River, Coastal and Estuarine Morphodynamics: RCEM2011 © 2011 Tsinghua University Press, Beijing

Morphological evolution of navigation channel in Dinh An estuary, Vietnam NGUYEN Viet-Thanh State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering College of Harbour, Coastal and Offshore Engineering, Hohai University, Nanjing 210098, China Faculty of Civil Engineering, University of Transport and Communications, Hanoi, Vietnam

ZHENG Jin-Hai State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering College of Harbour, Coastal and Offshore Engineering, Hohai University, Nanjing 210098, China

LUONG Phuong-Hau Department of Port and Waterways, National University of Civil Engineering, Hanoi, Vietnam

ABSTRACT:The stability of estuaries navigation channel has attracted considerable attention because of the complicated interactions with the prevailing hydrodynamics and ship navigation. This research examines the morphological evolution of Dinh An navigation channel by remote sensing image and matching topography maps. The results show that, the navigation channel is not stabilized and it has been changed due to the monsoon. The evolution of the navigation channel depends on the development of crescent bars systems at the estuary. For better understanding bedload transport in the Dinh An navigation channel, the radioactive tracer is used at three points in the estuary. Series of observations indicate that the bedload transport only transports in the internal of the estuary and around the initial point. The average bedload transport rate ranges from 3.5 m/d to 8.13 m/d. Current and wave are two the main factors which have significantly influence on the back silting in the Dinh An navigation channel. The observation results show that, in flood season, back silting intensity is larger than that it the dry season. The back siltation rate ranges from 0.13-0.53 m/month in the dry season and 0.20-1.61 m/month in the flood season.

1 INTRODUCTION The Mekong Delta begins in Phnom Penh, where the river divides into its two main distributaries, the Mekong River and the Bassac River. The Mekong River has six main channels and the Bassac River has three channels to form the "Nine Dragons" of the outer delta in Viet Nam. However, Bassac River has only two estuaries now: Dinh An and Tran De estuaries, the third estuary Bassac estuary was closed due to the development of Cu Lao Dung Island. The main delta is made up of a vast triangular plain which is five meters lower than the sea level. As a result large areas of the Delta are flooded every year. The movement of water within this complex channels network cannot be regarded as natural, due to the long history of natural evolution and human utilization. Levees were built hundreds of years ago along some of the main natural channels. Hydrology is not only dominated by the rivers but also by the tide, which has a large expansion in the dry season and which can slow down the drainage of the river during heavy flood periods in downstream area. Flood channels and ebb channels are very common and important geomorphologic features in many

estuaries. The geomorphology of a flood channel may be a combined result of flood-dominated tide, river flow, Coriolis force and sediment input/output in the channel (Zheng et al, 2002, Zhang et al., 2009, Zhang et al. 2010, Shen et al., 1995). A flood channel in an estuary is usually separated from an ebb channel by a shoal (Chen et al., 1982). Can Tho port is the largest port in Bassac river use for vessel 10,000 DWT berthing and is located in Can Tho City where is far about 120 km from Dinh An estuary. The navigation channel in Dinh An estuary is unstable and has crescent bars systems and shallow bars. Presently, only the vessels 5,000 DWT can be transited in the natural navigation channel. The main parameters of the channel are as follows: the width is 100.0 m; the design dredge level is -4.0 m (Chart Datum (CD)), the channel slope is 1/20. It needed to dredge twice a year and a lot of money were paid for keeping the navigation channel. Sometimes, the navigation was deposited intermediately after dredging. Previous studies has proposed a new navigation channel with design dredge level is -6.5 m for vessel 10,000 DWT entrance Can Tho Port through Bassac River to Quan Chanh Bo channel, and then to go to the South China Sea by the bypass channel, the bypass channel is a new excavation channel. This alternative has some issues should be clarified. Therefore, to understand the characteristics of estuarine morphological evolution and sediment transport is a very important basic work for the regulation navigation channel in Dinh An estuary. Dinh An estuary is one of Bassac River’s estuaries. It is known as the best estuary of the Nine Dragon estuaries, where an international navigation could be built for vessels from the South China Sea to go to the southwestern area and through Vam Nao River to the Mekong River and then to Phnompenh, Cambodia (Figure 1).

South China Sea

Dinh An Estuary

Figure 1

Navigation channels and ports in Mekong River (Mekong River Commission, 2002)

Dinh An estuary has the characteristics to become a delta estuary which has a near prismatic estuary where the tidal influence is small compared to the amount of runoff feeding the delta. The delta estuary is shown as a submerged delta which is a convex curve of shoreline and shallow bars in estuary. This is a result of the balance interaction between hydrodynamic factors of river and sea. On the other hand, Dinh An estuary also has the characteristics of a trumpet shape estuary where the banks have converged in the upstream direction, bars shoal in the middle and a wide trumpet shaped mouth. This is the natural shape of an alluvial estuary where the tidal energy is equally spread along the estuary. Therefore, Dinh An estuary has both delta and trumpet shaped characteristics (Figure 2).

469

DINH AN ESTUARY TRAN DE ESTUARY

Figure 2

Remote sensing images in 13-2-2002

Base on the tidal range classification proposed by Davies (1964), Dinh an estuary is a meso-tidal mixed-energy setting with moderate wave energy estuary with a tidal range between 2.5 and 4.14m and the average range between 2.95 and 3.25m. Beside the marine hydrodynamic factors, Dinh An estuary is governed and controlled by the runoff and sediment from the Bassac River with half water contents of Mekong River and a high volume of sediment transport about 22 million tons/year. The wind in Dinh An estuary complies with three seasons. The northeast wind season is from November to March, the transition season from March to May and the southwest wind season from May to October. The monsoons cause obvious differences in river discharge and coastal wave conditions between flood and dry seasons. The flood season begins in late May to October. At the Can Tho monitoring station on the Bassac River, the maximum monthly average discharge from 2000 to 2004 in the flood season is about ten times of the discharge in the dry season (Figure 3). Waves generated by the summer southwest monsoon are mostly from south to southwest, whereas the winter northeast monsoon generates relatively strong waves from the north to northeast. The bimodal distributions of wave direction in spring and autumn show them to be transitional periods. The north and northeasterly waves are generally higher than the south and southwesterly waves. Ocean currents show similar seasonal trends in direction to those of waves. Sediment transport is dominantly southwestward and northeastward in dry and flood seasons, respectively. In this research, the shorelines change was analyzed base on remove sensing from 1989 to 2001. The morphological changes of the Dinh An navigation channel base on the survey data from 2001 to 2005. We also interpret the results to provide insights into the evolution of the navigation channel by matching topography maps from 1980 to 2005, and provide an image of bedload transport by radioactive tracers study. The back siltation characteristics in the navigation channel were described from measurement data from 1980 to 2005.

470

(m3/s)

Month

Figure 3

Monthly average discharges at Can Tho station

2. METHODOLOGY 2.1 Morphological evolution analysis The decadal-scale changes of the shorelines change are analyzed with remote sensing image. Base on the bathymetry map of Dinh An estuary in 1997, all topography maps of navigation channel are matched together to analysis the morphological changes of the navigation channel. The area of survey map shows in figure 4.

Figure 4

Survey area, radioactive tracers and buoys position in Dinh An estuary

471

2.2 Bedload transport The radioactive tracer is used to better understand the bedload transport. The theoretical background and applicability has previously been described by Crickmore (1967) and Rathbun et al. (1978). In the study area three samples of radioactive tracers are used. The sediment samples are taken from the site and then grain size analysis are conducted by the sieve machine. Figure 5 shows grain size grade of sediment. The tracer element Iridium is added into a glass element with 0.55% of content. Density of glass element is selected ranges from 2.55-2.65 ton/m3. The radioactive tracer is produced in the Da Lat nuclear station and then handling to the site and drop down at three study points K1, K2 and K3 (show in Figure 4). Four observations during September, 2003 to April 2004 were carried out to determine the speed, direction and discharge of tracer elements. In each observation the central mass of radioactive cloud at the observation points were determined. Base on the position of central mass position the below parameters are defined: - The movement direction between of two observations; - The effective distance of bedload transport between two times of observations; - Average speed and discharge of bedload transport between two observations.

Figure 5

Distribution of grain size of samples and tracers

2.3 Back siltation Back siltation takes an important role in the stabilization of navigation channel. After dredging for a short time, the navigation channel is filled by back siltation sediment. All navigation channel survey data from 1981 to 2005 and previous studies are used to analysis the back siltation in Dinh An navigation channel. 3. RESULTS AND DISCUSSIONS 3.1 Shoreline changes and estuarine morphology The shorelines of the Dinh An estuary has changed asymmetrically over the last 30 years in response to net southwestward sediment transport due to the northeasterly winter monsoons. During the flood season, large volumes of sediments discharge from the river, At this time, wave direction is reversed in response to the

472

relatively weak southwesterly summer monsoon. Mud and very fine sand in the surface sediments of the northeastern beach transects tend to be removed during winter, indicating that the sediment supplied from the river during summer is temporarily deposited near the river mouth and later transported southwestward during the winter monsoon. The relief of intertidal bars on the beach increase during winter in response to higher waves. Remote sensing images in figure 6 show that, the shorelines in Dinh An is a alternate processes between erosion and accretion from 1989 to 2001, the average erosion rate is 4.5m/year and average accretion rate is 9.5 m/year, respectively. Shoreline in Tran De estuary area shows the accretion process is dominated with average accretion rate is 75m/year in left bank and 15m/year in right bank. Shoreline in Cu Lao Dung Island has average accretion rate 30 m/year.

Figure 6

Shorelines change from 1989 to 2001

Ocean currents and seasonal flows are dominant coastal flows in the Dinh An estuary. Flows in the direction of SW is primarily (about 54%) during the dry season and the NE (about 44.6%) one in the flood season. In the river channel, the tidal flow is asymmetric. During the dry season, the flood tide current is stronger than the ebb tide current. In the flood season, the river flow is still very large and the fresh water flow to the estuary to make the salt mix edge. Figure 7 describes the flood and ebb channels in the Dinh An estuary. When the water flows out of the Dinh An estuary, it tends to flow towards northeast due to the influence of offshore ocean currents. This explains the curvature of the channel. Monsoon causes the reversal flow direction changing from coastal

473

flood season to dry season and it also affects the flow in estuary. The seasonal changes of the flow mechanism cause the changes of channels and the natural evolution of shallow bars. Flow regime described above is more complex as the river flow changes greatly with the seasons. Geomorphologic process formation during the flood season is a process by which the delta is formed mainly due to the river, where sediment from river down to the estuaries at the deposited rate overwhelms the opposite process caused by the offshore driving force locally. However, the tidal activity is prevailed in the dry season, the relative small due to the river flow. The combination of seasonal changes and the reverse flows of coastal monsoon have created the unstable geomorphology in the Dinh An estuary.

Figure 7

Flood channels and ebb channels in Dinh An estuary (HAECON, 1999)

3.2 Natural morphological evolution of navigation channel The spatial variation of Dinh An navigation channel has related with the evolution of the crescent bar systems. Topographic maps and channel routes data are matched together as the show in figures 8 and 9. Before 1980, the shallow bar and crescent bar 01 did not occur. However, the sediment siltation of the route 1980 created the crescent bar 01 at the river mouth and resulted in the close of route 1980 several years later. Then the new channel route 1981-1983 appeared outside the south shore of the crescent bar 01. The developing of crescent bar 02, route 1981-83 was almost filled, and the river flows to create a new channel flowing route 1991. At this time, between two banks of crescent bar 01 began to form as a result of the meandering of route 1981-1983. The route 1991 seems fairly stables. The measurement data in 1994 showed the depth along the channel at an elevation of -4.0m. However, the channel is deflected to the north. This route existing from 1991 to 1994 was due to the initial water depth of channel 1991 at the river mouth being quite deep. Therefore, it took more times to develop the crescent bar 03. However, the crescent bar 03 appeared in 1997, which pushed the flood tide flows towards the north and then created a new route. The development of the crescent bar 01 tended towards the south was a reason led to create the route 1998. This route was existed until April, 2000 when a new dredging was performed in the May, 2000, and then the route 04-2000 was created (Figure 9). The heavy flood in 2000 flood season closed route 04-2000 and created route 03-2001. During the period from 2001 to 2004, the navigation channels have a little changed until the flood season in 2005. From the end of July to September 2005, the monsoon winds from the southwest and cyclones namely Washi, Matsa, Vicenty and Damray produced heavy rains and conducted the high flood in upstream of Bassac River. The crescent bar 02 developed, and a new channel

474

was created in 11-2005. The morphological changes of the navigation channel from 2001 to 2005 are shown in figure 10.

Figure 8

Evolution of Dinh An navigation channel during period 1980-1998

Figure 9

Evolution of Dinh An navigation channel during period 2000-2005

Both of the crescent bars 01 and 02 have bed elevations from - 0.5 to -1.0 m. There is no official data on the age of crescent bar 01, while the age of crescent bar 02 is about 10 years from 1981 to 1991, and reappearance in 2000 and 2005. Crescent bars 01 and 03 are still growing, and it is about -2.0 m now. Using historical topography maps, the water depth was estimated in the initial of crescent bar 03 around 3.0 to 4.0 m. Common characteristics of a meandering channel are a shallow beach in the middle, and Dinh An estuary is no exception. Crescent bar 01 began to develop during the mid of 1980s and since then the

475

curvature of the main channel has increased. Crescent bar 01 developed southward, and the shallow beach is located in the south of the main tidal channel and is being eroded. This suggests that the main tidal channel moving to the south or southwest.

Bathymetry surveyed in 12-2001

Bathymetry surveyed in 04-2002

Bathymetry surveyed in 12-2002

Bathymetry surveyed in 04-2003

Bathymetry surveyed in 04-2004

Bathymetry surveyed in 12-2004

Figure 10

Bathymetry surveyed in 11-2005 Bathymetry changed during period from 2001-2005

476

Figure 11 shows the variation of the longitudinal profiles of the navigation channel during period 2001-2005, the channels have one or three bars, the bar height above the dredge level -4.0 m ranges from 0.5 to 2.58 m and the bar length ranges from 1200 to 8400 m, and the bars have developed to tend to be offshore. The complexity development of the bar system is one of the reasons lead to the navigation channels had a complication changed in the plan as shown in figures 8 and 9.

Bars

Figure 11

Longitudinal profiles changes during period 2001-2005

Described above shows a general picture on the formation of geomorphology processing which has created the position of tidal channels for years. The complicated seasonal fluctuations of flows, together with high tidal range, increase the complexity of hydrodynamics in this area. This is one of the reasons why the channel route has complicated variation. River discharge changes greatly from the flood season to the dry season. During the flood season on the formation of geomorphology specific "formation delta processes" the material will deposit a crescent shape. During the dry season, due to significant reduction in river discharge, tide is dominated, so the nature of sedimentation in the flood season has been redistributed. The processing of formation of tidal delta is completely different from the formation river delta and the tendency to form shallow beach between the flood channel and ebb channel. 3.3 Transport of bedload The theoretical background and applicability of radioactive tracer has been described by Crickmore (1967) and Rathbun et al. (1978). In the study, the tracer particles are applied under the given hydraulic conditions to fulfill the following 3 criteria: (1) Exposed particles should be movable with the minimum discharge, and the resulting bottom shear stresses must be able to move the tracer particles exposed for motion, according to Shield's criterion. (2) Particles in motion should be movable along the bottom with the maximum discharge which means the particles must not be suspended. It can be obtained by means of the criterion, w > 0.8 Uf. For more detail, see Engelund and Fredsøbe (1976). (3) Particles should transport in a natural way, therefore the tracer size determined by (1) and (2) is to correspond to a main fraction of the natural bottom sediment. Observation results show that, after about six months from 20-09-2003 to 03-11-2003, at K1 position near buoy B9 and B7 the tracer moved firstly towards the NE with the azimuth is 640 during the flood season. The main direction is the same as the river flood current direction. The observation on 30-12-2003 indicated that, the tracer moved in the opposite SW direction with azimuth about 2400. It can be explained

477

by the NE wind and by the predominant sea hydrodynamics during this period. During periods from 30-12-2003 to 03-03-2004, and to 02-04-2004, the bedload transport tended to NE direction with azimuth about 680 and 500, respectively. From the initial observation point to the last point, the tracer moved to NE direction with azimuth is about 59 0. The result is due to the regime of the river higher than the sea. The bedload transport speed ranged from 1.44 to 4.84 m/day, the average speed about 3.5 m/day. The effective thickness of the transport substrate identified was 0.06 m. The density of the tracer in the study area is 1.45 t/m3. The segment from buoy B11 to buoy B7 of the navigation channel is a curved line, and it made an large angle between channel route and bedload transport direction. Therefore, the bedload transport can be back filled in the channel. Figure 12 shows the tracer transportation pathline during observation time, and table 1 shows the main transport parameters of point K1. Table 1

Main transport parameters of tracer of K1 Distance (m)

Speed (m/day)

From 20-09-2003 to 03-11-2003

175.00

3.89

194.48

64

From 03-11-2003 to 30/12/2003

276.00

4.84

362.07

240

From 30-12-2003 to 03-03-2004

92.10

1.44

293.10

68

From 03-03-2004 to 02-04-2004

140.00

4.83

681.38

50

3.50

382.76

59

Observation time

Average

Figure 12

Discharge (m3/day)

Azimuth (Degree)

Orbit of radioactive tracer at K1

Points K2 and K3 are mainly influenced by ocean dynamics. Therefore the bedload transport pathline is a zigzag line. At first, from K2 and K3 the bedload transports tended to the west with azimuth ranges from 2680-2760 and 2700-2800 during the time September to December 2003, respectively. The average transport speed is about 4.36 m/day. From January 1st to March 4th, 2004, the bedload at the point K2 transported to the NNW at azimuth about 3460 with speed of 2,67 m/day; while at the point K3 the bedload transported to the ESE at azimuth about 1150 with speed of 11.72 m/day. The observation on April 3rd, 2004 showed that, the bedload at K3 transported toward the ESE with of 15.41 m/day, while at K2 the bedload transported to the ESE with transport speed about 17.53 m/day (see Figure 13). The distances and speed of the bedload transport are shown in Tables 2 and 3. Six bed-stratum samples around

478

point K2 and K3 were collected and tested. The results shown that the effective thickness of the transport substrate identified were 0.05 m during the observation times. The density of the base material at the point K2 is 1.50 t/m3 and is 1.45 t/m3 at the point K3. Table 2

Main transport parameters of tracer of K2

Observation time

Distance (m)

Speed (m/day)

Discharge (m3/day)

Azimuth (Degree)

From 21-09-2003 to 04-11-2003

303.00

6.73

357.24

268

From 04-11-2003 to 01/01/2004

224.00

3.93

203.45

270

From 01-01-2004 to 04-03-2004

171.00

2.67

129.66

346

From 04-03-2004 to 03-04-2004

526.00

18.14

769.66

119

6.24

365.00

250

Average Table 3

Main transport parameters of tracer of K3

Observation time

Distance (m)

Speed (m/day)

Discharge (m3/day)

Azimuth (Degree)

From 21-09-2003 to 04-11-2003

158.00

3.51

176.55

270

From 04-11-2003 to 01/01/2004

247.00

4.33

223.45

280

From 01-01-2004 to 04-03-2004

750.00

11.72

552.41

115

From 04-03-2004 to 03-04-2004

447.00

15.41

864.14

256

Average

8.13

454.14

270

Figure 13

Orbit of radioactive tracers at K2 and K3 (around buoys B3 and B4)

479

The above results indicated that the bedload transported only internal of estuary and around the initial points. The observations identified that there was no other source of sediment at the navigation channel. In the flood season, wave direction is ENE, mud and very fine sand moved WSW by the wave current. During the transition season from March to May, the sediment has abnormal movement to ESE at point K2. This is also a reason why back siltation occur in the navigation channel. 3.4 Back siltation in Dinh An navigation channel A large dredging work was undertaken in May 1981 along the route 1981-1983. The bed elevation was -3.9 m (Chart Datum). The total dredging volume is 1,250,000 m3. The dredging program completed within 3 months, but the navigation channel was filled up to the level before dredging, the back siltation rate about 350,000 m3/month. This period correspond to the transition season and before the flood season. The second dredging took place in April and May 1983 along the route 1981-1983. The dredged channel has a length of 5.5 km, a width of 80.0m, a depth of -4.0 to -4.2 m, and a slope of 1/15. The total dredging volume is 470,000 m3. The first survey show that only one month after dredging, the channel had almost been filled up with sediment volume of 250,000 m3. Sedimentation rate was 0.35 m/month. This process has also taken place in the second survey. The next maintenance dredging conducted in July 1991 with 700,000 m3 of sediment along the route 1991. Dredged channel bottom width was 75m, the slope was 1/15, and dredging depth was -4.5m. During that time, observation data from Waterway Construction and Service Engineering Company (WACOSE) showed that, the back siltation rate is 1.61 m/month after 15 days of dredging, the average back siltation rate in flood season was about 0.75m/month (see Table 4). A fourth dredging was performed along to the route 1994-1996 in May, 1997. About 250,000 m3 of sediment were dredged along the length of 6.0 km, of the channel width was 80 m, the slope was 1/15 and the dredge depth was -4.20 m. The deposition took place very rapidly at a rate of 0.40 m/month. In August, 1997 the channel was filled completely. It should be noted that, dredge channel was not identical to the natural way of tidal flow (route 1997). On May 1998, route 1998 was dredged, and the dredged channel width was 80 m, the slope was 1/15 and the dredging depth is -3.8 m. Observation showed that, it was fully filled after only two months, the back siltation rate was 0.20 m/month. A numerical model results from HEACON (1998) showed the back siltation in flood season ranges from 0.04 to 0.53 m/month and in dry season ranges from 0.15 to 2.3 m/month (Table 4). Table 4 Method Numerical model (HEACON, 1997-1998)

Back siltation intensity navigation channel compared with previous studies Time Back-silting rate Remark (m/month) Dry season

0.04 - 0.53 0.29 0.03 - 0.15 0.150 - 2.30 1.00 - 1.20 0.05 - 0.15

Flood season

Measurement data (WACOSE, 1991)

From 30th June to 16th July From 16th July to 26th August From 20th August to 30th November

1.61 0.45 0.17

Average value in shallow area Average value in shallow area 15 days after dreging Dry season Dry season to begin of flood season

The surveyed bathymetry of the navigation channel during period 2000-2005 showed the back siltation only occurred in the segment from cross-section S3 to S6. The back siltation intensity ranges from 0.04 to 0.41 m/month, and the maximum intensity is 0.41 m/month in March, 2004 (Figure 14). During that period, the test pit results indicated that, the back siltation rate of 0.20m/month during period from 17th October to 7th December, 2003 and of 0.13 m/month during period from May 29th to July 25th, 2004 (An T.V, 2005). These results also indicated that, the back siltation in the flood season is larger than that in the

480

dry season.

Figure 14

Back siltation changed during 2001-2004

The back siltation in the Dinh An navigation channel changed due to monsoon influence. In flood season, the back silting intensity along the navigation is larger than that in the dry season. The average intensity was about 0.63 m/month and 0.21 m/month, respectively. The maximum intensity was 1.61 m/month which was observed in the navigation channel on June, 1991. Current and waves are two main factors have the significant influence to back silting in the navigation channel. The river current takes an important role to create the channel and the formation of bars while the waves combine with the current cause the unstable of the navigation channel in the curve segment and offshore segments of the channel. Tide current is one of the basic factors to create the ebb channel. Tide produces a periodic process of hydrodynamic, sediment transport and back siltation. 4. CONCLUSIONS The spatial variation of the Dinh An navigation channel is related to the evolution of the crescent bars systems. The evolution of the navigation channel depends on the development of crescent bars systems at the estuary. The upper part of the main tidal channel continues to move to the south with the developing of crescent bar 01, and it connects with relatively deep-water in the lower part. This results in that the channel trends to straight and the main current flows from the sea in the south-east direction. On the other hand, the crescent bar 03 develops toward the north, therefore the main tidal channel move to the north. As a result, the curvatures of the main channel increase. Radiotracer method results show that bedload transport in the internal of estuary and around initial points. The observations also indicated that, there was no other source of sediment at the navigation channel. The back siltation result show that the segments from cross-section S3 to S7 in the Dinh An navigation channel have occurred back siltation, the highest intensity occurred around cross-section S6 to S7. This study results is indicated that a detail observation and understanding of the sediment transport and navigation channel evolution in Dinh An estuary can contribute to regulate works in the future. 5 ACKNOWLEDGEMENTS The first author would like to thank to Assoc Prof. Trinh Viet An, State Key Laboratory of River and Coastal Engineering, Institute for Water Resources Research, Hanoi, Vietnam for his enthusiastic support during the data collection period.

481

REFERENCES An T.V., 2005. Study the solutions to stabilized bed of channel in Dinh An estuary service to waterway transport. States level project, No.2003/19. Minstry of Science and Technology. (in Vietnamese). Crickmore, M.J., 1967. Measurement of sand transport in rivers with special reference to tracer methods. Sedimentology, Vol.8. Chen J.Y. et al, 1982. The model of development of the Changjiang Estuary during the last 2000 years. In: Kennedy, V.S. (Ed.), Estuary Comparison. Academic Press, New York, pp. 655–666. Chen J.Y. et al, 1999. The processes of dynamic sedimentation in the Changjiang Estuary. Journal of Sea Research 41 (1999) 129-140. Duc N.A. et al, 2008. Using salt intrusion measurements to determine the freshwater discharge distribution over the branches of a multi-channel estuary: The Mekong Delta case. Estuarine, Coastal and Shelf Science 77 (2008) 433-445. HAECON, 1999. Feasibility Study for the improvement of the Entrance Channel to the Bassac River, Vietnam. Ministry of Transport of Vietnam. Hubert H.G. Savenije, 2005. Salinity and tides in alluvial estuaries. ELSEVIER BV Radarweg 29, PO Box 211 1000 AE Amsterdam, The Netherlands. Michael J. Kennish, 2003. Estuarine Research, Monitoring and Resource Protection. CRC Press LLC, 2000 N.W. Corporate Blvd., Boca Raton, Florida 33431. Mekong River Commission, 2006. Annual Flood Report. Flood Management and Mitigation Progamme. Mekong River Commission, Vientiane, Lao PDR. PORTCOAST Consultant Corporation, 2006. Feasibility project of Waterway for heavy-tonnages ships to enter the Hau River. Ministry of Transport, Vietnam. Rathbun, R.E., and Kennedy, V.C. (1978). Transport and dispersion of flourscent tracer particles for the dune-bed condition, Atrisco Feeder Canal near Bernalilla, New Mexico. Geological Survey Professional Paper 1037. Shen et al, 1995. Evolution and regulation of flood channels in estuaries. Oceanologia Et Limnologia Sinica 26 (1), 83–89. Simon et al, 2006. Long-term morphological change and its causes in the Mersey Estuary, NW England. Geomorphology 81 (2006) 185–206. SNC-LAVALIN International Inc., Canada in association with Royal Haskoning, the Netherlands, Delft Hydraulics, the Netherlands and Transport Engineering Design Inc. – South (TEDI-South), Vietnam, 2005. “Feasibility study for improvement of the Bassac river final report, volume 1: chapter 5 technical assessment of Quan Chanh Bo channel and modelling report”. Ministry of Transport, Vietnam. SOUTH INSTITUTE OF WATER RESOURCES RESEARCH, 2002-2006. Investigation in Mekong River’s estuaries and Bassac River’s estuaries. (in Vietnamese). Tanabe S. et al, 2001. Delta evolution model inferred from the Mekong Delta, southern Vietnam. In: Posamentier, H.W., et al.(Eds.), Deltas of Southeast Asia and Vicinity-Sedimentology, Stratigraphy, and Petroleum Geology. SEPM Special Publication, in press. Thanh T.D. et al, 1995. Coastal morphological changes concerning the management of the coastal zone in Vietnam. Proceeding Coastal Changes, Bordeaux, 10–16 February 1995, 451–462. Thorkild Thomsen, 1980. The application of radioactive tracers for determination of bed-load transport in alluvial rivers. Nordic Hydrology, 11-1980, 133-144. Toru Tamura et al, 2009. Monsoon-influenced variations in morphology and sediment of a mesotidal beach on the Mekong River Delta coast. Geomorphology 116 (2010) 11–23. Trung, V.K et al., 2007. Project research origination, development and propose hydraulic solutions, exploitation of alluvial ground in coastal zone Southern Vietnam. Second base of Water Resources University, Hochiminh City, Vietnam (in Vietnamese). Viet N.T. et al, 2006. Interaction between morphology change and salinity distribution in the Dinh An estuary, Vietnam. Vietnam-Japan Estuary Workshop 2006, 112-117. Weng Qihao, 2010. Remote sensing of coastal environments. CRC Press Taylor & Francis Group. Waterway construction and service engineering company (WACOSE), 1991-1992. Study the evolution of Dinh An navigation channel before and after dredging seasons on the basis of measurement data analysis - Ministry of Transport, Vietnam. (in Vietnamese). Yan Yixin, Gao Jin, Mao Lihua, Zheng Jinhai. Calculation of diversion ratio of the North Channel in the Yangtze River Estuary. China Ocean Engineering, 2000, 14(4): 525-532. Zheng Jinhai,Yan Yixin, Zhu Yuliang. Three dimensional baroclinic numerical model for simulating fresh and salt water mixing in the Yangtze Estuary. China Ocean Engineering, 2002, 16(2): 227-238. Zhang et al, 2009. Temporal and spatial variability of annual extreme water level in the Pearl River Delta region, China. Global and Planetary Change 69 (2009) 35–47. Zhang et al, 2010. Long-term change in tidal dynamics and its cause in the Pearl River Delta, China. Geomorphology 120 (2010) 209–223.

482

Morphological evolution of navigation channel in Dinh ...

... has the characteristics of a trumpet shape estuary where the banks have converged in the ... In each observation the central mass of radioactive cloud at the ..... Study the solutions to stabilized bed of channel in Dinh An estuary service to ...

2MB Sizes 1 Downloads 199 Views

Recommend Documents

morphological evolution in a clade of endangered ...
2Hull York Medical School, The University of Hull, Cottingham Road, Hull, HU6 ... study, we investigated the morphological diversity and evolution of red ..... been major sources for the recolonization of lowlands .... USA), Museum für Naturkunde of

INVITED PAPERS 3D morphological evolution of ...
Jan 10, 2014 - e-mail: [email protected] ... provides a markerless, automated tomography.19 This was .... Therefore, an automated markerless local nano-.

Morphological priming without morphological relationship
Using a masked priming technique, in which the prime is visually presented during 43ms ..... fumoir is built on the verbal stem /fym/—the present indicative inflected form. .... RT analyses (outliers corresponded to 1.1% of the data). The results .

Quyet dinh kiem dinh an toan.pdf
vp, quy6n hpn vd co c6u td chiic ctra Cr,rc An todn lao d6ng; . Cdn cri k6t qui d6nh gi6 h6 so vd Dcrn dC ngh! sira aOi va b6 sung Giay. chring nhQn du di€u ki6n hoat dQng ki6m dinh k! thupt an tohn lao dQng cta COng,J. ty C6ng ty c6 phAn chirng nh

Morphological dormancy in seeds of the autumn-germinating shrub ...
Morphological dormancy in seeds of the autumn-germina ... cera caerulea var. emphyllocalyx (Caprifoliaceae).pdf. Morphological dormancy in seeds of the ...

Morphological correlates of ant eating in horned lizards ...
analysed the data in a strict phylogenetic context to test for any ... were determined visually based on the height and width of ..... to show a divergent morphology.

Morphological characterization of in vitro neuronal ...
Aug 14, 2002 - ln(N)/ln( k , solid line and regular graphs lreg n/2k, open triangles. Data for our networks are also compared to other real networks open dots, data taken from Albert and Barabasi 26,. Table I. b The network's clustering coefficient c

Variation of morphological traits in natural populations ...
Une analyse en composantes principales a été employée pour expliquer la variance .... The statistical analysis of the data was carried out using the SPSS.

Morphological dormancy in seeds of the autumn-germinating shrub ...
Morphological dormancy in seeds of the autumn-germina ... cera caerulea var. emphyllocalyx (Caprifoliaceae).pdf. Morphological dormancy in seeds of the ...

Variation of morphological traits in natural populations ...
The statistical analysis of the data was carried out using the SPSS version 9.0 and ... Location map of the nine native maritime pine populations sampled in this ...

Three-dimensional morphological measurements of ...
Nov 23, 2012 - were taken at X-ray energies that can provide clear contrast between LCO and NMC particles in the composite cathodes. ... Journal of Power Sources 227 (2013) 267e274 ... during preparation, all cathode samples were gently cut with ....

/ CHANNEL(
May 1, 2009 - endpoints in a data network via a monitoring unit and a control unit. .... Nr. 21, (Oct. 1989), Cited on EP Search RepOIt for EP application.

Morphological variability of Brachidontes Swainson ...
of Mexico, Florida,. Antilles .... Florida to Pernambuco, and B. dominguensis Lamarck, ..... energy. Several authors have explained similar variations. (general shell shape, growth, width, ...... progress) will show in more detail how environmental.

/ CHANNEL(
May 1, 2009 - Huang, G M., et al., “A New Had Algorithm for Optimal Routing of. Hierarchically ... Kieser, H “Software fur eine digitale Vermittlungsanlage mit modularem ... egies between Lost-call-cleared and Reservation Traf?c”, Proceed.

Evolution of Voting in the US - Home
1975 - Further amendments to the. Voting Rights Act require that many voting materials ... 1947 - Miguel Trujillo, a Native. American and former Marine, wins a.

Combining Sensorial Modalities in Haptic Navigation ...
Recent development of haptic technology has made possible the physical interaction ... among several subjects in order to discuss this issue. Results state that a ... of the information required for these skills is visual information. Therefore, it i

Navigation Protocols in Sensor Networks
We wish to create more versatile information systems by using adaptive distributed ... VA 23187-8795; email: [email protected]; D. Rus, Computer Science and .... on a small set of nodes initially configured as beacons to estimate node loca-.

Morphological characterization of durum wheat
Cluster analysis for morphological data divide the whole-wheat genotypes into six cluster groups ... Keywords: Clusters analysis, diversity, germplasm, quantitative characters. Introduction ..... International Centre for Advanced. Mediterranean ...

Morphological differentiation of aboriginal human populations from ...
May 25, 2007 - Argentina), and such differentiation is associated to lati- tudinal location of populations (see Guichón, 2002). Some investigators proposed that the existence of this geographic pattern suggests that the differentiation of. Tierra de