Perceptual models of uncertainty for socio-hydrological systems: a flood risk change example     

Ida K. Westerberg  Keith J. Beven  Gemma Coxon  Tobias Krueger 《水文科学杂志》2020,65(Z2):1705-1713

ABSTRACT

Characterizing, understanding and better estimating uncertainties are key concerns for drawing robust conclusions when analyzing changing socio-hydrological systems. Here we suggest developing a perceptual model of uncertainty that is complementary to the perceptual model of the socio-hydrological system and we provide an example application to flood risk change analysis. Such a perceptual model aims to make all relevant uncertainty sources – and different perceptions thereof – explicit in a structured way. It is a first step to assessing uncertainty in system outcomes that can help to prioritize research efforts and to structure dialogue and communication about uncertainty in interdisciplinary work.  相似文献   

Faecal indicator bacteria in New Zealand freshwater fish: a pilot study     

Sarah Coxon  Jon S Harding  Brent Gilpin 《新西兰海洋与淡水研究杂志》2019,53(3):470-479

Recent studies have suggested that poikilothermic animals, such as fish, may represent a previously overlooked source of the faecal indicator bacteria (FIB) used for the assessment of water quality. However, quantitative studies of FIB in poikilotherms are scarce. We investigated the presence of FIB in the faeces of five freshwater fish species. E. coli and enterococci were detected in 71 and 76% of faecal samples, respectively. Concentrations were highly variable, with maximum concentrations (2.1?×?10⁴ E. coli and 1.3?×?10⁶ enterococci per gram of faecal material) up to four orders of magnitude higher than present in the water column. FIB were not detected in faecal samples from marine fish. Our findings suggest that FIB ingested from the environment may be capable of replication within the fish gut, making fish a potential source and transport mechanism for FIB in New Zealand freshwaters. This may have implications for water quality monitoring.  相似文献   

Hydrological characterization of dammed rivers in the NW Mediterranean region          下载免费PDF全文

Gemma Piqué  Ramon J. Batalla  Sergi Sabater 《水文研究》2016,30(11):1691-1707

Water scarcity and climatic variability in the Mediterranean region have traditionally required the construction of dams to guarantee water supply for irrigation, industrial and urban uses and hydropower production. Reservoirs affect the hydrology of the river downstream, but the magnitude and persistence of these effects are still poorly unknown. Understanding the magnitude of these effects is the objective of this paper, in which we analyse the flow regimes of twelve rivers located in the NW Mediterranean region. Different temporal scales (daily, monthly and annual) are used for the analysis and also to estimate flow variables associated with flow magnitude, frequency, duration and variability. It is shown that dams alter the hydrological regime of most of the studied rivers, with special influence on monthly flows and flood magnitude and frequency. The most altered rivers (Muga and Siurana, NE Iberian Peninsula) experience a complete overturn in their flow regime with, for instance, flood reduction reaching up to 76% for the 2‐year flood event. Other rivers showed lower changes in hydrology (e.g. Orb and Têt). Annual runoff showed a pattern of decrease in all the studied rivers (regulated and non‐regulated) indicating that besides dams (i.e. reservoir evaporation), other factors likely affect water yield. A general recovery downstream from dams is also observed at all temporal scales, mainly because of the inflow from tributaries. Although dams have a clear impact on the hydrology of Mediterranean rivers, water withdrawals and diversions for irrigation and other consumptive uses also affected the hydrological patterns. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

Understanding the fate of iron in a modern temperate estuary: Leirárvogur,Iceland     

Gemma M. Byrne  Richard H. Worden  David M. Hodgson  David A. Polya  Paul R. Lythgoe  Craig D. Barrie  Adrian J. Boyce 《Applied Geochemistry》2011

Fluvial dissolved Fe concentrations decrease upon mixing with seawater, resulting in the formation of Fe-floccules. However, a clear understanding of the fate of these floccules has yet to be established. Assessing how tidal processes affect the formation of Fe-colloids in the Leirárvogur estuary, SW Iceland, is an important step in understanding the formation and potential deposition of estuarine Fe-rich minerals within this estuarine system. The Leirárvogur estuary drains predominately Fe-rich basalt, increasing the likelihood of detecting changes in Fe-phases. Fluvial waters and local lake waters that drain into the estuary were compared and the effects of seasonal changes were considered, in an attempt to understand how varying end-members and external factors play a role in Fe-rich mineral formation. Aqueous and colloidal Fe concentrations were found to be greater towards the head of the Leirárvogur estuary, suggesting that potential Fe-rich minerals and complexes are forming at sites of fluvial input. Increasing suspended colloidal Fe towards the estuary mouth suggests that Fe-colloids are readily transported seaward.  相似文献   

Growth and grazing rate dynamics of major phytoplankton groups in an oligotrophic coastal site   总被引：1，自引：0，他引：1  

Andrés Gutiérrez-Rodríguez  Mikel Latasa  Renate Scharek  Ramon Massana  Gemma Vila  Josep M. Gasol 《Estuarine, Coastal and Shelf Science》2011

There has been more attention to phytoplankton dynamics in nutrient-rich waters than in oligotrophic ones thus requiring the need to study the dynamics and responses in oligotrophic waters. Accordingly, phytoplankton community in Blanes Bay was overall dominated by Prymnesiophyceae, remarkably constant throughout the year (31 ± 13% Total chlorophyll a, Tchl a) and Bacillariophyta with a more episodic appearance (20 ± 23% Tchl a). Prasinophyceae and Synechococcus contribution became substantial in winter (Prasinophyceae = 30% Tchl a) and summer (Synechococcus = 35% Tchl a). Phytoplankton growth and grazing mortality rates for major groups were estimated by dilution experiments in combination with high pressure liquid chromatography and flow cytometry carried out monthly over two years. Growth rates of total phytoplankton (range = 0.30–1.91 d⁻¹) were significantly higher in spring and summer (μ > 1.3 d⁻¹) than in autumn and winter (μ ∼ 0.65 d⁻¹) and showed a weak dependence on temperature but a significant positive correlation with day length. Microzooplankton grazing (range = 0.03–1.4 d⁻¹) was closely coupled to phytoplankton growth. Grazing represented the main process for loss of phytoplankton, removing 60 ± 34% (±SD) of daily primary production and 70 ± 48% of Tchl a stock. Chla synthesis was highest during the Bacillarophyceae-dominated spring bloom (Chl a_synt = 2.3 ± 1.6 μg Chl a L⁻¹ d⁻¹) and lowest during the following post-bloom conditions dominated by Prymnesiophyceae (Chl a_synt = 0.23 ± 0.08 μg Chl a L⁻¹ d⁻¹). This variability was smoothed when expressed in carbon equivalents mainly due to the opposite dynamics of C:chl a (range = 11–135) and chl a concentration (range = 0.07–2.0 μg chl a L⁻¹). Bacillariophyta and Synechococcus contribution to C fluxes was higher than to biomass because of their fast-growth rate. The opposite was true for Prymnesiophyceae.  相似文献   

Growth and feeding patterns of European anchovy (Engraulis encrasicolus) early life stages in the Aegean Sea (NE Mediterranean)     

Ignacio A. Catalán  Arild Folkvord  Isabel Palomera  Gemma Quílez-Badía  Fotini Kallianoti  Anastasios Tselepides  Argyris Kallianotis 《Estuarine, Coastal and Shelf Science》2010

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Tracing seafloor methane emissions with benthic foraminifera: Results from the Ana submarine landslide (Eivissa Channel,Western Mediterranean Sea)     

Giuliana Panieri  Angelo Camerlenghi  Isabel Cacho  Cristina Sanchez Cervera  Miquel Canals  Sara Lafuerza  Gemma Herrera 《Marine Geology》2012

The hypothesis that benthic foraminifera are useful proxies of local methane emissions from the seafloor has been verified on sediment core KS16 from the headwall of the Ana submarine landslide in the Eivissa Channel, Western Mediterranean Sea. The core MS312 from a nearby location with no known methane emissions is utilised as control. The core was analysed for biostratigraphy, benthic foraminiferal assemblages, Hyalinea balthica and Uvigerina peregrina carbon and oxygen stable isotope composition, and sedimentary structures. The upper part of the core records post-landslide deglacial and Holocene normal marine hemipelagic sediments with highly abundant benthic foraminifera species that are typical of outer neritic to upper bathyal environment. In this interval, the δ¹³C composition of benthic foraminifera indicates normal marine environment analogous to those found in the control core. Below the sedimentary hiatus caused by the emplacement of the slide, the foraminiferal assemblages are characterised by lower density and higher Shannon Index. Markedly negative δ¹³C shifts in benthic foraminifera are attributed to the release of methane through the seabed. The mean values of the ¹³C anomaly in U. peregrina are ? 0.951 ± 0.208 in the pre-landslide sediments, and ? 0.269 ± 0.152 in post-slide reworked sediments deposited immediately above the hiatus. The δ¹³C anomaly in Hyalinea balthica is ? 2.497 ± 0.080 and ? 2.153 ± 0.087, respectively. To discard the diagenetic effects on the δ¹³C anomaly, which could have been induced by Ca–Mg replacement and authigenic carbonate overgrowth on foraminifera tests, a benthic foraminifera subsample has been treated following an oxidative and reductive cleaning protocol. The cleaning has resulted, only in some cases, in a slight reduction of the anomaly by 0.95% for δ¹³C and < 0.80% for δ¹⁸O. Therefore, the first conclusion is that the diagenetic alteration is minor and it does not alter significantly the overall carbon isotopic anomaly in the core. Consequently, the pre-landslide sediments have been subject to pervasive methane emissions during a time interval of several thousand years. Methane emissions continued during and immediately after the occurrence of Ana Slide at about 61.5 ka. Subsequently, methane emissions decreased and definitely ceased during the last deglaciation and the Holocene.  相似文献   

New seismo-stratigraphic and marine magnetic data of the Gulf of Pozzuoli (Naples Bay, Tyrrhenian Sea, Italy): inferences for the tectonic and magmatic events of the Phlegrean Fields volcanic complex (Campania)     

Gemma Aiello  Ennio Marsella  Vincenzo Di Fiore 《Marine Geophysical Researches》2012,33(2):97-125

A detailed reconstruction of the stratigraphic and tectonic setting of the Gulf of Pozzuoli (Naples Bay) is provided on the basis of newly acquired single channel seismic profiles coupled with already recorded marine magnetics gathering the volcanic nature of some seismic units. Inferences for the tectonic and magmatic setting of the Phlegrean Fields volcanic complex, a volcanic district surrounding the western part of the Gulf of Naples, where volcanism has been active since at least 50 ka, are also discussed. The Gulf of Pozzuoli represents the submerged border of the Phlegrean caldera, resulting from the volcano-tectonic collapse induced from the pyroclastic flow deposits of the Campanian Ignimbrite (35 ka). Several morpho-depositional units have been identified, i.e., the inner continental shelf, the central basin, the submerged volcanic banks and the outer continental shelf. The stratigraphic relationships between the Quaternary volcanic units related to the offshore caldera border and the overlying deposits of the Late Quaternary depositional sequence in the Gulf of Pozzuoli have been highlighted. Fourteen main seismic units, both volcanic and sedimentary, tectonically controlled due to contemporaneous folding and normal faulting have been revealed by geological interpretation. Volcanic dykes, characterized by acoustically transparent sub-vertical bodies, locally bounded by normal faults, testify to the magma uprising in correspondence with extensional structures. A large field of tuff cones interlayered with marine deposits off the island of Nisida, on the western rim of the gulf, is related to the emplacement of the Neapolitan Yellow Tuff deposits. A thick volcanic unit, exposed over a large area off the Capo Miseno volcanic edifice is connected with the Bacoli-Isola Pennata-Capo Miseno yellow tuffs, cropping out in the northern Phlegrean Fields.  相似文献   

A sedimentary record of the rise and fall of the metal industry in Bergslagen,south central Sweden     

Dan Hammarlund  Anson W. Mackay  David M. J. Fallon  Gemma Pateman  Luisa C. Tavio  Melanie J. Leng  Neil L. Rose 《Journal of Paleolimnology》2008,39(4):463-475

Detailed stratigraphic analyses of sediments deposited in Lake Botjärnen, a small boreal forest lake in the shield terrain of central Sweden, clearly reflect progressively increasing human impact on terrestrial and aquatic ecosystems following settlement and establishment of an iron industry in the 17th century. Rising frequencies of pollen and spores from light-demanding plants provide evidence of extensive forest clearance for charcoal and timber production, which peaked in the early 20th century. An associated increase in catchment erosion is reflected by changing carbon and nitrogen elemental content and carbon–isotope composition of sediment organic matter and by increased magnetic susceptibility of the sediments. Records of air-borne pollutants (lead, zinc and sulphur) can be correlated to the development of local and regional mining and metal industry as inferred from historical accounts. Rapid recession of the iron industry led to re-forestation and recovery of the aquatic nutrient status to pre-industrial conditions over the past 100 years. The chronology of the sediment succession, which is based on ²¹⁰Pb and ¹³⁷Cs radionuclide data in combination with radiocarbon dating, is confirmed by historical lead pollution trends established for the region.  相似文献   

Experimental field assessment of suspended sediment pathways for characterizing hydraulic habitat     

Gemma L. Harvey  Nicholas J. Clifford 《地球表面变化过程与地形》2010,35(5):600-610

The distribution of particulate matter within river channels, including sediments, nutrients and pollutants, is fundamental to the survival of aquatic organisms. However, the interactions between flow and sediment transport at the patch scale of river systems represents an under‐researched component of physical habitat studies, particularly those concerning the characterization of ‘physical biotopes’ (riffles, runs, pools, glides). This paper describes a field methodology for exploring the transfer of particulate matter at small scales within river channels, which may be used to aid hydraulic habitat characterization. The field protocol combines field measurement of high frequency flow properties, to characterize hydraulic habitat units, and deployment of spatial arrays of turbidity probes, to detect the passage of artificially‐induced sediment plumes through different biotope units. Sediment plumes recorded by the probes are analysed quantitatively in the manner of the flood hydrograph, and qualitative inferences are made on the dominant mixing processes operating within different parts of the channel. Relationships between the nature of spatio‐temporal hydraulic variations within glide, riffle and pool biotopes, and the character and mixing behaviour of sediment plumes within these habitat units are identified. Results from these preliminary experiments suggest that investigating and characterizing the transfer and storage of sediments, nutrients and pollutants within and between different biotopes is a viable avenue for further research, with potential to contribute to improved physical habitat characterization for river management and habitat restoration. The experiments are also an illustration of the value of neglected synergies between process geomorphology, ecology and river hydraulics. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献