The document summarizes guidance presented at the Mekong Forum on Water, Food and Energy in Phnom Penh from December 7-9, 2011 regarding sustainable hydropower development in the Mekong River Basin. The guidance focused on preliminary design, navigation, fish passage, sediment management, dam safety, and environmental flow. Key recommendations included incorporating fish passage into dams, limiting mortality through fishways, allocating a portion of low season flows to fish passage, and requiring developers to establish funds to modify fishways if needed.
Vietnam presentation for intercultural communications class
MRC Preliminary Design Guidance
1. Mekong Forum on Water, Food and Energy
7-9 Dec 2011, Phnom Penh , Cambodia
MRC Preliminary Design
Guidance
MRC Initiative on
Sustainable Hydropower
Dec 2011
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2. Mekong Forum on Water, Food and Energy
7-9 Dec 2011, Phnom Penh , Cambodia
Meetings to disseminate the content of the
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MRC Preliminary Design Guidance
3. Mekong Forum on Water, Food and Energy
7-9 Dec 2011, Phnom Penh , Cambodia
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4. 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
5. Mekong Forum on Water, Food and Energy
7-9 Dec 2011, Phnom Penh , Cambodia
Guidance for navigation lock design
and operations
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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6. Mekong Forum on Water, Food and Energy
7-9 Dec 2011, Phnom Penh , Cambodia
Preliminary Recommendations for Lock Dimensions on
the Mekong River
Length 130m
Width 12m
Depth 4m
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
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7. Mekong Forum on Water, Food and Energy
7-9 Dec 2011, Phnom Penh , Cambodia
Fish migration in the Mekong
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
8. Mekong Forum on Water, Food and Energy
7-9 Dec 2011, Phnom Penh , Cambodia
Guidance for Fish passage
Fish movement at Khone Falls
from Baran 2006 – Fish migration triggers in the LMB and other tropical freshwater systems
9. Mekong Forum on Water, Food and Energy
7-9 Dec 2011, Phnom Penh , Cambodia
Dams impact on river fisheries
Barrier to fish migration
– upstream and downstream|
Result is fish cannot complete their life cycle
Spawning reduced or stopped
Population size reduced
Declining fisheries yield
Impact on people
10. Mekong Forum on Water, Food and Energy
7-9 Dec 2011, Phnom Penh , Cambodia
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
11. Mekong Forum on Water, Food and Energy
7-9 Dec 2011, Phnom Penh , Cambodia
Mitigation – fish ladder – low dams only (<6-10 m)
12. Mekong Forum on Water, Food and Energy
7-9 Dec 2011, Phnom Penh , Cambodia
Mitigation – fish lock – low-medium dams (<10 m dams)
13. Mekong Forum on Water, Food and Energy
7-9 Dec 2011, Phnom Penh , Cambodia
Mitigation – fish lift or elevator – potentially high dams
14. Mekong Forum on Water, Food and Energy
7-9 Dec 2011, Phnom Penh , Cambodia
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
15. Mekong Forum on Water, Food and Energy
7-9 Dec 2011, Phnom Penh , Cambodia
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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16. Mekong Forum on Water, Food and Energy
7-9 Dec 2011, Phnom Penh , Cambodia
Environmentally friendly flushing
Send downstream only the concentration of sediment that
the environment can withstand
600m3/s
Weak
concentration
C = 1g/l
Half depth gate
C1 Q1
Bottom gate
Concentration20 g/l g/l
C = 20 C2 Q2
peaks up to 80 g/l
gate discharge
regulation
REAL TIME
Concentration 5g/l Concentration
measurement
Francis Fruchart, CNR France 16
17. Mekong Forum on Water, Food and Energy
7-9 Dec 2011, Phnom Penh , Cambodia
Need 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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18. Mekong Forum on Water, Food and Energy
7-9 Dec 2011, Phnom Penh , Cambodia
Cumulative
impacts in
sensitive
areas
Alluvial
reach
Alluvial reaches are
most sensitive to
morphological change
because they have
highly erodable bed
and banks Alluvial
reach
Planned
mainstream
dam 18
19. Mekong Forum on Water, Food and Energy
7-9 Dec 2011, Phnom Penh , Cambodia
Water Quality and Aquatic Ecology
In general
satisfactory
based on
WQ monitoring
Ecological
Health
Monitoring
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20. Mekong Forum on Water, Food and Energy
7-9 Dec 2011, Phnom Penh , Cambodia
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
21. Mekong Forum on Water, Food and Energy
7-9 Dec 2011, Phnom Penh , Cambodia
Guidance 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.
22. Mekong Forum on Water, Food and Energy
7-9 Dec 2011, Phnom Penh , Cambodia
• 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
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23. Mekong Forum on Water, Food and Energy
7-9 Dec 2011, Phnom Penh , Cambodia
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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24. Mekong Forum on Water, Food and Energy
7-9 Dec 2011, Phnom Penh , Cambodia
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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25. Mekong Forum on Water, Food and Energy
7-9 Dec 2011, Phnom Penh , Cambodia
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26. Mekong Forum on Water, Food and Energy
7-9 Dec 2011, Phnom Penh , Cambodia
“The major problems in the world are the result of differences between the way nature
works and the way people think.”
Gregory Bateson 26
Notas del editor
Hydropower developments could pose a barrier to navigation, but they also offer the possibility of providing more reliable and consistent water depths that will facilitate larger vessel capacities.The MRC AGREEMENT, Article 9: promotes “Freedom of Navigation” where the content says“ On the basis of equality of right, freedom of navigation shall be accorded throughout the mainstream of the Mekong river without regard to the territorial boundaries, … ““ The Mekong river shall be kept free from obstructions, measures, conduct and actions that might directly or indirectly impair navigability, …We have to bear in mind the long-term nature of planning and investment for navigation locks. After dams, locks are the biggest and most expensive works on a navigable river. It is almost impossible to alter lock dimensions after construction, although building a second lock is possible. Lock dimensions must accommodate traffic increases in view of a 50 year planning horizon. The current situation in the Greater Mekong Region, is not a relevant frame of reference due to the rapid pace of development. Future uses of the river are expected to include transportation of heavy cargo such as mineral ores, containerised waterborne transportation and the introduction of inland cruise vessels.
2. Determination of Optimal Ship Size When proposing the exact dimensions for ship locks, it is imperative to know what the longitudinal depth profile of the Mekong River will be after possible hydropower dam development. Information required from the Optimisation Study of the Mekong Mainstream Hydropower Projects:The minimum and maximum water levels that can be maintained in the back water of the dams. The extent of the free-flowing stretches of each hydropower dam.The water level and the conditions of the navigation fairway that can be maintained in the free flowing stretches. 3. MRC Recommendations for Standard Specifications for Ship Locks on Mekong Mainstream DamsPhase 1 includes a Review of International Ship Lock Dimensions and their Relevance to the Proposed Hydropower Developments on the Mekong Mainstream (completed)Phase 2, Standard Specifications for Construction and Operation of Navigation Locks (to be started upon completion of the Optimisation Study)However, until the results of the Optimisation Study are fully known, minimum requirements should not be lower than the planned design of the Gan Lan Ba Dam in China:Furthermore, a parallel slot is reserved for a second lock to double the capacity during a future expansion.ly way to efficiently realise the benefits of inland waterway navigation in harmony with hydropower development is the construction of navigation locks
Dams interrupt the natural continuity of sediment transport in river systems, inducing deposition within the reservoir and releasing sediment‐starved water downstream, which typically produce channel adjustments and potentially reduce the tailwater. Deposition of sediment in reservoirs will shorten the reservoir’s economic life and can interfere with reservoir functions, as well as increase pressure on the dam and increase backwater effects. Changes in either river flow or sediment load can also induce changes in the form and dimensions of alluvial channels downstream. Localized sediment deposition may also affect critical mechanical equipment at the dam, such as reservoir flood gates and turbine intakes. Sediment that builds up in the wrong location can compromise the safe working of the dam, its ability to pass the design flood without overtopping and the longevity of the turbines.
On the Mekong River system, sediment starvation can be expected to result in loss of large bedforms and gravel/sand bars, and ultimately increased bank erosion in alluvial reaches, reducing channel complexity and affecting habitats formed of loose alluvium. Changes in sediment delivery may affect the Tonle Sap and exacerbate existing problems of coastal erosion in the Mekong Delta caused by sand extraction from the river channel.
Water quality and biodiversityDesign recommendationsPerformance targetsWater quality criteria or standardsTemperatureEnvironmental flows Design and operating principles for mitigationWhat can be done to fulfil the targetsCompliance monitoring and adaptive managementMonitoring performanceMonitoring and optimisationWater quality goal for the MekongMRC Procedures for Water Quality - To maintain good/acceptable WQ in the Mekong River BasinPerformance target for the impoundments:Criteria and standards for human health and aquatic life and framework for water quality emergencyMonitoring: MRC Water Quality Monitoring Network Specific monitoring inside and downstream the impoundmentProposal for guidance:Criteria from the Technical Guidelines of Procedures for Water Quality with amendment related to deep impoundments Water quality issuesDissolved oxygen- Low oxygen concentrations due to anoxic conditions at the bottom of deep impoundmentsTemperature alterationsCold water from the bottom of impoundmentsAmmonia and sulphide release- Chemical reduction due to anoxic conditions at the bottom of impoundmentsDetermining factorsPhysical dimensionsUpstream water sourceOperationBiodiversity issuesPotential ecosystem and biodiversity impacts- dependence on natural hydrological variability- ecological balance, - habitat fragmentation Performance targets:Environmental flows maintaining minimum flows Temperature within natural variabilityWater quality managementMinimisationOf stagnation/stratification of the impoundment.Optimisation of water quality and temperatureCriteria in the Technical Guidelines of Procedures for Water QualityHigh levels of dissolved oxygenLow levels of phosphorus, nitrogen, BOD, bacteria causing diseasesMinimising temperature deviations from natural conditions.Minimum flow requirements and restrictions on changes to natural variability.Questions for discussionHow important will this aspect be?Care should be taken not to ignore it just because the WQ is very good now and care should be taken not to blow it out of dimensionsHow to approach this?Proposal for a study to document the existing situation in impoundments in the LMB, national and international experiences outside the basin and suggest best practices
To identify Safety issues associated with characteristics of the proposed low-head damsMechanical and electrical control equipment very thoroughly backed up/doubled up, to ensure capability in emergencies. Comprehensive dam safety reviews need to be scheduled at least once every five years. Use of Relevant national standards and application of government framework for the safety Adopting international best practice(i) a construction supervision plan (ii) a quality assurance plan (iii) an instrument plan (iv) an operation and maintenance (O&M) plan, and(v) an emergency preparedness plan (EPP).