coastal dynamics 2013 the arcay spit and lay … · two other stations made of bottom-mounted adcp...

Coastal Dynamics 2013

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THE ARCAY SPIT AND LAY ESTUARY (VENDEE, FRANCE): NEW DATA TO HIGHLIGHT SEDIMENT DYNAMICS AND SUPPORT COASTAL MANAGEMENT

Aurelie Dehouck1, Stephane Kervella1, Virginie Lafon1, Cecile Curti1, Frederik Alexandre2, Eric Chaumillon3, Xavier Bertin3, Aldo Sottolichio4, Nicolas Robin5, Pascal Naulleau6, Cyril Vanroye6

Abstract This article presents data that have been recently collected along the Arçay Spit and Lay Estuary in South Vendée (Atlantic coast of France) to fill the gap of knowledge considering the hydrodynamics and sediment dynamics of this macrotidal system. The issue is to provide coastal stakeholders and users with fundamental knowledge that will support sediment management strategy. Main results show sediment processes to be tidally-controlled in the estuary with strong spring ebb currents associated with freshwater releases, causing fine-sediment resuspension and exportation downstream the estuary as a turbid plume. The question of sand accumulation in the lower estuary is unraveled considering the effect of onshore-directed winds that reinforce flood currents at the Arçay Spit carrying sand inside the estuary, while turning off ebb currents favouring sand deposition. The assessment of recent bathymetric changes highlights that the navigation channel is self-maintained in the upper and central estuary while the sediment budget is more heterogeneous in the lower estuary. Key words: Hydrodynamics, suspended particulate matter, sediment budget, bathymetric change, dredging, macrotidal

inlet 1. Introduction The purpose of this paper is to provide new insights in the understanding of sediment dynamics along the Arçay/Lay system which is characterized by the rapid growing of the Arçay Spit (>20 m per year), the sandy infill of the downdrift mixed-energy inlet and the muddy infill of the Lay estuary. These questions are commonly addressed at coastal inlets (e.g., FitzGerald 1996, Lafon et al., 2000, Bertin et al., 2009;

Capo et al., this issue) where navigation, water quality and ecosystem dynamics may be affected by inlet morphological changes. In particular, the study area is subject to navigation problems that may affect the durability of aquaculture and fishing activities, marine submersion and flooding hazards (Xynthia storm in 2010 caused severe material and human damage) and freshwater management issues in a high-value environmental frame (Natura 2000, national and local reserves of biosphere). The motivation of this study is to promote knowledge of Arçay/Lay functioning in order to anticipate future evolution and perform adequate management decisions.

Previous studies have focused on the Arçay Spit morphodynamic evolution considering wave and sediment transport processes (Bertin et al., 2007; Allard et al., 2008), beach surveys (Chaumillon et al.,

2011) and shoreline changes at seasonal to decadal timescales (Galichon, 1984; Allard et al., 2008;

Chaumillon et al., 2011). The issue of these academic works was to assess the capability of the Arçay Spit

1GEO-Transfert, UMR EPOC, University of Bordeaux, Avenue des Facultés, Talence 33405, France.

[email protected]; [email protected] 2GINGER Environnement, Merignac 33700, France. 3UMR LIENSs, University of La Rochelle, 2 rue Olympe de Gouges, La Rochelle 17000, France.

[email protected]; [email protected] 4UMR EPOC, University of Bordeaux, Avenue des Facultés, Talence 33405, France. [email protected]

bordeaux1.fr 5CEFREM, University of Perpignan, 52 avenue Paul Alduy, Perpignan 66860, France. [email protected] 6DDTM 85, Direction Mer et Littoral, 1 quai Dingler, Les Sables d’Olonne 85108, France.

[email protected]; [email protected]


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to be considered as a sedimentary record of swell climatic variations (Allard et al., 2008). But knowledge was completely lacking about the Lay estuary, motivating the acquisition of new data to highlight in particular estuarine processes associated with fine sediments and tidal forcing, and quantify bathymetric changes at the global scale. This paper outlines (1) the background, (2) data collection and analysis, (3) the main results concerning hydrodynamics, sediment dynamics and bathymetric changes over the Arçay Spit and Lay estuary and (4) a discussion for supporting coastal management needs. 2. Background The study area is located along the French Atlantic coast in the department of Vendée (Fig. 1). The Arçay Spit is set in a semi-diurnal macrotidal context (spring tidal range of 6 m) and exposed to the west to moderate Atlantic swells (Hs~1.5 m) subject to strong transformations when propagating over the wide sandy nearshore. Wind forcing is of importance over the Pertuis Breton blowing from the south to west directions and from the northeast during wintertime. The Lay river is flowing between Arçay Spit to the west, which is offering shelter from oceanic agitation, and the L’Aiguillon Spit to the east (Fig. 1c) which shoreline has been protected at the end of the 19th century to stop coastal dune retreat. Lay river outflow is controlled by the “Braud” dam, built in 1958 and located about 10 kms upstream the inlet. The channel of the Lay river is partially dredged every 2 years in a few locations of the lower estuary and tidal inlet. In 2006, about 50,000 m3 of sandy sediments mainly were dredged, deposited offshore and also used for the nourishment of L’Aiguillon beaches. Since then, minor dredging operations (15,000 m3) are realized every 2 years for ensuring navigation.

The Pertuis Breton is an ancient incised valley of the Lay, Vendée and Sèvre rivers. It was partially infilled around 5000 yr BP by vast sand bodies deposited by the paleo littoral drift (Chaumillon and Weber, 2006). Academic research studies have focused on the yearly to secular morphodynamics of the Arçay Spit which is a spectacular geomorphological feature considering its very rapid progradation (~22 m/yr over last 400 years; Galichon, 1984; Allard et al., 2008). The Arçay Spit is made of successive hook ridges formed on the intertidal beach by the considerable amount of sand driven by the littoral drift. Variations in the progradation rate of the Arçay Spit at annual and decadal timescales have been recently correlated with variations in wave climate with rapid progradation occurring during periods of severe storms while moderate energy conditions are more favourable to the eastward (alongshore) elongation of hook ridges (Allard et al., 2008). Sediment accumulation at the Arcay spit has been evaluated to a total amount of 48,000 – 78,000 m3/yr (Chaumillon et al., 2011) what corroborates the estimation of annual longshore transport of 40,000 – 100,000 m3/yr (Bertin et al., 2007) combining fluorescent tracer experiment and numerical modeling. The morphodynamics of the wave-dominated area, namely Arçay Spit, is well known (Bertin et al., 2007; Allard et al., 2008) and have permitted to understand spit elongation processes. In contrast, information about the Lay estuary and fine-sediment dynamics is really lacking.

3. Methods 3.1. Waves, currents and SPM concentrations New data have been acquired in early November 2012 (29 October – 12 November) in 4 locations over the study area. Two ADV Nortek currentmeters were deployed along the river banks of the Lay estuary at low tide levels, the first one in the upper estuary a few hundred meters downstream the “Braud” dam and the second one in the central part of the estuary, about 3 kms downstream L’Aiguillon s/mer and La Faute s/mer. Two other stations made of bottom-mounted ADCP (Sontek and RDI) coupled to OBS-3a and OBS-5+ sensors were deployed, one in the inlet at the Arçay spit (at a depth of 1 m under spring low tide levels) and the second offshore the spit (1.5 m deep). The ADVs were deployed 0.34 m and 0.44 m above the bottom in locations 1 and 2 (Fig. 2), respectively, and the ADCPs 0.73 m above the seabed in locations 3 and 4. Data consists of hydrodynamic recordings of sea surface elevation, wave- and tide-driven currents and concentrations in suspended particulate matters (SPM). The experiment lasted 14 days covering a neap-spring tidal cycle. A variety of energy conditions were recorded due to the occurrence of several wind


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Figure 1. Location map of the study area (a) global situation (b) bathymetry along the coasts of south Vendée and Charente Maritime (c) Arçay sandspit, Lay estuary and L’Aiguillon sandspit viewed by SPOT-5 (Allard, 2008).

Dashed lines represent successive phases of anthropic shoreline progradation since the 18th century.

events (wind speed raising to 30-50 km/h) between November 1-6 generating wave heights of 0.8-1.5 m along Arçay beaches. Water height and mean currents were computed averaging data over the burst duration (every 10 min). SPM concentrations were measured near the seabed with the OBS at locations 3-4 and also at the surface at location 3. OBS and ADV signals were processed converting backscattering signal into SPM concentrations using empirical relationships calibrated in laboratory with sediment from the study area.


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Figure 2. Deployment of instrumentation in the Lay estuary (ADV at locations 1 and 2), at the Arçay Spit (ADCP/OBS

at location 3) and off the Arçay beaches (ADCP/OBS at location 4). 3.2. SPM regional dynamics using satellite imagery 190 MODIS satellite images (250 m resolution) were collected on the NASA website over a period of

approximately 2 years from December 2010 to November 2012 (1 image every 4 days). These images are

very suitable to investigate variations in the color of coastal waters inferred by the suspended sediment

load. The archive was compared to environmental forcing factors at the time and prior to satellite

acquisitions, namely tide, wind, waves and river discharge. Satellite images were sorted in 5 configurations

depending on the observation of Lay and Sevre river plumes and on their degree of connection. 3.3. Morphological changes Bathymetric surveys of the Lay river are realized by the Vendee department council (Conseil Général de la

Vendée) twice a year over the time period 2004-2012. They aim at monitoring seasonal and annual morphological changes affecting the navigation channel and at preparing dredging operations. A reference bathymetry has been realized over the study arera in march 2013. This data is composed of

multi-beam bathymetric soundings covering elevation from -7 m to +4 m (datum is relative to the hydrographic chart) while intertidal areas are surveyed by means of a topographic LIDAR. Only

bathymetric data interpolated to a 5-m resolution are analyzed in this paper. This dataset is compared to an ancient bathymetry dated of 1985 and interpolated to a 50-m resolution obtained by the Laboratoire Central d’Hydraulique de France (LCHF). Thus, decadal morphological changes are assessed comparing 1985 and

2013 bathymetries. Date-to-date elevation change and sediment budgets are computed to monitor erosion and accretion processes at annual and decadal timescales.


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4. Results 4.1. Hydrodynamics Inside the estuary, mean currents are essentially tide-driven with the magnitude and direction of mean currents being controlled by diurnal and neap-spring variations in the tidal range. Tides are asymmetrical in terms of current velocity and temporal duration. Figure 3 shows that ebb current is stronger and longer than

the flood in the estuary mainly (Fig. 3a-b) and still a little at the inlet (Fig. 3c). This result contrasts with observations gathered in the neighboring Sèvre river where currents are flood-dominated (Demagny, 2005), observations that have been frequently extrapolated to the Lay estuary. On open-ocean locations (Fig. 3d), it appears that mean currents are more like flood-dominated but this pattern may be put in perspective with the contribution of wind-generated currents oriented towards the estuary (see Fig. 4 later on).

Figure 3. Direction and temporal occurence of mean currents (m/s) (a) in the Lay upper estuary (down the Braud dam),

(b) in the central estuary, (c) in the inlet in front of Arçay sand spit, (d) offshore Arçay beaches. Ebb (downstream-oriented) current is reaching a maximum velocity of 1 m/s in the upper estuary (Fig. 3a), and about 0.8 m/s in the central and lower estuary (Fig. 3b-c). Ebb currents always attain their maximum velocity at the end of the spring falling tide which often coincides during the period of observation with

freshwater release at the Braud dam. Thus, downstream-oriented (i.e. ebb) currents seem to be significantly controlled by freshwater outflows which influence is not easy to decorrelate from tidal influence.

Analyzing ebb current velocity upon the occurrence of freshwater release (in location 1) suggests that

spring ebb current velocity is respectively about 0.2 m/s (without any discharge) and 0.8 m/s consecutively

to the dam opening. The impact of freshwater release is hypothesized to disappear in the central estuary

(location 2) where it has not been properly assessed from the data. The analysis of sea surface elevation data reveals the occurrence of a double high tide during neap tides

(not shown) resulting in an asymmetrical shape of the tidal curve. Flood is a little longer (~7h) than ebb

(~5h) during neap tides and flood velocities rarely exceed 0.1 m/s. This pattern is observed in all


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recordings of the Lay estuary from the upstream location down to the inlet. Nicolle (2006) has already

reported such a phenomenon over the study area which was explained by a phase gap between the main

tide waves M2 and M4. Figure 4 shows a time series of mean currents at the Arçay Spit (location 3) during windy conditions.

The two first cycles on October 31 are representative of spring tides associated with calm wave conditions

(Hs=0.2 m). As wind blew stronger, wave height increased progressively in the afternoon of October 31

until reaching wave heights of 1.6 m on November 1 (Hs=0.8-1 m at the inlet) during the two consecutive high tide levels. During the storm peak, flood currents are very intensified (above 1 m/s) prevailing during

all the rising tide while ebb currents, opposed to surface wind stress, are totally turned off. Under onshore

wind conditions, we suggest that advection of sandy sediment towards the lower estuary may considerably

be increased all long the rising tide, then particles settling down during the falling tide. These windy

conditions are thus supposed to cause sand accumulation in the lower estuary.

Figure 4. Characteristics of mean currents at the Arçay Spit (location 3) during a wind event. Displayed period of observation extends from October 30 to November 2, 2012. Time periods during which currents are affected by wind

blowing are indicated in grey. 4.2. Sediment dynamics Figure 5 shows time series of SPM concentrations during growing wave conditions (October 31 to

November 1). In the estuary (Fig. 5b), SPM peaks are tidally-modulated with maximum concentrations (reaching 2 g/l) being associated with flood currents at the beginning of the rising tide. Note that heavy

SPM concentrations prevail during all the rising tide on the afternoon of November 1 what is coherent with

the increase in flood current magnitude under wind forcing (Fig. 4). At the Arçay spit and along Arçay

beaches (Fig. 5c-d), SPM resuspension events are both tidally- and wave-controlled as they occur at low tide levels when wave action is the strongest on the seabed. Secondary SPM peaks are also recorded on the

decreasing tide on November 1 (Fig. 5c) while ebb currents were very reduced due to wind blowing in

opposition to the tidal flow. At the open-ocean location, surface SPM concentrations are about two to three times lower than near the seabed (Fig. 5e). The magnitude of near-bottom SPM concentrations reached


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over the study area follows an alongshore gradient with respectively, about 2 g/l in the central estuary, 0.8

g/l in the inlet and 0.3 g/l at the beaches. This is in agreement with spatial variations in sediment grain size

and wave forcing. This information on SPM concentrations is completed by the archive of MODIS satellite images (190

scenes downloaded for 2 years) that gives valuable insight on SPM regional dynamics. Image analysis

reveals a strong tidal control on the occurrence of turbid plumes (63% of time) getting out the Sèvre and

Lay rivers (Fig. 6). This result converges with previous findings showing large SPM concentrations in the

Lay estuary to be associated with spring tidal currents (Fig. 5b). Also, the stronger tidal range is, the more

likely the Sèvre turbid plume will spread throughout the Pertuis Breton (refer to panels of Fig. 6 for spring

tides). In contrast, we suggest that the spatial extent of the Lay river plume may rather be controlled by a

non-climatic forcing factor, probably the occurrence of freshwater discharges at the Braud dam, as correlation with tidal range, wind/wave conditions and upstream river outputs are poor. When wind and

tidal range are weak, no turbid plume is observed (14% of occurrence), coastal waters are relatively clear.

Under wind sea conditions, the suspended sediment load in the water column is high all over the area (8%

of occurrence).

Figure 5. Spring-tide SPM concentrations (g/l) in different locations (B: central estuary, C: Arçay spit, D-E: Arçay beaches) as a function of tidal level and wind conditions (A). All panels B-D display SPM concentrations near the

bottom layer while panel E is for surface concentrations.


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Figure 6. MODIS image sequence (April 15-26, 2011) showing changes in coastal surface turbidity and river plume configuration (boundaries of Lay and Sèvre plumes are figured in yellow and red, respectively) following variations in tidal range and for stable wind conditions (wind force unchanged for the observed period while wind direction moving

from north to south-east between April 20-22).

4.3. Bathymetric changes Figures 7 and 8 depict elevation changes in the bathymetry along the study area (1985-2013 period) and along the Lay navigation channel (2005-2013), respectively. Figure 7 highlights a general accretion pattern over the study area of +31 cm in average (+1.1 cm/yr) over the timespan 1985-2013. The sediment budget is reaching about +10.7 M m

3 (384000 m

3/yr) what outlines the predominance of the littoral drift for

driving sediment and corroborates observations of shoreline progradation (GEOS-DHI, 2007; Allard et al., 2008). Large depositional areas are observed downdrift the Lay inlet at the « Banc des Jaux » and down the Aiguillon Spit, these areas being both concerned by a very large accretion of the order of 1 to 1.5 m (+5

cm/yr). This result is in line with Weber (2004) who highlighted huge sediment deposition (more than 3-m difference i.e. larger than 2 cm/yr) at the Aiguillon sandspit between 1824 and 1960. Along the Arçay Spit,

accretion is less intense (+20-50 cm in average) attaining locally 1-2 m along what are supposed to be nearshore sediment structures oriented parallel to the shoreline (origin unknown). An area extending along

1 km of the Arçay coast is concerned by erosion that contrasts with the overall accretion pattern over the

study area. Erosion is visible at the lowest tidal levels (-20 to -80 cm) and in the nearshore zone (-50 cm to -2 m). This erosional pattern coincides with shoreline retreat which has been estimated to about -2 to -3.5 m/yr over the period 1975-2001 at this particular location (GEOS-DHI, 2007).

Figure 8 reveals an overall deepening of the upstream channel of the Lay river with an erosion of 20-70 cm in average between 2005 and 2013. This behavior is general from the Braud dam up to four kilometers downstream i.e. close to the “Banc des Marsouins”. From there, sediment budget is more spatially-variable. The erosion trend is much less significant while numerous channel sections experiment accretion. Some of them are known dredged areas (noted 1-3 on Fig. 8). In contrast, there is a 800-m long section (only partially including dredging area n°3 and facing ancient hook ridges) which experiments a 20-50 cm accretion (2-6 cm/yr). We can also notice that the Lay channel is getting more and more constrained at the inlet due to the southeastward progradation of the Arçay spit pushing the channel towards mussel farm infrastructures. The sediment budget over the period 2005-2013 is reaching -148000 m3 (-18000 m3/yr) in the Lay channel and -48000 m3 (-6000 m3/yr) in the inlet. Note that respectively, about a half of this


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Figure 7. Decadal bathymetric changes over the period 1985-2013. Changes in elevation (m) are expressed following

to the color scale (hot colors for sediment deposition, cold colors for erosion). Areas of non-significant change are outlined in grey. Mussel farms are also drawn in black.

volume of materials in the estuary (74700 m3) and a third in the inlet (17300 m3) were concerned by dredging operations and have definitively exited the system. Thus, the natural erosion of the Lay channel is estimated to be about 6 cm over the recent period (2005-2013) while being of the order of 2 cm in the Lay inlet. 5. Discussion Results have shown that sand infilling of the Lay inlet and lower estuary is a reality of course, but may be put in perspective with the global sediment budget over exposed oceanic beaches. To a certain extent, all beaches are concerned by accretion processes occurring either in the nearshore and/or intertidal areas (increase of the seabed elevation by 30 cm in average for the last 30 years) what is in agreement with the rapid shoreline progradation prevailing along the Arçay Spit (several meters per year). More than 10 millons of cubic meters of sandy sediments have been deposited along Arçay and L’Aiguillon spits in 30 years. In comparison, the inlet sediment stock is more or less stable over the recent period (2005-2013) evaluated to only 30,000 m3 even leaving naturally the inlet. Most of the sediments driven by the littoral drift along Arçay spit have been deposited downdrift the inlet at the « Banc des Jaux » and at the head of L’Aiguillon spit where seabed elevation have raised from 1 to 1.5 m and disturbs aquaculture installations. Only a fraction of the sand carried by the littoral drift is entering the Lay estuary at the favor of wind sea conditions that cause sediment resuspension and reinforce flood tidal currents. Sediments are advected inside the estuary and deposited as the tide decreases when ebb currents are particularly insignificant. Sandy sediments may also originate from an internal source, namely ancient hook ridges extending towards the lower estuary that may occasionally be washed out during storm events. The analysis of channel annual


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Figure 8. Bathymetric changes in the Lay estuary over the period 2005-2013. Changes in elevation (m) are expressed

following to the color scale (hot colors for sediment deposition, cold colors for erosion). Areas of non-significant change are outlined in grey. Mussel farms are also drawn in black. Numbered red boxes locate dredging areas over the

period of interest. bathymetric changes has put in evidence a number of information that could be integrated in a forthcoming

sediment management plan, i.e. by optimizing dredging operations, moving mussel infrastructures that are

currently bordering the channel and would cause river meandering at the inlet in the coming years, and the

proposition for the closure of a sinuous secondary river arm in order to optimize river self-maintenance, for instance. By now, the question of the muddy infilling of the Lay estuary has only been addressed considering

channel bathymetric changes. Results have shown that in the upper and central estuary, the channel is

currently self-maintained with a clear erosion trend that is probably linked to the strong ebb currents measured associated with freshwater releases at the Braud dam. Navigation is certainly easiest than it was

in 2005 in this part of the estuary but the channel alongshore slope has seriously decreased that may cause

problems in case of flooding/submersion events. These issues are of priority importance for coastal


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stakeholders and will be balanced together with the durability of fishing activities, the development of tourism and the need for preserving the environment to finally result in the definition of an integrated sediment management plan. 6. Conclusion This paper have demonstrated :

• strong bathymetric changes along open-ocean beaches of the Arçay Spit and L’Aiguillon Spit with an average accretion of 30 cm in 28 years (+10.7 M m3 of sediment) but local accretion of 1 m to 1.5 m downdrift the inlet. These changes coincide with the rapid shoreline progradation observed along the Arçay Spit as well as the seabed elevation noticed by fishermen along L’Aiguillon Spit. In contrast, sediment budget is quite stable at the inlet over the period 2005-2013 and significantly showing an erosion trend in the Lay navigation channel.

• The impact of onshore-directed wind events for carrying sediment inside the estuary; • The influence of spring ebb currents probably associated with freshwater releases for causing fine-

sediment resuspension, driving them down the estuary and self-maintaining the navigation channel.

These findings should be of help to coastal stakeholders to promote an integrated sediment management plan focusing on the knowledge of Arçay/Lay functioning that will be balanced with the needs of protecting population from flooding/submersion hazards, ensuring aquaculture and fishing activities, developing sailing tourism, and the will to preserve this singular geomorphologic environment. Acknowledgements This study is funded by the Marine Office of Vendée (DDTM85) in the frame of the public contract “Estuaire du Lay-Baie de l’Aiguillon: étude de caractérisation du site et de définition des modalités de gestion”. The bathymetric survey of the Lay channel is the property of Conseil Général de Vendée (CG85), the 1985 bathymetry of LCHF and the 2013 bathymetry of DDTM85. References Allard J., 2008. Enregistrements des changements environnementaux dans les sédiments littoraux : cas des Pertuis

Charentais et du Bassin d’Arcachon. PhD Thesis, University of La Rochelle, 286 p. Allard J., Bertin X., Chaumillon E., Pouget F., 2008. Sand spit rhythmic development: A potential record of wave

climate variations? Arçay Spit, western coast of France, Marine Geology, 253: 107–131 Bertin X., Deshouilieres A., Allard J., Chaumillon E., 2007. A new fluorescent tracers experiment improves

understanding of sediment dynamics along the Arcay Sandspit (France), Geo-Marine Letters, 27: 63–69 Bertin X., Fortunato, A.B., Oliveira A., 2009. A modeling-based analysis of processes driving wave-dominated inlets.

Continental Shelf Research, 29: 819-834. Capo S., Marieu V., Lubac L., Bonneton P., 2013. Decadal morphodynamics evolution of a mixed-energy inlet using

multispectral SPOT imagery. Coastal Dynamics 2013. CETMEF, 2011. Estuaire du Lay - Impact hydraulique des dragages de l’estuaire, report, 13 p. (in french). Chaumillon E., Ozenne F., Tiphaneau P., Bertin X., 2011. Evolutions morphologiques interannuelles des plages de St

Trojan, de la Coubre et de la Pointe d’Arcay : comparaison avec le climat de houle, Rapport d’étude Université de la Rochelle/Conseil Général de Charente Maritime, 36 p. (in french)

Chaumillon E., Weber N., 2006. Spatial variability of modern incised valleys on the French Atlantic coast : comparison between the Charente and the Lay-Sèvre incised valleys, SEPM (Society for Sedimentary Geology), 85: 57-85.

Demagny J. (2005). Approche du fonctionnement hydro-sédimentaire de la Baie de l’Aiguillon et de l’estuaire de la Sèvre niortaise. Eléments de compréhension de la dynamique d’envasement et propositions d’études. Rapport de stage Master 2 IIBSN/Univ Caen/Univ Angers, 54 p.

FitzGerald, D.M., 1996. Geomorphologic variability and morphodynamic and sedimentologic controls on tidal inlets. Journal of Coastal Research 23 :47–71.


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Galichon P., 1984. Hydrodynamique sédimentaire des flèches littorales sableuses : cas de la Pointe d’Arçay (Vendée). PhD Thesis, Université Paris Sud, 234 p.

GEOS – DHI, 2007. Etude de connaissance des phénomènes d’érosion sur le littoral vendéen, rapport final DHI/GEOS pour la DDE85, 355 p.

Lafon V., Froidefond J.M., Castaing P., 2000. Méthode d’analyse de l’évolution morphodynamique d’une embouchure tidale par imagerie satellite. Exemple du bassin d’Arcachon (France), Comptes Rendus de l’Académie des Sciences -Series IIA- Earth and Planetary Science, 331(5) : 373-378.

Nicolle A., 2006. Modélisation des marées et des surcotes dans les Pertuis Charentais. PhD thesis, University of La Rochelle, 307 p.

Weber N., 2004. Morphologie, architecture des dépôts, évolution séculaire et millénaire du littoral charentais -Apports de la sismique réflexion combinée à des suivis bathymétriques et validée par des vibrocarottages, PhD thesis, University of La Rochelle, 372 p.

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