90 research outputs found
Système expert pour le calcul des flux dans les rivières à partir des réseaux nationaux de surveillance «QUALITE» et «HYDRO »
No full textMoatar-Bertrand Florentina, Meybeck Michel, Curie F., Raymond Sébastien. Système expert pour le calcul des flux dans les rivières à partir des réseaux nationaux de surveillance «QUALITE» et «HYDRO ». In: 35es journées de l’hydraulique de la Société Hydrotechnique de France. Hydrométrie 2013. Paris, 15-16 mai 2013. 2013
Transferring measured discharge time series: Large-scale comparison of Top-kriging to geomorphology-based inverse modeling
No full text[Departement_IRSTEA]Eaux [TR1_IRSTEA]ARCEAUWater Resour. Res. ISI Document Delivery No.: DW5KO Times Cited: 0 Cited Reference Count: 65 de lavenne, A. Skoien, J. O. Cudennec, C. Curie, F. Moatar, F. Etablissement Public Loire; Agence de l'eau Loire Bretagne; European Regional Development Fund; "Eutrophisation-Trend "project This research was funded by Etablissement Public Loire, Agence de l'eau Loire Bretagne, European Regional Development Fund, and the "Eutrophisation-Trend "project. The discharge data used for this study are freely provided by the French Banque hydro database (www.hydro.eaufrance.fr). Amer geophysical union WashingtonInternational audienceFew methods directly transfer streamflow measurements for continuous prediction of ungauged catchments. Top-kriging has been used mainly to predict the statistical properties of runoff, but has been shown to outperform traditional regionalization approaches of rainfall-runoff models. We applied the Top-kriging approach across the Loire river basin and compared predictions to a geomorphology-based approach. Whereas Top-kriging uses spatial correlation, the other approach has the advantage of being more physically-based by using a well-known geomorphology-based hydrological model (WFIUH) and its inversion. Both approaches require an equal degree of calibration and provide similar performances. We also demonstrate that the Ghosh distance, which considers the nested nature of catchments, can be used efficiently to calculate weights and to identify the suitability of gauged catchments for use as donor catchments. This result is particularly relevant for catchments with Strahler orders above five, i.e., where donor catchments are more strongly nested. This article is protected by copyright. All rights reserved
Agir dans la complexité : instruments et pratiques d’une gestion intégrée
No full textEditors: G. Pinay, C. Gascuel, A. Ménesguen, Y. Souchon, M. Le Moal, A. Levain, F. Moatar, A. Pannard, P. Souchu Consultable en ligne : http://www.cnrs.fr/inee/communication/breves/eutrophisation.htm
Agir dans la complexité : instruments et pratiques d’une gestion intégrée
No full textEditors: G. Pinay, C. Gascuel, A. Ménesguen, Y. Souchon, M. Le Moal, A. Levain, F. Moatar, A. Pannard, P. Souchu Consultable en ligne : http://www.cnrs.fr/inee/communication/breves/eutrophisation.htm
Agir dans la complexité : instruments et pratiques d’une gestion intégrée
No full textEditors: G. Pinay, C. Gascuel, A. Ménesguen, Y. Souchon, M. Le Moal, A. Levain, F. Moatar, A. Pannard, P. Souchu Consultable en ligne : http://www.cnrs.fr/inee/communication/breves/eutrophisation.htm
Daily variability of suspended particulate concentrations and yields and their effect on river particulates chemistry
No full textInternational audienceDaily total suspended solids concentrations (TSS, mg L-1), yields (Y, kg day-1 km-2) and runoff (q, L s-1 km-2) in world rivers are described by the median (C50), the upper percentile (C99), the discharge-weighted average concentrations (C*), and by their corresponding yields (Y50, Y99, Y*) and runoff (q*, q50, q99). These intra-station descriptors range over two to six orders of magnitude at a given station. Inter-station variability is considered through three sets of dimensionless metrics: (i) q*/q50, C*/C50 and Y*/Y50, defining the general temporal variability indicators, and q99/q50, C99/C50 and Y99/Y50, defining the extreme variability indicators; (ii) river flow duration (W2) and flux duration (M2) in 2% of time; and (iii) the truncated rating curve exponent (b50sup) of the C vs q relationship for the upper flows. The TSS and Y variability, measured on US, French and world rivers, are first explained by hydrological variability through the b50sup metric, the variability amplifier, then by basin size, erodibility, relief and lake occurrence. Yield variability is the product of runoff variability × TSS variability. All metrics are considerably modified after river damming. The control of river particulate matter (RPM) composition by TSS or yields depends on the targeted component. For major elements (Al, Fe, Mn, Ti, Si, Ca, Mg, Na, K), the average RPM chemistry is not dependent on C* and Y* in most world hydroregions, except in the tropical hydrobelt where it is controlled by basin relief. By contrast, the particulate organic carbon content (POC, as a percentage of RPM) is inversely correlated to TSS concentrations for (i) intra-station measurements in any hydroregion, and (ii) inter-station average POC and TSS figures in world rivers. TSS controls heavy metal content (ppm) in highly contaminated basins (e.g. Cd in the Seine vs the Rhone), and total metal concentration (ng/L) in all cases. Relations between RPM composition and TSS should be taken into account when assessing riverine fluxes, as ignoring them could lead to overestimation
A quality-control method for physical and chemical monitoring data. Application to dissolved oxygen levels in the river Loire (France)
No full text
Continuous measurement of nitrate concentration in a highly event-responsive agricultural catchment in south-west of France: is the gain of information useful?
No full textA nitrate sensor has been set up to measure every 10 min the nitrate signal in a stream draining a small agricultural catchment dominated by fertilized crops during a 2-year study period (2006–2008) in the south-west of France. An in situ sampling protocol using automatic sampler to monitor flood events have been used to assume a point-to-point calibration of the sensor values. The nitrate concentration exhibits nonsystematic concentration and dilution effects during flood events. We demonstrate that the calibrated nitrate sensor signal gathered from the outlet is considered to be a continuous signal using the Nyquist–Shannon sampling theorem. The objectives of this study are to quantify the errors generated by a typical infrequent sampling protocol and to design appropriate sampling strategy according to the sampling objectives. Nitrate concentration signal and flow data are numerically sampled to simulate common sampling frequencies. The total fluxes calculated from the simulated samples are compared with the reference value computed on the continuous signal. Uncertainties are increasing as sampling intervals increase; the method that is not using continuous discharge to compute nitrate fluxes bring larger uncertainty. The dispersion and bias computed for each sampling interval are used to evaluate the uncertainty during each hydrological period. High underestimation is made during flood periods when high-concentration period is overlooked. On the contrary, high sampling frequencies (from 3 h to 1 day) lead to a systematic overestimation (bias around 3%): highest concentrations are overweighted by the interpolation of the concentration in such case. The in situ sampling protocol generates less than 1% of load estimation error and sample highest concentration peaks. We consider useful such newly emerging field technologies to assess short-term variations of water quality parameters, to minimize the number of samples to be analysed and to assess the quality state of the stream at any time
Assessment of heavy metals' bonding with various sedimentary phases in Shefa-Rud river (Guilan Province)
No full textIn the present investigation, bulk and chemical partitioning of elements in the Shefa-Rud riverbed sediments are studied. Higher concentrations of elemental concentrations have been observed in estuarine zone when compared with riverine sediments (except for Al, Fe, Pb and Mn). Manganese is mobilized under anoxic conditions prevailing in the Caspian Sea. Lithogenous materials are greatly diluted in the estuarine zone by various pollutants present in the Caspian Sea. Organic metallic bonds are not significantly present in the area of study. Geological units of the area of study have resulted in the lower concentrations of elemental concentrations of riverbed sediments when compared with published values for mean crust and world sediments ones. Though, cluster analysis has clearly shown the importance of alumina-silicates in controlling the distribution of Fe and Mn in riverbed sediments but it could not depict controlling mechanism for other studied elements. Geochemical Index (Igeo) and Enrichment Factor (EF) values are indicative of a clean environment throughout the river course. These values are in a well agreement with results of chemical partitioning data. Quantification of EF values is not logically possible and therefore Igeo values can be used more effectively.PhDAdvisors: Karbasi, A.; counsellors: Moatar, F
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