Variabilité climatique et production de maïs en culture pluviale dans l'est Ivoirien     

Dabissi Noufé  Gil Mahé  Eric Servat 《水文科学杂志》2013,58(1):152-167

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Neotectonics and seismic hazard assessment in Hengchun Peninsula,southern Taiwan     

Claudio Vita-Finzi  Jiun-Chuan Lin 《Comptes Rendus Geoscience》2005,337(13):1194-1199

Neotectonic data may indicate whether stored elastic energy will be dissipated or released destructively. The Hengchun Peninsula of Taiwan is the southern extremity of the Central Range of Taiwan and thus an emergent part of the accretionary wedge resulting from subduction of Eurasia beneath the Philippine Sea plate at the Manila Trench. Radiocarbon dating of fossil shorelines on the peninsula shows that it has been uplifted at an average rate of 3.8 mm/yr during the Holocene. About $1/3$ of the uplift is due to deformation along the Hengchun reverse fault but, in contrast with the Chelungpu and other low angle reverse faults west of the Central Range, it accommodates strain principally by aseismic creep. To cite this article: C. Vita-Finzi, J.-C. Lin, C. R. Geoscience 337 (2005).  相似文献   

太阳双尾藻的形态研究     

周汉秋 《海洋科学集刊》1995,(36):223-228

太阳双尾藻 Ditylum sol 是双尾藻属中两个现存种之一,是广泛分布于亚热带和热带海洋的一种浮游硅藻。截至目前,它的分类均依据光学显微镜所观察到的形态特征为标准,本文在光学显微镜观察的基础上,又补充了扫描电子显微镜的形态观察,对其进行描述,因而填补了以往观察的欠缺,并纠正了有些硅藻学者把双尾藻属的壳套当作其壳面的“外三角形”的失误。  相似文献   

Soil moisture estimation using ERS 2 SAR data: a case study in the Solani River catchment/Estimation de l’humidité du sol grâce à des données ERS-2 SAR: étude de cas dans le bassin de la rivière Solani     

《水文科学杂志》2013,58(2)

Abstract

Abstract The information regarding spatial and temporal variation of soil moisture in a catchment is of utmost importance in hydrological, as well as many other studies. Point measurements from gravimetric and other methods for soil moisture determination are insufficient to understand the spatial behaviour of soil moisture in a region. Microwave remote sensing data from active sensors on board various satellites are increasingly being used to map spatial distribution of soil moisture within the 0–10 cm top surface. The northern part of India has a network of large rivers and canals and, therefore, spatial and temporal distribution of soil moisture in this region has a significant bearing on the hydrology of the region. In this paper, results on estimation of soil moisture from an ERS-2 SAR image in the catchment of the Solani River (a tributary to the River Ganga) in and around the town of Roorkee, India, have been presented. The radar backscatter coefficient for each pixel of the image has been modelled from the digital numbers of the SAR image. Gravimetric measurements have been made simultaneously during the satellite pass to determine the concurrent value of volumetric soil moisture at a large number of sample points within the satellite sweep area. The backscatter coefficient is found to vary from –30 dB to –42 dB for a variation in soil moisture from 30 to 75%. Regression analyses between volumetric soil moisture and both the digital numbers and backscatter coefficients were performed. Strong correlations between volumetric soil moisture and digital number were observed with R ² values of 0.84, 0.75 and 0.83 for bare soil, vegetative and combined surfaces, respectively. A similar trend was observed with the relationship between backscatter and volumetric soil moisture with R ² values of 0.60, 0.89 and 0.67 for bare soil, vegetative and combined surfaces, respectively. These results demonstrate the utilization of SAR data for estimation of spatial distribution of soil moisture in the region of the present study.  相似文献   

A Modified Neural Network for Improving River Flow Prediction/Un Réseau de Neurones Modifié pour Améliorer la Prévision de L'Écoulement Fluvial     

《水文科学杂志》2013,58(2)

Abstract

Artificial neural network (ANN) models provide huge potential for simulating nonlinear behaviour of hydrological systems. However, the potential of ANN is yet to be fully exploited due to the problems associated with improving the model generalization performance. Generalization refers to the ability of a neural network to correctly process input data that have not been used for calibrating the neural network model. In the hydrological context, better generalization performance implies higher precision of forecasting. The primary objectives of this study are to explore new measures for improving the generalization performance of an ANN-based rainfall–runoff model, and to evaluate the applicability of the new measures. A modified neural network model (entitled goal programming (GP) neural network) for modelling the rainfall–runoff process has been developed, in which three enhancements are made as compared to the widely-used backpropagation (BP) network. The three enhancements are (a) explicit integration of hydrological prior knowledge into the neural network learning; (b) incorporation of a modified training objective function; and (c) reduction of network sensitivity to input errors. Seven watersheds across a range of climatic conditions and watershed areas in China were selected for examining the alternative networks. The results demonstrate that the GP consistently outperformed the BP both in the calibration and verification periods and three proposed measures yielded improvement of performance.  相似文献   

Multiple criteria rainfall–runoff model calibration using a parallel genetic algorithm in a cluster of computers / Calage multi-critères en modélisation pluie–débit par un algorithme génétique parallèle mis en œuvre par une grappe d'ordinateurs     

《水文科学杂志》2013,58(6)

Abstract

Genetic algorithms are among of the global optimization schemes that have gained popularity as a means to calibrate rainfall–runoff models. However, a conceptual rainfall–runoff model usually includes 10 or more parameters and these are interdependent, which makes the optimization procedure very time-consuming. This may result in the premature termination of the optimization process which will prejudice the quality of the results. Therefore, the speed of optimization procedure is crucial in order to improve the calibration quality and efficiency. A hybrid method that combines a parallel genetic algorithm with a fuzzy optimal model in a cluster of computers is proposed. The method uses the fuzzy optimal model to evaluate multiple alternatives with multiple criteria where chromosomes are the alternatives, whilst the criteria are flood performance measures. In order to easily distinguish the performance of different alternatives and to address the problem of non-uniqueness of optimum, two fuzzy ratios are defined. The new approach has been tested and compared with results obtained by using a two-stage calibration procedure. The current single procedure produces similar results, but is simpler and automatic. Comparison of results between the serial and parallel genetic algorithms showed that the current methodology can significantly reduce the overall optimization time and simultaneously improve the solution quality.  相似文献   

Simulated long-term changes in river discharge and soil moisture due to global warming / Simulations à long terme de changements d’écoulement fluvial et d’humidité du sol causés par le réchauffement global     

《水文科学杂志》2013,58(4)

Abstract

Abstract By use of a coupled ocean–atmosphere–land model, this study explores the changes of water availability, as measured by river discharge and soil moisture, that could occur by the middle of the 21st century in response to combined increases of greenhouse gases and sulphate aerosols based upon the ?IS92a? scenario. In addition, it presents the simulated change in water availability that might be realized in a few centuries in response to a quadrupling of CO₂ concentration in the atmosphere. Averaging the results over extended periods, the radiatively forced changes, which are very similar between the two sets of experiments, were successfully extracted. The analysis indicates that the discharges from Arctic rivers such as the Mackenzie and Ob’ increase by up to 20% (of the pre-Industrial Period level) by the middle of the 21st century and by up to 40% or more in a few centuries. In the tropics, the discharges from the Amazonas and Ganga-Brahmaputra rivers increase substantially. However, the percentage changes in runoff from other tropical and many mid-latitude rivers are smaller, with both positive and negative signs. For soil moisture, the results of this study indicate reductions during much of the year in many semiarid regions of the world, such as the southwestern region of North America, the northeastern region of China, the Mediterranean coast of Europe, and the grasslands of Australia and Africa. As a percentage, the reduction is particularly large during the dry season. From middle to high latitudes of the Northern Hemisphere, soil moisture decreases in summer but increases in winter.  相似文献   

Clark's and Espey's unit hydrographs vs the gamma unit hydrograph / Les hydrogrammes unitaires de Clark et de Espey vs l'hydrogramme unitaire de forme loi gamma     

《水文科学杂志》2013,58(6)

Abstract

A two-parameter gamma distribution for synthetic unit hydrographs (SUH) is compared with the Clark's and Espey's SUHs. A critical comparison of Clark's and gamma UHs, in terms of recession characteristics and time–area curve, is presented. It is observed that, in principle, a gamma UH can represent the hydrograph recession better than the Clark's UH does. Selection of a time–area curve is needed for obtaining the Clark's UH. The main problem in developing a SUH using the Clark's method is identified as the non-availability of a parametric form of the time–area curve. The time–area curve as represented in the hydrological model HEC-1, for the use in Clark's method, is found inadequate and unjustified. Gamma UHs obtained without optimization, for several examples, are found consistent with their physical meanings and better than the respective Clark's UH in reproducing runoff obtained with optimization. The parameters of Clark's UH (i.e. time of concentration and recession constant), as optimized through the HEC-1 program, are found inconsistent with their empirical origins and physical meanings; these lose their physical meaning and serve only as fitting parameters. This is due to the inappropriate time–area curve. A gamma UH has also the advantage of having fewer parameters than Clark's UH, which makes it more identifiable while still maintaining a connection with the physics of the problem. Espey's SUH for urban watersheds is transmuted to a gamma distribution using the empirical equations for the peak and time to peak of the UH. A numerical UH for a gauged catchment, generally obtained through linear programming or a least-squares approach, can be easily transmuted to a gamma UH and, hence, can be given a conceptual interpretation. Thus, these can also be used for developing a SUH.  相似文献   

Evolution récente des paramètres cryo-climatiques et des teneurs isotopiques des précipitations dans les Andes Boliviennes: La Paz et Glacier du Zongo     

Robert Gallaire  Jean-Denis Taupin  Anne Coudrain 《水文科学杂志》2013,58(4):467-483

Résumé

A proximité de La Paz, Bolivie, les indicateurs marquants de la tendance climatique sont: (a) une augmentation de la température de ré-analyse à 500 hPa de 0.017°C an^-1 entre 1973 et 2004; (b) à la station météorologique Laïca Cota, entre 1995 et 2004, une élévation de la température de 0.03°C an^-1 et une diminution de l'humidité relative de 0.6 % an^-1; et (c) une augmentation du δ¹⁸O des précipitations de 0.26‰ an^-1 et de leur excès en deutérium de 0.1‰ an^-1. Une des principales conséquences de cette tendance est un recul du front du Glacier Zongo de 12 m an^-1 entre 1991 et 2004 (réduction de 2% par an des surfaces glaciaires de 1997 à 2004: 1.84 km² en 2004). L'analyse temporelle concomitante des données montre que la variabilité des conditions ENSO a des conséquences en phase à l'échelle infra-annuelle pour la température, l'humidité relative, la précipitation, le bilan glaciaire, et des conséquences en déphasage, sur des périodes dépassant l'année, pour le rapport isotopique des précipitations andines.  相似文献   

La méthode SHYREG débit—application sur 1605 bassins versants en France métropolitaine     

Yoann Aubert  Patrick Arnaud  Pierre Ribstein  Jean-Alain Fine 《水文科学杂志》2013,58(5):993-1005

Résumé

La méthode SHYREG est une approche développée pour la connaissance régionale de l’aléa pluvial (SHYREG pluie) et hydrologique (SHYREG débit) en tout point du territoire français. Elle est basée sur le couplage d’un générateur stochastique de pluie horaire et d’un modèle hydrologique. Cet article présente les résultats de la mise en ?uvre de la méthode sur 1605 bassins versants répartis sur la France métropolitaine. Sur les fréquences courantes (c.à.d. périodes de retour inférieures à 10 ans), la méthode restitue correctement les quantiles de débit de crue ajustés à une loi statistique sur les observations (loi GEV, selon le critère de Nash-Sutcliffe). Plusieurs critères sont utilisés pour valider l’extrapolation des débits à des fréquences extrêmes: (a) en la confrontant à de longues chroniques de débits observés, (b) en analysant dans le modèle hydrologique la saturation du réservoir de production synonyme de comportement asymptotique avec les pluies, et (c) en étudiant la stabilité de la méthode à travers les critères statistiques.