P. Castaing's research while affiliated with Université Bordeaux 1 and other places

Publications (58)

Article
Full-text available
The Gironde estuary is the largest estuary of the European Atlantic coast, with a well developed turbidity maximum zone (TMZ) characterized by high suspended sediment concentrations (SSC), over 1 g.l -1 . In a context of climate change, understanding and predicting trends of turbidity are crucial issues for better predicting the future evolution of...
Article
Full-text available
The Gironde estuary, one of the largest European ones, presents temporary low dissolved oxygen content in its fluvial section close to the Bordeaux urban area. In a context of population growth and of long-term environmental changes, the development of a high-frequency monitoring programme of the fluvial-estuarine system of the Gironde, called MAGE...
Article
The short-lived natural radionuclides 7Be (T1/2=53days), 234Thxs (T1/2=24.1days) and 210Pbxs (T1/2=22.3years), i.e. 234Th and 210Pb in excesses of that supported within particles by the decay of their parent isotopes, were analysed in suspended particulate matter (SPM) to study the particle dynamics in the Gironde fluvial estuarine system (France),...
Conference Paper
Full-text available
Metallic and organic contaminations, urban waste waters decrease the Gironde estuary water quality and disoxygenation periods used to be observed in the fluvial part. The Maximum Turbidity Zone comportment, depending from hydrodynamic and morphodynamic processes, is also a major controlling factor for water quality determination. Since 2004, the MA...
Article
In comparison to their temperate counterparts, sediment processes in tropical estuaries are poorly known and especially in African ones. The hydrodynamics of such environments is controlled by a combination of multiple processes including morphology, salinity, mangrove vegetation, tidal processes, river discharge, settling and erosion of mud and by...
Article
Over a 1-year period, field and satellite measurements of surface water turbidity were combined in order to study the dynamics of the turbidity maximum zone (TM) in a macrotidal estuary (the Gironde, France). Four fixed platforms equipped with turbidity sensors calibrated to give the suspended particulate matter (SPM) concentration provided continu...
Article
The Patos Lagoon is a choked, microtidal coastal laggon situated in southern Brazil between 30°S and 32°S. The response of the lagoon to tidal oscillations is studied through data analysis and numerical modeling experiments. Two types of high frequency oscillations are observed in the tidal frequency band: mixed tides, predominantly diurnal; and fo...
Article
Full-text available
This study concerns the quantification of suspended particulate matter in the highly turbid estuarine waters of the Gironde, France, from high spatial resolution remotely sensed data, SPOT (Satellite Pour l'Observation de la Terre) High Resolution Visible (HRV), Landsat Enhanced Thematic Mapper Plus (ETM+). The methodology is based on calibration r...
Article
The Konkouré Estuary in the Republic of Guinea is a poorly understood atypical mangrove system. Sediment dynamics in tropical estuaries are controlled by a combination of processes including river discharge, morphology, salinity, erosion and deposition processes, the settling of mud, physico-chemical processes and mangrove swamps. Here we present a...
Article
Full-text available
Variations of sediment type (grain size and refractive index) and changing illumination conditions affect the reflectance signal of coastal waters and limit the accuracy of sediment-concentration estimations from remote-sensing measurements. These effects are analyzed from numerous in situ remote-sensing measurements carried out in the Gironde and...
Article
Full-text available
This letter presents an empirical relationship that may be used to estimate the suspended particulate matter concentrations in highly turbid waters from remote sensing re ectance measurements. Numerous measurements carried out in the Gironde estuarine waters (France) in 2000 and 2001 are presented and analysed. It was observed that the near-infrare...
Article
Full-text available
The determination of shallow water depth in high-energy tidal inlets is essential to model and to forecast the navigation channel position or the short-term topographic evolution of beaches. Colour satellite imagery provides, at low cost, complete maps of areas that are difficult to map by traditional hydrographic means due to their size and their...
Article
An experimental method for determining water composition from “ocean colour” satellite data, in visible and near-infrared (NIR) wavelengths, is applied to highly turbid waters. Numerous spectroradiometric measurements are carried out in the Gironde estuary, for suspended particulate matter (SPM) concentrations ranging between 35 and more than 2000...
Article
An experimental method for determining water composition from “ocean colour” satellite data, in visible and near-infrared (NIR) wavelengths, is applied to highly turbid waters. Numerous spectroradiometric measurements are carried out in the Gironde estuary, for suspended particulate matter (SPM) concentrations ranging between 35 and more than 2000...
Article
Some basic features concerning the subtidal circulation of Patos Lagoon were studied through time series analysis of wind, freshwater discharge, and water level records, as well as by means of experiments carried out with a 3D numerical model. The results indicate that during low to moderate river discharge the wind is the main forcing mechanism in...
Article
Two numerical models are applied to the Gironde estuary in order to study basic mechanisms of turbidity maximum formation. A 2D depth-averaged model reproduces the turbidity maximum location for different river flow conditions, wherein tidal wave propagation is the only hydrodynamic forcing. Yet, excessive sediment escape to the ocean and associate...
Article
Full-text available
The channels and sandbanks located in the tidal inlet of Arcachon move with the local strong dynamical conditions. To model the evolution of the inlet, with intent for example to forecast the position of the navigation channel, it is necessary to obtain accurate bathymetric maps. As the hydrographic charts are rare and incomplete, particularly in t...
Article
Full-text available
Sedimentary processes and facies on the northern Aquitaine shelf, France. The Aquitaine shelf in France is a storm-dominated shelf similar to the Californian shelf in the US. It exhibits a thin veneer (about 1–2 m) of sandy sediments overlying coarse-grained deposits. This surficial sand sheet is shaped into various bed forms corresponding to the c...
Article
Two turbidity peaks can be identified in the Gironde estuary waters. The first one, in a steady position, is possibly related to a mud-trapping zone in the main channel. The second one is the actual turbidity maximum, capable of shifting seasonally along the estuary. Its length and position can be readily predicted as functions of the river flow. F...
Article
Full-text available
Spatial and temporal characteristics of the water masses and the dispersion of the suspended particulate matter were investigated using current meter, hydrographic and nephelometric observations, gathered during the ECOFER experiment (1989–1991) in the Cap-Ferret Canyon on the Aquitanian margin of the Bay of Biscay. While characteristics of the dee...
Article
Under present-day conditions, rivers are the main source of fine sediments dispersed to the Bay of Biscay. They deliver about 2.5×106 t yr−1 of continental fine sediments, 60% of which is derived from the Gironde estuary. Of this flux, 65% is believed stored on the shelf. Two kinds of mud fields can be found in the Bay of Biscay: coastal mud and sh...
Article
Numerous oceanographic cruises (with hydrology, water sampling, drift current measurements) carried out since 1980 on the continental shelf of the Bay of Biscay, together with available NOAA/AVHRR infra-red images, form the basis of a proposed explanation for the processes responsible for the distribution of suspended sediments on the shelf. The se...
Article
AVHRR/NOAA-11 satellite images of the C1 (580–680nm) and C2 (725–1100nm) channels were used to quantify the suspended particulate matter discharged into the ocean by the Gironde estuary (France). The calibration method is based on a comparison between satellite values (AVHRR reflectances) and suspended particulate matter (SPM) concentrations at the...
Article
The detailed analysis of the Cd distribution coupled with 137Cs measurements have been conducted in a core recovered from a flood-tidal dock of the Bordeaux harbour. They enabled reconstruction and dating of the record of industrial contamination which has developed over recent decades. The cadmium distribution accurately reflects the different sta...
Article
In this work, we document the historical record (≈70yr) of contamination from industrial activity along the Garonne River and its tributaries (SW France), through the geochemical study of a sediment core recovered from the inner section of a flood-tidal dock, located in the city of Bordeaux, along the Garonne River. The chronology of the core was e...
Article
The isotopic composition of silty clay sediments in the Gironde Estuary, which were sampled between 1986 and 1995, shows homogeneity. The sediments from the Garonne and the Dordogne Rivers, including the tributary Isle River, are well mixed within the turbidity maximum zone.The composition of the clay solid load of the upstream Garonne River was al...
Chapter
The Patos Lagoon (Fig. 5.1a) situated in Southern Brazil, between 30 and 32°S is a very important water resource system for the Rio Grande do Sul State. It serves as nursery ground for important commercial fish and shrimp species sustaining a fishery production of 182 kg ha-1 yr-1 in average (Castello 1985). Major man activities are navigation and...
Article
The fine-grained sediments of the West Gironde mud patch derive mainly from materials supplied via the Gironde estuary. Between 1500 and 1200/1300 years BP and 300/400 years BP and the present day, the Sr isotopic and chemical compositions of the estuarine silty clay inputs are the same. In contrast, these compositions were different during the per...
Article
For the first time on the Atlantic insular shelf, megaripple fields, present in coarse to very coarse sands and in gravels, have been recognized by side-scan sonar between 20 and 60 m depth. Similar sedimentary structures have been already spotted on the shelves of Guadeloupe and Colombia. Megaripple characteristics indicate the sedimentary structu...
Article
Full-text available
The Arcachon tidal inlet (France) is a sandy place where tidal currents, swells and storms produce important sand movements. For example the emerged sand banks move several tens of meter a year. To study and understand these movements traditional methods are often inefficient. Remote sensing seems to be the best means to follow and quantify year af...
Article
Oceanographic measurements and satellite images recorded during the same period show that the data from the visible wavelengths of channel 1 and 2 of the AVHRR sensor (satellite NOAA-11) can be used to establish the distribution of total suspended particulate matter (TSPM) on the inshore continental shelves.The near-infrared channel (C2 = 725–1100...
Article
Oceanographic data (Ecofer, Givapa and Gastel cruises) and satellite images evidence that the channels 1 and 2 (visible and near infra-red regions) of AVHRR/NOAA-11 can be used to estimate the total concentration of suspended sediments on the sea surface, with a daily frequency when under cloudless skies. The near infra-red channel is used for atmo...
Article
A SPOT satellite image covering the Gironde estuary turbid plume during a flood (flow > 2000 m3/s) is analyzed. Radiometric data from the three SPOT channels are compared. The findings show that the XS1 (500–590 nm) and SX2 (610–680 nm) channels are complementary for the study of the turbid plume structure; the XS1 channel shows variation ranges hi...
Article
To understand fully the mechanisms involved in the transport of sediments to the sea, we chose in this study to consider a specific, highly illustrative example: that of the delivery of estuarine suspended matter form the Gironde Estuary.-from English summary
Article
Sewage discharge (chiefly waste waters into the Pointe à Pitre bay originates from the neighboring developing town (60,000 inhabitants) A sampling campaign carried out in March 1984 permitted the assessment of both water and sediment quality in the bay, as well as the evaulation of heavy metal contents Industrial pollution appears insignificant whi...
Article
The prime importance of the morphology of this lagoon is quite evident. The greater part of flows is guided or by the reef outside the lagoon, either by channels inside the lagoon. This dynamic situation corresponds to a transitory period between the end of wet season and the beginning of dry season and is certainly perceptibly different during rai...
Article
The increasing turbulence at the shelf break in the Bay of Biscay provokes frequent resuspension of the fine sands covering this part of the shelf. The off-shelf dispersion of these suspended sediments is controlled by seasonal upwelling.-Authors
Article
Full-text available
During the past 20 years, numerous sedimentological studies in the Gironde have outlined the sedimentological evolution of this macrotidal coastal plain estuary. An ongoing study of bathymetric charts of the estuary, dating back to the 18th century have shown the main long term impacts of man made modifications on sedimentation patterns. Les études...
Article
A highly concentrated (1-10g/l) turbidity maximum develops at the upstream limit of the salinity intrusion in the Gironde estuary, noursihed by the large seasonal influx of alluvial suspended sediment. The estuary contains two distinct channel systems. In the deeper southern channel, a marked tidal cycle occurs: during neap tides, fluid mud accumul...
Article
Monitoring n° 30 of the BLAYAIS nuclear power plant takes into account studies conducted between April and November 2007. Physicochemistry, Bathymetry, Hydrobiology, Bacteriology, Zooplankton, Benthic macrofauna, are reported. L'étude de surveillance n° 30 du site électronucléaire du BLAYAIS (département de la Gironde) concerne la période de avril...

Citations

... The WGMP is located in a macro-tidal environment with a tidal range from 1.5 to 5 m [26,29]. The continental shelf around the Mouth of the Gironde Estuary is dominated by strong swells/waves, which can reach maximal amplitudes of 15 m and time periods of 15 s during winter storms [30]. These hydrological conditions prevent the sedimentation of fine particles in the immediate vicinity of the Mouth of the Estuary. ...
... Furthermore, the high contamination at S1b by microplastics could be due to inputs from outside the island but also from an influence of the Riviere Salée. In this channel, water flows in both directions (north to south and south to north depending on the season, the tide, and the wind ( Castaing et al. 1984, Pujos et al. 1992. ...
... However, the water flows in the Gironde estuary remain relatively high in summertime, and its turbidity maximum zone (TMZ) induces high concentrations of suspended sediments over large areas , therefore flight from stressful conditions would be compromised and mortality risk would increase for allis shad juveniles when migrating through such estuaries. et al., 2011;Lanoux et al., 2013). Thus, at ages when young allis shads potentially initiated their downstream migration in the GGD watershed, adverse local conditions of temperature and oxygen saturation might only occur during extreme hypoxic events and heat waves. ...
... Suspended sediment load is about one order of magnitude lower than that of the Gironde estuary, as it provides on average 4 to 5 t.km − 2 .yr − 1 of suspended sediment to the Marennes-Oléron Bay (Castaing and Jouanneau, 1987; Gonzalez et al., 1991). Although not measured, suspended sediment loads of the three other rivers (Lay, Sèvre Niortaise and Seudre Rivers, Fig. 1c) are likely non-significant, as their water discharges are very weak (flood maxima not higher than 90 m 3 .s ...
... The Gironde estuary is the most important contributor-at least 60% of its sediment reaches the Bay of Biscay (Castaing, 1981). Some of the suspended matter discharged from the Gironde estuary and the Charente is diverted northwards by river flows and density currents where it contributes to the formation of mudflats (Allen and Castaing, 1977;Castaing, 1981;Froidefond et al., 1996;Jouanneau et al., 1999). Half of the small watersheds of the Cantabrian margin are connected to small straight canyons, leading to the Cap-Breton Canyon, while others feed into a network of canyons, converging to form the Torrelavega Canyon (Brocheray, 2015). ...
... Although the main part of the volcanic products were projected westward (Le Friant et al., 2003), and the northeast trade winds would have carried airborne volcanic products mainly SW (Pujos et al., 1992), volcanogenic deposits also occur east of Mount Pelée volcano. They are found on the northern and northeastern flanks of the volcano (Le Friant et al., 2003;Germa, 2009), as well as spread on the northeastern part of the submarine platform (Durand et al., 1996). ...
... The MTZ is mostly found in the low salinity region and migrates seasonally along the estuary due to hydrological influence, e.g., reaching the city of Bordeaux in low discharge conditions (Fig. 1). Expulsion events of the MTZ to the coastal area are partial along the year, explaining why the sediment annual supply of ~1.5-3 million tons from the Garonne and Dordogne Rivers mounts up to ~4-6 million tons within the MTZ (i.e., SPM residence time within the estuary of 1-2 years, established by Castaing and Jouanneau 1979, and verified in this work). ...
... Therefore, the WGMP can a priori be considered as a potential temperate type 2 RiOMar [5]. The sedimentology of the WGMP has been extensively studied based on stratigraphic sequences, palynological data, X-rays radiographies, and radiochronographies [25,26,[31][32][33][34][35][36][37][38][39][40][41][42][43]. Sedimentological surveys have attributed a major role to hydrodynamics in controlling the spatial structuration of the WGMP [25,26,35,38,42]. ...
... The seasonal variability in suspended sediment concentration is particularly high with bottom values ranging from less than 0.1 up to a few kg.m -3 (Sottolichio and Castaing, 1999). The longitudinal location of the ETM in the estuary depends on the seasonal dynamics of the river flow and changes in salinity intrusion (Allen et al., 1980;Jalon-Rojas et al., 2015;Sottolichio et al., 2000). During high river flow, the density gradient is well developed and the ETM is located at the density node (Allen et al., 1980). ...
... Therefore, the WGMP can a priori be considered as a potential temperate type 2 RiOMar [5]. The sedimentology of the WGMP has been extensively studied based on stratigraphic sequences, palynological data, X-rays radiographies, and radiochronographies [25,26,[31][32][33][34][35][36][37][38][39][40][41][42][43]. Sedimentological surveys have attributed a major role to hydrodynamics in controlling the spatial structuration of the WGMP [25,26,35,38,42]. ...