The rivers are alive: on the potential for diatoms as a tracer of water source and hydrological connectivity     

Laurent Pfister  Jeffrey J. McDonnell  Sebastian Wrede  Daša Hlúbiková  Patrick Matgen  Fabrizio Fenicia  Luc Ector  Lucien Hoffmann 《水文研究》2009,23(19):2841-2845

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Sensitivity analysis of prior model probabilities and the value of prior knowledge in the assessment of conceptual model uncertainty in groundwater modelling     

Rodrigo Rojas  Luc Feyen  Alain Dassargues 《水文研究》2009,23(8):1131-1146

A key point in the application of multi‐model Bayesian averaging techniques to assess the predictive uncertainty in groundwater modelling applications is the definition of prior model probabilities, which reflect the prior perception about the plausibility of alternative models. In this work the influence of prior knowledge and prior model probabilities on posterior model probabilities, multi‐model predictions, and conceptual model uncertainty estimations is analysed. The sensitivity to prior model probabilities is assessed using an extensive numerical analysis in which the prior probability space of a set of plausible conceptualizations is discretized to obtain a large ensemble of possible combinations of prior model probabilities. Additionally, the value of prior knowledge about alternative models in reducing conceptual model uncertainty is assessed by considering three example knowledge states, expressed as quantitative relations among the alternative models. A constrained maximum entropy approach is used to find the set of prior model probabilities that correspond to the different prior knowledge states. For illustrative purposes, a three‐dimensional hypothetical setup approximated by seven alternative conceptual models is employed. Results show that posterior model probabilities, leading moments of the predictive distributions and estimations of conceptual model uncertainty are very sensitive to prior model probabilities, indicating the relevance of selecting proper prior probabilities. Additionally, including proper prior knowledge improves the predictive performance of the multi‐model approach, expressed by reductions of the multi‐model prediction variances by up to 60% compared with a non‐informative case. However, the ratio between‐model to total variance does not substantially decrease. This suggests that the contribution of conceptual model uncertainty to the total variance cannot be further reduced based only on prior knowledge about the plausibility of alternative models. These results advocate including proper prior knowledge about alternative conceptualizations in combination with extra conditioning data to further reduce conceptual model uncertainty in groundwater modelling predictions. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

Part 2 The Link between GIS and spatial analysis     

Luc Anselin 《Journal of Geographical Systems》2000,2(1):11-15

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Micromechanics of saturated and unsaturated porous media     

Xavier Chateau  Luc Dormieux 《国际地质力学数值与分析法杂志》2002,26(8):831-844

The homogenization method is used to determine the formulation of the behaviour of both saturated and unsaturated porous media. This approach makes it possible to assess the validity of the effective stress concept as a function of the properties of the porous media at the microscopic scale. Furthermore, the influence of the morphologies of the solid and fluid phases on the macroscopic behaviour is studied. The strain induced by drying is examined as a function of the morphological properties. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

Perspectives of Taiwan Tectonics from TAIGER Project     

Francis T Wu  Hao Kuo-Chen  Kirk McIntosh  Luc Lavier 《地质学报》2013,87(Z1):84-85

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On the Influence of a Simple Microphysics Parametrization on Radiation Fog Modelling: A Case Study During ParisFog     

Xiaojing Zhang  Luc Musson-Genon  Eric Dupont  Maya Milliez  Bertrand Carissimo 《Boundary-Layer Meteorology》2014,151(2):293-315

A detailed numerical simulation of a radiation fog event with a single column model is presented, which takes into account recent developments in microphysical parametrizations. One-dimensional simulations are performed using the computational fluid dynamics model Code_Saturne and the results are compared to a very detailed in situ dataset collected during the ParisFog campaign, which took place near Paris, France, during the winter 2006–2007. Special attention is given to the detailed and complete diurnal simulations and to the role of microphysics in the fog life cycle. The comparison between the simulated and the observed visibility, in the single-column model case study, shows that the evolution of radiation fog is correctly simulated. Sensitivity simulations show that fog development and dissipation are sensitive to the droplet-size distribution through sedimentation/deposition processes but the aerosol number concentration in the coarse mode has a low impact on the time of fog formation.  相似文献   

Flood frequency analysis using historical data: accounting for random and systematic errors     

Luc Neppel  Benjamin Renard  Michel Lang  Pierre-Alain Ayral  Denis Coeur  Eric Gaume 《水文科学杂志》2013,58(2):192-208

Abstract

Flood frequency analysis based on a set of systematic data and a set of historical floods is applied to several Mediterranean catchments. After identification and collection of data on historical floods, several hydraulic models were constructed to account for geomorphological changes. Recent and historical rating curves were constructed and applied to reconstruct flood discharge series, together with their uncertainty. This uncertainty stems from two types of error: (a) random errors related to the water-level readings; and (b) systematic errors related to over- or under-estimation of the rating curve. A Bayesian frequency analysis is performed to take both sources of uncertainty into account. It is shown that the uncertainty affecting discharges should be carefully evaluated and taken into account in the flood frequency analysis, as it can increase the quantiles confidence interval. The quantiles are found to be consistent with those obtained with empirical methods, for two out of four of the catchments.

Citation Neppel, L., Renard, B., Lang, M., Ayral, P.-A., Coeur, D., Gaume, E., Jacob, N., Payrastre, O., Pobanz, K. & Vinet, F. (2010) Flood frequency analysis using historical data: accounting for random and systematic errors. Hydrol. Sci. J. 55(2), 192–208.  相似文献   

Comparison of two snowmelt modelling approaches in the Dudh Koshi basin (eastern Himalayas,Nepal)     

Bijay Kumar Pokhrel  Pierre Chevallier  Vazken Andréassian  Adnan Ahmad Tahir  Yves Arnaud  Luc Neppel 《水文科学杂志》2013,58(8):1507-1518

Abstract

The glaciers in the Nepalese Himalayas are retreating due to rising temperatures. Lack of data and information on Nepal’s cryosphere has impeded scientific studies and field investigations in the Nepalese Himalayas. Therefore, IRD France and Ev-K2 CNR Italy have conducted the PAPRIKA (CryosPheric responses to Anthropogenic PRessures in the HIndu Kush-Himalaya regions: impacts on water resources and society adaptation in Nepal) project in Nepal with the financial support of the French and Italian scientific agencies. This project aims to address the current and future evolution of the cryosphere in response to overall environmental changes in South Asia, and its consequences for water resources in Nepal. Thus, two hydrological models, the GR4J lumped precipitation–runoff model and the snowmelt runoff model (SRM), were used in the Dudh Koshi basin. The GR4J model has been successfully applied in different parts of Europe. To obtain better results in such a harsh and rugged topography, modifications needed to be made, particularly in the snow module. The runoff pattern is analysed herein both for past years and, in a sensitivity analysis, for possible future climatic conditions (i.e. precipitation and temperature) using the SRM and GR4J modelling approaches. The results reveal a significant contribution of snow- and glacier-melt to runoff, and the SRM model shows better performance in Nepalese catchments than the GR4J model.