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551.
The Netherlands knows a persistent threat of flooding. To adapt to this dangerous reality, the Dutch have cultivated what disaster research literature has labeled ‘disaster subcultures’ or a set of cultural (tangible and intangible) tools to deal with the recurrent hazard. While there is abundant attention for the way the Dutch ‘coastal’ and ‘low-lying’ communities deal with the recurrent threat of (coastal) flooding, less is known about the way the Dutch ‘high-lands’ deal with the yearly threat of (fluvial) flooding. This article presents the findings of an explorative research endeavor (2011–2013) aimed at discerning if the disaster subculture concept has contemporary relevance in the Netherlands, particularly with respect to flooding, and if so, whether applying this lens would reveal more about the nature of existing disaster subcultures. Because less is known about the Dutch ‘high-lands,’ we chose to look into the existence and attributes of disaster subcultures in the parishes Borgharen and Itteren, which experience a systematic threat of flooding. Our findings suggest that the disaster subculture lens is valuable as it enables the empirical appreciation of disaster subcultures, even in a small country like the Netherlands, and it unveiled elements of these neighboring parishes’ flood reality that otherwise might have gone unnoticed and that seem central to understanding these two parishes’ levels of vulnerability and resilience. It is our contention that the concept ‘disaster subculture’ makes a greater understanding possible of the cultural context from which vulnerability and resilience to specific and recurrent threats emerge. 相似文献
552.
The natural aging process of Chesapeake Bay and its tributary estuaries has been accelerated by human activities around the shoreline and within the watershed, increasing sediment and nutrient loads delivered to the bay. Riverine nutrients cause algal growth in the bay leading to reductions in light penetration with consequent declines in sea grass growth, smothering of bottom-dwelling organisms, and decreases in bottom-water dissolved oxygen as algal blooms decay. Historically, bay waters were filtered by oysters, but declines in oyster populations from overfishing and disease have led to higher concentrations of fine-sediment particles and phytoplankton in the water column. Assessments of water and biological resource quality in Chesapeake Bay and tributaries, such as the Potomac River, show a continual degraded state. In this paper, we pay tribute to Owen Bricker’s comprehensive, holistic scientific perspective using an approach that examines the connection between watershed and estuary. We evaluated nitrogen inputs from Potomac River headwaters, nutrient-related conditions within the estuary, and considered the use of shellfish aquaculture as an in-the-water nutrient management measure. Data from headwaters, nontidal, and estuarine portions of the Potomac River watershed and estuary were analyzed to examine the contribution from different parts of the watershed to total nitrogen loads to the estuary. An eutrophication model was applied to these data to evaluate eutrophication status and changes since the early 1990s and for comparison to regional and national conditions. A farm-scale aquaculture model was applied and results scaled to the estuary to determine the potential for shellfish (oyster) aquaculture to mediate eutrophication impacts. Results showed that (1) the contribution to nitrogen loads from headwater streams is small (about 2 %) of total inputs to the Potomac River Estuary; (2) eutrophic conditions in the Potomac River Estuary have improved in the upper estuary since the early 1990s, but have worsened in the lower estuary. The overall system-wide eutrophication impact is high, despite a decrease in nitrogen loads from the upper basin and declining surface water nitrate nitrogen concentrations over that period; (3) eutrophic conditions in the Potomac River Estuary are representative of Chesapeake Bay region and other US estuaries; moderate to high levels of nutrient-related degradation occur in about 65 % of US estuaries, particularly river-dominated low-flow systems such as the Potomac River Estuary; and (4) shellfish (oyster) aquaculture could remove eutrophication impacts directly from the estuary through harvest but should be considered a complement—not a substitute—for land-based measures. The total nitrogen load could be removed if 40 % of the Potomac River Estuary bottom was in shellfish cultivation; a combination of aquaculture and restoration of oyster reefs may provide larger benefits. 相似文献
553.
Kathleen M. Swanson Judith Z. Drexler David H. Schoellhamer Karen M. Thorne Mike L. Casazza Cory T. Overton John C. Callaway John Y. Takekawa 《Estuaries and Coasts》2014,37(2):476-492
Salt marsh faunas are constrained by specific habitat requirements for marsh elevation relative to sea level and tidal range. As sea level rises, changes in relative elevation of the marsh plain will have differing impacts on the availability of habitat for marsh obligate species. The Wetland Accretion Rate Model for Ecosystem Resilience (WARMER) is a 1-D model of elevation that incorporates both biological and physical processes of vertical marsh accretion. Here, we use WARMER to evaluate changes in marsh surface elevation and the impact of these elevation changes on marsh habitat for specific species of concern. Model results were compared to elevation-based habitat criteria developed for marsh vegetation, the endangered California clapper rail (Rallus longirostris obsoletus), and the endangered salt marsh harvest mouse (Reithrodontomys raviventris) to determine the response of marsh habitat for each species to predicted >1-m sea-level rise by 2100. Feedback between vertical accretion mechanisms and elevation reduced the effect of initial elevation in the modeled scenarios. Elevation decreased nonlinearly with larger changes in elevation during the latter half of the century when the rate of sea-level rise increased. Model scenarios indicated that changes in elevation will degrade habitat quality within salt marshes in the San Francisco Estuary, and degradation will accelerate in the latter half of the century as the rate of sea-level rise accelerates. A sensitivity analysis of the model results showed that inorganic sediment accumulation and the rate of sea-level rise had the greatest influence over salt marsh sustainability. 相似文献
554.
555.
Melanie Hayn Robert Howarth Roxanne Marino Neil Ganju Peter Berg Kenneth H. Foreman Anne E. Giblin Karen McGlathery 《Estuaries and Coasts》2014,37(1):63-73
West Falmouth Harbor, a shallow lagoon on Cape Cod, has experienced a threefold increase in nitrogen load since the mid- to late 1990s due to input from a groundwater plume contaminated by a municipal wastewater treatment plant. We measured the exchange of nitrogen and phosphorus between the harbor and the coastal waters of Buzzards Bay over several years when the harbor was experiencing this elevated nitrogen load. During summer months, the harbor not only retained the entire watershed nitrogen load but also had a net import of nitrogen from Buzzards Bay. During the spring and fall, the harbor had a net export of nitrogen to Buzzards Bay. We did not measure the export in winter, but assuming the winter net export was less than 112 % of the load, the harbor exported less than half of the watershed nitrogen load on an annual basis. For phosphorus, the harbor had a net import from coastal waters in the spring and summer months and a net export in the fall. Despite the large increase in nitrogen load to the harbor, the summertime import of phosphorus from Buzzards Bay was sufficient to maintain nitrogen limitation of primary productivity during the summer. Our findings illustrate that shallow systems dominated by benthic producers have the potential to retain large terrestrial nitrogen loads when there is sufficient supply of phosphorus from exchange with coastal waters. 相似文献
556.
The challenges of a changing world, which are progressively threatening sustainable use of groundwater resources, can only be rationally and effectively addressed through close collaboration between experts and practitioners from different disciplines. Furthermore, science and management need to build on stakeholder opinions and processes in order to generate useful knowledge and positive outcomes in terms of sustainable and equitable groundwater management. This essay provides a discussion of the status of and vision for participatory and inter-disciplinary approaches to groundwater evaluation and management as well as a conceptual framework and relevant research questions that will facilitate such approaches. 相似文献
557.
Karen M. Vanlandingham Sumner Starrfield † Steven N. Shore † George Sonneborn † 《Monthly notices of the Royal Astronomical Society》1999,308(2):577-587
We present our analysis of the UV spectra of the fast ONeMg Nova LMC 1990#1. Observations with the IUE began on 1990 January 18 and continued through to 1990 March 15. We have analysed these spectra, and determined line fluxes and physical parameters as a function of time. Using both He ii lines and the Balmer decrement, we find the reddening for the nova to be E ( B − V )≃0.22. Using the photoionization code cloudy 90.03b and the minimization routine minuit , we derive elemental abundances for the ejecta. We find the following abundances, relative to solar material: He=1, C=8, N=109, O=20, Ne=62, Mg=16, Al=257 and Si=41. These results are based on independent fits to different data sets acquired three weeks apart. These abundances are extremely similar to those found for V693 Corona Austrinae 1981. Given the position of V693 CrA in the Galaxy and the range of distances found for it, the similar abundances imply that the V693 CrA outburst took place on an older population white dwarf. The high N/O ratio implies an outburst on a massive white dwarf. 相似文献
558.
Ian R. Stevens David K. Strickland Karen A. Wills 《Monthly notices of the Royal Astronomical Society》1999,308(3):L23-L27
We investigate the X-ray emission from the central regions of the prototypical starburst galaxy M82. Previous observations have shown a bright central X-ray point source, with suggestions as to its nature including a low-luminosity active galactic nucleus or an X-ray binary. A new analysis of ROSAT HRI observations finds four X-ray point sources in the central kiloparsec of M82, and we identify radio counterparts for the two brightest X-ray sources. The counterparts are probably young radio supernovae (SNe) and are amongst the most luminous and youthful SNe in M82. We therefore suggest that we are seeing X-ray emission from young SNe in M82, and in particular that the brightest X-ray source is associated with the radio source 41.95+57.5. We discuss the implications of these observations for the evolution of X-ray-luminous SNe. 相似文献
559.
Stratigraphic and paleoecologic (palynomorph, macrobotanical) data obtained from a cutbank of the Souris River in southwestern Manitoba establish some fundamental parameters of Folsom land‐use in association with a proglacial lake on the Canadian Prairies. By dating the regression of glacial Lake Hind, we observed that recorded Folsom sites are restricted to areas of the Hind basin drained shortly before 10,400 yr B.P. This pattern may therefore record the interception of seasonal resources on recently‐drained proglacial lake surfaces. Based on paleovegetation reconstructions, we note that these surfaces were rapidly colonized by emergent and aquatic vegetation following regression, generating a viable resource base for Folsom hunter‐gatherers. However, low plant productivity and diversity may have greatly limited the extent to which this locale was exploited, in contrast to nonperiglacial regions on the Plains. We also suggest that wetland plant succession during the Pleistocene‐Holocene transition was due, at least locally, to climate‐forced fluctuations in groundwater levels. © 2003 Wiley Periodicals, Inc. 相似文献
560.
Jonathan D. Phillips Heather Golden Karen Cappiella Bain Andrews Tamara Middleton David Downer Deonna Kelli Lee Padrick 《地球表面变化过程与地形》1999,24(1):23-39
In agricultural basins of the southeastern coastal plain there are typically large disparities between upland soil erosion and sediment delivered to streams. This suggests that colluvial storage and redistribution of eroded soil within croplands is occurring, and/or that processes other than fluvial erosion are at work. This study used soil morphology and stratigraphy as an indicator of erosion and deposition processes in a watershed at Littlefield, North Carolina. Soil stratigraphy and morphology reflect the ways in which mass fluxes associated with cultivation transform the local soils. Fluvial, aeolian and tillage processes were all found to be active in the redistribution of soil. The soil transformations are of five general types. First, erosion and compaction in the cultivated area as a whole result in the thinning of Arenic and Grossarenic Paleudults and Paleaquults to form Arenic, Typic and Aquic Paleudults and Paleaquults. Second, redistribution of surficial material within the fields results in transitions between Arenic and Typic or Aquic subgroups as loamy sand A and E horizons are truncated or accreted. Third, aeolian deposition at forested field boundaries leads to the formation of compound soils with podzolized features. Fourth, sandy rill fan deposits at slope bases create cumulic soils distinct from the loamy sands of the source area or the darker, finer terrace soils buried by the fan deposits. Finally, tillage and fluvial deposition in upland depressions results in the gradual burial of Rains (poorly drained Typic Paleaquults) soils. Results confirm the importance of upland sediment storage and redistribution, and the role of tillage and aeolian processes as well as fluvial processes in the region. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献