Flood Events of Selected European Rivers in the Sixteenth Century     

Rudolf Brázdil  Rüdiger Glaser  Christian Pfister  Petr Dobrovolný  Jean-Marc Antoine  Mariano Barriendos  Dario Camuffo  Mathias Deutsch  Silvia Enzi  Emanuela Guidoboni  Oldřich Kotyza  Fernando Sanchez Rodrigo 《Climatic change》1999,43(1):239-285

The severity and frequency of sixteenth-century floods of the Rhine, the Main, the middle and upper Elbe with its tributaries, rivers of northern and central Italy, the Garonne and rivers in Catalonia and Andalusia are analyzed using documentary evidence. The basic topographical and hydrological characteristics of the rivers investigated as well as the synoptic causes of their flooding during the instrumental period are presented. Different examples of modifications of the run-off process due to anthropogenic activity are discussed. Prevalence in flood occurrence during the second half of the sixteenth century in comparison to the first half is typical for central European and Andalusian rivers (mainly in the 1560s and 1590s) and agrees with the evolution of precipitation patterns. On the other hand, Italian and Catalonian rivers, in part, had a higher occurrence of floods during the first half of the century. Changes in the flooding seasons in both halves of the century are not unambiguous. Results of an analysis on a broader European scale show floods to be a random natural phenomena with limited areal extent defined by the spatial influence of forcing meteorological factors (continuous heavy rains, sudden melting of thick snow cover, etc.). Despite some limitations of documentary evidence, series of reconstructed historical floods are valuable sources of proxy data which can be utilized for the study of the flooding fluctuations in the pre-instrumental period.  相似文献   

Hydrology needed to manage droughts: the 2015 European case   总被引：1，自引：0，他引：1       下载免费PDF全文

Henny A.J. Van Lanen  Gregor Laaha  Daniel G. Kingston  Tobias Gauster  Monica Ionita  Jean‐Philippe Vidal  Radek Vlnas  Lena M. Tallaksen  Kerstin Stahl  Jamie Hannaford  Claire Delus  Miriam Fendekova  Luis Mediero  Christel Prudhomme  Ekaterina Rets  Renata J. Romanowicz  Sébastien Gailliez  Wai Kwok Wong  Mary‐Jeanne Adler  Veit Blauhut  Laurie Caillouet  Silvia Chelcea  Natalia Frolova  Lukas Gudmundsson  Martin Hanel  Klaus Haslinger  Maria Kireeva  Marzena Osuch  Eric Sauquet  James H. Stagge  Anne F. Van Loon 《水文研究》2016,30(17):3097-3104

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Analysis of historical landslide time series in the Emilia‐Romagna region,northern Italy     

Mauro Rossi  Annette Witt  Fausto Guzzetti  Bruce D. Malamud  Silvia Peruccacci 《地球表面变化过程与地形》2010,35(10):1123-1137

A catalogue of historical landslides, 1951–2002, for three provinces in the Emilia‐Romagna region of northern Italy is presented and its statistical properties studied. The catalogue consists of 2255 reported landslides and is based on historical archives and chronicles. We use two measures for the intensity of landsliding over time: (i) the number of reported landslides in a day (D_L) and (ii) the number of reported landslides in an event (S_event), where an event is one or more consecutive days with landsliding. From 1951–2002 in our study area there were 1057 days with 1 ≤ D_L ≤?45 landslides per day, and 596 events with 1 ≤ S_event ≤ 129 landslides per event. In the first set of analyses, we find that the probability density of landslide intensities in the time series are power‐law distributed over at least two‐orders of magnitude, with exponent of about ?2·0. Although our data is a proxy for landsliding built from newspaper reports, it is the first tentative evidence that the frequency‐size of triggered landslide events over time (not just the landslides in a given triggered event), like earthquakes, scale as a power‐law or other heavy‐tailed distributions. If confirmed, this could have important implications for risk assessment and erosion modelling in a given area. In our second set of analyses, we find that for short antecedent rainfall periods, the minimum amount of rainfall necessary to trigger landslides varies considerably with the intensity of the landsliding (D_L and S_event); whereas for long antecedent periods the magnitude is largely independent of the cumulative amount of rainfall, and the largest values of landslide intensity are always preceded by abundant rainfall. Further, the analysis of the rainfall trend suggests that the trigger of landslides in the study area is related to seasonal rainfall. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Polychlorinated biphenyls in sediments of selected coastal environments in northern Morocco     

Rossano Piazza  Bouchta El Moumni  Mauro Frignani  Silvia Giuliani  Roberta Zangrando 《Marine pollution bulletin》2009,58(3):431-438

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Morphodynamics and seismostratigraphy of a deep hole at tidal channel confluence     

Silvia Susana Ginsberg  Salvador Aliotta  Guillermo O. Lizasoain   《Geomorphology》2009,104(3-4):253-261

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Monitoring forest areas from continental to territorial levels using a sample of medium spatial resolution satellite imagery     

Hugh Eva  Silvia Carboni  Frédéric Achard  Nicolas Stach  Laurent Durieux  Jean-François Faure  Danilo Mollicone 《ISPRS Journal of Photogrammetry and Remote Sensing》2010,65(2):191-197

A global systematic sampling scheme has been developed by the UN FAO and the EC TREES project to estimate rates of deforestation at global or continental levels at intervals of 5 to 10 years. This global scheme can be intensified to produce results at the national level. In this paper, using surrogate observations, we compare the deforestation estimates derived from these two levels of sampling intensities (one, the global, for the Brazilian Amazon the other, national, for French Guiana) to estimates derived from the official inventories. We also report the precisions that are achieved due to sampling errors and, in the case of French Guiana, compare such precision with the official inventory precision.We extract nine sample data sets from the official wall-to-wall deforestation map derived from satellite interpretations produced for the Brazilian Amazon for the year 2002 to 2003. This global sampling scheme estimate gives 2.81 million ha of deforestation (mean from nine simulated replicates) with a standard error of 0.10 million ha. This compares with the full population estimate from the wall-to-wall interpretations of 2.73 million ha deforested, which is within one standard error of our sampling test estimate. The relative difference between the mean estimate from sampling approach and the full population estimate is 3.1%, and the standard error represents 4.0% of the full population estimate.This global sampling is then intensified to a territorial level with a case study over French Guiana to estimate deforestation between the years 1990 and 2006. For the historical reference period, 1990, Landsat-5 Thematic Mapper data were used. A coverage of SPOT-HRV imagery at 20 m × 20 m resolution acquired at the Cayenne receiving station in French Guiana was used for year 2006.Our estimates from the intensified global sampling scheme over French Guiana are compared with those produced by the national authority to report on deforestation rates under the Kyoto protocol rules for its overseas department. The latter estimates come from a sample of nearly 17,000 plots analyzed from same spatial imagery acquired between year 1990 and year 2006. This sampling scheme is derived from the traditional forest inventory methods carried out by IFN (Inventaire Forestier National). Our intensified global sampling scheme leads to an estimate of 96,650 ha deforested between 1990 and 2006, which is within the 95% confidence interval of the IFN sampling scheme, which gives an estimate of 91,722 ha, representing a relative difference from the IFN of 5.4%.These results demonstrate that the intensification of the global sampling scheme can provide forest area change estimates close to those achieved by official forest inventories (<6%), with precisions of between 4% and 7%, although we only estimate errors from sampling, not from the use of surrogate data.Such methods could be used by developing countries to demonstrate that they are fulfilling requirements for reducing emissions from deforestation in the framework of an REDD (Reducing Emissions from Deforestation in Developing Countries) mechanism under discussion within the United Nations Framework Convention on Climate Change (UNFCCC). Monitoring systems at national levels in tropical countries can also benefit from pan-tropical and regional observations, to ensure consistency between different national monitoring systems.  相似文献   

Bikini Atoll coral biodiversity resilience five decades after nuclear testing     

Richards ZT  Beger M  Pinca S  Wallace CC 《Marine pollution bulletin》2008,56(3):503-515

Five decades after a series of nuclear tests began, we provide evidence that 70% of the Bikini Atoll zooxanthellate coral assemblage is resilient to large-scale anthropogenic disturbance. Species composition in 2002 was assessed and compared to that seen prior to nuclear testing. A total of 183 scleractinian coral species was recorded, compared to 126 species recorded in the previous study (excluding synonomies, 148 including synonomies). We found that 42 coral species may be locally extinct at Bikini. Fourteen of these losses may be pseudo-losses due to inconsistent taxonomy between the two studies or insufficient sampling in the second study, however 28 species appear to represent genuine losses. Of these losses, 16 species are obligate lagoonal specialists and 12 have wider habitat compatibility. Twelve species are recorded from Bikini for the first time. We suggest the highly diverse Rongelap Atoll to the east of Bikini may have contributed larval propagules to facilitate the partial resilience of coral biodiversity in the absence of additional anthropogenic threats.  相似文献   

Simplified seismic fragility analysis of structures with two types of friction devices     

Silvia L. Dimova  Kazuta Hirata 《地震工程与结构动力学》2000,29(8):1153-1175

This paper presents a method and results of seismic fragility estimation of frame structures with friction devices and with friction devices and restrictors. The seismic intensity parameter, defined as the mean value of the pseudovelocity spectrum in a specified periods band, is proved to allow the use of linear regression analysis of the response parameters of the considered non‐linear structures on seismic intensity. A simplified method of fragility estimation is proposed, based on the concept of ‘mean seismic excitation’ and linear regression of the seismic response parameters on seismic intensity parameter. The key risk contributors for the system with friction devices and for the system with friction devices and restrictors are identified on the basis of the fragility analysis, and recommendations for improvement of the seismic response of the respective systems are derived. The results of the fragility study show that when the initial ‘bare’ frame is retrofitted by rigidly connected bracings the effect is much lower than in the case of connecting the bracings by friction devices and especially by friction devices and restrictors. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献   

The Space and Time Features of Global SST Anomalies Studied by Complex Principal Component Analysis     

Silvia Alessio  Arnaldo Longhetto  Luo Meixia 《大气科学进展》1999,16(1):1-23

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Space–time variability of the Plata plume inferred from ocean color     

Alberto R. Piola  Silvia I. Romero  Uriel Zajaczkovski 《Continental Shelf Research》2008

Satellite ocean color and surface salinity data are used to characterize the space–time variability of the Río de la Plata plume. River outflow and satellite wind data are also used to assess their combined effect on the plume spreading over the Southwestern South Atlantic continental shelf. Over the continental shelf satellite-derived surface chlorophyll-a (CSAT) estimated by the OC4v4 SeaWiFS retrieval algorithm is a good indicator of surface salinity. The log (CSAT) distribution over the shelf presents three distinct modes, each associated to: Subantarctic Shelf Water, Subtropical Shelf Water and Plata Plume water. The log (CSAT) 0.4–0.8 range is associated with a sharp surface salinity transition across the offshore edge of the Plata plume from 28.5 to 32.5. Waters of surface salinity <31, derived from mixtures of Plata waters with continental shelf waters, are associated to log (CSAT)>0.5. In austral winter CSAT maxima extend northeastward from the Plata estuary beyond 30°S. In summer the high CSAT waters along the southern Brazil shelf retreat to 32°S and extend south of the estuary to about 37.5°S, only exceeding this latitude during extraordinary events. The seasonal CSAT variations northeast of the estuary are primarily controlled by reversals of the along-shore wind stress and surface currents. Along-shore wind stress and CSAT variations in the inner and mid-shelves are in phase north of the estuary and 180° out of phase south of the estuary. At interannual time scales northernmost Plata plume penetrations in winter (∼1200 km from the estuary) are associated with more intense and persistent northeastward wind stress, which in the period 2000–2003, prevailed over the shelf south of 26°S. In contrast, in winter 1999, 2004 and 2005, characterized by weaker northeastward wind stress, the plume only reached between 650 and 900 km. Intense southwestward plume extensions beyond 38°S are dominated by interannual time scales and appear to be related to the magnitude of the river outflow. The plume response to large river outflow fluctuations observed at interannual time scales is moderate, except offshore from the estuary mouth, where outflow variations lead CSAT variations by about 2 months.  相似文献