated with hydropower developments

Length 130m

Width 12m

Depth 4m


Approximately 50% of total fish catch in the lower Mekong basin is dependent on long distance migration – white fishes (about 1 million tonnes worth >US$1,500-2,000 million)

Important for rural livelihoods

Biodiversity – 2nd to Amazon

Fish migration in the Mekong


Fish movement at Khone Falls from Baran 2006 – Fish migration triggers in the LMB and other tropical freshwater systems

Guidance for Fish passage


Dams impact on river fisheriesDams impact on river fisheries

Barrier to fish migration – upstream and downstream|

Result is fish cannot complete their life cycleSpawning reduced or stoppedPopulation size reducedDeclining fisheries yieldImpact on people


Solution = Build a fish pass ??Solution = Build a fish pass ??

Three requirements for successful fish passes

1. Fish must find entrance

2. Fish must be able to ascend / descend

3. Fish must exit and continue migration


Mitigation – fish ladder – low dams only (<6-10 m)


Mitigation – fish lock – low-medium dams (<10 m dams)


Mitigation – fish lift or elevator – potentially high dams


Design guidance document

52. Fish passage must be incorporated – upstream and downstream

53. Safe passage for 95% target species, all flow conditions

57. Adopt best international practice, utilise core expert group, developer pays

63. Mortality through fishways < 5%

65. 10% of low season flows through fish pass

84. Contingency fund for modification – 20% of initial cost of fishway


Sediment management and River Morphology

Sediment management and River Morphology

As dams trap sediment. They release waters with reduced sediment loads, called

sediment‐starved or “hungry” water. These flows downstream of the dam possess more energy to

transport sediment, but may have little or no sediment. The excess energy of these flows can typically cause erosion of

the channel bed and banks. If coarse materials are not present in the bed, bed incision

cannot be stopped and can reach significant depths of many meters.

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Environmentally friendly flushingSend downstream only the concentration of sediment that

the environment can withstand

Environmentally friendly flushingSend downstream only the concentration of sediment that

the environment can withstand

C = 1g/l

C = 20 g/lConcentration 20 g/l peaks up to 80 g/l

Weak concentration

C1 Q1

C2 Q2

REAL TIME Concentration measurement

gate discharge regulation

Concentration 5g/l

Half depth gate

Bottom gate

600m3/s

C = 1g/l

C = 20 g/lConcentration 20 g/l peaks up to 80 g/l

Weak concentration

C1 Q1

C2 Q2

REAL TIME Concentration measurement

gate discharge regulation

Concentration 5g/l

Half depth gate

Bottom gate

600m3/s

Francis Fruchart, CNR France


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Need for a coordinating body for dam operationNeed for a coordinating body for dam operation

Major roles

Optimise operation of dam cascade for electricity generation

Manage flood risk

Coordinate and optimise sediment flushing activities

Coordinate environmental monitoring

Feedback to dam operation


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Cumulative impacts in sensitive

areas

Cumulative impacts in sensitive

areasAlluvial reach

Alluvial reach

Planned mainstream dam

Alluvial reaches are most sensitive to morphological change because they have highly erodable bed and banks


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Water Quality and Aquatic EcologyWater Quality and Aquatic Ecology

In general satisfactory based on

WQ monitoring

Ecological Health Monitoring


MRC Procedures for Water Quality -MRC Procedures for Water Quality -

To maintain good/acceptable WQ in the Mekong River Basin

Performance target for the impoundments:• Criteria and standards for human health and aquatic life and

framework for water quality emergency

Monitoring: • MRC Water Quality Monitoring Network • Specific monitoring inside and downstream the

impoundment

Proposal for guidance: • Criteria from the Technical Guidelines of Procedures for

Water Quality with amendment related to deep impoundments


Guidance for Safety of DamsGuidance for Safety of Dams

The safe design, construction and operation of dams depends on more than engineering factors.

Dam safety is a complex process.National requirements and international

good practice for the safety of dams.


DAM SAFETY MEASURESDAM SAFETY MEASURES

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• Safety issues associated with characteristics of the dam

• Mechanical and electrical control equipment backed up/doubled up, to ensure capability in emergencies.

• Comprehensive dam safety reviews

• Relevant national standards and government framework for the safety


World Bank Operational Policy on Safety of Dams

World Bank Operational Policy on Safety of Dams

Experienced and competent professionals design and supervise construction.

Dam Safety Panel An instrument plan O&M procedures and arrangements A clear communication strategy to engage with

stakeholders on dam safety issues and emergency preparedness activities

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EMERGENCY PREPAREDNESS PLAN (EPP)

EMERGENCY PREPAREDNESS PLAN (EPP)

In particular, developers / owners / operators should – prepare and implement a Dam Safety Management

System (DSMS)– be responsible to check for periodic updates of the

World Bank Operational Policy– be responsible for all cost associated with

implementing all aspects of this guidance on the safety of dams

– clearly detail all such costs in the project budgets for the design, implementation and operation stages

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“The major problems in the world are the result of differences between the way nature works and the way people think.”

Gregory Bateson

MRC Preliminary Design Guidance

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Transcript of MRC Preliminary Design Guidance