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221.
Michael Mitchell Rod Griffith Paul Ryan Greg Walkerden Brian Walker Valerie A. Brown 《社会与自然资源》2014,27(3):299-314
Natural resource management (NRM) organizations are increasingly looking to resilience thinking to provide insights into how social and environmental systems interact and to identify points of intervention. Drawing on complex systems analysis, resilience thinking emphasizes that landscapes constantly change from social and ecological interactions, and focuses NRM planners’ attention on identifying key variables, feedbacks, and thresholds that can help improve intervention strategies. More deliberative approaches are being developed to use resilience thinking in ways that engage and build human capacity for action. This article documents experiences shared with NRM agencies in rural Australia as we developed new approaches to link resilience thinking with collective learning principles. We present an emerging framework through which heuristics associated with resilience thinking is being used as part of a planning-by-doing process. The framework is being tested to assess whether and how it can enable change agents to advance their capacities for adaptation and transformation. 相似文献
222.
Bias corrections of global models for regional climate simulations of high-impact weather 总被引:1,自引:1,他引:0
Cindy L. Bruyère James M. Done Greg J. Holland Sherrie Fredrick 《Climate Dynamics》2014,43(7-8):1847-1856
All global circulation models (GCMs) suffer from some form of bias, which when used as boundary conditions for regional climate models may impact the simulations, perhaps severely. Here we present a bias correction method that corrects the mean error in the GCM, but retains the six-hourly weather, longer-period climate-variability and climate change from the GCM. We utilize six different bias correction experiments; each correcting different bias components. The impact of the full bias correction and the individual components are examined in relation to tropical cyclones, precipitation and temperature. We show that correcting of all boundary data provides the greatest improvement. 相似文献
223.
Mustafa A. Eissa James M. Thomas Ronald L. Hershey Maher I. Dawoud Greg Pohll Kamal A. Dahab Mohamed A. Gomaa Ashraf R. Shabana 《Environmental Earth Sciences》2014,71(4):1855-1869
The Wadi Watir delta in the Wadi Watir watershed is a tourist area in the arid southeastern part of the Sinai Peninsula, Egypt, where development and growth of the community on the delta are constrained by the amount of groundwater that can be withdrawn sustainably. To effectively manage groundwater resources in the Wadi Watir delta, the origin of groundwater recharge, groundwater age, and changes in groundwater chemistry in the watershed needs to be understood. Mineral identification, rock chemistry, water chemistry, and the isotopes of hydrogen, oxygen, and carbon in groundwater were used to identify the sources, mixing, and ages of groundwater in the watershed and the chemical evolution of groundwater as it flows from the upland areas in the watershed to the developed areas at the Wadi Watir delta. Groundwater in the Wadi Watir watershed is primarily from recent recharge while groundwater salinity is controlled by mixing of chemically different waters and dissolution of minerals and salts in the aquifers. The El Shiekh Attia and Wadi El Ain areas in the upper Wadi Watir watershed have different recharge sources, either from recharge from other areas or from different storm events. The downgradient Main Channel area receives groundwater flow primarily from the El Shiekh Attia area. Groundwater in the Main Channel area is the primary source of groundwater supplying the aquifers of the Wadi Watir delta. 相似文献
224.
Groundwater resource sustainability in the Wadi Watir delta, Gulf of Aqaba, Sinai, Egypt 总被引:3,自引:2,他引:1
Mustafa A. Eissa James M. Thomas Greg Pohll Ronald L. Hershey Kamal A. Dahab Maher I. Dawoud Abdelfattah ElShiekh Mohamed A. Gomaa 《Hydrogeology Journal》2013,21(8):1833-1851
The Wadi Watir delta, in the arid Sinai Peninsula, Egypt, contains an alluvial aquifer underlain by impermeable Precambrian basement rock. The scarcity of rainfall during the last decade, combined with high pumping rates, resulted in degradation of water quality in the main supply wells along the mountain front, which has resulted in reduced groundwater pumping. Additionally, seawater intrusion along the coast has increased salinity in some wells. A three-dimensional (3D) groundwater flow model (MODFLOW) was calibrated using groundwater-level changes and pumping rates from 1982 to 2009; the groundwater recharge rate was estimated to be 1.58?×?106 m3/year. A variable-density flow model (SEAWAT) was used to evaluate seawater intrusion for different pumping rates and well-field locations. Water chemistry and stable isotope data were used to calculate seawater mixing with groundwater along the coast. Geochemical modeling (NETPATH) determined the sources and mixing of different groundwaters from the mountainous recharge areas and within the delta aquifers; results showed that the groundwater salinity is controlled by dissolution of minerals and salts in the aquifers along flow paths and mixing of chemically different waters, including upwelling of saline groundwater and seawater intrusion. Future groundwater pumping must be closely monitored to limit these effects. 相似文献
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An algorithm for determining the area of a spherical polygon of arbitrary shape is presented. The kernel of the problem is to compute the interior angle at each vertex of the spherical polygon; a well-known relationship between the area of a spherical polygon and the sum of its interior angles then may be exploited. The algorithm has been implemented as a FORTRAN subroutine and a listing is provided. Both algorithm and subroutine are general in their capabilities and can be used, for example, to determine the area of a spherical polygon containing one or more holes. 相似文献
229.
Dale A. Lang Trevor P. Bastow Ben G.K. Van Aarssen Ben Warton Greg B. Davis Colin D. Johnston 《Ground Water Monitoring & Remediation》2009,29(4):85-93
Hydrocarbon and nonhydrocarbon components dissolving in water from fresh diesel and field samples of highly weathered diesel (spilled up to 50 years ago) from two sites were investigated. The fresh and weathered diesels were equilibrated with water using a slow-stirring method, and the product and equilibrated aqueous water samples analyzed by a range of analytical procedures. The water phase equilibrated with weathered diesels had higher total dissolved organics concentrations (96 and 8.6 mg/L at the two sites) compared to the water phase equilibrated with fresh diesel (average of 3.4 mg/L). Compound class characterization of dissolved organics in water from the weathered diesel showed that polar components were a significant compound class (98% and 42% at the two sites) and appeared largely as an unresolved complex mixture (UCM) in the total ion chromatograms (TICs). Identification of 1-adamantanol in the polar fraction of both weathered diesel samples (3.6 and 0.3 μg/L at the two sites) suggested that at least some of the associated polar components are from a petroleum source. The analysis of total petroleum hydrocarbons (TPH) is aimed at measuring only dissolved carbon and hydrogen-containing compounds, and dissolved polar compounds present as a UCM are often assumed to be from natural organic matter (NOM) and removed. This may result in a gross underestimation of the total soluble organic material in water associated with weathered diesels. In addition, the risk posed by these fuel-derived polar compounds is unknown. 相似文献
230.
Greg Balco Jason Briner Robert C. Finkel John A. Rayburn John C. Ridge Joerg M. Schaefer 《Quaternary Geochronology》2009,4(2):93-107
The major uncertainty in relating cosmogenic-nuclide exposure ages to ages measured by other dating methods comes from extrapolating nuclide production rates measured at globally scattered calibration sites to the sites of unknown age that are to be dated. This uncertainty can be reduced by locating production rate calibration sites that are similar in location and age to the sites to be dated. We use this strategy to reconcile exposure age and radiocarbon deglaciation chronologies for northeastern North America by compiling 10Be production rate calibration measurements from independently dated late-glacial and early Holocene ice-marginal landforms in this region. 10Be production rates measured at these sites are 6–12% lower than predicted by the commonly accepted global 10Be calibration data set used with any published production rate scaling scheme. In addition, the regional calibration data set shows significantly less internal scatter than the global calibration data set. Thus, this calibration data set can be used to improve both the precision and accuracy of exposure dating of regional late-glacial events. For example, if the global calibration data set is used to calculate exposure ages, the exposure-age deglaciation chronology for central New England is inconsistent with the deglaciation chronology inferred from radiocarbon dating and varve stratigraphy. We show that using the regional data set instead makes the exposure age and radiocarbon chronologies consistent. This increases confidence in correlating exposure ages of ice-marginal landforms in northeastern North America with glacial and climate events dated by other means. 相似文献