Digital mapping of coastal boulders – high-resolution data acquisition to infer past and recent transport dynamics     

Fabian Boesl  Max Engel  Rodrigo C. Eco  JaN B. Galang  Lia A. Gonzalo  Francesca Llanes  Eva Quix  Helmut Brückner 《Sedimentology》2020,67(3):1393-1410

Coastal boulder fields provide clues to long-term frequency-magnitude patterns of coastal flooding events and have the potential to play an important role in coastal hazard assessment. Mapping boulders in the field is time and labour-intensive, and work on intertidal reef platforms, as in the present study, is physically challenging. By addressing coastal scientists who are not specialists in remote sensing, this contribution reports on the possibilities and limitations of digital applications in boulder mapping in Eastern Samar, Philippines, where recent supertyphoons Haiyan and Hagupit induced high waves, coastal flooding and boulder transport. It is demonstrated how satellite imagery of sub-metre resolution (from Pléiades and WorldView-3 imagery) enables efficient analysis of transport vectors and distances of larger boulders, reflecting variation in latitudes of both typhoon tracks and approaching angles of typhoon-generated waves. During the investigated events, boulders with a-axes of up to 8 m were clearly identified to have been shifted for up to 32 m, mostly along the seaward margin of the boulder field. It is, however, hard to keep track of smaller boulders, and the length of a-axes and b-axes including their orientation is often impossible to map with sufficient accuracy. Orthophotographs and digital surface models created through the application of an unmanned aerial vehicle and the ‘Structure from Motion’ technique provide ultra-high-resolution data, and have the potential to not only improve the results of satellite image analysis, but also those from field mapping and may significantly reduce overall time in the field. Orthophotographs permit unequivocal mapping of a-axes and b-axes including their orientation, while precise values for c-axes can be derived from the respective digital surface models. Volume of boulders is best inferred from boulder-specific Structure from Motion-based three-dimensional models. Battery power, flight speed and altitude determine the limits of the area covered, while patches shielded by the boulders are difficult to resolve. For some tasks, field mapping remains mandatory and cannot be replaced by currently available remote sensing tools: for example, sampling for rock type, density and age dating, recording of lithological separation of boulders from the underlying geological unit and of geomorphic features on a millimetre to decimetre-scale, or documentation of fine-grained sediment transport in between the boulders in supratidal settings. In terms of future events, the digital products presented here will provide a valuable reference to track boulder transport on a centimetre to decimetre-scale and to better understand the hydrodynamics of extreme-wave events on a fringing reef coastline.  相似文献   

How much does an extreme rainfall event cost? Material damage and relationships between insurance,rainfall, land cover and urban flooding   总被引：1，自引：0，他引：1  

Miguel Leal  Inês Boavida-Portugal  Marcelo Fragoso  Catarina Ramos 《水文科学杂志》2019,64(6):673-689

This research aims to understand how insurance, rainfall, land cover and urban flooding are related and how these variables influenced the material damage in the Lisbon Metropolitan Area (LMA) during the 2000–2011 period. Correlation coefficients show strong relationships between built-up areas and claims (0.94) and payouts (0.88). Despite no significant relationships being found between rainfall and the amount of material damage per event, three likelihood levels of flooding were determined for hourly rainfall. Unlike the studied period, the number of claims and their spatial distribution during the 2008 extreme rainfall event were strongly dependent on rainfall. Flooding related to the old watercourses assumed greater importance during this extreme event, recovering a more natural/ancient hydrological behaviour. In the LMA, the greatest material damage was the result of high-magnitude/low-probability rainfall events. Lower magnitude events can trigger numerous claims in heavily built-up areas, but they are hardly capable of producing large material damage.  相似文献   

Biocrust landscape-scale spatial distribution is strongly controlled by terrain attributes: Topographic thresholds for colonization in a semiarid badland system     

Emilio Rodríguez-Caballero  José Raúl Román  Sonia Chamizo  Beatriz Roncero Ramos  Yolanda Cantón 《地球表面变化过程与地形》2019,44(14):2771-2779

Biological soil crust, or biocrust communities, are the dominating life form in many extreme habitats, such as arid and semiarid badlands, where water scarcity and highly erodible substrates limit vegetation cover. While climate, soil and biotic factors have been described as environmental filters influencing biocrust distribution in such biomes, little is known about the effect of terrain attributes on creating specific microhabitats that promote or restrict biocrust colonization. This study aimed to identify the main terrain attributes controlling biocrust distribution in the driest badland system in Europe, the Tabernas Badlands (SE Spain). To do this, we analysed the influence of different terrain attributes related to landscape stability and microclimate formation on the spatial distribution of lichen and cyanobacteria, using field measurements and topographical information from a LiDAR survey. Our results showed that the spatial distribution of cyanobacteria-dominated biocrusts, which are physiologically and morphologically adapted to extreme drought and high UVA radiation, was mostly associated with areas of high potential incoming solar radiation. The exception was bare south-aspect hillslopes with very high sediment transport potential, where bare physically crusted soils were the dominant ground cover. Lichen-dominated biocrusts, in contrast, colonized near the top of north-aspect hillslopes, characterized by low potential incoming solar radiation and potential evapotranspiration, and their cover decreased downstream, as conditions became good enough for vascular plants. © 2019 John Wiley & Sons, Ltd. © 2019 John Wiley & Sons, Ltd.  相似文献   

How Well Does Chlorophyll Explain the Seasonal Variation in Phytoplankton Activity?     

Maren Moltke Lyngsgaard  Stiig Markager  Katherine Richardson  Eva Friis Møller  Hans Henrik Jakobsen 《Estuaries and Coasts》2017,40(5):1263-1275

The seasonal variation in phytoplankton activity is determined by analysing 1385 primary production (PP) profiles, chlorophyll a (Chl) concentration profiles and phytoplankton carbon biomass concentrations (C) from the period 1998–2012. The data was collected at six different stations in the Baltic Sea transition zone (BSTZ) which is a location with strong seasonal production patterns with light as the key parameter controlling this productivity. We show that the use of Chl as a proxy for phytoplankton activity strongly overestimates the contribution from the spring production to annual pelagic carbon flow. Spring (February and March) Chl comprised 16–30% of the total annual Chl produced, whereas spring C was much lower (8–23%) compared to the annual C. Spring PP accounted for 10–18% of the total annual PP, while the July–August production contributed 26–33%, i.e. within the time frame when zooplankton biomass and grazing pressure are highest. That is, Chl failed in this study to reflect the importance of the high summer PP. A better proxy for biomass may be C, which correlated well with the seasonal pattern of PP (Pearson correlation, p < 0.05). Thus, this study suggests to account for the strong seasonal pattern in C/Chl ratios when considering carbon flow in coastal systems. Seasonal data for PP were fitted to a simple sinusoidal wave model describing the seasonal distribution of PP in the BSTZ and were proposed to present a better parameterizaton of PP in shallow stratified temperate regions than more commonly applied proxies.  相似文献   

Groundwater Modeling with MODFLOW as a Web Application          下载免费PDF全文

Yao Hu  Albert J. Valocchi  Samantha A. Lindgren  Evan A. Ramos  Rebecca A. Byrd 《Ground water》2015,53(6):834-835

  相似文献   

Application of diffracted wave analysis to time‐lapse seismic data for CO2 leakage detection     

Faisal Alonaizi  Roman Pevzner  Andrej Bóna  Mohammad Alshamry  Eva Caspari  Boris Gurevich 《Geophysical Prospecting》2014,62(2):197-209

Time‐lapse seismic analysis is utilized in CO₂ geosequestration to verify the CO₂ containment within a reservoir. A major risk associated with geosequestration is a possible leakage of CO₂ from the storage formation into overlaying formations. To mitigate this risk, the deployment of carbon capture and storage projects requires fast and reliable detection of relatively small volumes of CO₂ outside the storage formation. To do this, it is necessary to predict typical seepage scenarios and improve subsurface seepage detection methods. In this work we present a technique for CO₂ monitoring based on the detection of diffracted waves in time‐lapse seismic data. In the case of CO₂ seepage, the migrating plume might form small secondary accumulations that would produce diffracted, rather than reflected waves. From time‐lapse data analysis, we are able to separate the diffracted waves from the predominant reflections in order to image the small CO₂ plumes. To explore possibilities to detect relatively small amounts of CO₂, we performed synthetic time‐lapse seismic modelling based on the Cooperative Research Centre for Greenhouse Gas Technologies (CO2CRC) Otway project data. The detection method is based on defining the CO₂ location by measuring the coherency of the signal along diffraction offset‐traveltime curves. The technique is applied to a time‐lapse stacked section using a stacking velocity to construct offset‐traveltime curves. Given the amount of noise found in the surface seismic data, the predicted minimum detectable amount of CO₂ is 1000–2000 tonnes. This method was also applied to real data obtained from a time‐lapse seismic physical model. The use of diffractions rather than reflections for monitoring small amounts of CO₂ can enhance the capability of subsurface monitoring in CO₂ geosequestration projects.  相似文献   

Early contamination of European flounder (Platichthys flesus) by PCDD/Fs and dioxin-like PCBs in European waters     

Margarida Nunes  Filipe Martinho  Anaïs Vernisseau  Philippe Marchand  Bruno Le Bizec  Henk W. van der Veer  Henrique N. Cabral  Fernando Ramos  Miguel A. Pardal 《Marine pollution bulletin》2014

Contamination levels and profiles of 7 polychlorinated-p-dioxins, 10 polychlorinated furans (PCDD/Fs) and 12 dioxin-like polychlorinated biphenyls (dl-PCBs) were investigated in juvenile European flounder (Platichthys flesus) captured in different nursery areas in the northeastern Atlantic coast across its geographical distribution range. The toxic equivalent concentrations (WHO-TEQ_fish) were also determined in order to evaluate which P. flesus population was more exposed to dioxin-like toxicity. Juveniles caught in the Sørfjord (Norway) showed the lowest WHO-TEQ_fish concentration (0.052 pg WHO-TEQ_fish g⁻¹ wet weight) whereas the highest value was observed in fish from the Wadden Sea (The Netherlands; 0.291 pg WHO-TEQ_fish g⁻¹ ww), mainly due to the greater contribution of 2,3,7,8-tetrachlorodibenzo-p-dioxin, the most toxic congener. Nonetheless, when comparing the results with existent tissue residue-based toxicity benchmarks, no adverse effects resulting from PCDD/Fs and dl-PCBs are expected to occur in flounder from the studied systems.  相似文献   

Removal of Pyridine from Aqueous Solution by Adsorption on an Activated Carbon Cloth     

Pedro Alonso‐Davila  Oliva L. Torres‐Rivera  Roberto Leyva‐Ramos  Raul Ocampo‐Perez 《洁净——土壤、空气、水》2012,40(1):45-53

Pyridine is a very toxic pollutant that has to be removed from wastewater. In this work, adsorption of pyridine on activated carbon cloth (ACC) is studied as a possible alternative for eliminating pyridine from aqueous solution. The ACC was produced from polyacrylonitrile. The adsorption equilibrium data of pyridine on ACC was obtained in a batch adsorber. The experimental data was interpreted with the isotherms of Langmuir, Freundlich, and Prausnitz‐Radke (PR), and the PR isotherm better represented the experimental data. The capacity of ACC for adsorbing pyridine was favored increasing the solution pH from 3 to 6, and this effect was due to the π–π dispersive and electrostatic interactions between the pyridine species in solution and the surface complexes of ACC. The modified Langmuir model fitted reasonably well the influence of pH on the adsorption capacity. In this model was assumed that both neutral pyridine and pyridinium were simultaneously adsorbed on ACC accordingly to the experimental results. The adsorption capacity was almost independent of temperature. The reversibility study revealed that 75% of the pyridine can be desorbed from ACC indicating that part of the pyridine was irreversibly adsorbed, and possibly chemisorbed.  相似文献   

Illicit Drugs in the Environment: Occurrence,Analysis, and Fate Using Mass Spectrometry     

Eva Pocurull 《洁净——土壤、空气、水》2012,40(11):1307-1307

  相似文献   

全球重要农业文化遗产(GIAHS)经济评估概念框架:以中国稻鱼共生系统为例（英文）   总被引：2，自引：1，他引：1  

Sonja BERWECK  Parviz KOOHAFKAN  Mary Jane Ramos dela CRUZ  闵庆文  焦雯珺  孙业红  刘某承 《资源与生态学报(英文版)》2013,4(3):202-211

全球重要农业文化遗产(GIAHS)项目是2002年由联合国粮农组织(FAO)发起,旨在建立全球重要农业文化遗产及其有关的景观、生物多样性、知识和文化保护体系,并在世界范围内得到认可与保护,使之成为可持续管理的基础。农业文化遗产地往往被认为比非遗产地更具经济价值,但目前还没有经济学分析来证明这一点,也没有任何针对农业文化遗产地的复杂的经济性能标准来长期监测其经济功能。本研究的目的在于建立一个经济评价方法,可用于遗产地与非遗产地之间比较。为此,本文选择了成本效益分析(CBA)方法。鉴于数据可得性的限制,经济分析的框架应该包括分析的方向、假设和数据要求,由此指导未来对GIAHS的经济评价。本研究选择中国青田稻鱼共生系统作为案例,根据数据可得性并针对不同活动(旅游,国内和国际市场的销售产品)以及相似系统间比较进行计算。  相似文献