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11.
TERRY COPPOCK ERIC ANDERSON 《International journal of geographical information science》2013,27(1):3-11
Abstract This paper comprises the thoughts and perceptions of an interested outsider, an accountant and economist by training, who has recently chaired a Committee of Enquiry into the handling of geographical information. It focuses on the real barriers to getting more practical use from geographical information systems (GIS), most of which have research implications—but not of a technical nature. To an outsider GIS appears as a solution, or more strictly a tool, in search of a problem. Of course, there are numerous problems for GIS to tackle, but the difficulty is that those who have the problems are often either unaware of GIS and the questions they can deal with or, more seriously, are unaware that they have problems and of the questions they should be asking. GIS as a tool is about aiding managers to carry out their jobs more efficiently and effectively, and, more particularly, about better decision-making 相似文献
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Abstract A novel approach for mapping river runoff is presented. It is based on a disaggregation of the mean annual streamflow measured at the outlet of a basin to estimate water depths on elements of an exact partition of this basin. The developed technique is based on geostatistical interpolation procedures to which a global constraint of water balance has been added. The methodology is illustrated by a case study from a tributary to the Rhône River, France. The results were compared to an established method-the nested approach, and a cross-validation was performed for each mapping technique. The disaggregation approach appears to give the most consistent results. Finally, two gridded maps were derived by applying the disaggregation twice to assess water depth on an increasingly finer grid mesh. The global constraint of water balance was applied to each element of the coarser mesh to give estimates for the finer one. 相似文献
19.
ALEXIS GODET KARL B. FÖLLMI STÉPHANE BODIN ERIC
De KAENEL VIRGINIE MATERA THIERRY ADATTE 《Sedimentology》2010,57(4):1088-1125
Urgonian‐type carbonates are a characteristic feature of many late Early Cretaceous shallow‐marine, tropical and subtropical environments. The presence of typical photozoan carbonate‐producing communities including corals and rudists indicates the prevalence of warm, transparent and presumably oligotrophic conditions in a period otherwise characterized by the high density of globally occurring anoxic episodes. Of particular interest, therefore, is the exploration of relationships between Urgonian platform growth and palaeoceanographic change. In the French and Swiss Jura Mountains, the onset and evolution of the Urgonian platform have been controversially dated, and a correlation with other, better dated, successions is correspondingly difficult. It is for this reason that the stratigraphy and sedimentology of a series of recently exposed sections (Eclépens, Vaumarcus and Neuchâtel) and, in addition, the section of the Gorges de l’Areuse were analysed. Calcareous nannofossil biostratigraphy, the evolution of phosphorus contents of bulk rock, a sequence‐stratigraphic interpretation and a correlation of drowning unconformities with better dated sections in the Helvetic Alps were used to constrain the age of the Urgonian platform. The sum of the data and field observations suggests the following evolution: during the Hauterivian, important outward and upward growth of a bioclastic and oolitic carbonate platform is documented in two sequences, separated by a phase of platform drowning during the late Early Hauterivian. Following these two phases of platform growth, a second drowning phase occurred during the latest Hauterivian and Early Barremian, which was accompanied by significant platform erosion and sediment reworking. The Late Barremian witnessed the renewed installation of a carbonate platform, which initiated with a phase of oolite production, and which progressively evolved into a typical Urgonian carbonate platform colonized by corals and rudists. This phase terminated at the latest in the middle Early Aptian, due to a further drowning event. The evolution of this particular platform segment is compatible with that of more distal and well‐dated segments of the same northern Tethyan platform preserved in the Helvetic zone of the Alps and in the northern subalpine chains (Chartreuse and Vercors). 相似文献
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MARTIN ROSS PATRICK LAJEUNESSE KEVIN G. A. KOSAR 《Boreas: An International Journal of Quaternary Research》2011,40(1):73-91
Ross, M., Lajeunesse, P. & Kosar, K. G. A. 2010: The subglacial record of northern Hudson Bay: insights into the Hudson Strait Ice Stream catchment. Boreas, 10.1111/j.1502‐3885.2010.00176.x. ISSN 0300‐9483. In this paper, we present new insights into the glacial dynamics and potential configuration of the Hudson Strait Ice Stream catchment in the northern Hudson Bay–western Hudson Strait region. Our reconstruction is based on new field observations and till compositional data from Southampton Island, remote sensing imagery and multibeam bathymetric data from the Hudson Bay sea floor, as well as on a re‐examination of previously published data from this vast region. Our findings suggest that, during the late Quaternary, the HSIS catchment consisted of a number of ice‐stream tributaries feeding a curvilinear trunk that potentially extended into western Hudson Bay. In contrast to previous interpretations, the occurrence of fluted bedrock hills, over‐deepened basins, Dubawnt erratics and carbonaceous till on the islands at the head of Hudson Strait is taken to imply that cold‐based conditions did not prevail on these islands. The upland area of Southampton Island and the surrounding channels played an important role in controlling the location of the main tributaries, with the higher central terrain forming a large inter‐ice‐stream zone lacking carbonate detritus. Coats Island contains abundant evidence of vigorous ice flow, such as mega‐scale glacial lineations (MSGLs). MSGLs also occur on the sea floor southwest of Coats Island but the sea‐floor imprint is highly discontinuous. Observations on the western Hudson Bay mainland show evidence of southeastward fast ice flow that is spatially consistent with the Dubawnt dispersal train. Despite the geomorphological discontinuities, this may indicate that the HSIS onset zone extended far inside the Laurentide Ice Sheet and across contrasting geological domains. 相似文献