Hiroshi Takebayashi Disaster Prevention Research Institute, Kyoto University

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1 Morpho2D in iric Hiroshi Takebayashi Disaster Prevention Research Institute, Kyoto University

2 What can we do using Morpho2D?

3 What can we do using Morpho2D? Horizontal two dimensional i lflow and bed ddeformation analysis

4 What can we do using Morpho2D? Boundary fitted structured grids can be used (governing equations are written in general coordinate system The Yoshino River, JAPAN ± メートル ,000 2,000

5 What can we do using Morpho2D? Non-uniform sediment (graded sediment) can be treated Sediment size class Percentage passing (%) Size distribution The Kiso River, JAPAN

6 What can we do using Morpho2D? Effect of vegetation on flow can be considered (a) Without vegetation The Yoshino River, JAPAN (b) With vegetation Velocity magnitude

7 What can we do using Morpho2D? Sediment transport on rigid bed (ex. rocks) can be reproduced Grabel Rock The Naka River, JAPAN

8 Governing equation of Morpho2D in iric

9 Governing equations Mass conservation equation of water Seepage flow z hu hv hu g g hv g g 0 t J J J J J Momentum conservation equation of water in longitudinal direction hu huu huv t J J J hu hv U V U V J x x J y y 1 1 gh J x y J x x y y J z s z s b Fv J Vegetation h h h h J x J x x J y x J y x xx xx yx yx J x y J x y J y J y y h xy h xy h yy h yy 2

10 Vegetation model Fv Cdv v u v hv Water velocity Drag coefficient Vegetation Density Water depth or Vegetation height s v nd 2 s s 2 i th f id ll i th b f d i th ll d i th d s 2 is the area of grid cell, n is the number of woods in the cell, d is the averaged diameter of wood

11 Vegetation model Fv Cdv v u v hv Water depth or Vegetation height Bed Small flood h v h v Large flood

12 Vegetation height Crest of vegetation Bed surface

13 Governing equations (for graded sediment) Non-uniform sediment Bed elevation equation n n n ce b b zb q bk q b k 1 1 wk csbek csbk 0 t J t J k1 J k1 J k1 J Mass conservation equation of each sediment size class for bed load layer Bed dload dlayer model ce b bfbk zb q bk q bk 1 1 Fbk wk csbek csbk 0 t J t J J J J for deposition layer Stratigraphy E f E F t J t J d1 d1k d1 dk 0 Bed load equation (originally from Ashida & Michiue, 1972 ) u u u q K K f r 3 2 * e * ck * ck bk 17 1 c 1 c 2 bk b s g u* u* Bed load layer 1 2 : Bed

14 Concept of modeling using bed load layer model (a) Non-cohesive material bed Water level Water level (b) Rigid bed Fresh water (and Suspended sediment) E b E be Bed Bed load Bed E b Sediment r 1 b Rigid bed (rock and so on) r b E E b be u u u q K K r 3 2 * e * c * c b 17 1 c 1 c 2 b s g u* u*

15 Governing equations (for graded sediment) Bed load layer model Equilibrium suspended concentration at reference level (originally from Lane & Kalinske, 1941 ) u w * fk csbek 5.55 exp fbkr b 2 wfk u * Transport equation of depth averaged concentration of suspended load hcsk hcsk hcsk 1 U V w c c t J J J J fk sbek sbk csk 1 c sk h Dx Dy Dx D y J x y J x x y y csk 1 c h sk Dx Dy Dx Dy J x x y y J x y

16 Calculation condition dialog of Morpho2D

17 Calculation condition dialog of Morpho2D

18 Calculation condition dialog of Morpho2D

19 Calculation condition dialog of Morpho2D

20 Calculation condition dialog of Morpho2D

21 Calculation condition dialog of Morpho2D

22 Calculation condition dialog of Morpho2D

23 Calculation condition dialog of Morpho2D : : Bed load layer Initial Bed Transition layer 2 1

24 Calculation condition dialog of Morpho2D

25 Calculation condition dialog of Morpho2D

26 Calculation condition dialog of Morpho2D

27 Run!!!

28 Input file format

29 Input file format Time (s) Comma Water discharge Water Level Discharge1.txt Stage1.txt

30 Input file format Diameter of each sediment size class (m) Comma SurfaceGS.txt Fraction of each sediment size class SubsurfaceGS.txt

31 Input file format Total number of data (node) X coordinate Ratio of vegetation density Y coordinate Vegetation Density.anc

32 Input file format Total number of data (node) X coordinate Height of vegetation from initial iti lbed d( (m) Bed Y coordinate Vegetation Height.anc

33 Input file format Total number of data (node) X coordinate Height of rigid bed (m) Water level Bed Sdi Sediment Rock Y coordinate Fixed Bed Elevation.anc

34 Results of calculations

35 Effect of vegetation on flow Velocity is fast in the main channel Velocity is small in the vegetation area (a) () Without vegetation Averaged water surface level is higher (b) With vegetation

36 Effect of sediment size distribution on bed deformation (a) Mean diameter

37 Morpho2D 1.21E+06 CAMBODIA Upstream boundary 1.20E E+06 VINH XUONG HONG AN 1.20E E+06 River bank 1970 River bank 1990 River bank 2003 National Border Erosion Deposition 1.20E+06 TAN AN THUONG PHUOC 1.19E km TAN CHAU Downstream boundary 1.19E E E E E E E E E E+05 Mekong River near Tan Chau City One of the most active channel deformation area of the Mekong River!

38 Effect of vegetation (bed deformation from initial bed ) With vegetation Without vegetation Horizontal distribution of vegetation

39 Horizontal distribution of mean diameter 1 Bed deformation from initial bed Mean diameter of bed matrial

40 Thank you

SEDIMENTATION AND ITS COUNTERMEASURE AT THE OFF-TAKE AREA OF NEW DHALESWARI RIVER

SEDIMENTATION AND ITS COUNTERMEASURE AT THE OFF-TAKE AREA OF NEW DHALESWARI RIVER Tanjir Saif AHMED* MEE15634 Supervisors: Prof. EGASHIRA Shinji** Assoc. Prof. YOROZUYA Atsuhiro*** ABSTRACT Present study