Dr Alice Lefebvre

Where and when you can find me

My office in the main MARUM building, on the first floor room 1420.
I am usually in my office from 9am until 5pm.

My postal address is
MARUM
Leobener Strasse
28359 Bremen
Germany


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Interest

I am particularly interested in the interaction of hydro- morpho- and sediment dynamics in the coastal zone. I currently work on characterising topographic and hydraulic roughness above large compound bedforms.

I have been working mainly on field data collected during cruises in the Jade Bay (Germany) and in the Knudedyb tidal channel (Denmark), during which current velocities and seabed morphology were measured over a transect during a whole tidal cycle. This work showed that the roughness associated with compound bedforms varies during a tidal cycle and it is hypothesised that these variations are related to the presence/absence of recirculation on the bedform downstream side.

In order to overcome some limitations that appeared from field measurements, I am now using a numerical model (DELFT3D) to assess the influence of bedform shape (in particular asymmetry and steepness) on the recirculation that occurs on the bedform downstream side.

Please get in touch if you would like to know more or check out my publications.

You can also visit the MARUM Coastal Geosciences Group webpage for more infos.

Left: example of bathymetry (ranging from 20 m below mean sea level (MSL) in blue to 12 m below MSL in red) in the Jade Bay (Germany) showing large primary bedforms (mean wavelength of about 200 m and height of 3.5 m) and superimposed secondary bedforms (mean wavelength of 5 m and height of 0.4 m).

Above: example of current velocities above the transect (black line) shown on the left. Flow is from left to right (flood)

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Education and work

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Publications

PEER-REVIEWED PUBLICATIONS:

2011
- Lefebvre, A., Ernstsen, V.B., Winter, C., 2011. Influence of compound bedforms on hydraulic roughness in a tidal environment. Ocean Dynamics, DOI 10.1007/s10236-011-0476-6.

- Lefebvre, A., Ernstsen, V. B., Winter, C., 2011. Bedform characterization through 2D spectral analysis. Journal of Coastal Research SI64, 781-785.

- Ernstsen, V.B., Lefebvre, A., Bartholdy, J., Bartholomä, A. Winter, C., 2011. Spatiotemporal height variations of large-scale bedforms in the Grådyb tidal inlet channel (Denmark): a case study on coastal system impact. Journal of Coastal Research SI64, 746-750.

- Paul, M., Lefebvre, A., Manca, E., Amos C. L., 2011. An acoustic method for the remote measurement of seagrass metrics. Estuarine, Coastal and Shelf Science 93, 68-79.

- Stark, N., Hanff, H., Svenson, C., Ernstsen, V.B., Lefebvre, A., Winter, C., Kopf, A., 2011. Coupled penetrometer, MBES and ADCP assessments of tidal variations of the surface sediment layer along active subaqueous dunes, Danish Wadden Sea. Geo-Marine Letters, DOI 10.1007/s00367-011-0230-6

2010
- Garel, E., Lefebvre, A., 2010. Wave-induced Sand re-Suspension at Dredged Gravel Pits based upon Hydrodynamic Measurements (Tromper Wiek, Baltic Sea). Journal of Coastal Research SI51, 195-204.

- Lefebvre, A., Thompson, C.E.L., Amos, C.L., 2010. Influence of Zostera marina canopies on unidirectional flow, hydraulic roughness and sediment movement. Continental Shelf Research 30, 1783-1794.

2009
- Lefebvre, A., Thompson, C.E.L., Collins, K., Amos, C.L., 2009. Use of a high-resolution profiling sonar and a towed video camera to map a Zostera marina bed, Solent, UK. Estuarine, Coastal and Shelf Science 82, pp. 323-334.



CONFERENCES PROCEEDINGS:
- Lefebvre, A., Lyons, A.P, 2011. Quantification of roughness for seabed characterization. Underwater Acoustic Measurements Conference, Kos (Greece), 20 – 24 June 2011, 8pp. See the paper.

- Lefebvre, A., Lyons, A.P., Thompson, C.E.L., Amos, C.L., 2009. A new system for seafloor characterisation: BRAD, the Benthic Roughness Acoustic Device. Underwater Acoustic Measurements: Technology and Results, Nafplion (Greece) 21 – 26 June 2009, 8pp. See the paper.

- Lefebvre, A., Thompson, C.E.L., Collins, K.J., Amos, C.L., 2009. Use of a high-resolution profiling sonar for seagrass detection. Underwater Acoustic Measurements: Technology and Results, Nafplion (Greece) 21 – 26 June 2009, 8pp. See the paper.

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Conferences and general public outreach

- CONFERENCE PARTICIPATION:
EGU 2012 (European Geosciences Union), Vienna (Austria), 22-27 April 2012
poster presentation: Alice Lefebvre, Andries J. Paarlberg, Christian Winter. A numerical investigation of flow separation over bedforms. See the poster.

ECC (2nd Young Scientists Excellence Cluster Conference), Bremen (Germany), 3-5 October 2011
Participation in the jury for best poster award

UAM 11 (Underwater Acoustic Measurements): Technology and Results, Kos Island (Greece) 20 – 24 June 2011.
Oral presentation: Alice Lefebvre, Anthony P. Lyons, 2011. Quantification of roughness for seabed classification.

ICS 2011 (International Coastal Symposium), 9 – 14 May 2011, Stettin (Poland).
Oral presentation: Alice Lefebvre, Verner B. Ernstsen, Christian Winter. Bedforms characterisation through 2D spectral analysis.

PECS 10 (Physics of Estuaries and Coastal Seas) Conference, 14 – 17 September 2010, Mount Lavinia (Sri Lanka).
Oral presentation: Alice Lefebvre, Verner B. Ernstsen, Christian Winter. Influence of compound bedforms on hydraulic roughness in a tidal environment.

UAM 09 (Underwater Acoustic Measurements): Technology and Results, Nafplion (Greece) 21 – 26 June 2009.
Oral presentation: Alice Lefebvre, Ken Collins, Charlotte Thompson, Carl L. Amos, 2009. Use of a high-resolution profiling sonar for seagrass detection.
Oral presentation: Alice Lefebvre, Anthony P. Lyons, Charlotte Thompson, Carl L. Amos. A new system for seafloor characterisation: BRAD, the Benthic Roughness Acoustic Device.

ECSA 44 (Estuarine Coastal and Shelf Science): Science and management of estuaries and coasts, a tale of two hemispheres, in Bahia Blanca (Argentina), 29 September – 3 October 2008.
Poster presentation: Alice Lefebvre, Charlotte Thompson, Carl L. Amos. Influence of Zostera marina canopy on the flow: a study of the effect of density and patchiness in an annular flume.

YCSEC (Young Costal Scientists and Engineers Conference), University of Southampton (UK), 19th and 20th of April 2006.
Poster presentation: Monique Villatoro, M. and Alice Lefebvre. Tidal inlet dynamics and evolution, Venice Lagoon.


- GENERAL PUBLIC OUTREACH:
Alice Lefebvre. A bord du Pourquoi Pas ? La vie dans les abysses (Onboard the Pourqupoi Pas? Life in the abyss). Aquaforum (talks about the ocean for the general public), Bègles(France), 3rd March 2011.

Interview by BBC Radio 4 for the program “Science in the Making” during fieldwork on the RV Callista (6/06/2008).


Organisation and presentation of 2 stands for the coastal group participation during the open day, NOC (14/03/2009, 15/03/2008, 17/03/2007, 18/03/2006).


Alice Lefebvre. MOSE sauvera-t-il Venise et sa lagune? (Will MOSE save Venice and its lagoon?) (talk). Aquaforum (talks about the ocean for the general public), Bègles (France), 21st December 2006.

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Responsabilities

Since 2010: Co-organiser of monthly MARUM post-doc meetings with Aline Govin.

Since 2010: Organiser of weekly MARUM Coastal Geoscience Group Meetings

26/05/2010: Organisation and chair of the MARUM North Sea workshop.

2005-2009: Part of the Post Graduate Team (PhD representant), NOCS.



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