Papers by Vincent Bustillo
Water Resources Research, 2014
The study of the relationship between flow structure and morphodynamic of bars in a channel expan... more The study of the relationship between flow structure and morphodynamic of bars in a channel expansion/contraction is essential to better understand the processes that control the evolution of rivers. Thus, multibeam echosoundings and Acoustic Doppler Profiler (ADP) measurements were performed with a high temporal resolution in an expansion/contraction zone of the Loire River (France) occupied by bars. During the monitoring period, the macroforms presented successively an alternate, a lateral and a transverse configuration. Field data were analyzed to study how the primary and secondary velocities, the flow directions, the bed shear stresses, and the bed roughnesses (associated to dunes) evolve as a function of the water discharge and bars configuration. The bars modify the flow structure imposed by the channel width variations. In fact, the bars induce a topographic forcing which enables the separation and reducing of the mixing of two currents formed in the upstream channel expansi...
River Research and Applications, 2016
Hydrological Sciences Journal, 2013
ABSTRACT In discrete water quality surveys, riverine fluxes are associated with unknown uncertain... more ABSTRACT In discrete water quality surveys, riverine fluxes are associated with unknown uncertainties (biases and imprecisions). Annual flux errors have been determined from the generation of discrete surveys by Monte Carlo sorting for monthly sampling, from 10 years of daily records (120 records). Eight calculation methods were tested for suspended particulate matter, dissolved solids and dissolved and total nutrients in medium to large basins (103 to 106 km2) covering a wide range of hydrological conditions and riverine biogeochemistry. The performance of each method was analysed first by type of riverine material, which appeared to be much less pertinent than the flux variability matrix. The latter combines the river flow duration in two percent of time (W 2%) and the truncated exponent (b 50sup) defining the relationship of concentration vs discharge (C–Q) at higher flows (C = aQb 50sup). As flux variability increases (high W 2% and/or high b 50sup), averaging and rating curve methods become less efficient compared to hydrograph separation methods. Flux biases and imprecisions were plotted in the [W 2%, b 50sup] matrix for discrete monthly surveys.Editor Z. W. KundzewiczCitation Raymond, S., Moatar, F., Meybeck, M., and Bustillo, V., 2013. Choosing methods for estimating dissolved and particulate riverine fluxes from monthly sampling. Hydrological Sciences Journal, 58 (6), 1326–1339.
Hydrological Processes, 2013
This paper investigates three categories of models that are derived from the equilibrium temperat... more This paper investigates three categories of models that are derived from the equilibrium temperature concept to estimate water temperatures in the Loire River in France and the sensitivity to changes in hydrology and climate. We test the models' individual performances for simulating water temperatures and assess the variability of the thermal responses under the extreme changing climate scenarios that are projected for 2081-2100. We attempt to identify the most reliable models for studying the impact of climate change on river temperature (T w). Six models are based on a linear relationship between air temperatures (T a) and equilibrium temperatures (T e), six depend on a logistic relationship, and six rely on the closure of heat budgets. For each category, three approaches that account for the river's thermal exchange coefficient are tested. In addition to air temperatures, an index of day length is incorporated to compute equilibrium temperatures. Each model is analysed in terms of its ability to simulate the seasonal patterns of river temperatures and heat peaks. We found that including the day length as a covariate in regression-based approaches improves the performance in comparison with classical approaches that use only T a. Moreover, the regression-based models that rely on the logistic relationship between T e and T a exhibit root mean square errors comparable (0.90 C) with those obtained with a classical five-term heat budget model (0.82 C), despite a small number of required forcing variables. In contrast, the regressive models that are based on a linear relationship T e = f(T a) fail to simulate the heat peaks and are not advisable for climate change studies. The regression-based approaches that are based on a logistic relationship and the heat balance approaches generate notably similar responses to the projected climate changes scenarios. This similarity suggests that sophisticated thermal models are not preferable to cruder ones, which are less time-consuming and require fewer input data.
Vitiforest est un projet exploratoire dont les objectifs étaient d'évaluer et de décrire l'impact... more Vitiforest est un projet exploratoire dont les objectifs étaient d'évaluer et de décrire l'impact de l'arbre sur le comportement agronomique de la vigne, le microclimat, ainsi que sur la biodiversité aérienne et du sol. Il s'est aussi intéressé aux aspects technico-économiques. Une équipe pluridisciplinaire a testé divers protocoles et outils de mesure à l'échelle parcellaire. Six parcelles de vignes agroforestières ont été sélectionnées sur trois terroirs viticoles du sud-ouest de la France aux caractéristiques assez différentes (Bordelais, Côtes de Gascogne et Cahors) : Trois nouvellement plantées et trois plus anciennes. Toutes les parcelles ont bénéficié de mesures pour établir un état initial selon divers paramètres (biodiversité aérienne, lombric, communautés microbiennes) et pour caractériser l'hétérogénéité intrinsèque. Les trois parcelles plus anciennes, dites "fonctionnelles" ont été décrites de manière plus détaillée (état hydrique et azoté de la vigne, rendement, composition du raisin, paramètres microclimatiques, etc.). Au niveau des résultats, un rafraîchissement des vignes voisines du rang d'arbres a été observé lors de journées à forte demande évaporative, dans le cas de larges allées. Sur le plan agronomique, la présence d'arbres depuis 8 ou 9 ans à proximité de la vigne n'a pas d'effet direct sur sa vigueur et la composition des raisins. Ce résultat est encourageant mais devra être confirmé par de nouveaux suivis du système au cours des dix prochaines années. Il n'y a pas pour le moment d'effets forts et homogènes des arbres sur les arthropodes épigés et du feuillage. C'est le même constat pour les ravageurs. Au niveau du sol, on n'observe pas non plus d'effets sur l'abondance et la diversité microbienne. La composition des communautés microbiennes semble cependant légèrement impactée par la présence des arbres. Enfin, une abondance supérieure de lombrics a été mesurée sur les lignes d'arbres. Concernant les aspects technico-économiques, des travaux complémentaires seront nécessaires. La modélisation sera certainement un outil à privilégier pour tenir compte de la diversité et de la complexité de ces systèmes. Mots-clés : Agroforesterie viticole, approche parcellaire et exploratoire, comportement agronomique de la vigne, microclimat de la parcelle, biodiversité aérienne et du sol, état des connaissances technicoéconomiques, vignobles du sud-ouest de la France.
Journal of Landscape Ecology
The Oued Srou watershed located in the Middle Atlas Mountain of Morocco has been a subject of ser... more The Oued Srou watershed located in the Middle Atlas Mountain of Morocco has been a subject of serious soil erosion problems due to the combination of natural factors and anthropic activities. Therefore, soil erosion hazard assessment and mapping can be handy to initiate remedial measures in the area. In this study, the improved Erosion Potential Model (EPM) integrated with GIS and remote sensing techniques is employed to map and assess the vulnerability of the Oued Srou watershed to the water erosion phenomenon and its impact on the silting of the Ahmed El Hansali dam. The results of the EPM model showed that the maximum annual soil loss rates were in the range of 5-652 m3/km2/year, with an average of 49 m3/km2/year. The delivery coefficient ratio showed that about 34433 t/year of the sediments reach the outlet of the watershed. The correlation analysis between all erosion factors revealed the following order of their importance in the water erosion control: soil sensitivity to eros...
HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific r... more HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Mapping the height of heterogeneous vegetation from UAV-borne visible images and DSM Juliette Grimaldi, F Helen, Charlotte Pelletier, Vincent Bustillo, Thomas Houet
Good estimates of fluxes of suspended particulate matter (SPM), total dissolved solids (TDS) and ... more Good estimates of fluxes of suspended particulate matter (SPM), total dissolved solids (TDS) and nutrients and contaminants are required for both Earth System science and river basin management. However, in most cases discrete sampling (weekly to monthly) is the rule. Few flux calculation methods are commonly used, yet their performances, i.e. uncertainties for given frequencies, at given stations and for each water quality variables, remain unknown. Based on a rare set of 1085 station-year of daily flux record for SPM, TDS and nutrients (dissolved and total), the performance of 9 calculations methods is explored.
Les changements climatiques annonces vont-ils induire une modification du cycle de l'eau et d... more Les changements climatiques annonces vont-ils induire une modification du cycle de l'eau et des debits dans un bassin comme la Loire, geologiquement contraste et soumis a des climats varies (oceanique, continental, cevenol) ? Nos resultats suggerent une diminution des ressources en eau disponibles en moyennes eaux et en etiage. En revanche la dynamique et l'intensite des crues ne devraient pas varier significativement.
Soil moisture measurements are very important for climate studies, weather predictions, analyzes ... more Soil moisture measurements are very important for climate studies, weather predictions, analyzes of floodplains or aquifers refill. In agricultural areas, a real-time analysis of the soil water status would allow the operator to optimize the management of its plots (tillage treatments, irrigation ... ). In partnership with the Auch CESBIO (Centre d’Etudes Spatiales de la BIOsphère) team, an experiment of detection of the soil moisture variations through GNSS reflectometry (GNSS-R) is currently being conducted on an agricultural plot in Lamasquère (Midi-Pyrénées, FRANCE) .
En presence de Stephane Le Foll, le seminaire europeen d’agroforesterie se deroulera du 23 au 25 ... more En presence de Stephane Le Foll, le seminaire europeen d’agroforesterie se deroulera du 23 au 25 mai 2016. Organise par l’EURAF (Association europeenne d’agroforesterie), il reunira environ 200 personnes de plus de 20 nationalites. Cette rencontre sera notamment l’occasion de faire le point sur les recherches en cours pour developper des programmes agroforestiers dans de nombreux pays. L’agroforesterie, point cle du projet agro-ecologique. Lors de ce seminaire, le ministre de l’Agriculture, de l’Agroalimentaire et de la Foret presentera le plan de developpement de l’agroforesterie, lance le 17 decembre 2015 au niveau national. Element cle dans le projet agro-ecologique, ce plan porte sur la recherche, les aspects reglementaires et financiers de l’agroforesterie, la formation et le conseil, la valorisation economique des productions et les questions internationales, et comporte egalement un volet outre-mer. Ce plan concerne la periode 2015-2020. Il a ete elabore avec de multiples par...
Agronomy
The objective of this study is to address the capabilities of multi-temporal optical images to es... more The objective of this study is to address the capabilities of multi-temporal optical images to estimate the fine-scale yield variability of wheat, over a study site located in southwestern France. The methodology is based on the Landsat-8 and Sentinel-2 satellite images acquired after the sowing and before the harvest of the crop throughout four successive agricultural seasons, the reflectance constituting the input variables of a statistical algorithm (random forest). The best performances are obtained when the Normalized Difference Vegetation Index (NDVI) is combined with the yield maps collected during the crop rotation, the agricultural season 2014 showing the lower level of performances with a coefficient of determination (R2) of 0.44 and a root mean square error (RMSE) of 8.13 quintals by hectare (q.h−1) (corresponding to a relative error of 12.9%), the three other years being associated with values of R2 close or upper to 0.60 and RMSE lower than 7 q.h−1 (corresponding to a r...
Arabian Journal of Geosciences
The dynamics of suspended sediment transport in the Noun River has been quantified using 93 runof... more The dynamics of suspended sediment transport in the Noun River has been quantified using 93 runoff samples. Daily flow and monthly normalized difference vegetation index (NDVI), leaf area index (LAI), rainfall, and dam management data allowed the quantification of the total suspended solid (TSS), on the one hand, and the interpretation of the dynamics of solid transport within the drainage basin, on the other hand. The TSS concentrations range from 3 to 1375 mg L −1 for a volume weighted mean concentration of 90.33 to 110.49 mg L −1 and a specific sediment yield (SSY) of 41 to 57 t km −2 year −1 . The basin’s hydrological characteristics between March to June and December to February have been reversed, revealing a strong impact of a dam. The maximum TSS concentration obtained during the second hydrological year at the beginning of the rainy season (April) is paradoxically three times higher compared to that recorded in July during the first measurement period. This occasional high TSS concentration for the single month of April released sedimentary fluxes superior to those recorded over the period of July to November combined, in comparison to those obtained during the first year. This situation causes sediment depletion not only on the next regular maximum TSS concentrations but also on the quantities of sediments exported later. The monthly TSS concentration/discharge does not present a clockwise hysteresis curve observed on tropical streams such as the Mbam and Sanaga in Ebebda, with annual variations in its evolution.
Proceedings of 2nd International Electronic Conference on Geosciences
The objective of this study is to address the capabilities of multi-temporal optical images to es... more The objective of this study is to address the capabilities of multi-temporal optical images to estimate the fine-scale yield variability of wheat over a study site located in southwestern France. The methodology is based on the use of Landsat-8 and Sentinel-2 satellite images acquired after the sowing and before the harvest of the crop throughout four successive agricultural seasons, the reflectance constituting the input variables of a statistical algorithm (random forest). The best performances are obtained when the NDVI (Normalized Difference Vegetation Index) is combined with the previous yield maps, the agricultural season 2014 showing the lower level of performances with a R² of 0.44 and a RMSE (Root Mean Square Error) of 8.13 q.h−1 (corresponding to a relative error of 12.9%), the three other years being associated with values of R² close or upper of 0.60 and RMSE lower than 7 q.h−1 (corresponding to a relative error inferior to 11.3%).
Proceedings of 3rd International Electronic Conference on Remote Sensing
Recent advances in sensors onboard harvesting machines allow accessing the intra-plot variability... more Recent advances in sensors onboard harvesting machines allow accessing the intra-plot variability of yields, spatial scale fully compatible with numerous on-going satellite missions. The aim of this study is to estimate the sunflower yield at the intra-plot spatial scale using the multi-temporal images provided by the Landsat-8 and Sentinel-2 missions. The proposed approach is based on a statistical algorithm, testing different sampling strategies to partition the dataset into independent training and testing sets: A random selection (testing different ratio), a systematic selection (focusing on different plots) and a forecast procedure (using an increasing number of images). Emphasis is put on the use of high spatial and temporal resolution satellite data acquired throughout two agricultural seasons, on a study site located in southwestern France. Ground measurements consist in intra-plot yields collected by a surveying harvesting machine with GPS system on track mode. The forecast...
Proceedings of 2nd International Electronic Conference on Geosciences
The aim of this study is to assess the possibilities of the VNIR (Visible and Near InfraRed) and ... more The aim of this study is to assess the possibilities of the VNIR (Visible and Near InfraRed) and SWIR (Short Wavelength InfraRed) satellite data for estimating intra-plot patterns of soil electrical resistivity consistent with ground measurements. The methodology is based on optical reflectances that constitute the input variables of random forest, alone or in combination with parameters derived from a digital elevation model (DEM). Over a field located in southwestern France, the results show high level of accuracy for the 0–50 and 0–100 cm soil layers (with R² of 0.69 and 0.59, and a relative RMSE of 18% and 16%, respectively), the performances being lower for the 0–170 cm layer (R² of 0.39, relative RMSE of 20%). The combined use of optical reflectances with parameters derived from the DEM slightly improves the performances, whatever the considered layer. The influence of each reflectance on soil electrical resistivity estimates is finally analyzed, showing that the wavelengths a...
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Papers by Vincent Bustillo