Hydrologic changes resulting from urban cover in seasonally snow‐covered catchments          下载免费PDF全文

M. Catherine Eimers  Ethan C. McDonald 《水文研究》2015,29(6):1280-1288

There are few multibasin analyses of the effects of urban land cover on seasonal stream flow patterns within northern watersheds where winter snow cover is the norm. In this study, the effects of urban cover on stream flow were evaluated at nine catchments in southern Ontario, Canada, which vary greatly in urban impervious cover (1–84%) but cluster into two groups having ≥54% urban impervious area (‘urban’) and ≤11% impervious cover (‘rural’), respectively. Annual and seasonal run‐off totals (millimetres) were similar between the rural and urban groups and were relatively insensitive to urban cover. Instead, urban streams had significantly greater high flow frequency, flow variability and quickflow and lower baseflow compared with rural streams. Furthermore, differences in high flow frequency between urban and rural stream groups were largest in the summer and fall and less extreme in the winter and spring, perhaps because of the homogenizing effect of winter snow cover, frozen ground and spring melt on surface imperviousness. Although the clear clustering of streams into urban and rural groups precluded the identification of a threshold above which urban cover is the primary cause of flow differences, relatively high extreme flow frequency and flow variability in the two most urbanized of the rural streams (10–11% impervious) suggest that it may lie close to this range. Furthermore, whereas total run‐off volumes were not affected by urban cover, increases in stream flashiness and a greater frequency of high flow events particularly during the summer and fall may negatively impact stream biota and favour the transfer of surface‐deposited pollutants to urban streams. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Incorporating landscape features to obtain an object‐oriented landscape drainage network representing the connectivity of surface flow pathways over rural catchments     

Chantal Gascuel‐Odoux  Pierre Aurousseau  Thibaut Doray  Hervé Squividant  Francis Macary  Daniel Uny  Catherine Grimaldi 《水文研究》2011,25(23):3625-3636

A topological representation of a rural catchment is proposed here in addition to the generally used topographic drainage network. This is an object‐oriented representation based on the identification of the inlets and outlets for surface water flow on each farmer's field (or plot) and their respective contributing areas and relationships. It represents the catchment as a set of independent plot outlet trees reaching the stream, while a given plot outlet tree represents the pattern of surface flow relationships between individual plots. In the present study, we propose to implement functions related to linear and surface elements of the landscape, such as hedges or road networks, or land use, to obtain what we call a landscape drainage network which delineates the effective contributing area to the stream, thus characterizing its topological structure. Landscape elements modify flow pathways and/or favour water infiltration, thus reducing the area contributing to the surface yield and modifying the structure of the plot outlet trees. This method is applied to a 4·4‐km² catchment area comprising 43 955 pixels and 312 plots. While the full set of 164 plot outlet trees, with an average of 7 plots per tree, covers 100% of the total surface area of the catchment, the landscape drainage network comprises no more than 37 plot outlet trees with an average of 2 plots per tree, accounting for 52 and 7% of the catchment surface area, when taking account of linear elements and land use, respectively. This topological representation can be easily adapted to changes in land use and land infrastructure, and provides a simple and functional display for intercomparison of catchments and decision support regarding landscape and water management. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Improving the accuracy of daily MODIS OWL flood inundation mapping using hydrodynamic modelling     

Catherine Ticehurst  Dushmanta Dutta  Fazlul Karim  Cuan Petheram  Juan Pablo Guerschman 《Natural Hazards》2015,78(2):803-820

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Evidence of inter-territorial collaborative economic development strategies in Ontario,Canada     

Godwin Arku  Catherine Oosterbaan 《GeoJournal》2015,80(3):361-374

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Selected contributions from the 11th Gas in Marine Sediments International Conference of September 2012, Nice: an introduction     

Catherine Pierre  Patrice Imbert  Jean Mascle 《Geo-Marine Letters》2014,34(2-3):85-87

This Introduction presents an overview of selected contributions from the 11th Gas in Marine Sediments International Conference held on the 4–7 September 2012 in Nice, France, and published in this special issue of Geo-Marine Letters under the guest editorship of Catherine Pierre, Patrice Imbert and Jean Mascle. These cover fluid seepage dynamics at widely varying spatiotemporal scales in a giant buried caldera of the Caspian Sea, mud volcanoes and pockmarks in the Mediterranean and adjoining Gulf of Cadiz, as well as Lake Baikal, pockmarks of shallower waters along the Atlantic French coast and in Baltic Sea lagoons, deepwater pockmarks and cold seeps on the Norwegian margin and the Hikurangi Margin of New Zealand, asphalt seepage sites offshore southern California, and the tectonically controlled southern Chile forearc. We look forward to meeting all again at the 12th Gas in Marine Sediments conference scheduled for 1–6 September 2014 in Taipei, Taiwan.  相似文献   

Modeling the impacts of bottom trawling and the subsequent recovery rates of sponges and corals in the Aleutian Islands, Alaska     

Christopher N. Rooper  Mark E. WilkinsCraig S. Rose  Catherine Coon 《Continental Shelf Research》2011,31(17):1827-1834

The abundance of some marine fish species are correlated to the abundance of habitat-forming benthic organisms such as sponges and corals. A concern for fisheries management agencies is the recovery of these benthic invertebrates from removal or mortality from bottom trawling and other commercial fisheries activities. Using a logistic model, observations of available substrate and data from bottom trawl surveys of the Aleutian Islands, Alaska, we estimated recovery rates of sponges and corals following removal. The model predicted the observed sponge and coral catch in bottom trawl surveys relatively accurately (R²=0.38 and 0.46). For sponges, the results show that intrinsic growth rates were slow (r=0.107 yr⁻¹). Results show that intrinsic growth rates of corals were also slow (r=0.062 yr⁻¹). The best models for corals and sponges were models that did not include the impacts of commercial fishing removals. Subsequent recovery times for both taxa were also predicted to be slow. Mortality of 67% of the initial sponge biomass would recover to 80% of the original biomass after 20 years, while mortality of 67% of the coral biomass would recover to 80% of the original biomass after 34 years. The modeled recovery times were consistent with previous studies in estimating that recovery times were of the order of decades, however improved data from directed studies would no doubt improve parameter estimates and reduce the uncertainty in the model results. Given their role as a major ecosystem component and potential habitat for marine fish, damage and removal of sponges and corals must be considered when estimating the impacts of commercial bottom trawling on the seafloor.  相似文献   

The K–Ar Cassignol–Gillot technique applied to western Martinique lavas: A record of Lesser Antilles arc activity from 2 Ma to Mount Pelée volcanism     

Aurélie Germa  Xavier Quidelleur  Pierre Lahitte  Shasa Labanieh  Catherine Chauvel 《Quaternary Geochronology》2011,6(3-4):341-355

We present 23 new ages from three volcanic complexes of the Lesser Antilles arc in Martinique Island (French West Indies). These ages obtained with the K–Ar Cassignol–Gillot technique are distributed within the whole Quaternary. They allowed us to reconstruct a detailed history of successive volcanic growth and flank collapse stages. Trois Ilets Volcanism has been active during at least 2 Ma, between 2.35 ± 0.03 Ma and 346 ± 27 ka, with monogenetic volcanoes of basaltic-andesite to andesitic compositions. We here propose that magma mixing, which characterizes this volcanism, could have been initiated between 617 and 346 ka by the activation of arc-parallel and arc-transverse fault systems. Meanwhile, the Carbet complex was active 25 km to the north from 998 ± 14 to 322 ± 6 ka, and was partially destroyed by a flank collapse after 602 ± 10 ka. Together with geochemical data, our ages show that Mount Conil and Mount Pelée volcanoes are parts of the same edifice sharing a single magmatic reservoir. Mount Conil started to emerge before 543 ± 8 ka, and andesites erupted until 127 ± 2 ka, when a flank collapse destroyed the western flank of the edifice, probably triggering the emplacement of Piton Marcel, the last eruption of this first stage. We note that this collapse occurred during the transition from oxygen stages 6 to 5, i.e. during glacial to interglacial change, when eustatic level rapidly increased. After that, and until present, Mount Pelée volcano was built with periods of cone growth intercalated by flank collapse events. We here show that a peak of activity occurred between 550 and 330 ka in western Martinique within the three complexes, which are spaced of 15–25 km. Since 330 ka volcanic activity is limited to the northernmost Mount Conil–Mount Pelée complex. Our data are in agreement with the regional scale observations that the whole recent Lesser Antilles arc was subject to a high volcanic activity since 600 ka, probably linked to an increase in magma production. This permanent establishment of rising magma in regularly spaced batches and tectonically controlled, could explain the individual chemical evolution of each edifice and the different eruptive dynamisms occurring at the same time along the recent arc.  相似文献   

Microanalysis of the iron oxidation state in (Mg,Fe)O and application to the study of microscale processes     

Micaela Longo  Catherine A. McCammon  Steven D. Jacobsen 《Contributions to Mineralogy and Petrology》2011,162(6):1249-1257

We report application of the flank method using the electron microprobe to a suite of twelve (Mg,Fe)O samples with composition 2–47 wt% Fe and Fe³⁺/ΣFe = 1 to 11%, where Fe³⁺/ΣFe was determined independently using Mössbauer spectroscopy on the same grains used for the flank method measurements. A calibration curve of the form Fe²⁺ = A + B × (ΣFe)² + C × (Lβ/Lα) was fit to the data and gave excellent agreement between Fe³⁺/ΣFe calculated from the flank method and Fe³⁺/ΣFe determined using Mössbauer spectroscopy. We found the method to be sufficiently sensitive to determine meaningful variations in Fe³⁺/ΣFe for geophysically relevant compositions of (Mg,Fe)O (<25 wt% Fe), and calibration parameters remained constant within experimental uncertainty over the course of the entire study (20 months). Flank method measurements on an inhomogeneous sample of synthetic (Mg,Fe)O showed evidence of diffusion processes resulting from rupture of the capsule during the high-pressure experiment and the possibility to measure Lβ/Lα variations with a spatial resolution of a few microns. We detected the presence of exsolved magnesioferrite in a suite of (Mg,Fe)O single crystals using transmission electron microscopy and Mössbauer spectroscopy. Flank method measurements on the same suite of single crystals showed enhanced Fe³⁺/ΣFe values, consistent with the presence of magnesioferrite even though the grains were too small to be resolved by conventional electron microprobe measurements.  相似文献   

A 500 yr speleothem-derived reconstruction of late autumn–winter precipitation, northeast Turkey     

Catherine N. Jex  Andy Baker  Jonathan M. Eden  Warren J. Eastwood  Ian J. Fairchild  Melanie J. Leng  Louise Thomas  Hilary J. Sloane 《Quaternary Research》2011,75(3):399-405

A verified instrumental calibration of annually resolved δ¹⁸O for a stalagmite from Gümü?hane in northeast Turkey is presented and cross-validated using a ‘leave-one-out’ technique. The amount of late autumn to winter precipitation is negatively correlated with stalagmite δ¹⁸O between AD 1938 and 2004. The observed relationship is extrapolated back to ~ AD 1500 leading to the first long winter precipitation reconstruction for this region. Modern day October to January precipitation is linked to pressure fields in Western Russia. Anomalously lower reconstructed rainfall is recorded in AD 1540–1560 at which time higher pressure over the Caspian Sea region is inferred.  相似文献   

Geomorphic and climatic change over the past 12,900 yr at Swiftcurrent Lake, Glacier National Park, Montana, USA     

Kelly R. MacGregor  Catherine A. Riihimaki  Mark D. Shapley 《Quaternary Research》2011,75(1):80-90

Glaciated alpine landscapes are sensitive to changes in climate. Shifts in temperature and precipitation can cause significant changes to glacier size and terminus position, the production and delivery of organic mass, and in the hydrologic energy related to the transport of water and sediment through proglacial environments. A sediment core representing a 12,900-yr record collected from Swiftcurrent Lake, located on the eastern side of Glacier National Park, Montana, was analyzed to assess variability in Holocene and latest Pleistocene environment. The spectral signature of total organic carbon content (%TOC) since ~ 7.6 ka matches that of solar forcing over 70-500 yr timescales. Periodic inputs of dolomite to the lake reflect an increased footprint of Grinnell Glacier, and occur during periods when sediment sinks are reduced, glacial erosion is increased, and hydrologic energy is increased. Grain size, carbon/nitrogen (C/N) ratios, and %TOC broadly define the termination of the Younger Dryas chronozone at Swiftcurrent Lake, as well as major Holocene climate transitions. Variability in core parameters is linked to other records of temperature and aridity in the northern Rocky Mountains over the late Pleistocene and Holocene.  相似文献