The document summarizes findings from an environmental study of the Lancang-Mekong Development Plan (LMDP) and the proposed Pak Beng dam project. Key findings include changes to hydrology and sediment flows due to Chinese dams, impacts to aquatic ecology, and identification of environmentally sensitive areas. The study recommends establishing a network of conservation areas along the Mekong River to help mitigate impacts from proposed developments. Specific mitigation strategies are provided for each of three zones studied.

1. MRC International Conference: 2-3 April 2018, Siem Reap,
Cambodia
Jeremy Carew-Reid
LANCANG-MEKONG DEVELOPMENT PLAN
ENVIRONMENTAL STUDY
FINDINGS AND CONCLUSIONS

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. 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. 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. 3 IMPACT ASSESSMENT AND MANAGEMENT ZONES

6. KEY STUDY STEPS
6
2016 2017 2018
MRC
International
Conference

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. 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. 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. 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. 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. 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. 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. 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. Zoomed in conservation area
- DANGEROUS AREA 1

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. 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. 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. 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. ZONE 2 – THAI-LAO BORDER TO PAK BENG
Potential
Biodiversity
Conservation
Management
Area
Whole Zone 2 =
KBA (birds and
fish)

22. 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

23. 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

24. 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

25. ZONE 3 – PAK BENG TO
LUANG PRABANG
Potential
Biodiversity
Conservation
Management
Area
Part Zone 3
down to no. 14
rapid =
KBA (birds and
fish)

27. 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

28. PakBeng

29. 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

30. 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

31. 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

32. THANK YOU
Jeremy Carew-Reid, ICEM
jecr@icem.com.au