National Consultation with TNMC 3 May 2005, Bangkok WUP-FIN Phase II – Bank erosion study

2 Vientiane bank erosion ~ 30 km long part of the Mekong

3 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

4 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

5 Hydrographic atlas data

6 Model interface for pilot model EIA 3D model system Hydrodynamic Sediment transportation

7 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

8 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

9 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

10 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

11 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

12 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

13 Field data collection Material analysis in river bed and bank Bank profile and landuse Recording current meter

14 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-FIN