Post on 27-Dec-2015
Sediment and Flocculation dynamics in the area of Zeebrugge
Marc Sas, Alexander Breugem and Andrew Manning
Apr 19, 2023 / Sediment and Flocculation dynamics in the area of Zeebrugge / slide 2
Overview
• Objectives
• Overview of the measurement campaign• Global overview
• Long term measurements
• Through tide measurements • Coastal zone
• Harbour of Zeebrugge
• Near bed measurements using HCBS frame
• INSSEV settling velocity measurements
• Flocculation Dynamics
• Conclusion
Apr 19, 2023 / Sediment and Flocculation dynamics in the area of Zeebrugge / slide 4
Objectives
• The project :
Langdurige monitoring van zout/zoet-verdeling in de haven van Zeebrugge en monitoring van zoutconcentratie, slibconcentratie en hooggeconcentreerde slibsuspensies in de Belgische kustzone
• Waterbouwkundig Laboratorium
• Maritieme Toegang
Apr 19, 2023 / Sediment and Flocculation dynamics in the area of Zeebrugge / slide 5
Objectives
• Objective of the complete project• The first goal of the study and the survey is to detect the
occurrence of near-bed high-concentration mud suspensions (referred to as high-concentration benthic suspensions - HCBS), their dynamic behaviour and the conditions and locations of their occurrence
• The second goal is to gain insight in density currents between harbour and sea, and their relationship to siltation in the harbour of Zeebrugge.
• Objective of the present presentation• Give overview of the measurements and some details about the
flocculation dynamics inside the harbour of Zeebrugge.
Apr 19, 2023 / Sediment and Flocculation dynamics in the area of Zeebrugge / slide 6
Global Overview
• Survey 1 : autumn-winter 2006-2007
• Survey 2 :summer 2007
Apr 19, 2023 / Sediment and Flocculation dynamics in the area of Zeebrugge / slide 7
Long term measurement locations
• Period:
• June 2006-Aug 2007
• RCM9 at:• MOW 1
• Sterneneiland
• CTD at:• LNG terminal
• Hermespier
Apr 19, 2023 / Sediment and Flocculation dynamics in the area of Zeebrugge / slide 8
Long term measurement setup
RCM-9•Velocity•Salinity•SSC•Pressure•Temperature
CTD•Salinity•Pressure•Temperature
Apr 19, 2023 / Sediment and Flocculation dynamics in the area of Zeebrugge / slide 9
Through tide measurement locations
• Harbour entrance:• One spring and one neap tide meas.
• ADCP and SiltProfiler
• Inside the harbour:• One summer and one winter meas.
• SiltProfiler and CTD
• Coastal zone:• Two transects in winter
• Three transects in summer
• SiltProfiler (summer and winter)
• ADCP (summer only)
Apr 19, 2023 / Sediment and Flocculation dynamics in the area of Zeebrugge / slide 10
Through tide measurement instruments : ADCP + CTD
ADCP:•Velocity profile•Sediment concentration profile
CTD:•Salinity (multiple depths)•Temperature
Apr 19, 2023 / Sediment and Flocculation dynamics in the area of Zeebrugge / slide 11
Through tide measurement instruments : ADCP + CTD
Harbour entrance; Neap tide 2h before HW
Harbour; Neap tide 3.30 h before HW
Apr 19, 2023 / Sediment and Flocculation dynamics in the area of Zeebrugge / slide 12
Through tide measurement instruments : SiltProfiler
SiltProfiler:•Sediment concentration profile•Salinity profile•Temperature profile
Specifications
High Frequency (100 Hz)
Wireless Data Transfer via Bluetooth technology
Freefall Profiling
3 Silt sensors:o1 Seapoint BS sensor (0-700 mg/l)o2 Transmittance Extinction Sensors (500-5000 mg/land 3500 – 50000 mg/l)
CTD sensor
Apr 19, 2023 / Sediment and Flocculation dynamics in the area of Zeebrugge / slide 13
Through tide measurement instruments : SiltProfiler
Navigation channel; winter. Avg. tide; 5h after HW
Harbour; summer. Avg. tide; 0.20h after HW
Apr 19, 2023 / Sediment and Flocculation dynamics in the area of Zeebrugge / slide 14
Near bed measurement locations
• Campaigns:• 1 x Summer
• 1 x Winter
• Two different frames
• Deployment: 2-4 weeks
Apr 19, 2023 / Sediment and Flocculation dynamics in the area of Zeebrugge / slide 15
Near bed measurements (HCBS Frame)
• Valeport Midas and RCM-9:• Velocity (0.3 m and 1.0 m above bed)
• Sediment concentration
• Argus: Sediment concentration profile
• Altus echo sounder: Bed level
Apr 19, 2023 / Sediment and Flocculation dynamics in the area of Zeebrugge / slide 16
Near bed measurements (HCBS Frame) : ARGUS
MOW 1 during winter.
Apr 19, 2023 / Sediment and Flocculation dynamics in the area of Zeebrugge / slide 17
Near bed measurements (HCBS Frame) : Altus
MOW 1; Winter
Apr 19, 2023 / Sediment and Flocculation dynamics in the area of Zeebrugge / slide 18
INSSEV Settling velocity measurements
INSSEV floc camera surface electronics in laboratory on RV Lancaster survey vessel
Example of floc images
Hydrodynamic sensors on bed frame being deployed from RV Lancaster survey vessel
1.2 mm
Apr 19, 2023 / Sediment and Flocculation dynamics in the area of Zeebrugge / slide 19
• 15 INSSEV samples from Albert-II Dok
• Obtained 0.6m above the bed
• 8th November 2006
• HW +1hr• 16m deep
• Water Temp ~ 12.8oC
• Salinity = 32
• U = 0.14 m/s
• SPM = 200-400 mg/l
• TMZ (17:00hr – HW+2.5hr)• SPM rose to 5 g/l
• U = 0.03 m/s
INSSEV Settling velocity measurements
Apr 19, 2023 / Sediment and Flocculation dynamics in the area of Zeebrugge / slide 20
• Shear stress range:
• HW+1 = 2 Pa
• TMZ = 0.4 Pa
• LW = 0.15 Pa
• Dmean response:
• 130 m 375 m
• Wsmean response:
• 2 mm/s at HW+1
• Four-fold rise in TMZ to 8.5 mm/s
INSSEV Settling velocity measurements
Apr 19, 2023 / Sediment and Flocculation dynamics in the area of Zeebrugge / slide 21
INSSEV Settling velocity measurements
Apr 19, 2023 / Sediment and Flocculation dynamics in the area of Zeebrugge / slide 22
INSSEV Settling velocity measurements
Apr 19, 2023 / Sediment and Flocculation dynamics in the area of Zeebrugge / slide 23
Sediment & Flocculation Dynamics
• A significant data set has been collected
• There is no evidence for a tick HCBS layer in the navigation channels in the vicinity of Zeebrugge
• Siltation of the harbour of Zeebrugge is strongly influenced by tidal filling and the eddy pattern in the harbour mouth.
• Siltation of the harbour of Zeebrugge shows a strong influence on the neap-spring tidal cycle.
• Density differences due to the fresh water discharge into the harbour have only a limited effect on the harbour siltation.
Apr 19, 2023 / Sediment and Flocculation dynamics in the area of Zeebrugge / slide 24
Conclusion
• A significant data set has been collected on fine cohesive sediment characteristics in the vicinity of Zeebrugge, calling for:• A regular follow up: a series of fixed stations is highly
recommended
• Efforts should be put in characterizing the physical conditions leading to the siltation rate in the access channels and the port
• Integration of wave/wind characteristics is necessary
• Integration of biological parameters is recommended