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171.
Determining the extent of flooding is an important role of the hydrological research community and provides a vital service to planners and engineers. For large river systems located within distant settings it is practical to utilize a remote sensing approach. This study combines a remote sensing and geomorphic approach to delineate the extent of a large hurricane generated flood event in the lower Pánuco basin (98,227 km2), the seventh largest river system draining into the Gulf of Mexico. The lower Pánuco basin is located within the coastal plain of eastern Mexico and has a complex alluvial valley. Data sources included a Landsat 5TM and Landsat 7ETM+ scene, and topographic and particle size data from fieldwork and laboratory analysis. The Landsat 5TM image was acquired after the peak of a large flood event in 1993, whereas the Landsat 7ETM+ scene was acquired during the dry season in 2000. The increasing number of days between flood crest and the date of flood image acquisition along the river valley provided the opportunity to examine several methods of flood delineation and to consider differences in floodplain geomorphology. Backswamp environments were easily delineated in flooded reaches within the Panuco and Tamuin valleys, whereas in the Moctezuma valley more sophisticated methods were required because of the greater time between image acquisition and flood peak, and the complex floodplain topography. This included Principal Component (PC) analysis and image classification. Within the floodplain, residual Holocene terraces complicated flood mapping. Classification of both images allowed consideration of the influence of permanent standing water. Although the flooded areas were greater in the lower reaches of the study area, because this portion of the valley contained large floodplain lakes, the amount of inundation was actually lower. Remote sensing offers the ability to examine large alluvial valleys in distant settings but does not imply that geomorphic criteria should be excluded. Indeed, because of heterogeneous floodplain topography this study illustrates the importance of including field based geomorphic analysis so that the complexity of distinct floodplain environments are considered. The findings from this study are significant because most remote sensing data obtained for the purpose of flood mapping will not coincide with the flood crest. Thus, this study provides an appropriate method for mapping flood inundation in large and complex floodplain settings after flood crest recession.  相似文献   
172.
I. INTRODUCTIONReservoir operation study in planning stage is an important task for the water resourcesdevelopment design. In the past. much attention has been paid to making the most ot' floodcontol. power generation, navigation. and water supply, but less to the unfavorable effectsdue to reservoir sedimentation. According to the survey of 425 reservoirs in Japan with a total storage capacity of 13.2 billion mJ a volume of 825 million m3 of sediment was depositedby the end of 1979. This…  相似文献   
173.
龙门山及其邻区的构造和地震活动及动力学   总被引:156,自引:37,他引:156       下载免费PDF全文
邓起东  陈社发 《地震地质》1994,16(4):389-403
论述了龙门山推覆构造带、岷山隆起、成都平原和龙泉山地区的构造和地震活动,讨论了构造活动特点和演化历史,并分析了它们的形成机制和动力学问题  相似文献   
174.
Saraswati Raju 《GeoJournal》2006,65(4):287-300
The policy environment on gender is fraught with contradictions and contestation of varying degrees in India that does not disappear even as recent transformative mode of participatory initiatives seem to place women’s agency at the core of empowerment agenda. Drawing from two collaborative projects at the grassroots, the paper argues that even well conceptualised projects miss the cutting edge distinction between women and gender and continue to engage with an instrumental logic of women’s development and empowerment at the expense of issues of gender equality and equity in translating the intention into action. It is also observed, however, that spatially embedded social and cultural specificities impact policy discourse resulting in very different outcomes of conceptually comparable policy formulations. According to the author acknowledging spatiality of experiences provides a vantage point to critically engage with context-specific strategies to resolve gendered conflicts and tensions resulting from confining social relations and normative gender codes.  相似文献   
175.
Postcolonial environmental justice: Government and governance in India   总被引:1,自引:0,他引:1  
In this paper, we investigate the context within which struggles for environmental justice are taking place in India. We explore the ways in which postcolonial patterns of government and governance in India affect the ends, the means and the representation of these struggles, focusing on three particular areas: state reform, the judiciary and public interest litigation, and environmental social movements. We argue that India differs from west in the ambitious yet incomplete and contradictory nature of government-sponsored intervention in the environment, and in the particular nature of its public sphere, both of which have been important in shaping struggles for environmental justice. Our wider intention is not merely to catalogue these differences, but to use the Indian material to raise questions about the emphases and implicit assumptions of western environmental justice literature, and reflect on how these may be need reconsideration when working in postcolonial contexts.  相似文献   
176.
在民族药资源的开发过程中,全面了解药材的基本状况及其种类、分布特征是至关重要的。整理分布在楚雄州的223种主要彝药植物药用情况、植物特征和市场现状等3方面的资料,建立彝药植物资源库。在此基础上,通过专家打分的方法,挑选出适合重点开发的药材种类,并运用GIS空间信息处理手段,提取重点开发药材的适宜区分布图。为宏观了解州内的药材状况、合理进行药材生产布局提供指导,并为其他地区药材资源的开发调查工作提供方法参考。  相似文献   
177.
A provenance and stratigraphic study of the Neoproterozoic Pontas do Salso Complex (PSC), western portion of the Dom Feliciano Belt (DFB), was conducted with U–Pb zircon geochronological analysis of the metasediments and the host rocks. The U–Pb isotopic data from detrital zircon of the metasediments indicate the source from the latest Middle Tonian to Late Cryogenian (between 897 and 684 Ma) and maximum depositional age of 685 ± 18 Ma in an arc-related basin setting adjacent in the Sao Gabriel Arc. The metasediments of the PSC form an elongated body in the N35°E direction and occur in the central portion of the São Gabriel Terrane (SGT), which is constituted by ophiolitic complexes and arc-related rocks, generated probably during the final consolidation of Rodinia supercontinent, although this question is still open. Low- to medium-K calc-alkaline, metaluminous affinity, and trace-element geochemistry suggest that the chemical composition of the protoliths was generated from metasomatized mantle sources in subduction zones. The PSC is composed of meta-arkoses, with subordinate metaconglomerates and metapelites. The meta-arkoses are disposed in plane-parallel layers, which also internally feature small-scale cross-bedding structures. The matrix has a blastopsammitic, poorly selected, fine to coarse texture, and hexagonal quartz and plagioclase porphyroclasts with superimposed thermal metamorphism. The polymict metaconglomerates are matrix-supported, with 15–55% of clasts of metavolcanic rocks, metasediments, undeformed granites, and quartz veins. The metapelites comprise mainly muscovite phyllites with syn-tectonic garnet and chloritoid porphyroblasts. The PSC represents a sedimentary succession deposited on an arc-related basin formed during the collapse and uplift of the SGT.  相似文献   
178.
Analyses of sustainable design and commodity networks often make a priori assumptions about the capacity of markets to provide solutions to environmental problems; and have a tendency to celebrate local scales of action. This paper offers a contrasting account, in which the national state sought to carefully manage scarce natural resources and to ensure equitable consumption at a time of deep crisis. We utilise the historical example of the British wartime Utility furniture scheme in order to draw out three lessons for sustainable and equitable environmental practice. First, we argue that national states do not simply provide an institutional backdrop to sustainable production but rather can act as important organising agents. Second, the paper emphasises that sustainability is best achieved through interventions across a commodity network, beyond simply modifications to a single node such as design. Finally, we underscore the value of ‘pragmatic centralism’ in environmental decision-making, calling attention to the collaborative practices that underpinned the scheme. The example of Utility’s adaptive responses—borne out of crisis, scarcity and shortage during wartime—offers much that is of intrinsic interest to current concerns about resource consumption and the drivers of sustainability in commodity networks.  相似文献   
179.
Current research in the Cartographic and Geographic Information Sciences at Penn State emphasizes map design, geovisual analytics, spatiotemporal pattern detection, spatial cognition, CyberGIS, geographic information retrieval, image analysis, and novel methods for geospatial education. Cartography and GIScience research and education at Penn State is organized through groups such as the GeoVISTA Center and the Peter R. Gould Center in the Department of Geography, the Institute for CyberScience, and the John A. Dutton e-Education Institute. Recent achievements in these units have included advances in extracting geographic information from social media, novel methods for pattern analysis from event data, and the development of the first massive open online course in geography.  相似文献   
180.
Indicating the Trophic State of Running Waters by Using TIM (Trophic Index of Macrophytes) – Exemplary Implementation of a New Index in the River Inninger Bach The river Inninger Bach represents the outflow of the lake Wörthsee (Bavaria). The mean pH of the calcareous river has a value of ca. 8 during the vegetation period, the mean conductivity is about 350 to 400 μS/cm. The macrophyte vegetation of the river course was mapped and the nutrient concentrations of both the water body and the sediment were measured. In every mapping section the Trophic Index of Macrophytes (TIM) was calculated. By cluster analysis the mapping sections were grouped into three zones which differed in macrophyte vegetation. These differences are not associated with varying nutrient concentrations but are mainly due to differences in the degree of shading. In spite of the characterisation of the lake Wörthsee as oligo‐mesotrophic the river Inninger Bach, which represents the outflow of the lake Wörthsee, is classified as meso‐eutrophic by the Trophic Index of Macrophytes TIM. The increased trophic state of the river compared to the lake is caused by the river Krebsbach, a small tributary flowing into the river Inninger Bach only a short stretch downstream of its outflow of the lake Wörthsee. The river Krebsbach shows a total phosphorus concentration of about 56 μg/L P. The input of diaspores of submerged macrophytes both from the oligo‐mesotrophic lake Wörthsee and the eutrophic river Krebsbach leads to a submerged vegetation comprising species with different optima in regard to the trophic situation. This is one of the main reasons why many values of the TIM have to be labeled as “not sure”.  相似文献   
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