Style Transfer applied to CT image downscaling: a study case from Brazilian Coquinas     

Souza  João Paulo da Ponte  Avansi  Michelle Chaves Kuroda  Belila  Aline Maria Poças  Vidal  Alexandre Campane 《Computational Geosciences》2021,25(5):1457-1471

Computational Geosciences - The identification of micropore systems in carbonate rocks is an important task of image processing because of the high impact these systems cause on fluid flow....  相似文献   

Transpiration in Quercus suber trees under shallow water table conditions: the role of soil and groundwater          下载免费PDF全文

Clara A. Pinto  Nadezhda Nadezhdina  Jorge S. David  Cathy Kurz‐Besson  Maria C. Caldeira  Manuel O. Henriques  Fernando G. Monteiro  João S. Pereira  Teresa S. David 《水文研究》2014,28(25):6067-6079

Water is one of the major environmental factors limiting plant growth and survival in the Mediterranean region. Quercus suber L. woodlands occupy vast areas in the Iberian Peninsula, frequently under shallow water table conditions. The relative magnitude of soil and groundwater uptake to supply transpiration is not easy to evaluate under these circumstances. We recently developed a conceptual framework for the functioning of the root system in Q. suber that simulates well tree transpiration, based on two types of root behaviour: shallow connected and deep connected. Although this significantly improved knowledge on the functional traits of Mediterranean Q. suber, the approach has the limitation of requiring root sap flow data, which are seldom available. In this work, we present alternative methodologies to assess if trees are connected to groundwater and to estimate the soil and groundwater contributions to tree transpiration. We provide evidence on the tree unrestricted access to groundwater solely based on meteorological, stem sap flow and leaf water potential data. Using a soil mass balance approach, we estimated the yearly soil and groundwater contributions to tree transpiration: 69.7% and 30.3%, respectively. Groundwater uptake became dominant in the dry summer: 73.2% of tree transpiration. Results reproduce extremely well those derived from root modelling. Because of its simplicity both in formulation and data requirements, our approach is potentially liable to be adapted to other groundwater‐dependent Mediterranean oak sites, where interactions between land use and water resources may be relevant. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Effect of temporal resolution of water level and temperature inputs on numerical simulation of groundwater–surface water flux exchange in a heavily modified urban river     

Girma Yimer Ebrahim  Kelly Hamonts  Ann van Griensven  Andreja Jonoski  Winnie Dejonghe  Arthur Mynett 《水文研究》2013,27(11):1634-1645

Groundwater interacts with surface water features nearly in all types of landscapes. Understanding these interactions has practical consequences on the quantity and quality of water in either system, because the depletion or contamination of one of the systems will eventually affect the other one. Many studies have shown that the use of heat as natural tracer in conjunction with water level measurements is an effective method for estimating water flow (fluxes) between groundwater and surface water. A number of studies have explored the effects of spatial and temporal variability of groundwater–surface water flux exchanges using temperature and water level measurements; however, the effect of temporal resolution of water level and temperature data on estimating flux remains unexplored. Therefore, this study investigated the effect of temporal resolution of input data on temporal variation of groundwater–surface water flux exchanges. To this end, we calibrated a variably saturated two‐dimensional groundwater flow and heat transport model (VS2DH) at hourly and daily time scales using temperatures measured at multiple depths below the riverbed of the Zenne River, located at a well‐known Belgian brownfield site. Results of the study showed that the computed water flux through the streambed ranged between ?32 mm/day and +25 mm/day using the hourly model and from ?10 mm/day to ?37 mm/day using the daily model. The hourly model resulted in detecting reversal of flow direction inducing short‐term surface water flow into the streambed. However, such events were not captured if daily temperature and water level measurements were used as input. These findings have important implications for understanding contaminant mass flux and their attenuation in the mixing zone of groundwater and surface water. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Intra‐messinian gypsum palaeokarst in the Northern Apennines and its palaeogeographic implications     

Jo De Waele  Giancarlo Pasini 《地学学报》2013,25(3):199-205

A short intra‐Messinian continental period has been recognised in some North Italian gypsum areas, mostly under the form of palaeokarst deposits. This emersion appears to have occurred only locally, and is explained as caused by the intra‐Messinian tectonic phase and a major sea level lowering. Evidences of this palaeokarst are mostly small, although at some places the palaeontological content of its fillings is of great importance. The discovery near Zola Predosa (Bologna) of a new intra‐Messinian extensive karst system and of its infilling sheds new light on the importance of this karst episode.  相似文献   

Kochi,India case study of climate adaptation to floods: Ranking local government investment options     

Supriya Mathew  Stefan Trück  Ann Henderson-Sellers 《Global Environmental Change》2012,22(1):308-319

Climate adaptation is uniquely linked to location, making it predominantly a local government and community responsibility. Despite the obligation to act, local governments are hindered by the absence of applicable guides to adaptation decision-making, especially adaptation to extreme events. In this paper, we describe a framework for prioritising adaptation options that could be locally implemented and illustrate it with a study of flooding in Kochi: a city in southern India. Unlike many demand driven, economics based studies, our new framework also incorporates non-economic dimensions of the extremes and potential adaptation options. Local knowledge is used to tackle data gaps and uncertainty related to extreme events: local experts select adaptation options that offer additional benefits besides those related to climate change. These co-benefits aid decision making under uncertainty by giving weight to community priorities. The Indian case study reveals that, risk evaluation and reduction need to be locally contextualised based on resources available, immediate community requirements, planning periods and local expert knowledge. Although there will be residual damage even after implementing selected options, we argue that, climate response will be most likely to be accepted when it also supports pressing needs.  相似文献   

A “large‐eddy” approach to acoustic remote sensing of turbulent kinetic energy dissipation rate ϵ     

Ann E. Gargett 《大气与海洋》2013,51(4):483-508

Abstract

This paper suggests that a “large‐eddy” technique may be used to determine ?, the rate of dissipation of turbulent kinetic energy per unit mass, from measurements of the largest energy‐containing scales of the turbulent velocity field. The suggestion has been examined using vertical velocity data from a narrow‐beam acoustic Doppler profiler and also direct measurements of ? (using airfoil probes) from a microscale profiler. Initial results are encouraging, rasing the possibility of simultaneously measuring space/time continuous fields of “mean” velocity, turbulent velocity and ? with near‐standard acoustic Doppler techniques.  相似文献   

Frequency and directional evaluation of the ocean data gathering program (ODGP) wave spectra at Hibernia     

Barbara‐Ann Juszko  Ross Graham 《大气与海洋》2013,51(3):441-456

Abstract

The frequency and directional wave‐modelling capability of the Ocean Data Gathering Program (ODGP) deep water spectral wave model is assessed through comparison with WAVEC data gathered at Hibernia. Both qualitative and quantitative analyses indicate better agreement with observations during storms and with the wind‐driven component of the wave spectra. There is statistically poor modelling of the swell. A coherence analysis on derived wave vectors indicates that the ODGP model does not simulate geophysical variability with time‐scales less than about 30 h for overall spectral energy and less than 24 h for wave energy of frequency greater than 0.6 rad s^?1 (0.095 Hz). The signals associated with swell waves are incoherent at nearly all time‐scales.  相似文献   

Polycyclic aromatic hydrocarbons in recent sediments from a subtropical estuary in Brazil     

Raphael Pietzsch  Sambasiva R. Patchineelam  João P.M. Torres 《Marine Chemistry》2010,118(1-2):56-66

The scope of this work was to evaluate the levels of polycyclic aromatic hydrocarbons (PAHs) and their possible sources in two shallow sediment cores from an estuarine area located in the south region of Brazil, the Guaratuba Bay. The estuary is encompassed by an Environmental Protection Area (EPA) of 1306 km², which is still considered to be pristine, despite recent urban growth. To assess levels of 14 selected PAHs in the sediments, among those listed as “priority pollutants” by the US Environmental Protection Agency, the cores were divided in several sections, followed by extraction, clean-up, fractionation and subsequent analysis using HPLC coupled to a fluorescence detector. Among the PAHs detected, phenanthrene and fluoranthene showed the highest concentrations. PAHs with more than four rings were usually present in low concentrations or were undetectable. To assist in the identification of possible sources, the ratios An/(An + Phe) and Flt/(Flt + Py) (anthracene to anthracene plus phenanthrene and fluoranthene to fluoranthene plus pyrene) and a PCA model were also used. Total concentrations of PAHs ranged between 1.5 and 3130 ng/g (mean 495) dry weight for the core collected in the inner part of the estuary, and between 78.5 and 3270 ng/g (mean 899) dry weight for the other core, collected in the outer part. Compared to values found in other studies in coastal zones along South American eastern margin, this area can be considered to range from low polluted to moderately polluted. From the data, it was also possible to conclude that there is predominance of petroleum sources, and essentially close to the more urbanised areas. Combustion sources have only minor contribution and are episodic, when compared to the latter.  相似文献   

Non‐synchronous deposition of North Atlantic Ash Zone II in Greenland ice cores,and North Atlantic and Norwegian Sea sediments: an example of complex glacial‐stage tephra transport     

Jo Brendryen  Haflidi Haflidason  Hans Petter Sejrup 《第四纪科学杂志》2011,26(7):739-745

Tephra provides regional chronostratigraphical marker horizons that can link different climate archives with highly needed accuracy and precision. The results presented in this work exemplify, however, that the intermittent storage of tephra in ice sheets and during its subsequent iceberg transport, especially during glacial stages, constitutes a potential source of serious error for the application of tephrochronology to Nordic Seas and North Atlantic sediment archives. The peak shard concentration of the rhyolitic component of the North Atlantic Ash Zone II (NAAZ‐II) tephra complex, often used to correlate marine and ice core records in Marine Isotope Stage (MIS) 3, is shown to lag the eruption event by ca. 100–400 years in some North Atlantic and Norwegian Sea cores. While still allowing for a correlation of archives on millennial timescales, this time delay in deposition is a major obstacle when addressing the lead–lag relationship on short timescales (years to centuries). A precise and accurate determination of lead–lag relationships between archives recording different parts of the climate system is crucial in order to test hypotheses about the processes leading to abrupt climate change and to evaluate results from climate models. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Sensitivity Analysis of Time Dependent Settlements in Hydraulic Fills     

João Flávio Vieira de Vasconcellos  Shailesh Singh  Nagaratnam Sivakugan 《Geotechnical and Geological Engineering》2010,28(4):351-360

This paper reports some numerical investigation carried out on hydraulic fills. A methodology based on the numerical solution of the governing equation via the finite volume method is introduced and tested, and proven to be very efficient. Typical dimensional performance curves are obtained and the influence of governing parameters is discussed. A sensitivity analysis is carried out in order to characterize the influence of the numerous parameters used to simulate the time dependent settlement in hydraulic fills on the outputs of the model.  相似文献