Vientiane – Nong Khai modelling status

National consultation with TNMC20th of April 2006, Bangkok

MRCS WUP-FIN

2

Bank erosion model in Vientiane- Nong Khai

magnitude of changemotivation: causes analysis, support in

protection measures, transboundary impact assessment

model developments, data collection (Lao-Thai cooperation)

3

Outline

Data status• Study area• WL• Field work• Aerial photos and

satellite images

Modelling status• Model framework• Calibration• Outcome

4

Measured WL

3 stations by JICA (01/2002- )

Vientiane port Nong Khai

Water levels at VTE - NK section of Mekong River (2002-2005), JICA data

154

156

158

160

162

164

166

168

170

172

14/0

1/20

02

14/0

3/20

02

14/0

5/20

02

14/0

7/20

02

14/0

9/20

02

14/1

1/20

02

14/0

1/20

03

14/0

3/20

03

14/0

5/20

03

14/0

7/20

03

14/0

9/20

03

14/1

1/20

03

14/0

1/20

04

14/0

3/20

04

14/0

5/20

04

14/0

7/20

04

14/0

9/20

04

14/1

1/20

04

14/0

1/20

05

14/0

3/20

05

14/0

5/20

05

14/0

7/20

05

Wat

er le

vel [

m]

amsl

Ban Sibounheuang Ban Chomcheng Ban Dongphosi

5

Field data: Vientiane – Nong Khai section of Mekong River

ADCP flow and TSS flux, morphometry; Laos- Thai cooperation team, May 2005- May 2006

Additional grant from Finland (Matti PhD)

CREST Yamanashi programme on Mekong morphometry, 2005-2006

Iwona Conlan PhD

6

Field team

Lao PDR: Prasit DimnivongPhoumyenh KhounthikoumanneKeomany Luanglith

Thailand: Sukkhawit Buaphuan Kiattiyot YotteentianSangwian Angkhuan

WUP-FIN: Matti KummuJorma Koponen

Juha Sarkkula

7

ADCP measurements coupled with TSS analysis

8

Discharge

9

Longitudinal section

10

Vientiane – Nong Khai

Measured discharges by ADCP

2000

4000

6000

8000

10000

12000

14000

2005

-06-

07

2005

-07-

07

2005

-08-

06

2005

-09-

05

2005

-10-

05

2005

-11-

04

2005

-12-

04

Dis

ch

arg

e [

m3

/s]

CS1

CS2

CS3

CS4

11

TSS measurements

9 point samples for each cross-section 6 times / year To correlate the backscatter of the

ADCP measurements

12

TSS measurements

TSS in Vientiane - Nong Khai field work

100

150

200

250

300

350

400

450

Jun Jul Aug Sep Oct Nov Dec

DateT

SS

[m

g/l

]

Surface

0.2*H

0.8*H

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

100 150 200 250 300 350 400 450

TSS concentration [mg/l]

Dep

th [

H]

15/06/2005 08/07/2005 12/08/2005 27/09/2005 30/11/05

13

Database

14

Historical bank erosion analysis

Based on aerial photos and satellite images + GPS survey

Aerial photos• 1960s• 1990s

Satellite images• SPOT5 image from 2004

15

Results

16

Modelling status

Data status• Study area• WL• Field work• Aerial photos and

satellite images

Modelling status

• Model framework• Calibration• Outcome

17

Model grid – 50m resolution

18

Grid elevations

19

Boundary conditions

Boundary at CS1: Discharge generated from water levels

Rating curve for CS1

y = 1177.3x - 188777

R2 = 0.9645

0

2000

4000

6000

8000

10000

12000

162 163 164 165 166 167 168 169 170 171

Water level [m] amsl

Dis

char

ge

[m3/

s]

Rating curve for CS4

y = 1371.98x - 212448.02

R2 = 0.98

0

2000

4000

6000

8000

10000

12000

14000

156 157 158 159 160 161 162 163 164

Water level [m], amslD

isch

arg

e [m

3/s]

Boundary at CS4: Rating curve based on the ADCP measurements

20

Model results: velocity fields

Surface:

Bottom:

21

Flow field

22

Modelled velocity distribution in the Vientiane harbor

23

Vientiane application

Done:• Improved topography• Addition of measured water levels

for calibration and validation• Solution of boundary instability• First results of the model calibration

(on-going task)

Remains to be done:• Hydrodynamic calibration and

validation• Calculation of sediment and

comparison with the measured values

• Cross section graphics correction

24

Outcome of the modelling work

Potential bank erosion rates due to the sediment transportation and flow

Impact of the changes in flow regime and/or sediment concentration from upstream

Local impacts ( built structures, bank protection, etc) on flow speeds, erosion, and sediment concentrations

Increase the understanding of the sediment dynamics in Mekong

Increase the understanding of the historical bank erosion Recommendations Understanding better the causes of bank erosion

MRCS/WUP-FINwww.eia.fi/wup-fin