Navigable Waterways of France

<p>Watershed management is an important issue throughout Europe. A key point is that business activities that prosper through fluvial transport require optimal conditions of navigation, leading to a double problematic. On one hand, urbanization, industrial, and agricultural activities have evolved to intensifying inflow to water ways (run off and effluents). Input of particulate matter to river networks has hampered functionality of water gates and fluvial circulation. On the other hand, due to human activities (industry, wastewater treatment plants, domestic and agricultural drains), particulate matter may become a contamination vector in the fluvial realm and thus may degrade sediment and water quality.</p><p>The territorial direction of the Voies Navigables de France (VNF) of the Nord-Pas-de-Calais is responsible of the maintenance of all water ways in the Northern France region. Regular dredging campaigns are necessary to maintain optimal navigation conditions, which produces ~100.000 m<sup>3</sup> of sediment waste each year. VNF has the ambition to both prevent particle and contaminant inputs into the water ways and valorize the dredged sediments. However, this is not feasible without a detailed knowledge of the contribution of particulate matter sources, which requires a source-to-sink approach for both sediments and contaminants.</p><p> </p><p>The present study aims to spatialize and quantify the contribution of particulate matter sources and their role on the sediment contamination using a sediment fingerprint approach (e.g. Haddadchi et al., 2013). The focus is on the canalized Denain-Trith reach of the Scheldt River which presents an important sediment accrual (about 18.000 m<sup>3</sup>/year) contaminated by heavy metals (Zn, Pb, Cd) and organic compounds.</p><p>Geochemical and mineralogical analyses were performed on about 200 riverbed sediments and 30 topsoil samples by powder X-ray diffraction, X-ray fluorescence, ICP-MS, and chemo-analytical methods adapted to organic compounds (RRLC-MS/MS, HPLC-MS). This set of analyses is used as tracers of the different particulate sources. Effluent samples are also analyzed to evaluate the contribution of anthropogenic inputs. Preliminary results have already demonstrated the spatial distribution of metal contamination in the reach, which can be related to spot sources, and led to a first estimation of their respective contributions. Geostatistical analyses (such as kriging) will be further used to assess the impact of contaminant sediment accrual on the sediment source quantification (Alary and Demougeot-Renard, 2010).</p><p>Alary, C., Demougeot-Renard, H., 2010. Factorial Kriging Analysis As a Tool for Explaining the Complex Spatial Distribution of Metals in Sediments. Environ. Sci. Technol. 44, 593–599. https://doi.org/10.1021/es9022305</p><p>Haddadchi, A., Ryder, D.S., Evrard, O., Olley, J., 2013. Sediment fingerprinting in fluvial systems: review of tracers, sediment sources and mixing models. International Journal of Sediment Research 28, 560–578. https://doi.org/10.1016/S1001-6279(14)60013-5</p>

La Loire, et en particulier sa partie aval, fait l'objet de nombreuses etudes et experimentations afin lui redonner un fonctionnement hydromorphologique plus proche de ce qu'il etait au XIXeme siecle. En effet, depuis cette epoque, de nombreux amenagements du chenal ont ete realises pour barrer les bras secondaires et concentrer le debit d'etiage dans un chenal unique. Les extractions massives de granulats ont amplifie le phenomene, avec pour resultat l'augmentation de la pente du lit et l'abaissement de la ligne d'eau.Ainsi, le Plan Loire Grandeur Nature a initie des etudes et des operations experimentales avec en premier lieu, en 1995, l'arret des extractions de sable en Loire.L'unite Hydrometrie de la DREAL Pays de la Loire participe a cet enjeu de connaissance et de restauration du plus long fleuve de France, d'une part dans le cadre de son activite quotidienne de suivi des courbes de tarage sur la station de Montjean/Loire, et d'autre part dans le cadre d'une collaboration avec VNF, maitre d'ouvrage d'une operation de remodelage d'epis entre Bouchemaine et Chalonnes sur Loire (Maine-et-Loire).Dans cet article, on montre comment l'evolution des courbes de tarage sert a quantifier l'enfoncement du lit de la Loire au cours du XIXeme et XXeme siecles, puis l'inversion de tendance depuis 2003, ce qui est rendu possible ici par l'anciennete de la station (1863).Le suivi courantologique de l'operation de VNF, datant de 2009, donne egalement ses premiers resultats encourageants, a savoir un debut de re-equilibrage de la repartition des debits entre bras principal et secondaire a l'endroit des travaux.

Abstract In a context of global change, inland navigation transport has gained interest with economic and environmental benefits. The development of this means of conveyance requires the improvement of its management rules to deal with the increase of navigation (schedules and frequency) and the potential impact of global change. To achieve this aim, it is first necessary to have a better knowledge about the dynamics of inland navigation networks and their interaction with the environment. Second, the potential effects of global change have to be anticipated. This article focuses on the modeling of inland navigation reaches. An inland navigation network is a large-scale distributed system composed of several interconnected reaches. These reaches are characterized by non-linearities, time delays, and generally no significant slope. To deal with these particularities, a gray-box model is proposed. It consists in determining the delays according to the physical characteristics of the system. The parameters of the model are identified with measured data. The gray-box model is used to reproduce the dynamics of the Cuinchy–Fontinettes reach located in the north of France.

Click to increase image sizeClick to decrease image sizeAs seaports have naturally "their feet in water", they always used and will be using hydraulic engineering. Their mission - which consists in giving to ships an area protected from open sea agitation - is not changing during centuries, but their size has been considerably growing up. Also the nature of associated hydrotechnical problems does not change but their importance has been increasing, as well as morphological and ecological effects on surrounding coastal area. Due to progress made in mathematical and physical modelisation (with fixed or moving bed, and possibly irregular waves), many problems are solved with a good accuracy. But considering random feature of sea medium, and because of discontinuous and long-term harbour facilities investments, the contracting authority has to take carefully the technical and economical decisions according to the results of models.

étude des transports solides estuaires et zones côtières