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21.
The concentrations of Ni, Mn, Cr, Cu, Co, Zn, Fe, Pb and organic carbon have been determined in sediments of the Pagassitikos Gulf. They vary with the ‘sand equivalent’ content, s′, characteristic of the grain size, and are related to it by the equation, in which the constants c1, k and d depend on the element. Consequently, since the metal concentrations in a sample are much less representative of the area from which it has been taken than its ‘sand equivalent’ content, a contour map of the latter constitutes a reliable guide to the general pattern of the elements. Superimposed on it, we detect isolated patches of moderate pollution close to the harbour of Volos and a few, slight, natural anomalies, such as increased Mn and Ni, the former in the east and the latter in the south of the Gulf. 相似文献
22.
Costa Alexandre C. Dupont Fanny Bier George van Oel Pieter Walker David W. Martins Eduardo S. P. R. 《Hydrogeology Journal》2023,31(3):751-769
Particularly in arid and semiarid areas, more and more populations rely almost entirely on imported water. However, the extent to which intentional discharge into transiting river systems and unintentional leakage may be augmenting water resources for communities along and down gradient of the water transfer scheme has not previously been subject to research. The objective of this study was to assess both the potential of a large-scale water transfer (WT) scheme to increase groundwater availability by channel transmission losses in a large dryland aquifer system (2,166 km²) in Brazil, and the capability of the receiving streams to transport water downstream under a prolonged drought. An integrated surface-water/groundwater model was developed to improve the estimation of the groundwater resources, considering the spatio-temporal variability of infiltrated rainfall for aquifer recharge. Aquifer recharge from the WT scheme was simulated under prolonged drought conditions, applying an uncertainty analysis of the most influential fluxes and parameters. The annual recharge (66 mm/year) was approximately twice the amount of water abstracted (1990–2016); however, the annual recharge dropped to 13.9 mm/year from 2012 to 2016, a drought period. Under similar drought conditions, the additional recharge (6.89 × 106 m³/year) from the WT scheme did not compensate for the decrease in groundwater head in areas that do not surround the receiving streams. Actually, the additional recharge is counteracted by a decrease of 25% of natural groundwater recharge or an increase of 50% in pumping rate; therefore, WT transmission losses alone would not solve the issue of the unsustainable management of groundwater resources.
相似文献23.
Jesús Revuelto Paul Billecocq François Tuzet Bertrand Cluzet Maxim Lamare Fanny Larue Marie Dumont 《水文研究》2020,34(26):5384-5401
The small scale distribution of the snowpack in mountain areas is highly heterogeneous, and is mainly controlled by the interactions between the atmosphere and local topography. However, the influence of different terrain features in controlling variations in the snow distribution depends on the characteristics of the study area. As this leads to uncertainties in high spatial resolution snowpack simulations, a deeper understanding of the role of terrain features on the small scale distribution of snow depth is required. This study applied random forest algorithms to investigate the temporal evolution of snow depth in complex alpine terrain using as predictors various topographical variables and in situ snow depth observations at a single location. The high spatial resolution (1 m x 1 m) snow depth distribution database used in training and evaluating the random forests was derived from terrestrial laser scanner (TLS) devices at three study sites, in the French Alps (2 sites) and the Spanish Pyrenees (1 site). The results show the major importance of two topographic variables, the topographic position index and the maximum upwind slope parameter. For these variables the search distances and directions depended on the characteristics of each site and the TLS acquisition date, but are consistent across sites and are tightly related to main wind directions. The weight of the different topographic variables on explaining snow distribution evolves while major snow accumulation events still take place and minor changes are observed after reaching the annual snow accumulation peak. Random forests have demonstrated good performance when predicting snow distribution for the sites included in the training set with R2 values ranging from 0.82 to 0.94 and mean absolute errors always below 0.4 m. Oppositely, this algorithm failed when used to predict snow distribution for sites not included in the training set, with mean absolute errors above 0.8 m. 相似文献
24.
Nicola Ranger St��phane Hallegatte Sumana Bhattacharya Murthy Bachu Satya Priya K. Dhore Farhat Rafique P. Mathur Nicolas Naville Fanny Henriet Celine Herweijer Sanjib Pohit Jan Corfee-Morlot 《Climatic change》2011,104(1):139-167
Managing risks from extreme events will be a crucial component of climate change adaptation. In this study, we demonstrate an approach to assess future risks and quantify the benefits of adaptation options at a city-scale, with application to flood risk in Mumbai. In 2005, Mumbai experienced unprecedented flooding, causing direct economic damages estimated at almost two billion USD and 500 fatalities. Our findings suggest that by the 2080s, in a SRES A2 scenario, an ??upper bound?? climate scenario could see the likelihood of a 2005-like event more than double. We estimate that total losses (direct plus indirect) associated with a 1-in-100 year event could triple compared with current situation (to $690?C$1,890 million USD), due to climate change alone. Continued rapid urbanisation could further increase the risk level. The analysis also demonstrates that adaptation could significantly reduce future losses; for example, estimates suggest that by improving the drainage system in Mumbai, losses associated with a 1-in-100 year flood event today could be reduced by as much as 70%.,We show that assessing the indirect costs of extreme events is an important component of an adaptation assessment, both in ensuring the analysis captures the full economic benefits of adaptation and also identifying options that can help to manage indirect risks of disasters. For example, we show that by extending insurance to 100% penetration, the indirect effects of flooding could be almost halved. We conclude that, while this study explores only the upper-bound climate scenario, the risk-assessment core demonstrated in this study could form an important quantitative tool in developing city-scale adaptation strategies. We provide a discussion of sources of uncertainty and risk-based tools could be linked with decision-making approaches to inform adaptation plans that are robust to climate change. 相似文献
25.
Fanny Sorbadere Pierre Schiano Nicole Métrich Antonella Bertagnini 《Contributions to Mineralogy and Petrology》2013,166(5):1305-1321
We report here major, trace element and Sr–Nd–Pb isotopic data for a new set of basaltic lavas and melt inclusions hosted in Mg-rich olivines (Fo86–91) from Mota Lava, in the Banks islands of the Vanuatu island arc. The results reveal the small-scale coexistence of typical island-arc basalts (IAB) and a distinct type of Nb-enriched basalts (NEB) characterized by primitive mantle-normalized trace element patterns without high-field-strength element (HFSE) depletion. The IAB show trace element patterns with prominent negative HFSE anomalies acquired during melting of mantle sources enriched with slab-derived, H2O-rich components during subduction. In contrast, the NEB display trace element features that compare favourably with enriched-mid-ocean ridge basalt (MORB) and the most enriched basalts from the Vanuatu back-arc troughs. Both their trace element and Nd–Sr isotopic compositions require partial melting of an enriched-MORB-type mantle source, almost negligibly contaminated by slab-derived fluids (~0.2 wt%). The coexistence of these two distinct types of primitive magma, at the scale of one volcanic island and within a relatively short span of time, would reflect a heterogeneous mantle source and/or tapping of distinct mantle sources. Direct ascent of such distinct magmas could be favoured by the extensive tectonic setting of Mota Lava Island, allowing decompression melting and sampling of variable mantle sources. Significantly, this island is located at the junction of the N–S back-arc troughs and the E–W Hazel Home extensional zone, where the plate motion diverges in both direction and rate. More broadly, this study indicates that crustal faulting in arc contexts would permit basaltic magmas to reach Earth’s surface, while preserving the geochemical heterogeneity of their mantle sources. 相似文献
26.
György Hetényi Benoît Taisne Fanny Garel Étienne Médard Sonja Bosshard Hannes B. Mattsson 《Bulletin of Volcanology》2012,74(2):457-482
Columnar jointing is a common feature of solidified lavas, sills and dikes, but the factors controlling the characteristic
stoutness of columns remain debated, and quantitative field observations are few in number. In this paper, we provide quantitative
measurements on sizing of columnar joint sets and our assessment of the principal factors controlling it. We focus on (1)
chemistry, as it is the major determinant of the physical (mechanical and thermal) properties of the lava, and (2) geology,
as it influences the style of emplacement and lava geometry, setting boundary conditions for the cooling process and the rate
of heat loss. In our analysis, we cover lavas with a broad range of chemical compositions (from basanite to phonolite, for
six of which we provide new geochemical analyses) and of geological settings. Our field measurements cover 50 columnar jointing
sites in three countries. We provide reliable, manually digitized data on the size of individual columns and focus the mathematical
analysis on their geometry (23,889 data on side length, of which 17,312 are from full column sections and 3,033 data on cross-sectional
area and order of polygonality). The geometrical observations show that the variation in characteristic size of columns between
different sites exceeds one order of magnitude (side length ranging from 8 to 338 cm) and that the column-bounding polygons’
average order is less than 6. The network of fractures is found to be longer than required by a minimum-energy hexagonal configuration,
indicating a non-equilibrium, geologically quick process. In terms of the development and characteristic sizing of columnar
joint sets, our observations suggest that columns are the result of an interplay between the geological setting of emplacement
and magma chemistry. When the geological setting constrains the geometry of the emplaced body, it exerts a stronger control
on characteristic column stoutness. At unconstrained geometries (e.g. unconfined lava flows), chemistry plays the major role,
resulting in stouter columns in felsic lavas and slenderer columns in mafic lavas. 相似文献
27.
An insight into the formation of severe ozone episodes: modeling the 21/03/01 event in the ESCOMPTE region 总被引：1，自引：0，他引：1
High ozone concentrations are observed more and more frequently in the lower troposphere. The development of such polluted episodes is linked to a complex set of chemical, physical and dynamical parameters that interact with each other. To improve air quality, it is necessary to understand and quantify the role of all these processes on the intensity of ozone formation. The ESCOMPTE program, especially dedicated to the numerical simulation of photochemical episodes, offers an ideal frame to investigate details of the roles of many of these processes through 3D modeling. This paper presents the analysis, with a 3D eulerian model, of a severe and local episode of ozone pollution that occurred on the 21st of March 2001 in the ESCOMPTE region. This episode is particularly interesting due to the intensity of the observed ozone peaks (450 μg/m3 during 15 mn) but also because it did not occur in summer but at the beginning of spring. As part of the premodeling work of the ESCOMPTE program, this study focuses on the sensitivity of the simulated ozone peaks to various chemical and physical phenomena (long-range transport, industrial emissions, local dynamic phenomena…) to determine their influence on the rise of high local photooxidant concentrations and to better picture the photochemistry of the ESCOMPTE region. Through sensitivity tests to dynamical calculation resolution and emissions, this paper shows how the combination of sea and pond breezes with emissions of reactive VOCs can generate local intense ozone peaks. 相似文献
28.
Hervé Piégay Fanny Arnaud Barbara Belletti Mélanie Bertrand Simone Bizzi Patrice Carbonneau Simon Dufour Frédéric Liébault Virginia Ruiz-Villanueva Louise Slater 《地球表面变化过程与地形》2020,45(1):157-188
The rivers of the world are undergoing accelerated change in the Anthropocene, and need to be managed at much broader spatial and temporal scales than before. Fluvial remote sensing now offers a technical and methodological framework that can be deployed to monitor the processes at work and to assess the trajectories of rivers in the Anthropocene. In this paper, we review research investigating past, present and future fluvial corridor conditions and processes using remote sensing and we consider emerging challenges facing fluvial and riparian research. We introduce a suite of remote sensing methods designed to diagnose river changes at reach to regional scales. We then focus on identification of channel patterns and acting processes from satellite, airborne or ground acquisitions. These techniques range from grain scales to landform scales, and from real time scales to inter-annual scales. We discuss how remote sensing data can now be coupled to catchment scale models that simulate sediment transfer within connected river networks. We also consider future opportunities in terms of datasets and other resources which are likely to impact river management and monitoring at the global scale. We conclude with a summary of challenges and prospects for remotely sensed rivers in the Anthropocene. © 2019 John Wiley & Sons, Ltd. 相似文献
29.
Due to the interdependency that exists between the ecosystem resources and its users, successful implementation of ecosystem-based management depends on the identification and understanding of different stakeholders, their practices, expectations and interests. Today, many scientists and resource managers agree that the involvement of stakeholders is a key factor for a successful management regime in the marine environment. The way stakeholders are involved in the process must reflect, or at least address, the existing complexity of the specific context. A comprehensive method that allows doing this is by use of stakeholder analysis and mapping. This article will focus on the various types and stages of stakeholder participation in a marine spatial planning process, and will illustrate how to conduct a stakeholder analysis that allows the involvement of stakeholders in an adequate way that is sustainable over time. 相似文献
30.
The importance of marine spatial planning in advancing ecosystem-based sea use management 总被引：2，自引：1，他引：1
During the past 10 years, the evolution of marine spatial planning (MSP) and ocean zoning has become a crucial step in making ecosystem-based, sea use management a reality. The idea was initially stimulated by international and national interest in developing marine protected areas, e.g., the Great Barrier Reef Marine Park. More recent attention has been placed on managing the multiple use of marine space, especially in areas where conflicts among users and the environment are already clear, e.g., in the North Sea. Even more recent concern has focused on the need to conserve nature, especially ecologically and biologically sensitive areas, in the context of multi-use planning of ocean space. Despite academic discussions and the fact that some countries already have started implementation, the scope of MSP has not been clearly defined. Terms such as integrated management, marine spatial management, and ocean zoning are all used inconsistently. This is one of the reasons why its importance is not more seriously reflected at the levels of policy and decision-making in most countries. This article attempts to deal with this problem. It describes why MSP is an essential step to achieve ecosystem-based sea use management, how it can be defined and what its core objectives are. The article concludes with an analysis of the use and achievements of MSP worldwide, with particular focus on new approaches in Europe. 相似文献