The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Philippe Merot - One of the best experts on this subject based on the ideXlab platform.
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contrasting behaviour of two riparian wetlands in relation to their location in the Hydrographic Network
Journal of Hydrology, 2011Co-Authors: Olivier Montreuil, Christophe Cudennec, Philippe MerotAbstract:Summary Although many studies have focused on the hydrological behaviour and classification of wetlands, the wide diversity of wetlands makes a clear and operational view difficult. The objective of this work is to compare the organisation and behaviour of two riparian wetlands (RWs) located, respectively, along Strahler order-2 and order-5 streams of the Scorff River catchment (Brittany, France). Groundwater table dynamics were monitored at the RWs during one hydrological year. Hydrochemistry was characterised during hydrological periods of high and low hydraulic head. The results show clearly the contrast in geomorphological and pedological organisation between the two RWs. In addition, the RW along an order-2 stream exhibited a strong hydrological connectivity with the adjacent hillslope whereas the RW along an order-5 stream showed a strong hydrological connectivity with the adjacent stream. We also observed the contrast between conditions favourable for high and permanent denitrification but on low nitrogen fluxes for order 2, and conditions less favourable to denitrification but on strong nitrogen fluxes for order 5. The relation between the contrasting hydrological and hydrochemical behaviour of these two RWs and their stream orders is discussed from the literature and local observations of the catchment. The results support the hypothesis of a relation between stream order and the hydrological and hydrochemical behaviour of the RWs and thus a catchment-scale organisation which may be taken into consideration in management strategies.
Pierreandre Garambois - One of the best experts on this subject based on the ideXlab platform.
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estimation of multiple inflows and effective channel by assimilation of multi satellite hydraulic signatures the ungauged anabranching negro river
Journal of Hydrology, 2020Co-Authors: Leo Pujol, Pierreandre Garambois, Pascal Finaudguyot, Jerome Monnier, Kevin Larnier, Robert MoseAbstract:Abstract With the upcoming SWOT satellite mission, which should provide spatially dense river surface elevation, width and slope observations globally, comes the opportunity to assimilate such data into hydrodynamic models, from the reach scale to the Hydrographic Network scale. Based on the HiVDI (Hierarchical Variational Discharge Inversion) modeling strategy ( Larnier et al. (2020) ), this study tackles the forward and inverse modeling capabilities of distributed channel parameters and multiple inflows (in the 1D Saint–Venant model) from multisatellite observations of river surface. It is shown on synthetic cases that the estimation of both inflows and distributed channel parameters (bathymetry-friction) is achievable with a minimum spatial observability between inflows as long as their hydraulic signature is sampled. Next, a real case is studied: 871 km of the Negro river (Amazon basin) including complex multichannel reaches, 21 tributaries and backwater controls from major confluences. An effective modeling approach is proposed using (i) WS elevations from ENVISAT data and dense in situ GPS flow lines ( Moreira (2016) ), (ii) average river top widths from optical imagery ( Pekel et al. (2016) ), (iii) upstream and lateral flows from the MGB large-scale hydrological model ( Paiva et al. (2013a) ). The calibrated effective hydraulic model closely fits satellite altimetry observations and presents real-like spatial variabilities; flood wave propagation and water surface observation frequential features are analyzed with identifiability maps following ( Brisset et al. (2018) ). Synthetic SWOT observations are generated from the simulated flowlines and allow to infer model parameters (436 effective bathymetry points, 17 friction patches and 22 upstream and lateral hydrographs) given hydraulically coherent prior parameter values. Inferences of channel parameters carried out on this fine hydraulic model applied at a large scale give satisfying results using noisy SWOT-like data at reach scale. Inferences of spatially distributed temporal parameters (lateral inflows) give satisfying results as well, with even relatively small scale hydrograph variations being inferred accurately on this long reach. This study brings insights in: (i) the hydraulic visibility of the signatures of multiple inflow hydrographs at a large scale with SWOT; (ii) the simultaneous identifiability of spatially distributed channel parameters and inflows by assimilation of satellite altimetry data; (iii) the need for prior information; (iv) the need to further tailor and scale Network hydrodynamic models and assimilation methods to improve the fusion of multisource information and potential information feedback to hydrological modules in integrated chains.
Sylvie Hurtrezbousses - One of the best experts on this subject based on the ideXlab platform.
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Hydrographic Network structure and population genetic differentiation in a vector of fasciolosis galba truncatula
Infection Genetics and Evolution, 2010Co-Authors: Sylvie Hurtrezbousses, Jean Emmanuel Hurtrez, H Turpin, C Durand, Patrick Durand, T De Meeus, C Meunier, Francois RenaudAbstract:We report a preliminary analysis on the relationships between drainage basin structure and genetic structure of populations of the European vector of fasciolosis, Galba truncatula. In the study area, 251 snails belonging to 12 populations were collected along different ditches of a same river Network. Each snail was genotyped at six variable microsatellite loci. Our results show that all sample sites are characterized by a low level of polymorphism and a very high and significant heterozygote deficiency. Our data reveal a significant genetic differentiation, even at a small scale, and failed to delimit clear patterns of isolation by euclidian distance. Our study shows that genetic differentiation significantly increases with Hydrographic distance along the streams (p < 0.002), in consistence with the hypothesis that dispersion along the stream is dependent on the direction of water flow. This study shows that relationships can exist between the organization of the hydrological Network and population biology of a disease vector, which has strong potential applications to drainage Network management issues.
Hariklia D Skilodimou - One of the best experts on this subject based on the ideXlab platform.
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karst collapse susceptibility mapping considering peak ground acceleration in a rapidly growing urban area
Engineering Geology, 2013Co-Authors: Kyriaki Papadopoulouvrynioti, George Kaviris, George D Bathrellos, Hariklia D Skilodimou, K. MakropoulosAbstract:Abstract Karst collapse occurrences represent a geological hazard that can cause damage to man-made structures. In the present study, a karst collapse susceptibility map was produced using a multivariate statistical method and a Geographical Information System. The case under study is the northern suburbs of Athens (Greece). The karstic features of the study area were recorded. Physical processes (slope angle and aspect, Hydrographic Network, springs, lithology, tectonic features) along with anthropogenic (road Network and land use) parameters were chosen as major factors affecting the karst collapse occurrences. The innovative method was combining karst collapse occurrences with seismic hazard assessment, which was achieved by calculating peak ground acceleration (PGA). The PGA was determined for a return period of 475 years, corresponding to a 90% probability of not being exceeded in 50 years. The logistic regression (LR) method was applied to evaluate these factors. Slope angle, PGA, lithology, and distance to springs and roads were statistically significant for the applied model. Among these factors, the slope angle and PGA have a negative effect, while the lithology, and distance to springs and roads have a positive effect on the karst collapse occurrences. The validation of the applied LR model indicated that the results are reliable and that the produced map is accurate. The karst collapse susceptibility map was classified into four classes. The areas of very high and high susceptibility were observed mainly in the eastern and southwestern parts of the study area. Almost 30% of the existing urban growth boundary of the study area is located in areas of very high and high susceptibility. The karst collapse susceptibility map can be used by planners and engineers for sustainable urban development.
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correlation between the structural pattern and the development of the Hydrographic Network in a portion of the western thessaly basin greece
Open Geosciences, 2012Co-Authors: E Kamberis, George D Bathrellos, Eleni Kokinou, Hariklia D SkilodimouAbstract:In the context of the present study the structural pattern in the Western Thessaly Basin (Greece) has been examined, based on structural data collected from the entire study area that were further correlated to the Hydrographic Network. The structural pattern of the area was revealed from tectonic analysis. Additionally, the topography, stratigraphy and sedimentology of the study area were taken into account. GIS techniques were used to map the spatial distribution of the geological and tectonic features on the topographic relief of the area.
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correlation between the structural pattern and the development of the Hydrographic Network in a portion of the western thessaly basin greece
Central European Journal of Geosciences, 2012Co-Authors: E Kamberis, George D Bathrellos, Eleni Kokinou, Hariklia D SkilodimouAbstract:In the context of the present study the structural pattern in the Western Thessaly Basin (Greece) has been examined, based on structural data collected from the entire study area that were further correlated to the Hydrographic Network. The structural pattern of the area was revealed from tectonic analysis. Additionally, the topography, stratigraphy and sedimentology of the study area were taken into account. GIS techniques were used to map the spatial distribution of the geological and tectonic features on the topographic relief of the area. The oldest structures are contractional in nature, deformed by normal faulting related to the extensional episodes initiated in Serravallian times. It is inferred that the orientation of the stress field in the area has changed several times: the N-S stress field which was dominant during Late Serravallian times changed to NW-SE (Messinian-Zanclian) up to E-W in Zanclian and subsequently to roughly NNW-SSE (in late Piacencian). The NE-SW stress that was dominant in Pleistocene became N-S in later times. In addition, some changes in orientation are also indicated for the transitional periods of the pre-mentioned extensional episodes, possibly related to local events, or as a block-related deformation. The development of the 7th order streams is probably related to the N-S extensional faulting initiated in Pliocene times, while the dominant direction of the 6th, 5th and 4th order streams is possibly connected with the presence of the NNE-SSW and NW-SE extensional faults. Finally, the lower order streams are probably related to the most recent E-W striking normal faults.
Olivier Montreuil - One of the best experts on this subject based on the ideXlab platform.
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contrasting behaviour of two riparian wetlands in relation to their location in the Hydrographic Network
Journal of Hydrology, 2011Co-Authors: Olivier Montreuil, Christophe Cudennec, Philippe MerotAbstract:Summary Although many studies have focused on the hydrological behaviour and classification of wetlands, the wide diversity of wetlands makes a clear and operational view difficult. The objective of this work is to compare the organisation and behaviour of two riparian wetlands (RWs) located, respectively, along Strahler order-2 and order-5 streams of the Scorff River catchment (Brittany, France). Groundwater table dynamics were monitored at the RWs during one hydrological year. Hydrochemistry was characterised during hydrological periods of high and low hydraulic head. The results show clearly the contrast in geomorphological and pedological organisation between the two RWs. In addition, the RW along an order-2 stream exhibited a strong hydrological connectivity with the adjacent hillslope whereas the RW along an order-5 stream showed a strong hydrological connectivity with the adjacent stream. We also observed the contrast between conditions favourable for high and permanent denitrification but on low nitrogen fluxes for order 2, and conditions less favourable to denitrification but on strong nitrogen fluxes for order 5. The relation between the contrasting hydrological and hydrochemical behaviour of these two RWs and their stream orders is discussed from the literature and local observations of the catchment. The results support the hypothesis of a relation between stream order and the hydrological and hydrochemical behaviour of the RWs and thus a catchment-scale organisation which may be taken into consideration in management strategies.
