Settling dynamics of muddy sediment in the Gironde-Garonne system

In the context of EMPHASE project (ANR-FRQ), two fields campaigns were carried out to determine the settling velocity and properties of suspended sediments during a semi-diurnal tidal cycle, as well as hydrodynamic conditions and water properties. The two sampling stations Bordeaux (Garonne Tidal River) and Fort Medoc (Gironde EStuary) were representative of two regions: a tidal river dominated by fresh water and an estuary affected by salty or brackish waters, inside the same land-sea continuum. Quasi in-situ measurements of settling velocity were carried out with a recently-patented instrument named System for the Characterisation of Aggregates and Flocs (SCAF).

In the context of EMPHASE project (ANR-FRQ), two fields campaigns were carried out to determine the settling velocity and properties of suspended sediments during a semi-diurnal tidal cycle, as well as hydrodynamic conditions and water properties. The two sampling stations Bordeaux (Garonne Tidal River) and Fort Medoc (Gironde EStuary) were representative of two regions: a tidal river dominated by fresh water and an estuary affected by salty or brackish waters, inside the same land-sea continuum. Quasi in-situ measurements of settling velocity were carried out with a recently-patented instrument named System for the Characterisation of Aggregates and Flocs (SCAF).

Disciplines

Physical oceanography

Keywords

settling velocity, higly turbid waters, SCAF, flocculation, Garonne Tidal River, Gironde Estuary, Sediment dynamics

Location

45.807249N, 44.501877S, -0.040117E, -1.479326W

Devices

This deposit contains the data presented in a paper entitled "Factors controlling mud floc settling velocity in a highly turbid macrotidal fluvial-estuarine system" by Sophie Defontaine, Isabel Jalon-Rojas, Aldo Sottolichio, Nicolas Gratiot, Cédric Legout and Camilla Lienart, and submitted to JGR-Oceans.

## ADCP DATA :

- sensor: Workhorse Sentinel 600 KHz
- files : ADCP_26sept2022.mat and ADCP_29sept2022.mat
- date of sampling : 26/09/2022 and 29/09/2022
- sites of sampling : Bordeaux (France) and Fort Médoc (France)

Each ADCP data files contains:
- 'U' : velocity component (m/s) projected the channel axis with positive values landward
- 'V' : velocity component (m/s) directed laterally toward the right bank
- 'Temps' : local time (UTC+2)
- 'Profondeur' : depth (m)

# -----------------------------------------

## MPx DATA :

- sensor: NKE MPx multiparameter probe
- files : SMATCH_26sept2022.mat and SMATCH_29sept2022.mat
- date of sampling : 26/09/2022 and 29/09/2022
- sites of sampling : Bordeaux (France) and Fort Médoc (France)

Each MPx data files contains:
- 'TIME' : local time (UTC+2)
- 'PROFONDEUR' : depth (m)
- 'TURBIDITE' : turbidity (NTU)
- 'SALINITE' : salinity (-)
- 'MES' : suspended sediment concentration (g/L)
- 'TEMPERATURE' : temperature (°C)

# -----------------------------------------

## Settling velocity data :

- sensor: SCAF
- files : ws_bottom_26092022.txt, ws_bottom_29092022.txt, ws_surface_26092022.txt and ws_surface_29092022.txt
- headers of each files contains the following informations : sampling site, date, sampling water depth, unity, time zone and sampling time.
- settling velocity distribution are presented in rows

!!! ws_bottom_26092022.txt file does not contains settling velocity distribution, because the suspended sediment concentration was too high and hence hindered settling occured. Only the settling velocity of the front is given. !!!

# -----------------------------------------

## Organic matter content data:

- instrument: Thermo Finnigan Flash EA 1112 analyzer
- file: Organic_matter.xlsx
- Data are presented in a table containing: water depth of sampling (surface/bottom), sampling site, date and time of sampling, C/N (-), COP (µm/L), NOP (µm/L), MES (g/L) and COP/MES (%)


# -----------------------------------------

## GRAIN SIZE DISTRIBUTION:

- instrument: Malvern laser-diffraction instrument
- file : grain_size_distrib.ods
- Data are presented in a table containing: sample name, date and time of sampling, site of sampling, depth, obscuration, residual-weighted, d (0.1), d (0.5), d (0.9), D [4, 3] - Volume weighted mean and Result Between User Sizes (Sizes in microns)

Data

FileSizeFormatProcessingAccessend of embargo
ADCP data
77 KoMATLABProcessed data 2025-06-01
ADCP data
78 KoMATLABProcessed data 2025-06-01
Grain size distribution
19 KoODSRaw data 2025-06-01
Organic matter
11 KoXLS, XLSXProcessed data 2025-06-01
Settling velocity 26/09 bottom
297 octetsTEXTProcessed data 2025-06-01
Settling velocity 29/09 bottom
8 KoTEXTProcessed data 2025-06-01
Settling velocity 26/09 surface
7 KoTEXTProcessed data 2025-06-01
Settling velocity 29/09 surface
7 KoTEXTProcessed data 2025-06-01
MPx DATA
78 KoMATLABProcessed data 2025-06-01
MPx DATA
72 KoMATLABProcessed data 2025-06-01
How to cite
Defontaine Sophie, Jalon-Rojas Isabel, Sottolichio Aldo, Gratiot Nicolas, Legout Cédric, Lienart Camilla (2024). Settling dynamics of muddy sediment in the Gironde-Garonne system. SEANOE. https://doi.org/10.17882/98376

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