I am currently working on my own DFG funded project "Modelling flow over bedform fields in tidal environments", as part of the Coastal Dynamics Group. This work adds on the work I have been doing as a MARUM and GLOMAR postdoc since 2009.
You can find me in my office everyday from 09:00 until 15:30. If I am not in the office, you can always send me an email.
I am particularly interested in the interaction of hydro- morpho- and sediment dynamics in the coastal zone. Since I arrived at MARUM, I have been working on characterising topographic and hydraulic roughness above bedform fields.
Bedforms (ripples and dunes) are ubiquitous features in rivers, coastal and deep sea environments, where they reflect the strength and pathways of sediment transport, strongly influence the overlying flow and have a major socio-economic relevance. In shallow tidal seas, large bedform fields develop due to the strong hydrodynamics and high availability of sandy sediment.
I have worked 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 due to the variation of bedform geometry compared to flow direction.
In order to overcome the limitations that appeared from field measurements, I have set up a 2DV numerical model using the Delft3D numerical software which allows to simulate with high-resolution hydrodynamics over bedforms.
However, bedform fields are intrinsically three-dimensional, with crestline bifurcations and terminations, they have complex profiles with slope discontinuities and low-angle lee sides. Therefore, my current DFG-funded project “Modelling flow over bedform fields in tidal environments” aims at extending this model in 3D. The proposed study will set up, calibrate and validate a 3D numerical model in order to characterise flow above natural bedform fields and morphological elements characteristic of bedform fields. This new model will allow for the first time to determine the patterns of current velocities and turbulence above natural bedforms fields in reversing tidal currents and to recognise the influence of each morphological elements and how they interact with each other.
Please get in touch if you would like to know more or check out my publications.
You can also visit the Coastal Dynamics Group webpage for more infos.
|10/2017 - present||Postdoc (own DFG-funded position), MARUM, University of Bremen, Germany|
|09/2012 - 10/2017||Associate Scientist within GLOMAR, MARUM, University of Bremen, Germany|
|10/2009 - 08/2012||Post-Doctoral researcher, Research Area SD, MARUM, University of Bremen, Germany and Senckenberg Institute, Wilhelmshaven, Germany|
|09/2009||Participation to the BATHYLUCK cruise onboard the Pourquoi Pas?|
|07 - 08/2009||Sediment processing assistant at the NOC, Southampton (UK).|
|04/2006 – 04/2009||National Oceanography Library Service Assistant, NOC (UK)|
|10/2005 – 07/2009||PhD candidate. National Oceanography Centre (NOC), University of Southampton, Southampton, UK.
“Bed roughness over vegetated beds: sonar imaging techniques and effect on unidirectional currents”
Supervisors: Prof C.L. Amos, Dr C.E.L. Thompson and Prof R.J. Nicholls.
|2003 – 2005||Master ENVOLH (MSc of environment, and coastal and deep sea oceanography). University Bordeaux 1, Bordeaux, France.
first year at the University Bordeaux 1, second year as an ERASMUS student at the NOC, Southampton, UK.
|2000-2003||BSc in Earth Sciences (DEUG and Licence Sciences de la Terre). University Bordeaux 1, France.|
|2000||Scientifique Baccalauréat, Spécialité Mathématiques, Lycée Michel de Montaigne, Bordeaux, France.|
Lefebvre, A., Paarlberg, A.J., Winter, C., 2016. Characterising natural bedform morphology and its influence on flow. Geo-marine Letters 36, 379–393. doi:10.1007/s00367-016-0455-5. See Publication
Lefebvre, A., and Winter, C., 2016. Predicting bed form roughness: the influence of lee side angle. Geo-Marine Letters 36:121-133. doi:10.1007/s00367-016-0436-8
Winter, C., Lefebvre, A., Benninghoff, M. and Ernstsen, V.B., 2015. Die Verteilung und Eigenschaften von Bodenformen in der Deutschen Bucht, eine Rekonstruktion der Karten von Ulrich (1973). Die Küste, 83, 65-76. In German, Abstract in English.
Chirol, C, Amos, CL, Kassem, H, Lefebvre, A, Umgiesser, G and Cucco, A, 2015. The Influence of Bed Roughness on Turbulence: Cabras Lagoon, Sardinia, Italy. Journal of Marine Science and Engineering, 3, 935-956; doi:10.3390/jmse3030935
Lefebvre, A, Paarlberg, AJ, Ernstsen, VB and Winter, C, 2014. Flow separation and roughness lengths over large bedforms in a tidal environment: A numerical investigation. Continental Shelf Research, 91, 57-69. doi:10.1016/j.csr.2014.09.001
Lefebvre, A, Paarlberg, AJ and Winter, C, 2014. Flow separation and shear stress over angle-of-repose bed forms: A numerical investigation. Water Resources Research, 50, 986–1005, doi:10.1002/2013WR014587.
Lefebvre, A, Ernstsen, VB and Winter, C, 2013. Estimation of roughness lengths and flow separation over compound bedforms in a natural-tidal inlet. Continental Shelf Research, 61-62. 98-111. doi:10.1016/j.csr.2013.04.030
Ernstsen, VB, Lefebvre, A, Kroon, A and Niemann, SL, 2013. Oblique second-order sand transport patterns on an intertidal sand flat in a natural tidal inlet system. Journal of Coastal Research, SI65, 1122-1127.
Lefebvre, A, Ernstsen, VB and Winter, C, 2011. Influence of compound bedforms on hydraulic roughness in a tidal environment. Ocean Dynamics, 61(12). 2201-2210. doi:10.1007/s10236-011-0476-6
Lefebvre, A, Ernstsen, VB and Winter, C, 2011. Bedform characterization through 2D spectral analysis. Journal of Coastal Research SI64, 781-785.
Ernstsen, VB, Lefebvre, A, Bartholdy, J, Bartholomä, A and 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 and Amos CL, 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, VB, Lefebvre, A, Winter, C and Kopf, AJ, 2011. Coupled penetrometer, MBES and ADCP assessments of tidal variations in surface sediment layer characteristics along active subaqueous dunes, Danish Wadden Sea. Geo-Marine Letters, 31(4). 249-258. doi:10.1007/s00367-011-0230-6
Garel, E and 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, CEL and Amos, CL, 2010. Influence of Zostera marina canopies on unidirectional flow, hydraulic roughness and sediment movement. Continental Shelf Research 30, 1783-1794.
Lefebvre, A, Thompson, CEL, Collins, K and Amos, CL, 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.
Lefebvre, A., Paarlberg, A.J., Winter, C., 2016. Influence of complex bedform morphology on flow and shear stress. MARID5 Marine and River Dune Dynamics, 4 – 5 April 2016, Caernarfon (Wales, UK), 4pp
Lefebvre, A, Paarlberg, AJ and Winter, C, 2013. Flow separation in the lee of bedforms: a numerical study on the influence of bedform height and length. Coastal Dynamics 2013, 24 – 28 June 2013, Arcachon (France), 12pp. See the paper.
Lefebvre, A, Ferret, Y, Paarlberg, AJ, Ernstsen, VB and Winter, C, 2013. Variations of flow separation over large bedforms during a tidal cycle. MARID4, Marine and River Dune Dynamics, 15 – 16 April 2013, Bruges (Belgium), 7pp.
Lefebvre, A and Lyons, AP, 2011. Quantification of roughness for seabed characterization. Underwater Acoustic Measurements Conference, Kos (Greece), 20 – 24 June 2011, 8pp.
Lefebvre, A, Lyons, AP, Thompson, CEL and Amos, CL, 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.
Lefebvre, A, Thompson, CEL, Collins, KJ and Amos, CL, 2009. Use of a high-resolution profiling sonar for seagrass detection. Underwater Acoustic Measurements: Technology and Results, Nafplion (Greece) 21 – 26 June 2009, 8pp.
Alice Lefebvre, 2009. Bed roughness over vegetated beds: sonar imaging techniques and effect on unidirectional currents. PhD Thesis, NOCS, Southampton, UK, 185p. Supervisors: Prof C.L. Amos, Dr C.E.L. Thompson and Prof R.J. Nicholls.
Teaching and education
Education within GLOMAR
> Monthly Research Seminars
> GLOMAR thesis workshops
> GLOMAR Introductory Course to Natural Sciences in the Marine Realm
Main teaching activities
> Teaching one week intensive course: “Introduction to coastal geomorphology and processes” for the ISATEC master, University of Bremen (May 2011, May 2012, May 2013, May 2014, May 2015)
> Onboard teaching: “SOES 2010: Physical Oceanography II” (February-March 2007, February-March 2008).
> Onboard teaching: “SOES 3040: Fieldwork for exchange student” (July 2006, July 2007, July 2008).
> Teaching: “SOES 1003: IT, Communication, Field and Laboratory Skills” (March 2006, March 2007 and March 2008).
Organiser of MARID VI - Marine and River Dune Dynamics 2019, 1-3 April 2019, Bremen, Germany
Administrator of marid.net
Part of the organising committee of the 5th Early Career Scientists Conference for Marine and Climate Research (ECC2014), 21-24/09/2014, Bremen, Germany (conference coordinator with Ulrike Holwartz, abstract management with Gopika Suresh, convener of the "Atlantic and Europe" session with Anna Joy Drury, moderator of the panel discussion on scientific networks).
Part of the organising committee of the ICYESS2013 Interdisciplinary Conference of Young Earth System Scientists (22-25/09/2013, Hamburg, Germany) and co-chair of the “Innovative Talks” session with Ulrike Holwartz.
Part of the organising committee of the Young Scientists Conference 2012 in Kiel and co-chair of the "do you dare?" session with Ulrike Holwartz.
2010-2017: Co-organiser of monthly MARUM post-doc meetings (with Alice Govin, then Gema Martínez Méndez and ultimately with Heather Johnstone).
2010-2013: Organiser of weekly MARUM Coastal Dynamics Group Meetings (now organised by Brice Blossier)
Conferences and outreach
- CONFERENCE PARTICIPATION (selected):
MARID V (Marine and River Dune Dynamics), Caernarfon (Wales, UK), 4-6 April 2016
Oral presentation: Alice Lefebvre, Andries J. Paarlberg, Christian Winter. Influence of complex bedform morphology on flow and shear stress.
ECC2014 (5th Early Career Scientists Conference for Marine and Climate Research: Natural and Social Aspects of the Earth System), Bremen, 21-24 September 2014
Conference coordinator with Ulrike Holwartz, abstract management with Gopika Suresh, convener of the "Atlantic and Europe" session with Anna Joy Drury, moderator of the panel discussion on scientific networks.
AGU2012 (American Geosciences Union Fall meeting) San Francisco (USA), 9–7 December 2012
Poster presentation: Alice Lefebvre, Andries J. Paarlberg, Christian Winter. A numerical investigation of flow separation over bedforms.
Judge in the OSPA (Outstanding Student Presentation Award)
Panellist during Town Hall Meeting “Research Made in Germany”
Panellist during the “Career Guidance Workshop – Research Career Made in Germany”
- GENERAL PUBLIC OUTREACH:
Part of the MARUM brochure
Part of the video join us for the MARUM experience
Participation in the University of Bremen Open Doors at MARUM booth (21/07/2013).
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.