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National Consultation with TNMC3 May 2005, Bangkok
WUP-FIN Phase II – Bank erosion study
2
Vientiane bank erosion
~ 30 km long part of the Mekong
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Tools
The EIA 3D hydrodynamic and basic sediment model
New developments for sediment modeling (sediment fractions, bed load, refined erosion and sediment transport description, bank erosion potential calculation)
Bank erosion model
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Model inputs
River and floodplain topography• Hydrographic atlas data • river cross-sections, • digital elevation map (DEM) for floodplain
Boundary conditions• Upstream discharge and water level• Upstream sediment concentrations (sediment fluxes)• Downstream rating curve (at Nong Khai)• Downstream sediment concentrations
Landuse Bed and bank material characteristics Wind
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Hydrographic atlas data
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Model interface for pilot model
EIA 3D model system
Hydrodynamic Sediment
transportation
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Existing data
Mekong River Commission River topography from the digital Mekong
Hydrographic atlas River bank location from the Mekong Hydrographic
atlas in early 1990s Hardcopy of old Hydrographic atlas from 1960s Digital elevation map for the land area with 50 m
resolution from old topographical maps and new SRTM elevation model with 90 m resolution
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Existing data
Lao PDR Historical TSS concentration measurements at
Vientiane port Daily water level and discharge in Vientiane port Bed changes during time have been measured in two
projects: JICA (2004) and bank protection project in 1988
Aerial photos from 1991 of Mekong around Vientiane and Nong Khai
Thailand Daily water level and discharge in Nong Khai
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Existing data
International Bank material analysis made by JICA (2004) and
Miazawa et al. (2004) Bed material analysis made by Miazawa et al. (2004)
and JICA (2004) Velocity profile measurements on Laos side on three
sites done by JICA (2004) Analysis of the bank erosion in Vientiane area made
by Rutherford and Bishop (1996) with some mapping comparing the old and new Mekong Hydrographic Atlas
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Data request from TNMC
Hydrology Hourly WL data from Nong Khai station (all the available
years) Water level data in other places than Nong Khai inside the
modelling area Data from ADCP runs at Nong Khai (all the available runs) Other discharge / flow velocity information
Water quality TSS concentration measurements at Nong Khai (all the
available years) Depth integrated suspended sediment concentration
measurements at Nong Khai Suspended sediment grain size analysis Bed load measurements
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Data request from TNMC
Soil and bathymetry data Bank material analysis for Thailand side from model area by
national agencies Bed material analysis for Thailand side from model area by
national agencies Bathymetry data for Mekong from model area (other data
than Hydrographic atlas data)
Other Aerial photos from 1960s of Mekong around Vientiane and
Nong Khai, archived in Bangkok Land use in the river banks, floodplains
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Field data collection
Lateral (morphological) changes in river bank• Comparing the aerial photos and satellite images
SS concentration combined with the ADCP measurements
Cross section changes• Selection of cross sections will be monitored
Longitudinal section changes Bathymetry of the river
• Missing areas from hydrographic atlas• Possible changes during the last 15 years
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Field data collection
Material analysis in river bed and bank Bank profile and landuse Recording current meter
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Direct model outputs
Vertical and horizontal velocity and sediment distributions
Bed shear stresses and bed erosion/ sedimentation
Bed sediment distributions and their changes over time
Bank erosion potential and changes over time Morphological changes
MRCS/WUP-FINwww.eia.fi/wup-fin