1) The document summarizes key baseline findings from an environmental study of the Lancang-Mekong River, including descriptions of three zones along the river with differing geomorphological characteristics.
2) Major findings include the identification of deep pools that are dry season fish habitats, changes to hydrology and sediment levels from Chinese dams, declines in the status of aquatic ecology indicators, and high fish diversity including endangered species that use deep pools.
3) Key drivers of environmental changes in the region include dams in the upper Mekong, land use changes, development activities, and increased pressures from activities like fishing, hunting, and agriculture.
CSR_Module5_Green Earth Initiative, Tree Planting Day
ย
Presentation 2: Baseline Assessment Findings
1. Final Workshop: 10 December 2018, MRC, Vientiane
Peter-John Meynell
Environmental Study of the
Lancang-Mekong Development Plan
Baseline assessment findings โ key issues, trends and
drivers
2.
3. Zone descriptions
โข ZONE 1 - Open flood plain and wide channel with sandy bed and banks
โ relatively more developed
โ wider channel and sandier with more and larger sand islands and wetlands
โ mostly flat terrain
โ large alluvial floodplains with cropping or settlements
โ fewer rocky outcrops and dangerous areas
โข ZONE 2 - Narrow steep channel mainly bed rock with V shaped valley
โ narrower, more incised, straighter and rockier
โ steep with short steep valleys running perpendicular to the river
โ many small tributaries
โ less developed with no large towns and has significant forest cover
โ more dangerous areas for navigation
โ few vegetated islands, sandbanks and wetlands
โข ZONE 3 - Multiple rapids and rocky outcrops in broad channel mixed bed rock and
sandy substrate
โ relatively narrow and rocky
โ steep forested terrain and many dangerous areas
โ valleys parallel to the river
โ many small tributaries entering
โ many deep and very deep pools associated with the river cutting through mountain ridges and
dangerous areas for navigation
โ river widens and development increases closer to and including Luang Prabang
6. A โfly overโ of the target Mekong River
PJ to show Google Earth Fly-over
7. KEY BASELINE FINDINGS: BATHYMETRIC
SURVEY (SWIM UNDER)
7
โข Deep pools: dry-season refuge for fish; spawning habitats
โข 52 fish species known to make use of deep pools
โข 19 deep (5 โ 20m) and 10 very deep (up to 90m) pools
โข Each pool - 10 to 15 ha
โข Very deep pools concentrated between Pak Beng dam site
and Pak Ou
8. KEY BASELINE FINDINGS: HYDROLOGY &
SEDIMENT
โข Increase in dry season flows, decrease in wet season flows due to China
dams
โข Significant reduction in suspended sediment concentrations at Chiang Saen
after 1992 dams
โข Land use changes - some evidence of increased sediment loads due to
tributary contributions in study zone with implications for reservoir
9. KEY BASELINE FINDINGS: HYDROLOGY &
SEDIMENT
Percentage of average flow originating in each countryduring
๏ง wet โ June to November (left โ 55% from China in study area)
๏ง dry โ December to May (right โ 75% from China in study area).
The study section is indicated by the red arrows
MRC 2005
10. 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)
11. KEY BASELINE FINDINGS:
AQUATIC ECOLOGY
Changes in status of indicators for geomorphology, aquatic vegetation and macroinvertebrates
between 1985 and 2015 (MRC Council study โ BioRa)
โขWater quality and river health
good; gradual decrease in Aquatic
Ecology Health Index since early
2000s
โขConsiderable changes in the
geomorphology, especially erosion
โขDecrease in the status of channel
biomass of riparian vegetation
โขMacroinvertebrate indicators in
upper reaches natural in 1985, but
many downstream of Pak Beng
moderately modified
โขBy 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
12. KEY BASELINE FINDINGS: FISH
The study area has exceptionally high species diversity and concentration of
Mekong endemics given its limited surface area (compared to the two larger
scales).
โข 199 native fish species (7 endemic and 38% migratory) in study area
โข Exceptionally high species diversity and concentration of endemics
โข 12 species on Red -List as critically endangered and endangered, 32 near threatened and vulnerable
โข Deep pools dry-season refuge for fish and spawning habitats - 52 species make use of deep pools
โข Fish abundance, size and diversity declined in past 5 โ 10 years
โข Significant presence of invasive exotic fish species
Study Area
13. KEY BASELINE FINDINGS: BIRDS
โข No endemics
โข 7 potentially threatened (limited info)
โข 32 extinct
โข Avifaunal collapse over the past 100โ150 years, due to ordinary human activities
14. KEY BASELINE FINDINGS:
AMPHIBIANS AND REPTILES
โข 25 amphibian and reptile species observed and 7 reported
โข 8 species (6 turtle species and 2 snake species) globally and nationally threatened
from overexploitation for food and traditional medicine
15. KEY BASELINE FINDINGS: NAVIGATION /WATERWAYS
15
โข 22 rapids and shoals between Huay Xay and Luang Prabang
โข No major improvements for navigation downstream of Chiang Saen
โข Minor removals of obstacles in Lao PDR
โข New Chiang Saen Port: capacity for 10 small, 4 large (300 DWT) boats
โข 32km (33%) hardened river banks on Thai section
โข Consequent geomorphological changes and bank erosion on the Lao side
โข Cargo flows increased significantly from 2004-14
16. KEY BASELINE FINDINGS: SOCIO-ECONOMICS
โข Poverty rates and minority numbers
high
โข Fish important for food security
โข Agribusiness undermining livelihoods
of vulnerable groups
โข Land titling a key issue
โข GT a hotspot for wildlife trade
Lao-Tai Mon-Khmer Hmong Lewmien Sino-Tibetan
ZONE ONE
Left bank population 21,100 16,200 8,600 10,400
Right bank population* unknown unknown unknown unknown
ZONE TWO
Left bank population 1,600 1,800 700 700
Right bank population 2,300 800 500 300
ZONE THREE
Left bank population 2,900 6,900 1,700 400
Right bank population 1,800 900 400 0
Province Poverty rate
2013
Change in poverty
rate since 2008
Oudomx
ay
30.1% -3.6%
Luang
Prabang
25.5% -1.7%
Xayabury 15.4% -0.2%
Bokeo 44.4% +11.8%
17. Key drivers of changeโฆ
Hydrology and sediment
๏ท Upper Mekong dams
๏ท Land clearing and
deforestation
๏ท Embankment developments
๏ท Climate change
Aquatic ecology
๏ท Changes of land use in the
watershed
๏ท Changes in agriculture down to the
river banks
๏ท Increases in urban run-off and
pollution
๏ท Increases in infrastructure
development.
๏ท Navigation improvements
๏ท Increase in navigation traffic
Fish
๏ท Deteriorating water quality
๏ท Declines in benthic fauna and
flora
๏ท Changes in water level
๏ท Increasing fishing pressure
๏ท Decline in algae
Amphibians and reptiles
๏ท Land clearing and
development
๏ท Forest degradation
๏ท Agriculture (banana, rubber,
rice)
๏ท Infrastructure
Birds
๏ท Local hunting pressure
๏ท Dogs and rats
๏ท Disturbance to nests and habitats
Socio-economics
๏ท Annual population growth rates
ranging from 0.38% in Chiang
Rai, up to 2.1% in Bokeo
๏ท Promotion of agri-business is
coming at the expense of the
livelihoods and food security of
poor and vulnerable
communities
๏ท Illegal logging is continuing to
grow
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
As detailed by Halls et al. (2013), most deep pools are 15 - 20 m deep and have areas of 10 to 15 ha. The deepest pools are 80 - 90 m deep and are found in particular between Huay Xai and Vientiane.
110 pools identified most occur in the section between Pak Tha and Pak Ou, while very deep pools are concentrated between Pak Beng dam site and Pak Ou;
Of the 206 fish species recorded in the study zone, 52 are known to make use of deep pools. Among these are 22 species of Cyprinidae (minnows and barbs), 10 species of Pangasiidae (panga catfish) and 3 species of Notopteridae (featherbacks), followed by 1 to 2 species in 14 other families (Figure 3).
MRC WQ mon. (3 locations; 2009-2015) WQ appears to be declining since 2011 but still good; MRC Aquatic Health Index (5 locations; 2005-2013) - generally good-excellent except Ban Xiengkok, which has been poor; study field trip macroinvertebrate sampling (13 locations) โ river health typically fair;
MRC condition surveyed 22 rapids and shoals between Huay Xay and Luang Prabang in 2008
Minor removals of obstacles are reported to have been undertaken in Lao PDR