DSD-INT 2015 - Assessment using delft3 d of the impact of canal del dique - johan henrotte

Canal del Dique

Coastal impact assessment using Delft3D

Johan Henrotte, Marcela

Busnelli, Mathijs van Ledden

4 November 2015

Canal Del Dique | 4 November 2015

Canal Del Dique - Introduction

2

Colombia, Caribbean Sea

120 km canal, 400 years old

Connection Rio Magdalena at

Calamar and Cartagena


Canal Del Dique - Introduction

Canal Del Dique system is

part of the old delta of the Rio

Magdalena

Area of 5500 km2 with large

lakes, wetlands of approx. 870

km2

Two national parks in coastal

zone (Rosario and San

Bernado Corals)


Key problems with Canal Del Dique

Widening has resulted in strong

increase in discharge and sediment

flux through Canal Del Dique

Sedimentation in Canal itself

requires substantial dredging near

entrance

Degradation of the swamps/marshes

with decreasing productivity and

quality of fishing resources

Fresh water and fine sediments

negatively affect marine

ecosystems in coastal zone


Key problems with Canal Del Dique – coastal zone


Key problems with Canal Del Dique – coastal zone


Canal del Dique project

The December 2010 flood triggered the start of an integrated approach to solve these

issues in the Canal del Dique system.

Environmental restoration of Canal del Dique

Studies, design and implementation of measures to restore the environmental

conditions and improve navigation on the Canal

Part of these studies:

A comprehensive coastal system study to assess the potential impacts of the

measures in the coastal zone

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System description

8

Canal del Dique

Rio Magdalena

Bahia de Barbacoas

Bahia de Cartagena

Islas de Rosario


Characteristics of the system

Micro-tidal system

No significant phase difference between the Bay of Barbacoas and the Bay of

Cartagena observed

Wind speed very low (average wind speed less than 5 m/s)

Moderate wave climate, both bays well protected

Strong stratification observed in the bays

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Stratification in Bay of Cartagena (measurements)

10


Stratification in Bay of Cartagena (measurements)

11


Model setup

Regional Model (3D)

Open Boundaries: Riemann

Boundary and initial conditions obtained from

HYCOM y de TOPEX 7.2

Turbulence model: k-epsilon

σ layer used in the vertical

20 vertical layers

Detailed Model (3D)

Open boundaries: Riemann

Boundary conditions obtained from regional model

(nesting)

The outlets are shematized as discharge points.

Information obtained from CDD SOBEK model

Turbulence model: k-epsilon

σ layer used in the vertical

10 vertical layers


Suspended Sediment Transport

DELFT3D-SED online

3 sediment fractions used

Coarse (6.9 mm/s)

Medium (0.35 mm/s)

Fine (0.011 mm/s)

Sediment concentrations at 5 outlet locations obtained from CDD SOBEK model

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Bathymetry

14

2013/2014Survey data

Nautical charts


Verification HYCOM-Delft3D

HYCOM Delft3D

23 November 2013


Verification HYCOM- Delft3D

HYCOM Delft3D

1 March 2014


Calibration - Tide

17


Calibration - Hydrodynamics

Measured & modelled discharges through Boca Chica and Boca

Grande at Bahia de Cartagena

18

-4000

-3000

-2000

-1000

0

1000

2000

3000

27/05/2014 15:36 27/05/2014 16:48 27/05/2014 18:00 27/05/2014 19:12 27/05/2014 20:24 27/05/2014 21:36 27/05/2014 22:48 28/05/2014 00:00

Q[m

^3/s

]

BOCA GRANDE - Modelo

BOCA CHICA - Modelo

Canal del Dique

TOTAL - Modelo

BOCA CHICA - Mediciones

BOCA GRANDE - Mediciones

TOTAL Mediciones

Balance basado en los niveles de agua medidos

Boca Grande

Boca Chica

Bahia de Cartagena:

8378ha


Calibration – Salinity profiles

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Calibration - profiles

Comparison measured and modelled sediment concentration, salinity and temperature

for entire survey campaign November

Only upper 0.5 m of water column

Model results are reasonable (temperature, suspended sediment) to well (salinity) in

line with the measurements

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Impact assessment

Sediment Concentration Salinity Temperature

Based on model simulations the sediment concentration, salinity and temperature

determined at the top 2m of the water column

- Maximum sediment concentration and temperature

- Minimum salinity


Results Impact Assessment

Minimum salinity concentration in top 2 m of water column for different alternatives

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Reference Alternative 1 Alternative 2 Alternative 3


Conclusions

A 3D model has been constructed to simulate the flow, salinity and suspended

sediment concentration profiles in the bays and Mar Caribe

σ layer used in the vertical, (z-layers was not yet fully operational for sediment

modelling)

DELFT3D-SED was used for sediment modelling

The model matches quite well the measurements at the Islas del Rosario but also in

the Bay of Cartagena and the Bay of Barbacoas in November 2014 regarding

discharges, salinity and suspended sediment concentrations profiles

The two validation periods (March and May 2014) show that the model performance

performs reasonable for the salinity profiles

Impact assessment shows significant reduction of fresh water in coastal area for

alternative 2 and alternative 3.

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Canal Del Dique | 4 November 2015 24

> Thank you for your attention

[email protected]

mailto:[email protected]


DELFT3D-SED settings

Parameter DELFT3D-SED ONLINE Unit

Critical bed shear stress for erosion (or

resuspension) 0.5 N/m2

Critical bed shear stress for deposition 1000 N/m2 (dummy value)

Settling velocity (coarse fraction) 6.9 mm/s

Settling velocity (medium fraction) 0.35 mm/s

Settling velocity (fine fraction) 0.011 mm/s

Specific density of sediment 2650 kg/m3

Dry bed density kg/m3

Erosion parameter 2x10-4 kg/m²/s

Initial sediment layer thickness 0 m

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DSD-INT 2015 - Assessment using delft3 d of the impact of canal del dique - johan henrotte

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