The influence of geology and land-use on inorganic stream water quality in the Oslo region,Norway     

Clemens Reimann  Tor Erik Finne  Øystein Nordgulen  Ola Magne Sæther  Arnold Arnoldussen  David Banks 《Applied Geochemistry》2009

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Bifurcation modelling in a meandering gravel–sand bed river     

Kees Sloff  Erik Mosselman 《地球表面变化过程与地形》2012,37(14):1556-1566

The Rhine bifurcation at Pannerden forms the major distribution point for water supply in the Netherlands, distributing not only water and sediment but also flooding risks and navigability. Its morphological stability has been a concern for centuries. We present experiences from more than two decades of numerical morphological modelling of this bifurcation with a gravel–sand bed and a meandering planform. Successive computations have shown the importance of upstream approach conditions, the necessity to include physical mechanisms for grain sorting and alluvial roughness, and the need to assume a thicker active layer of the river bed than is suggested by laboratory flume experiments using a constant discharge. The active layer must be thicker in the model to account for river bed variations due to higher‐frequency discharge variations that are filtered out in morphological modelling. We discuss limitations in calibration and verification, but argue that, notwithstanding these limitations, 2D and 3D morphological models are valuable tools, not only for pragmatic applications to engineering problems, but also for revealing the limitations of established knowledge and understanding of the relevant physical processes. The application of numerical models to the Pannerden bifurcation appeared to reveal shortcomings in established model formulations that do not pose particular problems in other cases. This application is therefore particularly useful for setting the agenda for further research. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Modelling the effect of climate change on the wave climate of the world’s oceans     

Erik Vanem  Bent Natvig  Arne Bang Huseby 《Ocean Science Journal》2012,47(2):123-145

This paper analyses the trends and the future projections of significant wave height in several ocean areas at different parts of the world. It uses a stochastic Bayesian hierarchical space-time model, with a regression component with atmospheric levels of CO₂ as covariates in order to estimate the expected long-term trends and make future projections towards the year 2100. The model was initially developed for an area in the North Atlantic ocean, and has been found to perform reasonably well there, and it is now investigated how the model performs for other ocean areas. 11 new ocean areas have been analysed with the model, and this paper presents the results pertaining to the estimated long-term trends and future projections of monthly maximum significant wave height for each of the 12 ocean areas.  相似文献   

Sensitivity of tidal motion in well-mixed estuaries to cross-sectional shape,deepening, and sea level rise     

Erik Ensing  Huib E. de Swart  Henk M. Schuttelaars 《Ocean Dynamics》2015,65(7):933-950

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Closed Circuit Television (CCTV) Earthquake Behaviour Coding Methodology: analysis of Christchurch Public Hospital video data from the 22 February Christchurch earthquake event     

Emily S. Lambie  Thomas M. Wilson  Erik Brogt  David M. Johnston  Michael Ardagh  Joanne Deely  Steven Jensen  Shirley Feldmann-Jensen 《Natural Hazards》2017,86(3):1175-1192

Earthquake epidemiological research indicates that the behavioural response influences the nature and severity of injuries sustained. However, there is no observational evidence of the actions individuals engage in during and immediately following earthquake shaking, and the context in which earthquake injuries and deaths are caused. Closed Circuit Television Earthquake Behaviour Coding Methodology has been developed as a tool to classify human behaviour during and immediately following earthquake shaking using real event video data. The coding methodology was applied to security video data captured during the 22 February 2011 M_w6.3 ‘Christchurch’ earthquake event from the Christchurch Public Hospital which experienced shaking intensity of MM9 lasting approximately 12–15 s. We applied this coding methodology to determine: demography, trans-event behavioural responses, post-event behavioural responses, influence of social context on behaviour, and influence of behaviour on injuries. A total of 213 individuals from 31 different camera views were analysed. Sixty-six per cent of the individuals were adult-aged females. The primary trans-event responses were to hold (26%) onto furniture, walls, and/or other people close to them and to look around (30%). No individuals were observed to perform all ‘Drop, Cover, Hold’ actions, the recommended action during strong earthquake shaking in New Zealand. Post-event behaviour included: running, walking, providing assistance, moving towards others, visual communication, and some individuals gave instructions. Social contextual behaviour varied depending on the role of the adult. There were no serious injuries linked to behaviour. The results of this initial study indicate the coding methodology can record the distribution of and variation in human behaviours. Therefore, objective observation of earthquake video data can provide a useful quantitative measure of human behaviour. Significantly, the process will enable researchers to look more closely at behaviours, as well as the social and physical contexts associated with injury risk during and immediately following earthquake shaking.  相似文献   

Magnetostratigraphic correlation of the Oxfordian–Kimmeridgian boundary     

Piotr A. Przybylski  James G. Ogg  Andrzej Wierzbowski  Angela L. Coe  Mark W. Hounslow  John K. Wright  François Atrops  Erik Settles 《Earth and Planetary Science Letters》2010,289(1-2):256-272

A magnetic polarity pattern for Boreal and Sub-Boreal ammonite zones of the Upper Oxfordian to Lower Kimmeridgian was established and confirmed in four British sections, including the proposed Global Boundary Stratotype Section and Point (GSSP) on the Isle of Skye (Scotland) to define the base of the international Kimmeridgian Stage. A coeval pattern for Sub-Mediterranean ammonite zones was compiled from seven sections in Poland, one German section and multi-section composites from France and Spain. The mean paleopole for the European Craton (excluding Spain) at the Oxfordian–Kimmeridgian boundary is 74.2°N, 181.3°E (Α₉₅ = 3.8°). The common magnetic polarity scale enables inter-correlation of ammonite subzones among these three faunal provinces and to the marine magnetic-anomaly M-Sequence. The proposed GSSP at the base of the Pictonia baylei Zone is near the base of an extended interval dominated by reversed polarity, which is interpreted to be Chron M26r. This GSSP level projects to the lower to middle part of the Epipeltoceras bimammatum Subzone, which is the middle subzone of this E. bimammatum Zone in the Sub-Mediterranean standard zonation. In contrast, the traditional placement of the Oxfordian–Kimmeridgian boundary in that Sub-Mediterranean standard zonation (base of Sutneria platynota Zone) is at the base of Chron M25r, or nearly 1 million years younger.  相似文献   

The role of biogenic structures on the biogeochemical functioning of mangrove constructed wetlands sediments - A mesocosm approach     

Gil Penha-Lopes  Erik Kristensen  Perrine Mangion  José Paula 《Marine pollution bulletin》2010,60(4):560-572

Benthic metabolism (measured as CO₂ production) and carbon oxidation pathways were evaluated in 4 mangrove mesocosms subjected daily to seawater or 60% sewage in the absence or presence of mangrove trees and biogenic structures (pneumatophores and crab burrows). Total CO₂ emission from darkened sediments devoid of biogenic structures at pristine conditions was comparable during inundation (immersion) and air exposure (emersion), although increased 2-7 times in sewage contaminated mesocosms. Biogenic structures increased low tide carbon gas emissions at contaminated (30%) and particularly pristine conditions (60%). When sewage was loaded into the mesocosms under unvegetated and planted conditions, iron reduction was substituted by sulfate reduction and contribution of aerobic respiration to total metabolism remained above 50%. Our results clearly show impacts of sewage on the partitioning of electron acceptors in mangrove sediment and confirm the importance of biogenic structures for biogeochemical functioning but also on greenhouse gases emission.  相似文献   

The Arctic is no longer put on ice: Evaluation of Polar cod (Boreogadussaida) as a monitoring species of oil pollution in cold waters     

Henrik Jonsson  Endre Aas  Steinar Sanni 《Marine pollution bulletin》2010,60(3):390-395

The withdrawing Arctic ice edge will facilitate future sea transport and exploration activities in the area, which calls for the establishment of relevant cold water monitoring species. The present study presents first results of field baseline levels for core oil pollution biomarkers in Polar cod (Boreogadussaida) sampled from pristine, Arctic waters. Furthermore, biomarker response levels were characterized in controlled laboratory exposure experiments running over 2 weeks. Fish exposed to a simulated petrogenic spill (1 ppm dispersed, crude oil) exhibited elevated hepatic EROD activity, bile PAH-metabolites, and hepatic DNA-adducts, whereas male individuals exposed to simulated produced water (30 ppb nonylphenol) exhibited a strong induction of plasma vitellogenin. In conclusion, the results demonstrated low and robust biomarker baseline levels that were clearly different from exposure responses. In combination with its high abundance and circumpolar distribution, the Polar cod seems well qualified for oil pollution monitoring in Arctic waters.  相似文献   

Hydrological response of an afforested catchment in a Mediterranean humid mountain area: a comparative study with a natural forest   总被引：1，自引：0，他引：1       下载免费PDF全文

Estela Nadal‐Romero  Erik Cammeraat  María Pilar Serrano‐Muela  Noemí Lana‐Renault  David Regüés 《水文研究》2016,30(15):2717-2733

The effects of afforestation on water resources are still controversial. The aim of this paper is to (i) analyse the hydrological response of an afforested area in the Central Pyrenees and (ii) compare the hydrological response of an afforested area with the response observed in a natural undisturbed forest. The Araguás catchment was cultivated until the 1950s, and then afforested with pines in an effort to control the active degradation processes. The hydrological response was variable and complex, because the discharge was generated by a combination of distinct runoff processes. The hydrological response showed that (i) afforestation produced moderate peak discharges, stormflows and recession limbs, and long rising limbs; (ii) no one single variable was able to explain the hydrological response: rainfall volume and intensity did not explain the hydrological response and antecedent rainfall and initial discharge (indicating antecedent moisture conditions) did play an important role; (iii) seasonal differences were observed suggesting different runoff generating processes; and (iv) the effect of forest cover on peak discharges became less important as the size of the hydrological event increased. The stormflow coefficient showed a clear seasonal pattern with an alternation between a wet period, when the catchment was hydrologically responsive, and a dry summer period when the catchment rarely responded to any event, and two transitional periods (wetting and drying). Compared with a natural forest, the afforested area recorded greater flows and peak discharges, faster response times and shorter recession limbs. Afforestation reduces the water yield and the number of floods compared with non‐vegetated areas and abandoned lands. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Comparison of linear and nonlinear shallow wave water equations applied to tsunami waves over the China Sea   总被引：4，自引：0，他引：4  

Yingchun Liu  Yaolin Shi  David A. Yuen  Erik O. D. Sevre  Xiaoru Yuan  Hui Lin Xing 《Acta Geotechnica》2009,4(2):129-137

This paper discusses the applications of linear and nonlinear shallow water wave equations in practical tsunami simulations. We verify which hydrodynamic theory would be most appropriate for different ocean depths. The linear and nonlinear shallow water wave equations in describing tsunami wave propagation are compared for the China Sea. There is a critical zone between 400 and 500 m depth for employing linear and nonlinear models. Furthermore, the bottom frictional term exerts a noticeable influence on the propagation of the nonlinear waves in shallow water. We also apply different models based on these characteristics for forecasting potential seismogenic tsunamis along the Chinese coast. Our results indicate that tsunami waves can be modeled with linear theory with enough accuracy in South China Sea, but the nonlinear terms should not be neglected in the eastern China Sea region.  相似文献