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91.
Challenges of analyzing multi-hazard risk: a review   总被引:9,自引:6,他引:3  
Many areas of the world are prone to several natural hazards, and effective risk reduction is only possible if all relevant threats are considered and analyzed. However, in contrast to single-hazard analyses, the examination of multiple hazards poses a range of additional challenges due to the differing characteristics of processes. This refers to the assessment of the hazard level, as well as to the vulnerability toward distinct processes, and to the arising risk level. As comparability of the single-hazard results is strongly needed, an equivalent approach has to be chosen that allows to estimate the overall hazard and consequent risk level as well as to rank threats. In addition, the visualization of a range of natural hazards or risks is a challenging task since the high quantity of information has to be depicted in a way that allows for easy and clear interpretation. The aim of this contribution is to give an outline of the challenges each step of a multi-hazard (risk) analysis poses and to present current studies and approaches that face these difficulties.  相似文献   
92.
Twenty paleogeographic maps are presented for Middle Eocene (Lutetian) to Late Pliocene times according to the stratigraphical data given in the companion paper by Berger et al. this volume. Following a first lacustrine-continental sedimentation during the Middle Eocene, two and locally three Rupelian transgressive events were identified with the first corresponding with the Early Rupelian Middle Pechelbronn beds and the second and third with the Late Rupelian Serie Grise (Fischschiefer and equivalents). During the Early Rupelian (Middle Pechelbronn beds), a connection between North Sea and URG is clearly demonstrated, but a general connection between North Sea, URG and Paratethys, via the Alpine sea, is proposed, but not proved, during the late Rupelian. Whereas in the southern URG, a major hiatus spans Early Aquitanian to Pliocene times, Early and Middle Miocene marine, brackish and freshwater facies occur in the northern URG and in the Molasse Basin (OMM, OSM); however, no marine connections between these basins could be demonstrated during this time. After the deposition of the molasse series, a very complex drainage pattern developed during the Late Miocene and Pliocene, with a clear connection to the Bresse Graben during the Piacenzian (Sundgau gravels). During the Late Miocene, Pliocene and Quaternary sedimentation persisted in the northern URG with hardly any interruptions. The present drainage pattern of the Rhine river (from Alpine area to the lower Rhine Embayment) was not established before the Early Pleistocene.  相似文献   
93.
The Kara Sea is one of the arctic marginal seas strongly influenced by fresh water and river suspension. The highly seasonal discharge by the two major rivers Yenisei and Ob induces seasonal changes in hydrography, sea surface temperature, ice cover, primary production and sedimentation. In order to obtain a seasonal pattern of sedimentation in the Kara Sea, sediment traps were deployed near the river mouth of the Yenisei (Yen) as well as in the central Kara Sea (Kara) within the framework of the German–Russian project “Siberian River run-off; SIRRO”. Two and a half years of time-series flux data were obtained between September 2000 and April 2003 and were analyzed for bulk components, amino acids, stable carbon and nitrogen isotopes as well as sterols and fatty acids.Sediment trap data show that much of the annual deposition occurred under ice cover, possibly enhanced by zooplanktonic activity and sediment resuspension. An early bloom of ice-associated algae in April/May occurred in the polynya area and may have been very important to sustain the life cycles of higher organisms after the light limitation of the winter months due to no/low insolation and ice cover. The strong river input dominated the months June–August in the southern part of the Kara Sea. The central Kara Sea had a much shorter productive period starting in August and was less affected by the river plumes. Despite different time-scales of sampling and trapping biases, total annual fluxes from traps were in the same order of magnitude as accumulation rates in surface sediments. Terrestrial organic carbon accumulation decreased from 10.7 to 0.3 g C m−2 a−1 from the riverine source to the central Kara Sea. Parallel to this, preservation of marine organic matter decreased from 10% to 2% of primary productivity which was probably related to decreasing rates of sedimentation.  相似文献   
94.
The age, petrology, major and trace element geochemistry, andSr–Nd–Hf–Pb isotopic geochemistry of basicand felsic rocks from the Val gabbro plutonic suite on the KerguelenArchipelago, Southern Indian Ocean, are used to constrain thetemporal and compositional relationships between sub-volcanicintrusions and flood basalt volcanism during the formation ofa major oceanic island. The 4 km2 Val gabbro plutonic suitewas emplaced at 24·25 ± 0·15 Ma (U–Pbzircon) into 25 Ma volcanic rocks of the Southeast Province,locally producing a large zone of overlying basaltic breccia.Cumulate basic–ultrabasic rocks are the dominant lithologyin the intrusion, with horizontally layered peridotites at thebase of the exposed part of the intrusion, overlain by verticallylayered, coarse-grained plagioclase-bearing peridotites, melagabbrosand equigranular gabbros. The intrusion was formed by repeatedinjections of relatively crystal-rich and crystal-poor magmasinto an open-system magma reservoir. Strong geochemical andisotopic similarities between the fine-grained marginal microgabbrosand cross-cutting felsic rocks and the hosting mildly alkalicbasalts and trachytes of the Southeast Province indicate thatthey were derived from similar alkalic basaltic parental magmas,which were dominated by the enriched component of the Kerguelenmantle plume source. At 25 Ma, the change from tholeiitic–transitionalto mildly alkalic basalts marks the terminal stage of floodbasalt volcanism on the Kerguelen Archipelago. This compositionalchange was associated with deeper melting within the Kerguelenplume source, lower extents of melting, a decrease in magmasupply, and the emplacement of high-level intrusions such asthe Val gabbro plutonic suite. KEY WORDS: Kerguelen Archipelago; Val gabbro plutonic suite; oceanic island; gabbros; sub-volcanic intrusion; alkalinity; Sr–Nd–Hf–Pb isotopes  相似文献   
95.
Large landscape planning for wildlife corridors often requires inclusion of private lands and willing landowners to establish successful pathways to and from protected core habitats. Using mail survey data, we spatially assessed carnivore occurrences, perceptions of carnivores, and landowner preferences toward conservation planning tools from three communities to quantify conservation opportunity and risk related to carnivore movement on the landscape. The mapping of social data illustrates the importance of understanding individuals for conservation planning. The approach has the potential to identify areas that pose risks or present opportunities for the implementation of on-the-ground conservation actions to facilitate long-term wildlife movement across private lands.  相似文献   
96.
We analyze the response of Kenyan maize yields to near-term climate change and explore potential mitigation options. We model county level yields as a function of rainfall and temperature during a period of increased regional warming and drying (1989–2008). We then do a counter factual analysis by comparing existing maize yields from 2000 to 2008 to what yields might have been if observed warming and drying trends had not occurred. We also examine maize yields based on projected 2026–2040 climate trends. Without the observed warming and drying trends, Eastern Kenya would have had an 8% increase in maize yields, which in turn would have led to a net production increase of 500,000 metric tons. In Western Kenya, the magnitude of change is higher but the relative changes in predicted values are smaller. If warming and drying trends continue, we expect future maize yields to decline by 11% in Eastern Kenya (vs. 7% in Western Kenya). We also examine whether these future losses might be offset through agricultural development. For that analysis, we use a household panel dataset (2000, 2005) with measurements of individual farm plot yields, inputs, and outputs. We find that under a scenario of aggressive adoption of hybrid seeds and fertilizer usage coupled with warming and drying trends, yields in Western Kenya might increase by 6% while those in Eastern Kenya could increase by 14%. This increase in yields might be larger if there is a corresponding increase in usage of drought-tolerant hybrids. However, wide prediction intervals across models highlight the uncertainty in these outcomes and scenarios.  相似文献   
97.
This study describes the development of a semi-automatic object-based image analysis approach for the detection and quantification of deforestation in Zalingei, Darfur, in consequence of the increasing concentration of refugees or internally displaced persons (IDPs) in the region. The classification workflow is based on a multi-scale approach, ranging from the analysis of high resolution SPOT-4 to very high resolution IKONOS and QuickBird satellite imagery between 2003 and 2008. The overall accuracy rates for the classification of the SPOT 4 data ranged from 92% up to 95%, while those for the QuickBird and IKONOS classification have shown values of 88 and 87%, respectively. The resulting trends in woody vegetation cover were compared with the development of the local population and the variability of precipitation. The results show that the strong increase in human population in the Zalingei IDP camps can be associated with considerable decrease in woody vegetation in the camp vicinity.  相似文献   
98.
1.7 × 107yr-lived 129I has been positively detected in two natural tellurium ores by activation analysis with the help of low-level sum-coincidence gamma-ray spectrometry. The observed 129I concentrations can be explained as induced by muon reactions on 130Te. The detection of 129I provides for the first time conclusive evidence for the occurrence of natural long-lived muon-induced nuclides. Most of the 129Xe and 131Xe anomalies observed in natural tellurides are best interpreted in terms of reactions induced by muons and their secondary neutrons.  相似文献   
99.
A new method to date uranium-bearing minerals exclusively by means of a mass spectrometric determination of Xe and/or Kr isotopic ratios has been developed and experimentally tested. It is based on the compositional differences between Xe produced by spontaneous fission of238U in nature and Xe from235U fission induced by thermal neutrons in a nuclear reactor. Xe is extracted in 5–10 release fractions at successively higher temperatures. This relates the radiogenic Xe contained in various structural elements of different retention characteristics to the respective U concentrations and allows to account for natural Xe losses, which are quite common. A monazite monitor mineral of known age is included in each irradiation and its Xe isotopes are measured in the same way.The samples analyzed include uranium oxides, REE phosphates, tantalum niobates, zircon and others.The results and comparisons with reported ages obtained by other means demonstrate the applicability of the new dating method for minerals with U contents up to a few percent. In age spectra the low-temperature release fractions of some samples indicate radiogenic Xe losses, while at high temperatures age plateaux can be obtained.  相似文献   
100.
During the 20th century the northeastern U.S.A. has undergone an annual temperature increase of 1 °C, the combined effect of winter warming and an increase in daily summer minimum temperatures. A significant cooling of spring through autumn in maximum air temperatures is also evident since 1950. Therefore, the primary objective of this study is to document these climate trends and variability over the last century. A secondary objective is to provide a preliminary analysis of how these changes may have impacted hydrologic and ecosystem processes. Specifically, with respect to ecosystem processes, we examine how the cooling of daytime maximum temperatures may have impacted plant respiration and biomass accumulation. The study site is the Black Rock Forest, an experimental forest located in Hudson Highlands of New York that has been maintained as a conservation area over the last 100 years. For the region centered about the forest, there exists a climate/weather record and an extensively maintained biomass record that extends continuously from the early part of the 20th century through present. With such an extensive physical and biological record to draw from, this forest provides a microcosm for studying how changes in 20th century local and regional climate may have impacted ecosystem processes such as species adaptation, biomass growth, and 20th century carbon sequestration. In a subsequent paper we will more extensively explore the relationship between this record of changing climate and eco-hydrological processes.  相似文献   
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