Comprehensive study undertaken to optimize the sediment management activities in a harbor affected by heavy siltation with a safety navigation focus

1. Dredging days, 9-10 Nov 2017
Dr. Faustino Manso
Senior Marine Advisor
Assessment of siltation processes &
implementation of nautical depth
in the Port of Cochin, India

2. Who are we?
How we did it?
Results
Conclusions
INDEX

3. 3
Antea Group

4. 4
Our presence

5. 5
“Our People are The Reason Behind Our Success”
Our team
• Multidisciplinary & multinational (comprehensive overview)
• Broad international background
• Academic & PhD researchers with commercial drive
• Experienced project managers

6. 6
International Expertise WorldwideOur competences – coastal & marine
• Offshore Cables & Pipelines
• Navigation and Shipping
• Data Acquisition and Management
• Environmental Impact Assessment
• Other Services
• Coastal & Port Engineering
• Climate Adaptation & ICZM
• Numerical Modelling
• Dredging & Sediments
• Geospatial (GIS) services

7. 7
Our Clients
PORT AU PRINCE
Haiti

8. Client
Cost >1m €
Period 2015-2016
Kerala’s backwaters
CPT ©
Cochin city
Willingdon Island
International Container
Transshipments (ICT)
Terminal
Liquefied natural gas
(LNG) Terminal
Vallarpadam
Island
Where? Cochin Harbour
Consortium
N

9. How? Methodology
Desktop study
Data acquisition
fieldworks & survey
design
Navigation studiesHydro sedimentary studies
2D numerical modelling
(hydro & sediment)
Scenario simulations
Physical modelling
3D simulation
Detail siltation understanding Safety navigation
1. Implementation nautical depth concept
2. Optimization sediment management tasks
Preparation
Goals

10. Phase 1 field data acquisition
April 2015 to April 2016
• Currents vel & direction (ADCP)
C1-C5 flow balance tributaries
C6 flow balance channel (horizontal)
C7 & C8 offshore
• Suspended sediment (water samples,
niskin): C1-C8
• Wave climate (height & direct.): C7 & C8
• Water level
T1 harbour
T2 outside
• Wind (speed and direction):
T2 harbour entrance
C7 outside
• Meteo (Temp + pressure + humidity)
T1 Inside harbour
T2 Outside harbour
• Bathy (dual freq. echo sounder) + silas
& sediment (RheoTune): monthly
In harbour (loose mud)
Out harbour (longshore transport)
CPT ©
Willingdon Island
ICT Terminal LNG Terminal
N
C3
C4
C5
C2
C1
C6
T2
T1
C7 C8
C3
C4
C5
C2
C1
C6
C7 C8C7 C8
T2
C7
T1
T2

11. Phase 2a Hydro sedimentary studies
A B
C D
m
m
E
• hydrodynamics, waves propagation & sediment transport/morph.
• Multi-phase approach:
1. pre-processing stage
2. 2D general models (development & calibration)
3. 3D local models for stratification effects
4. analysis of simulation results
1km
1km

12. • Physical modelling: Towing tank
• 12 combinations of layer thickness, density, viscosity and tide
• 3 designs of vessels: Container carrier/Tanker/Cargo vessel
• 3D simulation: Local pilots calibrate the model assisted by specialists
Phase 2b Navigation studies

13. • schematize processes
• 95% of siltation in the harbour is marine originated (entrained by Monsoon)
• Harbour channel acts as sediment trap
• Sediment enters inner harbour through the Gut
• Other applications
• simulate behaviour disposed material
• suggest methods for arresting siltation
• Keeping sediment navigable
• Keeping sediment out
• Keeping sediment moving
• outer harbour construction suggestions
Phase 3a siltation understanding

14. • Criteria for nautical depth: Safety navigation
• Approach: Field data (acoustics + ρ probe) applied in navigation models
• Definition: shallowest depth with the following safety limits:
1. Minimal UKC: 10% of the ship’s draft above hard bottom
2. Maximum penetration of keel in loose mud: 12% of ship’s draft
3. Maximum density of loose mud: 1170 gr/l
(acceptable level of mud yield strength & max. mud strength tested)
Phase 3b safety navigation
5
11
15
ρ= 1030
ρ (gr/L)
Top of mud, 210 kHz, ±1050 gr/L
ρ= 1150
Top of hard bottom, 33kHz. ±1350 gr/L
Nautical depth ???? gr/L“Consolidate
mud”
“loose
mud”
Depth
(m)

15. Results–Implementation of nautical depth
N
CPT ©
Willingdon Island
ICT Terminal LNG Terminal
Channels (Ernakulam & Mattancherry)
Additional dredging effort
Terminals:
LNG: Reduce dredging effort
ICT terminal: Reduce slightly dredging effort
General:
Schedule critical manoeuvres at high tide
Inner channel
Additional dredging required for bigger
vessels during Monsoon
Northern part of Gut slightly deeper
Outer channel
Offshore: Additional dredging required for
bigger vessels
Nearshore Additional dredging required for
bigger vessels during Monsoon

16. Results–Optimization sediment management tasks
Nearshore part outer channel & both terminals (LNG & ICT):
high siltation related to sediment traps:
• Over dredging does not help.
• Optimize efforts:
• Pre-Monsoon: remove the consolidated mud
• Monsoon & post-Monsoon:
remove denser part of the loose mud
combined with WID below nautical depth
support navigation
allow current flushing sediment
Disposed material: shifting disposal site reduces probability of return but low ROI
IHC systems
tms

17. Conclusions
When conditions in harbours with severe siltation problems are known:
1. Numerical models support decision making in harbours
• source and causes of siltation
• evolution of disposed material
• scenario simulations to quantify issues (within the intrinsic uncertainty)
2. Nautical depth can be determined:
• objectively (towing tank under controlled conditions)
• subjectively (simulation with human operator)
3. Optimizing sediment management activities is feasible

18. 18
Thank you
For further information please contact:
Dr. Faustino Manso faustino.manso@anteagroup.com
+32 492251286