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Lancang-Mekong Development Plan Environmental Study - Findings and Conclusions

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Phase 1 of the Development Plan of International Navigation on the Lancang-Mekong River (LMDP) aims to improve navigation in the Mekong mainstream from the Golden Triangle to Luang Prabang.

Projects include the development of three cargo ports at Xiengkok, Pak Beng and Luang Prabang in Laos; the improvement and maintenance of 146 rapids and shoals; and the construction of four emergency response and rescue ships and 1199 aids to navigation.
The environmental study aims to engage riparian communities, MRC member countries and local government in an exploration of the potential environmental impacts of the LMDP, and to support Mekong countries in ensuring that potential impacts of the LMDP are managed through appropriate enhancement and mitigation measures.

Implementation of the study includes:
- Key issues for biodiversity and navigation development
- Trends in the key issues without the LMDP
- Impacts of the LMDP on each of these trends
- Risks to be avoided or mitigated and benefits to be enhanced

Published in: Environment
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Lancang-Mekong Development Plan Environmental Study - Findings and Conclusions

  1. 1. MRC International Conference: 2-3 April 2018, Siem Reap, Cambodia Jeremy Carew-Reid LANCANG-MEKONG DEVELOPMENT PLAN ENVIRONMENTAL STUDY FINDINGS AND CONCLUSIONS
  2. 2. LANCANG-MEKONG DEVELOPMENT PLAN - KEY INGREDIENTS 2 Three cargo ports: 1. Xiengkok 2. Pak Ben 3. Luang Prabang  Partial clearing of 146 rapids, rocky outcrops and shoals to allow navigation for up to 500DWT vessels  Construction of four emergency response and rescue ships, 1199 aids to navigation  Promotes increased shipping, trade, passenger transport from Yunnan province to Luang Prabang 23 dangerous areas
  3. 3. PAK BENG – PROJECT DETAILS 3 • Concrete run-of-river dam 64m high (47m from river bed) x 900m long • 912 MW • Located 14km upstream of Pak Beng town • 97km long reservoir • Navigation lock for 500t boats • Fish passage cement canal 1.6 km long, 10 m bottom width • Additional water level at dam approx 20m
  4. 4. LANCANG MEKONG ENVIRONMENTAL STUDY - PURPOSE 4 Identify environmentally and socially sensitive areas & uses which require special management Assess effects of the LMDP & Pak Beng reservoir on those sensitive areas and uses Define environmental management strategies for LMDP and Pak Beng project  A site specific study focussing on biodiversity (300km river reach)  Part of the MRC Council Study and funded by CEPF  Two development scenarios (i) the navigation plan and (ii) the navigation plan & Pak Beng  If developments were to proceed what management responses are required
  5. 5. 3 IMPACT ASSESSMENT AND MANAGEMENT ZONES
  6. 6. KEY STUDY STEPS 6 2016 2017 2018 MRC International Conference
  7. 7. KEY BASELINE FINDINGS: HYDROLOGY & SEDIMENT • Increase in dry season flows, decrease in wet season flows due to China dams • Significant reduction in suspended sediment concentrations at Chiang Saen after 1992 dams • Land use changes - some evidence of increased sediment loads due to tributary contributions in study zone with implications for reservoir
  8. 8. KEY BASELINE FINDINGS: HYDROLOGY & SEDIMENT Percentage of average flow originating in each country during  wet – June to November (left – 55% from China in study area)  dry – December to May (right – 75% from China in study area). The study section is indicated by the red arrows MRC 2005
  9. 9. KEY BASELINE FINDINGS: HYDROLOGY & SEDIMENT Comparison of pre and post Manwan reservoir construction TSS concentrations at Chiang Saen (left) and Luang Prabang (right) (Adamson, 2009)
  10. 10. KEY BASELINE FINDINGS: ECOLOGY 10 • Water quality and river health good • Gradual decrease in Aquatic Ecology Health Index since early 2000s • Significant changes in geomorphology • 206 fish species in MK mainstem between Xieng Kok and Xayaburi • Fish abundance, size and diversity declined in past 5 – 10 years • 25 amphibian and reptile species observed and 7 reported • Wetlands / island terraces concentrated between Chiang Saen and Pak Tha • Sand banks located throughout, concentrated between Chiang Saen and Pak Tha • Rocky outcrops and tributaries throughout but more numerous downstream of Pak Tha • Significant presence of invasive exotic fish species
  11. 11. KEY BASELINE FINDINGS: BATHYMETRIC SURVEY 11 • Deep pools: dry-season refuge for fish; spawning habitats • 52 fish species known to make use of deep pools • 19 deep (5 – 20m) and 10 very deep (up to 90m) pools • Each pool - 10 to 15 ha • Very deep pools concentrated between Pak Beng dam site and Pak Ou
  12. 12. KEY BASELINE FINDINGS: AQUATIC ECOLOGY Changes in status of indicators for geomorphology, aquatic vegetation and macroinvertebrates between 1985 and 2015 (MRC Council study – BioRa) •Considerable changes in the geomorphology, especially erosion •Decrease in the status of channel biomass of riparian vegetation •Macroinvertebrate indicators in upper reaches natural in 1985, but many downstream of Pak Beng moderately modified •By 2015 most macroinvertebrate indicators above Pak Beng become moderately modified Indicator 1985 2015 China border to Pak Beng Pak Beng to Vientiane China border to Pak Beng Pak Beng to Vientiane Geomorphology Erosion A A D D Average bed sediment size in dry season A A B B Availability of exposed sandy habitat in dry season A A C C Availability of inundated sandy habitat in dry season A A C C Availability of exposed rocky habitats in dry season A A C C Avaialbility of inundated rocky habitats in dry season A A C C Depth of pools in bedrock in dry season A A B B Water clarity A A C C Aquatic Vegetation Channel extent of upper bank vegetation C C C C Channel extent of lower bank vegetation C C C C Channel biomass of riparian vegetation B B C C Macroinvertebrates Insects on stones B B B B Insects on sand B B B B Dry season emergence B C C C Burrowing mayflies B C C C Snails B C C C Aquatic snail diversity B C C C Bivalves B B B B Shrimps and crabs B C C C Littoral invertebrate diversity B C C C Benthic invertebrate diversity B C C C Zooplankton B B B B A Unmodified, natural B Largely natural C Moderately modified D Largely modified E Completely modified
  13. 13. KEY BASELINE FINDINGS: NAVIGATION /WATERWAYS 13 • 22 rapids and shoals between Huay Xay and Luang Prabang • No major improvements for navigation downstream of Chiang Saen • Minor removals of obstacles in Lao PDR • New Chiang Saen Port: capacity for 10 small, 4 large (300 DWT) boats • 32km (33%) hardened river banks on Thai section • Consequent geomorphological changes and bank erosion on the Loa side • Cargo flows increased significantly from 2004-14
  14. 14. ZONE 1 – GOLDEN TRIANGLE TO THAI-LAO BORDER Potential Biodiversity Conservation Management Area Whole Zone 1 = International Key Biodiversity Area (KBA) for birds and fish Habitats identified in survey – tributaries/deltas, vegetated islands, rapids, rocky outcrops, sandbanks and shoals, off main channel wetlands, deep pools
  15. 15. Zoomed in conservation area - DANGEROUS AREA 1
  16. 16. LMDP CHANNEL DESIGN CASE STUDY: HAT NGAO (DA-01) 16 Yellow = Mekong floodplain Purple = dredge depth 1.5-2.5m Blue = water depth • No rock removal necessary • Channel in sandy area, to be dredged • Without river training works upstream, gully might silt up • Some 103,000 m3 sand to be dredged annually
  17. 17. LMDP CHANNEL DESIGN CASE STUDY: KENG PHA DAI (DA-04) 17 • 20,501.499 m3 removal of rock - chiseling channel banks • Small part of rapid (6.97% of wet surface at low water level / 1.88% of total rapid surface) • 98.12% of rapid untouched • Vessels up to 1,500-1,600t (3m water depth) gains access Purple/pink: areas to be removed
  18. 18. ZONE 1: KEY IMPACTS (LMDP) Much depends on the quality of the work – past clearing has been poorly supervised and completed in a uncontrolled manner with little regard for environmental and social consequences. If work is done to international good practice, impacts can be minimised. Hydrology and Sediment • Bed and bank erosion due to: • Dredging of sediment from bed, banks and islands • Increased large boat traffic • Clearing of sediment for port construction Ecology • Risks to water quality due to dredging and increased large boat traffic • Low impacts on geomorphology, wetland habitats, aquatic vegetation and macroinvertebrates • Potential impacts on fish: • blasting (mortality) and dredging (reducing food sources, mortality in larvae) • partial filling of deep pools (reduced habitat) • increased wave action from boat traffic (mortality of small fish) • boat shear stress (mortality of fish eggs) • oil/grease spills (affects food sources) • river bank stabilisation (may reduce habitat but depends on spp)
  19. 19. ZONE 1: MITIGATION STRATEGIES Navigation clearing activity, port rehabilitation and functioning • Rock removal: store debris in coves between chiseling areas, maintain net flow obstacle and reduce turbulence from outcropping river banks • Sand dredging: dredged material dumped in small area, • Manage to minimise smothering of habitats • Control noise during rock blasting (fish) • Managed collection and disposal of waste • Habitat protection: • Groins and longitudinal training dykes to mitigate the effects of navigation on habitat • Bioengineering of banks, deltas and groins • Apply vegetation to protect riverbank • Minimise boat speed/weight and set min. distances from banks • Network of conservation areas protecting critical habitats • Deep pools • Tributary deltas • Sand and pebble bars • Pool-riffle (“Pha” and “Kok”, in Thai) Eg. Connection near the Khon Phi Long Rapid area – supports many fish species
  20. 20. ZONE 2 – THAI-LAO BORDER TO PAK BENG Potential Biodiversity Conservation Management Area Whole Zone 2 = KBA (birds and fish)
  21. 21. ZONE 2: KEY IMPACTS (PAK BENG RESERVOIR) Environmental impacts of the Pak Beng Reservoir and hydro operations will be significant and irreversible. Hydrology and sediment • Increased water levels, flooding of existing habitats • Decreased flow velocities • Changes in water chemistry • Blocking of sediment by dam wall • Reduced sediment transport due to lower velocities • New deltas forming at bottom of the tributaries; Ecology • High, permanent impacts on geomorphology, wetland habitats, aquatic vegetation, macroinvertebrates associated with inundation • Blockage of fish migration routes; • Change from riverine to lacustrine environment – change in fish assemblages, reduced oxygen and productivity in deep water; • Permanent loss of 9 deep pools, 12 rocky outcrops, 3 sand bars, 6 rapids • Alteration to 18 tributary connections – slowing flow and potential loss of connectivity through delta formation/sedimentation
  22. 22. ZONE 2: AQUATIC ECOLOGY IMPACTS Comparison of local impacts on aquatic ecology in Zones 1 - 3 Comparison of cumulative impacts on aquatic ecology in Zones 1 - 3
  23. 23. ZONE 2: MITIGATION STRATEGIES (Reservoir) Reservoir management • Bioengineering of fish passage  Natural features – excavated channel  Bioengineering of passage included constructed wetlands and vegetated and stabilised banks  study fish migration behavior • [Fish passage proposed by developer:  Fish passage cement canal 1.6 km long, 10 m bottom width.  Slope - 1.85%.  Resting pools  Entrance 1 km downstream of dam wall] • Maintain connection to the tributaries and recreate deltas • Top 30% of reservoir most promising because shallower • Create aquaculture Network of conservation areas • Creation of new tributary deltas • Constructed wetlands • Use of groins to create deltas and wetlands
  24. 24. ZONE 3 – PAK BENG TO LUANG PRABANG Potential Biodiversity Conservation Management Area Part Zone 3 down to no. 14 rapid = KBA (birds and fish)
  25. 25. ZONE 3: KEY IMPACTS (LMDP AND PAK BENG) Hydrology and sediment • Highest risk: altered flow regime • Reduced water quality • Change in the sediment size distribution of the channel bed • Reduced sediment load • Increased water level variability causing bed and bank erosion; • Dredging of bed and banks Ecology • Low impacts upon geomorphology, wetland habitats, aquatic vegetation, macroinvertebrates • Potential scouring and erosion of sensitive habitats - sand and pebble bars; deep pools • Impact from large boat traffic (erosion and water quality) • Disrupted fish behaviour: • Reproduction • Mortality due to release of cold and/or oxygen depleted water • Changes to dry season refuges
  26. 26. PakBeng
  27. 27. ZONE 3: MITIGATION STRATEGIES Dam operation • Run-of-river - no peaking power production (maintain natural flow regime) – outflows to approximate inflows at hourly or daily scale • Maintain natural migration of sediments: • i) ensure velocities in reservoir not too low • ii) ensure dam design allows for sediment movement • iii) include operating valves or other mechanisms to pass sediment through the dam wall • iii) excavate sedimentation upstream of the dam wall, reintroduce downstream • Manipulate water release mass and flow rate - prevent downstream deep pools scouring • Rakers and screens, optimised spill flows, fish friendly turbines Navigation clearing activity, port rehabilitation and functioning • Same as Zone 1 Network of conservation areas • 9 potential conservation areas • 13 dangerous areas • Rich habitat diversity • Use of groins to create deltas and wetlands
  28. 28. A KEY STRATEGIC RECOMMENDATION: Establish a transboundary Mekong mainstream conservation area network • A network of 19 candidate Mekong conservation areas in study area – a first piloting and demonstration phase with a vision for network extension along the entire Mekong mainstream • Activities for a “transboundary project” managed by MRC with Thailand and Laos:  Thorough survey and boundary definition  Formal designation of areas by Lao PDR and Thailand (in a Lao/Thai agreement)  Community and collaborative management arrangements for each site  Preparation of overall network management plan (including M&E)  Strategy for private sector financing – biodiversity offsets, PES, rehabilitation and natural area construction  Demonstration and piloting technologies for habitat maintenance and creation  Creation of fishing conservation zones  Definition of commercial vessel no go areas  Establishment of Lancang-Mekong Lao and Thai conservation management units for survey, monitoring, rehabilitation, bioengineering • Important to clearly define the role of MRC in transboundary network facilitation, studies, management planning and monitoring
  29. 29. CONSERVATION AREA HABITATS 1. Rapid/shoal 2. Tributary/delta 3. Vegetated island 4. Off-main channel wetland 5. Very deep pool 1 2 3 4 5 In zone 1 In zone 1In zone 3In zone 3: DA16 In zone 3: DA 22
  30. 30. THANK YOU Jeremy Carew-Reid, ICEM jecr@icem.com.au

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