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WATER CIRCULATION STUDY FOR THE DEVELOPMENT OF SONGDO WATERFRONT’S

CANAL SYSTEM

International Conference on Flood ResilienceExperiences in Asia and Europe

Dongwoo JANG1, Cristina AGAFON 1, Gyewoon CHOI 21International Center for Urban Water Hydroinformatics Research & Innovation, South Korea2Dept. of Civil and Environmental Engineering, Incheon National University, South Korea

5-7 September 2013Exeter United Kingdom

Abstract (Tahoma 48pt)

Songdo city is currently developing the waterfrontnear the coastline which is in line with its goal ofbeing a world class eco-friendly green city inIncheon. The city planned to have a canal systemsurrounding it where clean sea water will flow inthese canals.

There is a need to ensure that situations likestagnant waters and excessive flow velocities willnot occur. Also there is also a water qualityproblem.

In order to do this, a 3D numerical model, MIKE 3FM was used to investigate the water circulationsystem with respect to the operation of the fourwater gates present at the ends of the canalsystem, where ideal configurations of the gateoperations and water interaction with sea andcanal water will be determined.

Songdo Area

References•Sobey R. J. (2001). Evaluation of numerical models of flood and tide propagation in channels. In: Journal of Hydraulic Engineering / October 2001, 805-824•Durbarbier B., Castelle B. (2011). Numerical modeling investigation of the influence of tide on the formation and subsequent nonlinear evolution of rip channels. In: Journal ofCoastal Research, Special Issue 64, 1018 – 1022•Scott S.H., Jia Y. (September 19-21). Simulation of sediment transport and channel morphology change in large river systems. US-China Workshop on Advanced ComputationalModelling In Hydroscience & Engineering. http://www.irtces.org/zt/us_China/proceedings/scott_man_Revised.pdf (accessed 10 June 2013)•Szymkiewicz R. (2010). Numerical Modeling in Open Channel Hydraulics. In: Water Science and Technology Library, Volume 83. Faculty of Civil and Environmental Engineering,Gdansk University of Technology, Poland

CONCLUSION

Model Setup

The bathymetry of the channel system was builtwith the Mesh Generator from MIKE 3 FM, usingthe coordinates extracted from a CAD file ofSongdo area and the elevation given for eachchannel as input values .

Simulation Results

Figure 1. Incheon, South Korea

Figure 2. Songdo Waterfront PlanFigure 3. Water Quality Index(2012)>

Figure 4. Set up the Unstructured Mesh

The tidal wave for 15 days was provided by KHOAand tidal harmony is considered M2, S2, K1, O1which is available only for the Incheon area.

Figure 5. 15days Tidal Condition in Incheon

At each entry/exit should be placed a weir. For theinput the weir height was set at a El. (+)0.5 mand 50 m width and weir height El. of (-)1.0 mwith a weir width of 10 m at the output.

Figure 6. Weir Height at the Entry and Exit

There are 4 cases with different input and outputconditions that were simulated using theHydrodynamics and Transport module in MIKE 3 FMin order to see the direction of the water flow andwater exchange ratio for 15 days tidal.

-Case 1- -Case 2- -Case 3- -Case 4-

Figure 7. 4 Cases of the Water Circulation for the Songdo Canal System

Classification

Entry gate Exit gate

PositionWeir EL.

(m)

Weir width

(m)Position

Weir EL.

(m)

Weir width

(m)

Case 1 South 1

Gate

(+)0.5m 50m

North 2

Gate

(-)1m 10m

Case 2 North 1

Gate

South 2

Gate

Case 3South 1 &

North 1 Gate

South 2 & North

2 Gate

Case 4South 1 &

South 2 Gate

North 1 & North

2 GateFigure 8. Entry and Exit gate condition for each case

Figure 9. Data Extraction Points

Maximum Velocity in CanalMaximum

Tidal

Condition

Maximum Velocity (cm/s)

N1 N2 N3 W1 W2 W3 E1 E2 E3 S1 S2 S3

Case

1 0.9 4.3 10.3 43.8 16.6 37.3 41.2 12.4 23.3 9.0 9.7 7.0

2 11.7 34.3 24.6 27.1 18.0 61.7 22.2 12.2 43.5 3.2 2.5 2.2

3 4.9 14.3 7.5 9.0 2.3 19.4 14.9 3.6 5.5 5.3 6.0 3.0

4 1.0 2.3 9.3 42.6 16.3 37.0 39.1 11.8 24.8 1.7 3.4 5.8

The maximum velocity reached is 61.7 cm/s (Case2). If the velocity is higher, it will create an erosionproblem for the bed area. It is recommended thatthe velocity inside the canal should be below50cm/s in order to maintain a stable shipmovement.

Water Exchange Ratio from Sea Water to Canal Water

The next table is showing the percentage ofpolluted water exchanged with clean waterthrough a natural flow from sea and also the daywhen 90% of the water was exchanged.

Case

Elapsed Time (day)90%

Exchange

d

Time (day)0.5 5 10 15

All Canal

Case 1 6.9 66.2 97.2 99.2 7.7

Case 2 5.8 68.9 99.3 99.5 7.2

Case 3 6.8 73.4 87.6 95.8 11.8

Case 4 6.1 42.9 56.4 61.7 X

Next graph is showing the ratio of remained canalwater at each canal

The figure below is showing how the water istraveling through the channel and how fast itreaches the outflow.

Case 1, 2 have a more fast exchange with seawater compared with case 3, 4.

The result from Case 1 and 2 are showing a highexchange ration and a 7 days duration for a 90%exchange inside the canal.

CASE

Elapsed time

0.1 day 5 day 10 day 15 day

Case

1

Case

2

Case

3

Case

4

Sea water

more than

90%

The purpose of the current study was to find themost benefiting way of water circulation throughthe system. Canal water and sea water is mixedby gate operation in canal.The numerical modeling of the water flow helpedto determine the gate operation that will play animportant part in the water circulation. For eachinflow or outflow boundary was set an openingand a closing level so that it can be used as aguide in the real situation.Observing and comparing the various simulationresults, but also the real threats that can have abig influence on the quality of the system, case 1(South 1 gate input, North 2 gate output) wasselected as the most appropriate to beimplemented in Songdo waterfront area.