Regional crop water use assessment using Landsat-derived evapotranspiration     

Arun Bawa  Gabriel B. Senay  Sandeep Kumar 《水文研究》2021,35(1):e14015

Reliable information on water use and availability at basin and field scales are important to ensure the optimized constructive uses of available water resources. This study was conducted with the specific objective to estimate Landsat-based actual evapotranspiration (ETa) using the Operational Simplified Surface Energy Balance (SSEBop) model across the state of South Dakota (SD), USA for the 1986–2018 (33-year) period. Validated ETa estimations (r² = 0.91, PBIAS = −4%, and %RMSE = 11.8%) were further used to understand the crop water-use characteristics and existing historic mono-directional (increasing/decreasing) trends over the eastern (ESD) and western (WSD) regions of SD. The crop water-use characteristics indicated that the annual cropland water uses across the ESD and WSD were more or less met by the precipitation amounts in the area. The ample water supply and distribution have led to high rainfed and low percentage of irrigated cropland (~2.5%) in the state. The WSD faced greater crop-water use reductions than the ESD during drought periods. The landscape ETa responses across the state were found to be more sensitive than precipitation for the drought impact assessments. The Mann Kendall trend analysis revealed the absence of a significant trend (p > 0.05) in annual ETa at a regional scale due to the varying weather conditions in the state. However, about 12% and 9% cropland areas in the ESD and WSD, respectively, revealed a significant mono-directional trend at pixel scale ETa. Most of the pixels under significant trend showed an increasing trend that can be explained by the shift in agricultural practices, increased irrigated cropland area, higher productions, moisture regime shifts, and decreased risk of farming in the dry areas. The decreasing trend pixels were clustered in mid-eastern SD and could be the result of dynamic conversion of wetlands to croplands and decreased irrigation practices in the region. This study also demonstrates the tremendous potential and robustness of the SSEBop model, Landsat imagery, and remote sensing-based ETa modelling approaches in estimating consistent spatially distributed evapotranspiration.  相似文献   

A possible 5 km wide impact structure with associated 22 km wide exterior collapse terrain in the Alhabia–Tabernas Basin,southeastern Spain     

Sebastián Tomás Sánchez Gómez  Jens Ormö  Carl Alwmark  Sanna Holm-Alwmark  Gabriel Zachén  Robert Lilljequist  Juan Antonio Sánchez Garrido 《Meteoritics & planetary science》2023,58(10):1512-1539

The Tabernas–Alhabia Basin is a structural depression situated in the province of Almería, southeastern Spain. The basin is filled with Neogene, Pliocene, and Pleistocene sediments resting discordantly on a Paleozoic metamorphic basement. During the marine Tortonian sedimentation, a bed of breccia (Gordo megabed) was formed. It consists of rotated sedimentary megablocks commonly capped and/or surrounded by a polymict breccia composed mainly of up to dm-sized clasts of the crystalline (schist) basement. Previous work has suggested the bed to be a seismite corresponding to events induced by earthquakes. Here, we link the formation of the Gordo megabed with an ∼5 km wide, rimmed depression with exposed breccias on the northern flank of the Sierra de Gádor mountain. This semicircular structure, developed in mainly schists and dolostone of the basement, is delimited to the W, S, and E by an up to 350 m high escarpment with overturned stratigraphy. Toward the north, this crater-like structure opens toward the Gordo megabed of the Tabernas Basin. In the southern sector, the overturned strata transform outward for into a blocky allochthonous breccia with decreasing thickness and clast size. In the interior of the structure, there are occurrences of graded breccia and arenite superposed on a blocky, autochthonous breccia. Based on the presence of mineralogical shock metamorphic evidence, potential shatter cones, and a high Ir anomaly (∼500 ppb) as well as the position of the structure near the town of Alhama de Almería, we propose to call it the Alhama de Almería impact structure.  相似文献   

Trace metal behaviour in riverine sediments: Role of organic matter and sulfides     

Adeline CharriauLudovic Lesven  Yue GaoMartine Leermakers  Willy BaeyensBaghdad Ouddane  Gabriel Billon 《Applied Geochemistry》2011,26(1):80-90

Three sediment cores were collected in the Scheldt, Lys and Spiere canals, which drain a highly populated and industrialized area in Western Europe. The speciation and the distribution of trace metals in pore waters and sediment particles were assessed through a combination of computational and experimental techniques. The concentrations of dissolved major and trace elements (anions, cations, sulfides, dissolved organic C, Cd, Co, Fe, Mn, Ni, Pb and Zn) were used to calculate the thermodynamic equilibrium speciation in pore waters and to evaluate the saturation of minerals (Visual Minteq software). A sequential extraction procedure was applied on anoxic sediment particles in order to assess the main host phases of trace elements. Manganese was the most labile metal in pore waters and was mainly associated with carbonates in particles. In contrast, a weak affinity of Cd, Co, Ni, Pb and Zn with carbonates was established because: (1) a systematic under-saturation was noticed in pore waters and (2) less than 10% of these elements were extracted in the exchangeable and carbonate sedimentary fraction. In the studied anoxic sediments, the mobility and the lability of trace metals, apart from Mn, seemed to be controlled through the competition between sulfidic and organic ligands. In particular, the necessity of taking into account organic matter in the modelling of thermodynamic equilibrium was demonstrated for Cd, Ni, Zn and Pb, the latter element exhibiting the strongest affinity with humic substances. Consequently, dissolved organic matter could favour the stabilization of trace metals in the liquid phase. Conversely, sulfide minerals played a key role in the scavenging of trace metals in sediment particles. Finally, similar trace metal lability rankings were obtained for the liquid and solid phases.  相似文献   

An EUV imaging spectrograph for high-resolution observations of the solar corona     

Werner M. Neupert  Gabriel L. Epstein  Roger J. Thomas  William T. Thompson 《Solar physics》1992,137(1):87-104

An extreme ultraviolet (EUV) imaging spectrograph for the wavelength range from 235 to 450 Å has been developed and used for high resolution observations of the Sun. The instrument incorporates a glancing incidence Wolter Type II Telescope and a near-normal incidence toroidal grating spectrograph to achieve near-stigmatic performance over this spectral range. The design of the spectrograph entrance aperture enables both stigmatic spectra with spectral resolution adequate to observe emission line profiles and spectroheliograms of restricted portions of the Sun to be obtained concurrently. In this paper we describe the design and performance of the instrument and provide an overview of results obtained during a sounding rocket flight on May 5, 1989.  相似文献   

First Results on it p Modes from GOLF Experiment     

M. Lazrek  F. Baudin  L. Bertello  P. Boumier  J. Charra  D. Fierry-Fraillon  E. Fossat  A. H. Gabriel  R. A. García  B. Gelly  C. Gouiffes  G. Grec  P. L. Pallé  F. Pérez Hernández  C. Régulo  C. Renaud  J.-M. Robillot  T. Roca Cortés  S. Turck-Chièze  R. K. Ulrich 《Solar physics》1997,175(2):227-246

The GOLF experiment on the SOHO mission aims to study the internal structure of the Sun by measuring the spectrum of global oscillations in the frequency range 10^-7 to 10^-2 Hz. Here we present the results of the analysis of the first 8 months of data. Special emphasis is put into the frequency determination of the p modes, as well as the splitting in the multiplets due to rotation. For both, we show that the improvement in S/N level with respect to the ground-based networks and other experiments is essential in achieving a very low-degree frequency table with small errors ∼ 2 parts in 10^-5). On the other hand, the splitting found seems to favour a solar core which does not rotate slower than its surface. The line widths do agree with theoretical expectations and other observations.  相似文献   

Astronomy and astrophysics,sub-vol. a: Methods,constants, solar system: K. Schaifers and H. H. Voigt (editors): Landolt-Bornstein group VI,vol. 2 Springer,Berlin 1981. xviii + 305 pp. $237.50.     

A.H. Gabriel 《Planetary and Space Science》1983,31(1):141

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The influence of large-scale structures on halo shapes and alignments     

Gabriel Altay  Jörg M. Colberg  Rupert A. C. Croft 《Monthly notices of the Royal Astronomical Society》2006,370(3):1422-1428

Alignments of galaxy clusters (the Binggeli effect), as well as of galaxies themselves have long been studied both observationally and theoretically. Here, we test the influence of large-scale structures and tidal fields on the shapes and alignments of cluster-size and galaxy-size dark matter haloes. We use a high-resolution N -body simulation of a Λ cold dark matter (ΛCDM) universe, together with the results of Colberg, Krughoff & Connolly, who identified filaments connecting pairs of clusters. We find that cluster pairs connected by a filament are strongly aligned with the cluster–cluster axis, whereas unconnected ones are not. For smaller, galaxy-size haloes, there also is an alignment signal, but its strength is independent of whether the halo is part of an obvious large-scale structure. Additionally, we find no measurable dependence of galaxy halo shape on membership of a filament. We also quantify the influence of tidal fields and find that these do correlate strongly with alignments of haloes. The alignments of most haloes are thus caused by tidal fields, with cluster-size haloes being strongly aligned through the added mechanism of infall of matter from filaments.  相似文献   

Uncertainty in Shear-Wave Velocity Profiles     

Toro  Gabriel R. 《Journal of Seismology》2022,26(4):713-730

Journal of Seismology - This paper considers the uncertainty in the shear wave velocity (Vs) of soil and rock profiles for use in earthquake site response calculations. This uncertainty is an...  相似文献   

Analysis and catalogue of sneaker waves in the US Pacific Northwest between 2005 and 2017     

Gabriel García-Medina  H. Tuba Özkan-Haller  Peter Ruggiero  Rob A. Holman  Troy Nicolini 《Natural Hazards》2018,94(2):583-603

Sneaker waves are responsible for many casualties and beach rescues in the Pacific Northwest (PNW) region of the USA. In this paper, a catalogue of these events from 2005 to mid-2017 in Oregon and Northern California is presented. The events are grouped depending on the local characteristics into those involving structures, semi-enclosed beaches, and open-coast beaches. It was found that sneaker waves occurred between the months of October and April, which is also the time of the year of most storm activity in the PNW. The majority of the events are associated with long-period swell approaching the coast. Beach slope and significant wave height were not found to correlate with sneaker wave incidents. However, total water level analysis reveals that the run-up level was expected to reach the beachgoers for the majority of the investigated cases indicating that a forecasting system to warn beachgoers is possible.  相似文献   

Earthquake damage assessment for deterministic scenarios in Iquique,Chile     

Paula Aguirre  Jorge Vásquez  Juan Carlos de la Llera  Juan González  Gabriel González 《Natural Hazards》2018,92(3):1433-1461

Risk evaluation and loss analysis is key in foreseeing the impact of disasters caused by natural hazards and may contribute effectively in improving resilience in a community through the pre-evaluation of preparedness and mitigation actions. The pilot study presented herein is for the Chilean city of Iquique, which is located at the core of a seismic gap that extends from south Perú to north Chile, and has strategic geopolitical and economic importance for the country. The region was hit April 1, 2014, by an \(M_\mathrm{w}\) 8.2 earthquake that caused only moderate damage, but seismological evidence suggests that there is still a potential for a much larger event in the region. Therefore, a careful damage assessment study is fundamental to anticipate the possible physical, social, and economic consequences that Iquique may face in the future. In this work, the HAZUS-MH platform was adapted and used to simulate a set of ten plausible physics-based future seismic scenarios with magnitudes ranging from \(M_\mathrm{w}\) 8.40 to \(M_\mathrm{w}\) 8.98, which were proposed based on an analysis of interplate locking and the residual slip potential remaining after the April 1, 2014, earthquake. Successful application of this damage assessment methodology relies on the construction of a comprehensive exposure model that takes into account regional features and a good characterization of the physical vulnerabilities. For Iquique, a large body of public and local data was used to develop a detailed inventory of physical and social assets including an aggregated building count, demographics, and essential facilities. To characterize the response of the built environment to seismic demand, appropriate HAZUS fragility curves were applied, and outcomes were validated against the damage observed in the 2014 earthquake. After satisfactory testing, a deterministic earthquake damage assessment study was carried out for the collection of predictive scenarios aimed to estimate their expected impacts. This analysis provides data for future evaluations of different physical and social mitigation measures for the city.  相似文献