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571.
Validation of official erosion modelling based on high‐resolution radar rain data by aerial photo erosion classification
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Franziska Katharina Fischer Michael Kistler Robert Brandhuber Harald Maier Melanie Treisch Karl Auerswald 《地球表面变化过程与地形》2018,43(1):187-194
The universal soil loss equation (USLE) is the most frequently applied erosion prediction model and it is also implemented as an official decision‐making instrument for agricultural regulations. The USLE itself has been already validated using different approaches. Additional errors, however, arise from input data and interpolation procedures that become necessary for field‐specific predictions on a national scale for administrative purposes. In this study, predicted event soil loss using the official prediction system in Bavaria (Germany) was validated by comparison with aerial photo erosion classifications of 8100 fields. Values for the USLE factors were mainly taken from the official Bavarian high‐resolution (5 × 5 m2) erosion cadastre. As series of erosion events were examined, the cover and management factor was replaced by the soil loss ratio. The event erosivity factor was calculated from high‐resolution (1 × 1 km2, 5 min), rain gauge‐adjusted radar rain data (RADOLAN). Aerial photo erosion interpretation worked sufficiently well and average erosion predictions and visual classifications correlated closely. This was also true for data broken down to individual factors and different crops. There was no reason to assume a general invalidity of the USLE and the official parametrization procedures. Event predictions mainly suffered from errors in the assumed crop stage period and tillage practices, which do not reflect interannual and farm‐specific variation. In addition, the resolution of radar data (1 km2) did not seem to be sufficient to predict short‐term erosion on individual fields given the strong spatial gradients within individual rains. The quality of the input data clearly determined prediction quality. Differences between USLE predictions and observations are most likely caused by parametrization weaknesses but not by a failure of the model itself. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
572.
This study assesses the effects of a high rise building on the beach and dune at an intensively developed shoreline through field investigation of geomorphological and sedimentological characteristics and wind tunnel investigation of wind speed and direction. Results indicate that wind speed is increased close to the building, where wind is often deflected to a more onshore direction. Obliquely offshore northwesterly winds are the most dramatically altered and cause onshore flows (with pronounced upward flows) in the landward portion of the beach near the building. Onshore deflections in wind direction cause besanding of the boardwalk and create highly localized scour and deposition zones. A dune on the backbeach breaks up zones of sediment transport and scour and diminishes the likelihood that scour areas will cause increased hazard to landward buildings as a result of flooding. Generic large-scale studies are required to develop criteria for communities to use to specify optimum dimensions, locations and shapes of landforms that are modified or created by high rise structures. 相似文献
573.
Patrick J. Evans Rodney A. Fricke Karl Hopfensperger Tom Titus 《Ground Water Monitoring & Remediation》2011,31(4):103-112
Perchlorate and nitrate in vadose‐zone soil can be continuing sources of groundwater contamination and technologies for remediation of these sources are limited. Gaseous electron donor injection technology (GEDIT) is an in situ approach that was demonstrated at a site in California. A mixture of hydrogen, carbon dioxide, liquefied petroleum gas (LPG), and nitrogen was injected into the vadose zone over a period of 5 months followed by 3 months of LPG alone. Perchlorate and nitrate plus nitrite nitrogen concentrations were reduced by over 90% and both were capable of being reduced to nondetectable concentrations. Hydrogen was required for perchlorate destruction, although concentrations as low as 0.5% were effective. Hydrogen was not required for nitrate destruction. Contaminant destruction was observed in both fine‐grained and coarse‐grained soils ranging from clay to gravel. Hydrogen was an effective electron donor because of its low molecular weight and high diffusivity which likely promoted its penetration into low‐permeability formations. Contaminant destruction was also observed in moisture contents ranging from 6.8% to 36% demonstrating that GEDIT was effective in low‐ and high‐moisture soils. The radius of influence (ROI) for perchlorate destruction was approximately 3.0 to 4.6 m while that for nitrate was greater than 17 m. The ROI was limited by use of a single injection location. Use of a grid injection system is anticipated to greatly increase efficiency. This research represents the first demonstration of GEDIT for treatment of contaminants in the vadose zone. 相似文献
574.
Branislava Jovanovic Dean Collins Karl Braganza Doerte Jakob David A. Jones 《Climatic change》2011,108(3):485-517
A high-quality monthly total cloud amount dataset for 165 stations has been developed for monitoring and assessing long-term
trends in cloud cover over Australia. The dataset is based on visual 9 a.m. and 3 p.m. observations of total cloud amount,
with most records starting around 1957. The quality control process involved examination of historical station metadata, together
with an objective statistical test comparing candidate and reference cloud series. Individual cloud series were also compared
against rainfall and diurnal temperature range series from the same site, and individual cloud series from neighboring sites.
Adjustments for inhomogeneities caused by relocations and changes in observers were applied, as well as adjustments for biases
caused by the shift to daylight saving time in the summer months. Analysis of these data reveals that the Australian mean
annual total cloud amount is characterised by high year-to-year variability and shows a weak, statistically non-significant
increase over the 1957–2007 period. A more pronounced, but also non-significant, decrease from 1977 to 2007 is evident. A
strong positive correlation is found between all-Australian averages of cloud amount and rainfall, while a strong negative
correlation is found between mean cloud amount and diurnal temperature range. Patterns of annual and seasonal trends in cloud
amount are in general agreement with rainfall changes across Australia, however the high-quality cloud network is too coarse
to fully capture topographic influences. Nevertheless, the broadscale consistency between patterns of cloud and rainfall variations
indicates that the new total cloud amount dataset is able to adequately describe the broadscale patterns of change over Australia.
Favourable simple comparisons between surface and satellite measures of cloudiness suggest that satellites may ultimately
provide the means for monitoring long-term changes in cloud over Australia. However, due to the relative shortness and homogeneity
problems of the satellite record, a robust network of surface cloud observations will be required for many years to come. 相似文献
575.
Thomas Nicholas Karl E. Barth David M. Boyajian 《Geotechnical and Geological Engineering》2011,29(1):27-35
Strut-and-tie modeling is an analysis and design tool for reinforced concrete elements in which it may be assumed that internal stresses are transferred through a truss mechanism. The tensile ties and compressive struts serve as truss members connected by nodal zones. The internal truss idealized by the strut-and-tie model implicitly account for the distribution of both flexure and shear. In 1998, the AASHTO LRFD Bridge Specifications (1998) incorporated the strut-and-tie modeling procedure for the analysis and design of deep reinforced concrete members where sectional design approaches are not valid. In most instances, hammerhead piers can be defined as deep reinforced concrete members and therefore, should be designed using the strut-and-tie modeling approach. However, most bridge designers have not embraced the strut-and-tie model due to the unfamiliarity with the design procedure, the inability to check the truss model??s validity (without laboratory tests or a finite element model), and the time it takes to complete the strut-and-tie model analysis and design. Therefore, with the formulation of a well-defined strut-and-tie modeling procedure, practicing engineers will become more comfortable with the design method and employ the method more often and more consistently. This paper presents a uniform design procedure for employing strut-and-tie modeling for hammerhead piers that can be readily utilized by practicing engineers. Additionally, a comparison between the strut-and-tie method and standard sectional design practices will be performed for a typical hammerhead pier. 相似文献
576.
The option of storing CO2 in subsea rock formations to mitigate future increases in atmospheric CO2 may induce problems for animals in the deep sea. In the present study the deep-sea bivalve Acesta excavata was subjected to environmental hypercapnia (pHSW 6.35, PCO2 = 33,000 μatm) corresponding to conditions reported from natural CO2 seeps. Effects on acid–base status and metabolic rate were related to time of exposure and subsequent recovery. During exposure there was an uncompensated drop in both hemolymph and intracellular pH. Intracellular pH returned to control values, while extracellular pH remained significantly lower during recovery. Intracellular non-bicarbonate buffering capacity of the posterior adductor muscle of hypercapnic animals was significantly lower than control values, but this was not the case for the remaining tissues analyzed. Oxygen consumption initially dropped by 60%, but then increased during the final stages of exposure, which may suggest a higher tolerance to hypercapnia than expected for a deep-living species. 相似文献
577.
Olivier Jacquat Claire Rambeau Andreas Voegelin Natalia Efimenko André Villard Karl B. Föllmi Ruben Kretzschmar 《Swiss Journal of Geoscience》2011,104(3):409-424
In order to better understand the origin and enrichment mechanisms leading to elevated Zn concentrations in Jurassic limestone
of the Jura mountain range (JMR) and the Burgundy (B), we investigated four locations of Bajocian age (JMR: Lausen–Schleifenberg,
Gurnigel; B: Vergisson–Davayé, Lucy-le-Bois) and two locations of Oxfordian age (JMR: Dornach, Pichoux) for their Zn distribution
and speciation. Measurements of the acid-extractable and bulk Zn contents showed that Zn is stratigraphically and spatially
heterogeneously distributed, in association with permeable carbonate levels. Up to 3,580 and 207 mg/kg Zn was detected in
Bajocian and Oxfordian limestone, respectively, with numerous limestone samples having Zn contents above 50 mg/kg. Using X-ray
absorption near edge structure spectroscopy and micro-X-ray fluorescence spectrometry, the speciation and micro-scale distribution
of Zn was investigated for selected limestone samples. In Bajocian limestone sphalerite and/or Zn-substituted goethite and
a minor fraction of Zn-bearing carbonates were identified. In contrast, Zn-bearing carbonates (Zn-substituted calcite and
hydrozincite) were accounting for most of the total Zn in Oxfordian limestone. The micro-scale distribution of Zn for Bajocian
and Oxfordian limestone was however similar with localized Zn-rich zones in the limestone cement and at the rim of oolites.
The stratigraphic sporadicity and microscale heterogeneity of the Zn distribution together with the Zn speciation results
point to a hydrothermal origin of Zn. Occurence of Zn-goethite is probably linked to the oxidative transformation of framboidal
pyrite and hydrothermal sphalerite in contact with meteoritic waters. Difference in speciation between Bajocian limestone
and Oxfordian limestone may be related to differences in rock permeability and/or to various hydrothermal events. Isotopic
dating of the different mineralizations will be needed to decipher differences in Zn speciation and the precise chronology
of hydrothermal episodes. 相似文献
578.
Shaun Cole Will J. Percival John A. Peacock Peder Norberg Carlton M. Baugh Carlos S. Frenk Ivan Baldry Joss Bland-Hawthorn Terry Bridges Russell Cannon Matthew Colless Chris Collins Warrick Couch Nicholas J. G. Cross Gavin Dalton Vincent R. Eke Roberto De Propris Simon P. Driver George Efstathiou Richard S. Ellis Karl Glazebrook Carole Jackson Adrian Jenkins Ofer Lahav Ian Lewis Stuart Lumsden Steve Maddox Darren Madgwick Bruce A. Peterson Will Sutherland Keith Taylor 《Monthly notices of the Royal Astronomical Society》2005,362(2):505-534
579.
Ignazio Ciufolini Erricos C. PavlisAntonio Paolozzi John RiesRolf Koenig Richard MatznerGiampiero Sindoni Karl Hans Neumayer 《New Astronomy》2012,17(3):341-346
In this paper we respond to the criticisms of “Phenomenology of the Lense-Thirring effect in the Solar System” by Iorio et al. about the general relativistic phenomena of gravitomagnetism and frame-dragging. The claims of the paper by Iorio et al. are not reproducible in any of our independent analyses. 相似文献
580.
The Zweikofel Formation of the Rattendorf Group in the Carnic Alps (Austria) is 95–102 m thick and consists of a cyclic succession of thin‐ to thick‐bedded fossiliferous limestone and intercalated thin intervals of siliciclastic sediment. The siliciclastic intervals were deposited in a shallow marine nearshore environment. The variety of carbonate facies indicates deposition in a shallow neritic, normal‐saline, low‐ to high‐energy environment. The Zweikofel Formation is characterized by a paracyclic vertical arrangement of facies and represents sedimentary sequences that are not well understood elsewhere in the Tethys. Fusulinids and conodonts from the upper Grenzland and Zweikofel formations in the Carnic Alps clearly suggest that what has been called ‘Sakmarian’ in the Tethys includes both the Sakmarian and Artinskian stages of the Global Time scale. Fusulinids from the lower part of the Zweikofel Formation at Zweikofel closely resemble those of the Grenzland Formation and approximately correlate with the upper part of the Sakmarian and lower part of the Artinskian of the Global Time scale. The upper part of the Zweikofel Formation correlates approximately with the lower‐middle (?) parts of the Artinskian Stage of the Global Time scale. A new regional Hermagorian Stage of the Tethyan scale is proposed between the Asselian and Yakhtashian. The lower boundary of the Hermagorian Stage is proposed to be located at the base of bed 81 in the 1015 section of Darvaz (Tadzhikistan). The boundary between the Hermagorian and Yakhtashian stages is placed at the base of bed 73 in the Zweikofel section at Zweikofel, Carnic Alps. In the Darvaz region, Tadzhikistan, the type area for the Yakhtashian Stage, this boundary has never been precisely defined. The entire fusulinid assemblage of the upper part of the Grenzland and Zweikofel formations reported herein includes 62 species of 18 genera, of which one subgenus and 12 species and subspecies are new. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献