排序方式： 共有23条查询结果，搜索用时 31 毫秒
1.
Pradeep Adhikari Yang Hong Kimberly R. Douglas Dalia Bach Kirschbaum Jonathan Gourley Robert Adler G. Robert Brakenridge 《Natural Hazards》2010,55(2):405-422
Floods have profound impacts on populations worldwide in terms of both loss of life and property. A global inventory of floods
is an important tool for quantifying the spatial and temporal distribution of floods and for evaluating global flood prediction
models. Several global hazard inventories currently exist; however, their utility for spatiotemporal analysis of global floods
is limited. The existing flood catalogs either fail to record the geospatial area over which the flood impacted or restrict
the types of flood events included in the database according to a set of criteria, limiting the scope of the inventory. To
improve upon existing databases, and make it more comprehensive, we have compiled a digitized Global Flood Inventory (GFI)
for the period 1998–2008 which also geo-references each flood event by latitude and longitude. This technical report presents
the methodology used to compile the GFI and preliminary findings on the spatial and temporal distributions of the flooding
events that are contained in the inventory. 相似文献
2.
Laštovička Jan Burešová Dalia Boška Josef Bremer Jurgen Märcz Ferenc 《Studia Geophysica et Geodaetica》1997,41(2):171-180
Data from four A3 radio wave circuits in central Europe are used to analyse the representativeness of the ionization and gravity wave activity pattern in the lower ionosphere (85 – 100 km) in the CRISTA experiment interval (3 – 12 November 1994) for the given conditions. It has been found that the CRISTA experiment interval was run under conditions, which are highly representative both of October – November 1994 and autumn, low-moderate solar activity, the descending phase of solar cycle conditions, i.e. CRISTA measurements may be considered to provide values identical with, or close to climatological values (at least for central Europe, h = 85 – 100 km). 相似文献
3.
Assessment of shallow landslides from Hurricane Mitch in central America using a physically based model 总被引：5，自引：2，他引：3
Shallow landslides induced by heavy rainfall events represent one of the most disastrous hazards in mountainous regions because
of their high frequency and rapid mobility. Recent advancements in the availability and accessibility of remote sensing data,
including topography, land cover and precipitation products, allow landslide hazard assessment to be considered at larger
spatial scales. A theoretical framework for a landslide forecasting system was prototyped in this study using several remotely
sensed and surface parameters. The applied physical model SLope-Infiltration-Distributed Equilibrium (SLIDE) takes into account
some simplified hypotheses on water infiltration and defines a direct relation between factor of safety and the rainfall depth
on an infinite slope. This prototype model is applied to a case study in Honduras during Hurricane Mitch in 1998. Two study
areas were selected where a high density of shallow landslides occurred, covering approximately 1,200 km2. The results were quantitatively evaluated using landslide inventory data compiled by the United States Geological Survey
(USGS) following Hurricane Mitch’s landfall. The agreement between the SLIDE modeling results and landslide observations demonstrates
good predictive skill and suggests that this framework could serve as a potential tool for the future early landslide warning
systems. Results show that within the two study areas, the values of rates of successful estimation of slope failure locations
reached as high as 78 and 75%, while the error indices were 35 and 49%. Despite positive model performance, the SLIDE model
is limited by several assumptions including using general parameter calibration rather than in situ tests and neglecting geologic
information. Advantages and limitations of this physically based model are discussed with respect to future applications of
landslide assessment and prediction over large scales. 相似文献
4.
Brigitte Urban Kim J. Krahn Thomas Kasper Alejandro García-Moreno Jarod M. Hutson Aritza Villaluenga Elaine Turner Sabine Gaudzinski-Windheuser Dalia Farghaly Mario Tucci Antje Schwalb 《Boreas: An International Journal of Quaternary Research》2023,52(3):440-458
To spatially characterize the palaeolakeshore environment at the archaeological kill site Schöningen 13 II-4 of the Middle Pleistocene Reinsdorf sequence, in-depth palynological, geochemical, aquatic microfossil and archaeological analyses were undertaken on sediment sections with an average thickness of about 15 cm, concordantly overlain by faunal remains, dominated by horse, from the unique ‘Spear Horizon’ layers of the 1995 excavation campaign. The data reveal a distinctive lake level drop, documented by the change from a carbonate-rich lake marl to a carbonate-free organic mud with increased carbon content and decreasing C/N, Si/Al, Si/K and Fe/Al ratios, indicating a higher pedogenic supply of organic matter and drier conditions at the site. Compared with older, similar transitional phases of lake level changes occurring within the Reinsdorf sequence, it is important that these youngest sediments are undisturbed, indicating continuous development. Ostracod and diatom analyses indicate a lowering water level with higher salinities and rich aquatic vegetation. Mesorheophilic ostracod species along with tychoplanktic diatom taxa point to flowing waters and turbulence at the lakeshore, presumably related to spring-fed streams originating from nearby highlands. Palynological results reveal a very diverse zonal vegetation pattern around the palaeolakeshore considering an area of investigation of approximately 50 × 75 m and a tessellated type of regional vegetation during the formation of the archaeological horizons. On topographically lower elevated areas, birch groves and taxa favouring wet, marshy conditions such as Cyperaceae, indicative of terrestrialization, were predominating, while other stands of this transitional phase reveal a very dry, grass-dominated steppe woodland favouring a rich wildlife with a striking number of megaherbivores. Our results suggest that the lithological differences of the ‘Spear Horizon’ layers containing the archaeological finds were due to their respective topographical situation and that the layers were deposited almost simultaneously during the beginning of the lake level drop. Human activities seem to have concentrated in sparsely vegetated areas along the palaeolakeshore, rather than in areas of adjacent denser birch swamp forest stands. 相似文献
5.
Dalia Bach Kirschbaum Robert Adler Yang Hong Stephanie Hill Arthur Lerner-Lam 《Natural Hazards》2010,52(3):561-575
A systematic inventory of landslide events over the globe is valuable for estimating human and economic losses, quantifying
the relationship between landslide occurrences and climate variations and for evaluating emerging global landslide prediction
efforts based on remote sensing data. This study compiles a landslide catalog for rainfall-triggered events for several years,
drawing upon news reports, scholarly articles, and other hazard databases to provide a landslide catalog at the global scale.
While this database may only represent a subset of rainfall-triggered landslides globally, due to lack of reports, it presents
a lower boundary on the number of events globally and provides initial insight into the spatiotemporal statistical trends
in landslide distribution and impact. This article develops a methodology for landslide event compilation that can be used
in evaluating global landslide forecasting initiatives and assessing patterns in landslide distribution and frequency worldwide. 相似文献
6.
Locally recorded data for eighteen aftershocks of a magnitude(mb) 4.6 earthquake occurring near Ukhimath in the Garhwal Himalaya were analysed. A master event technique was adopted to locate
seventeen individual aftershock hypocentres relative to the hypocentre of the eighteenth aftershock chosen as the master event.
The aftershock epicentres define an approximately 30 km2 rupture zone commensurate with the magnitude of the earthquake. The distribution of epicentres within this zone and the limited
amount of first motion data support the view that a group of parallel, sub-vertical, sinistral strike-slip faults oriented
N46°, transverse to the regional NW-SE trend of the Garhwal Himalaya, was involved in this seismic episode. Since the estimated
focal depth range for aftershocks of this sequence is 3–14 km, we infer that this transverse fault zone extends through the
upper crustal layer to a depth of 14 km at least. 相似文献
7.
From the Indian coast only limited data are available on the benthic fauna of the seagrass communities. In this study, seasonal variation in the distribution of macrobenthos and influence of environmental parameters was explored at four seagrass beds and two mangrove stations along the Minicoy Island, Lakshadweep, India, from September 1999 to August 2001. A total of 160 macrobenthic species from eight major groups represented the macrofauna of the Minicoy Island. Of the identified taxa, molluscs 70（gastropods 41.46%, bivalves 7.5%）, polychaetes 27（16.88%）, crustaceans 30（18.75%）, echinoderms 11（6.88%） and remaining others. Average seasonal abundance of benthic macrofauna ranged from 219 to 711 ind./m2, species diversity varied from 1.45 to 3.64 bits per individual, species richness index ranged from 4.01 to 26.17, evenness 0.69 to 1.66. In general, the higher abundance and species diversity was noticed in southern seagrass stations and northern seagrass stations, but in the mangrove stations comparatively low species diversity was observed. Three-way analysis of variance indicated that all communities resulted as being significantly different between seagrass and mangrove station, mainly when the seasonal interaction was considered. Multivariate analyses were employed to help define benthic characteristic and the relationship between environmental parameters at the six monitoring stations. Results of cluster analyses and multidimensional scale plot suggest that for mangrove region, different physiographic provinces, lower salinity, dissolved oxygen and sediment biotic structure have a higher influence on the species composition and diversity than other oceanographic conditions. 相似文献
8.
Chuanrong Zhang Tian Zhao E. Lynn Usery Dalia Varanka Weidong Li 《Transactions in GIS》2020,24(2):508-525
Disaster response operations require fast and coordinated actions based on real‐time disaster situation information. Although crowdsourced geospatial data applications have been demonstrated to be valuable tools for gathering real‐time disaster situation information, they only provide limited utility for disaster response coordination because of the lack of semantic compatibility and interoperability. To help overcome the semantic incompatibility and heterogeneity problems, we use Geospatial Semantic Web (GSW) technologies. We then combine GSW technologies with Web Feature Service requests to access multiple servers. However, a GSW‐based geographic information system often has poor performance due to the complex geometric computations required. The objective of this research is to explore how to use optimization techniques to improve the performance of an interoperable geographic situation‐awareness system (IGSAS) based on GSW technologies for disaster response. We conducted experiments to evaluate various client‐side optimization techniques for improving the performance of an IGSAS prototype for flood disaster response in New Haven, Connecticut. Our experimental results show that the developed prototype can greatly reduce the runtime costs of geospatial semantic queries through on‐the‐fly spatial indexing, tile‐based rendering, efficient algorithms for spatial join, and caching, especially for those spatial‐join geospatial queries that involve a large number of spatial features and heavy geometric computation. 相似文献
9.
10.
Giorgiana De Franceschi Lucilla Alfonsi David Altadill Pal Bencze Alain Bourdillon Dalia Buresova Ljiljana R. Cander Benito de la Morena Lefteris Economou Miguel Herraiz Kirsti Kauristie Jan Lastovicka Silvia Pau Gracia Rodriguez Richard Stamper Iwona Stanislawska 《Earth, Moon, and Planets》2009,104(1-4):63-67
The objective of the COST296 Action MIERS (Mitigation of Ionospheric Effects on Radio Systems) is to develop an increased knowledge of the effects imposed by the ionosphere on practical radio systems, and for the development and implementation of techniques to mitigate the deleterious effects of the ionosphere on such systems (http://www.cost296.rl.ac.uk). The COST296 Community contributes to the international efforts of IHY with scientific and outreach activities as well. After the realization of a web site hosted by Istituto Nazionale di Geofisica e Vulcanologia (INGV), developed also to promote the ionospheric physics to the open public, the COST296 Community supported an initiative addressed to the pupils of the primary school of several European Countries: the realization of a school-calendar dedicated to the Sun and to the Sun-Earth connections. 相似文献