Runoff‐generating processes in hydromorphic soils on a plot scale: free gravity‐driven versus pressure‐controlled flow     

Benjamin Lange  Peter F. Germann  Peter Lüscher 《水文研究》2011,25(6):873-885

Draining soil water is an important runoff generator. This study aims to describe runoff‐generating processes on a plot scale (1 m²) in hydromorphic soils with different initial soil water contents. We irrigated 16 hydromorphic soils in the northern Pre‐Alps in Switzerland and recorded the variations in water content with time domain reflectometry (TDR) at five different depths per plot. Sprinkling was repeated three times at approximately 23‐h intervals and lasted for 1 h with a volume flux density of 70 mm h^?1. The comparison between the measured water content of the drainages with two physically based models revealed which of the flow processes dominated during water recessions. We distinguished between vertical drainage, lateral outflow and infiltration without drainage. Approximately 45% of all recorded time series of soil water content did not drain within approximately 20 h after the end of irrigation, about 25% drained laterally and 10% of the outflow was vertical. The drainage of the remaining 20% was the result of both lateral and vertical water flow (≈12%), or was not interpretable with the approaches applied (≈8%). Vertical flow was only observed in layers without any or with just a few hydromorphic features. Lateral draining horizons had approximately half the storage capacity and amplitude of water recession of those with vertical flow. Vertical flow was only observed in the upper soil horizons. Thus, vertical flow transmitted water to layers with lateral outflow and did not delay runoff by deep percolation. Increasing initial soil moisture increased the percentage of water content recordings according to a lateral outflow slightly, while vertical flow was less frequent. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Application of stable carbon isotopes for reconstructing salt‐marsh floral zones and relative sea level,New Jersey,USA     

Andrew C. Kemp  Christopher H. Vane  Benjamin P. Horton  Simon E. Engelhart  Daria Nikitina 《第四纪科学杂志》2012,27(4):404-414

We investigated use of δ¹³C in bulk organic sediment to define the botanical origin of samples preserved in coastal sediment as a means to reconstruct relative sea level in New Jersey, USA. Modern transects at three sites demonstrated that low and high salt‐marsh floral zones dominated by C₄ species (Spartina alterniflora and Spartina patens) were associated with sediment δ¹³C values between ?18.9‰ and ?15.8‰ and occurred from mean tide level (MTL) to mean higher high water (MHHW). Brackish transitional settings vegetated by Phragmites australis with Iva fructescens and Typha sp. (C₃ species) and freshwater upland samples (C₃ species) were characterized by bulk sediment δ¹³C values of ?27.0‰ to ?22.0‰ and existed above MHHW. Parallel transects at one site suggested that intra‐site variability was not discernible. The utility of δ¹³C values for reconstructing relative sea level in New Jersey is limited by an inability to differentiate between brackish sediments related to sea level and freshwater upland samples. To facilitate this distinction in a 4.4 m core, we used a multi‐proxy approach (δ¹³C values with presence or absence of agglutinated foraminifera) to recognize indicative meanings for four sample types. Sediment with δ¹³C values greater than ?18.9‰ was derived from a vegetated salt‐marsh and formed between MTL and MHHW. Sediment with δ¹³C values less than ?22.0‰ and containing agglutinated foraminifera formed in a brackish transitional zone between MHHW and highest astronomical tide (HAT). This is the narrowest elevational range of the four sample types and most precise sea‐level indicator. Sediment with δ¹³C values less than ?22.0‰ and lacking foraminifera can only constrain the upper bound of former sea level. Samples with intermediate values (?22.0‰ to ?18.9‰) formed between MTL and HAT. Using these indicative meanings and radiocarbon dates, we suggest that a transition from brackish to salt‐marsh δ¹³C values recorded in the core took approximately 350 years (from 1800 to 1450 cal. a BP). Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Improving radiometry of imaging spectrometers by using programmable spectral regions of interest     

Francesco Dell’Endice  Jens Nieke  Benjamin Koetz  Michael E. Schaepman  Klaus Itten 《ISPRS Journal of Photogrammetry and Remote Sensing》2009,64(6):632-639

Programmable imaging spectrometers can be adjusted to fit specific application requirements that differ from the instrument initial spectral design goals. Sensor spectral characteristics and its signal-to-noise ratio (SNR) can be changed by applying customized online binning patterns.We present a software utility that generates application driven spectral binning patterns by using an SNR dependent sensor model. The utility, named BinGO (BInning patterN Generator and Optimiser), is used to produce predefined binning patterns that either (a) allow an existing imaging spectrometer to optimize its spectral characteristics for a specific application, (b) allow an existing imaging spectrometer to spectral and/or spatially emulate another instrument, or (c) design new multispectral or imaging spectrometer missions (i.e. spaceborne, airborne, terrestrial). We present a variety of BinGO case studies, including the simulation of airborne (APEX) [Itten, K.I. et al., 2008. APEX — The hyperspectral ESA Airborne Prism Experiment. Sensors 8(1), 1–25], spaceborne (SENTINEL III) [Nieke, J., Frerick, J., Stroede, J., Mavrocordatos, C., Berruti, B., 2008. Status of the optical payload and processor development of ESA’s Sentinel 3 mission. In: Proceedings of the Geoscience and Remote Sensing Symposium IGARSS 2008, pp. 427–430], as well as scientific and performance optimized approaches. We conclude that the presented approach can successfully be used to increase the efficiency of spectral information retrieval by using imaging spectroscopy data and to simulate various missions and requirements, finally supporting proper trade-off decisions to be made between performance optimization and scientific requirements. In addition, if specific sensor parameters are known, BinGO can also model other imaging spectrometers.  相似文献   

Development of a foraminifera-based transfer function in the Basque marshes, N. Spain: Implications for sea-level studies in the Bay of Biscay     

Eduardo Leorri  Benjamin P. Horton  Alejandro Cearreta 《Marine Geology》2008,251(1-2):60-74

In order to reconstruct former sea level we have developed a foraminifera-based transfer function using three models based on a modern dataset of 59 samples and 23 species obtained from four Basque marshes in Northern Spain. The relationship between observed and foraminifera-predicted elevation illustrated the strong performance of the transfer function (r²_jack ranges from 0.74 to 0.81). These results indicated that precise reconstructions of former sea levels are possible (error ranges from 0.11 to 0.19 m). The transfer function was used to calibrate the foraminiferal assemblages collected from a 50 cm salt marsh core. We placed the foraminifera-based reconstructions into a temporal framework using ¹³⁷Cs, Pb concentrations, and ²¹⁰Pb-derived sediment accumulation rates. The resulting relative sea-level curve is in good agreement with regional tide-gauge data. Both instrumental data and microfossil records suggest a rate of relative sea-level rise of approximately 2 mm yr^− 1 for the 20th century.  相似文献   

A LiDAR–optical data fusion approach for identifying and measuring small stream impoundments and dams     

Benjamin Swan  Robert Griffin 《Transactions in GIS》2020,24(1):174-188

This article outlines a semi‐autonomous approach for using a fusion of light detection and ranging (LiDAR) and optical remote sensing data to identify and measure small impoundments (SIs) and their dams. Quantifying such water bodies as hydrologic network features is critical for ecosystem and species conservation, emergency management, and water resource planning; however, such features are incompletely mapped at national and state levels. By merging an airborne LiDAR‐derived point cloud with a normalized water index using airborne optical imagery we demonstrate an improvement upon single‐source methods for identifying these water bodies; classification accuracies increased over 10% by using this multi‐source fusion method. Furthermore, the method presented here illustrates a cost‐effective pathway to improve the National Inventory of Dams (NID) and includes a framework for estimating dam heights, with results showing strong correlations between derived dam heights and those recorded in the NID (r=.78). With the steady increase in available LiDAR coverage, the 87,000+ dams in the NID could be updated using this technique, a method which could also be expanded for global inventories of SIs and dams.  相似文献   

Numerical modelling of Cretaceous Pyrenean Rifting: The interaction between mantle exhumation and syn-rift salt tectonics     

Thibault Duretz  Riccardo Asti  Yves Lagabrielle  Jean-Pierre Brun  Anthony Jourdon  Camille Clerc  Benjamin Corre 《Basin Research》2020,32(4):652-667

The preshortening Cretaceous Pyrenean Rift is an outstanding geological laboratory to investigate the effects of a pre-rift salt layer at the sedimentary base on lithospheric rifting. The occurrence of a pre-rift km-scale layer of evaporites and shales promoted the activation of syn-rift salt tectonics from the onset of rifting. The pre- and syn-rift sediments are locally affected by high-temperature metamorphism related to mantle ascent up to shallow depths during rifting. The thermo-mechanical interaction between décollement along the pre-existing salt layer and mantle ascent makes the Cretaceous Pyrenean Rifting drastically different from the type of rifting that shaped most Atlantic-type passive margins where salt deposition is syn-rift and gravity-driven salt tectonics has been postrift. To unravel the dynamic evolution of the Cretaceous Pyrenean Rift, we carried out a set of numerical models of lithosphere-scale extension, calibrated using the available geological constraints. Models are used to investigate the effects of a km-scale pre-rift salt layer, located at the sedimentary cover base, on the dynamics of rifting. Our results highlight the key role of the décollement layer at cover base that can alone explain both salt tectonics deformation style and high-temperature metamorphism of the pre-rift and syn-rift sedimentary cover. On the other hand, in the absence of décollement, our model predicts symmetric necking of the lithosphere devoid of any structure and related thermal regime geologically relevant to the Pyrenean case.  相似文献   

Preface     

Benjamin Ross  Editor 《Engineering Geology》1989,26(4):III

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Constant‐ductility response spectra for sequential earthquake and tsunami loading          下载免费PDF全文

Michael H. Scott  H. Benjamin Mason 《地震工程与结构动力学》2017,46(9):1549-1554

Simplified approaches for examining structural system response under sequential earthquake and tsunami loading are helpful for understanding response trends. To aid understanding, nonlinear (constant‐ductility) response spectra are developed for elastoplastic single degree of freedom systems subjected to seismic loads followed by hydrodynamic tsunami loads. The forcing function is composed of long‐duration earthquake motion concatenated with a range of tsunami hydrodynamic forces that are proportional to the pseudo‐spectral acceleration produced by the earthquake motion. The constant‐ductility spectra are thus constructed for scenarios where the loading imposed by one hazard is not dominant over the other. The spectra and basic intensity measures indicate that the amplification of response for sequential earthquake and tsunami loading over the earthquake only case is most significant for systems with long natural periods and high‐ductility capacity under seismic loading. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

Interactions of Chlorine with Natural Organic Matter and Formation of Intermediates: Evidence by Differential Spectroscopy     

Georgy V. Korshin  Mark M. Benjamin  Hong‐Bin Xiao 《洁净——土壤、空气、水》2001,28(7):378-384

This communication describes the use of differential absorbance spectroscopy to explore the intermediates formed during halogenation of natural organic matter (NOM). The differential spectra of chlorinated NOM comprise two contributions. The primary component is negative and has a peak near 270 nm. The shape of this band is independent of chlorine dose, and its intensity increases monotonically with Cl₂ dose. The second component is positive, with a well‐defined peak near 280 nm and another, broader band in the 340...380 nm range. The second component is noticeable at low chlorine concentrations but disappears with increasing Cl₂ dose. We attribute this component to aromatic chlorinated intermediates formed prior to the release of identifiable smaller species such as haloacetic acids. We believe that this component of the differential spectra can be used to probe the identity, formation and breakdown of the halogenated intermediates.  相似文献   

Testing the preservation potential of early diagenetic dolomites as geochemical archives     

Mathias Mueller  Onyedika A. Igbokwe  Benjamin Walter  Chelsea L. Pederson  Sylvia Riechelmann  Detlev K. Richter  Richard Albert  Axel Gerdes  Dieter Buhl  Rolf D. Neuser  Giovanni Bertotti  Adrian Immenhauser 《Sedimentology》2020,67(2):849-881

Early marine diagenetic dolomite is a rather thermodynamically-stable carbonate phase and has potential to act as an archive of marine porewater properties. However, the variety of early to late diagenetic dolomite phases that can coexist within a single sample can result in extensive complexity. Here, the archive potential of early marine dolomites exposed to extreme post-depositional processes is tested using various types of analyses, including: petrography, fluid inclusion data, stable δ¹³C and δ¹⁸O isotopes, ⁸⁷Sr/⁸⁶Sr ratios, and U-Pb age dating of various dolomite phases. In this example, a Triassic carbonate platform was dissected and overprinted (diagenetic temperatures of 50 to 430°C) in a strike-slip zone in Southern Spain. Eight episodes of dolomitization, a dolostone cataclasite and late stage meteoric/vadose cementation were recognized. The following processes were found to be diagenetically relevant: (i) protolith deposition and fabric-preservation, and marine dolomitization of precursor aragonite and calcite during the Middle–Late Triassic; (ii) intermediate burial and formation of zebra saddle dolomite and precipitation of various dolomite cements in a Proto-Atlantic opening stress regime (T ca 250°C) during the Early–Middle Jurassic; (iii) dolomite cement precipitation during early Alpine tectonism, rapid burial to ca 15 km, and high-grade anchizone overprint during Alpine tectonic evolution in the Early Eocene to Early Miocene; (iv) brecciation of dolostones to cataclasite during the onset of the Carboneras Fault Zone activity during the Middle Miocene; and (v) late-stage regression and subsequent meteoric overprint. Data shown here document that, under favourable conditions, early diagenetic marine dolomites and their archive data may resist petrographic and geochemical resetting over time intervals of 10⁸ or more years. Evidence for this preservation includes preserved Late Triassic seawater δ¹³C_DIC values and primary fluid inclusion data. Data also indicate that oversimplified statements based on bulk data from other petrographically-complex dolomite archives must be considered with caution.  相似文献