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291.
运用超模博弈理论,以流域水资源管理制度形成的角度来解释流域各区段水资源管理政策执行面临的外部环境约束与激励,并通过模型描述了水资源管理域与外部关联域之间的博弈关系。分析发现:超模结构在当前钱塘江与黑河流域的水资源博弈中发挥着重要影响。钱塘江流域水资源管理制度收益函数对水功能区治理变量和经济域治理变量有递增差异。黑河流域水资源管理制度收益函数对分水治理变量和社会域治理变量有递增差异。由于这种关联作用对各区段主体策略集的限制,流域间水资源管理制度逐渐异质化,各流域管理结构呈现出一定的区域特色。钱塘江流域水资源管理偏重于扁平化、职能化管理,黑河流域为科层结构下水资源的层级分配。并依据以上研究结论提出了制度建议。 相似文献
292.
293.
Santanu Banerjee 《Gondwana Research》2000,3(4):521-528
The 1.2 Ga-old Koldaha shale, central India reveals three orders of depositional cyclicities in its basal storm-dominated shelf succession. Visual appraisal as well as Fourier and MEM analyses concurs in this respect. Only the major storm events at intervals of a few thousands of years have left recognizable imprints. Interbedding of storm sandstones and fairweather shales is apparently climate-controlled. Packaging of about seven such climatic cycles results the second-order cyclicity befitting eccentricity cycles of contemporary scale. Nonetheless, for the erratic storm bed-thickness trends within the cycles some other factor/s might have played a role. The third order cycles are, more dominantly, correlatable with basinal tectonics. 相似文献
294.
对“三江并流”,世外桃园的乡城地区的奇特旅游景观,罕见的地方情趣作简要介绍,为发展该区的旅游业提供参考。 相似文献
295.
层序和体系域的有机相构成及其研究意义 总被引:8,自引:0,他引:8
层序地层学为沉积盆地的充填史分析和储层预测提供了有效的格架,但其在源岩评价和预测中的意义未能引起充分的重视。本文对莺海、琼东甫盆地的各沉积层序进行了有机相分析,发现(1)浅水型沉积层序中各体系域的机相构成基本相同,且有机相的侧向变化不明显;(2)在深水型层序中,海进体系域上部和高位体系域下部有机质丰度较高、类型较好,有机相层序呈S性,但有机的侧向变化明显;(3)多层序有机相的总体演化趋势反映了盆地 相似文献
296.
Patricia A. Lockridge 《Natural Hazards》1990,3(4):403-412
While earthquakes generate about 90% of all tsunamis, volcanic activity, landslides, explosions, and other nonseismic phenomena can also result in tsunamis. There have been 53 000 reported deaths as a result of tsunamis generated by landslides and volcanoes. No death tolls are available for many events, but reports indicate that villages, islands, and even entire civilizations have disappeared. Some of the highest tsunami wave heights ever observed were produced by landslides. In the National Geophysical Data Center world-wide tsunami database, there are nearly 200 tsunami events in which nonseismic phenomena played a major role. In this paper, we briefly discuss a variety of nonseismic phenomena that can result in tsunamis. We discuss the magnitude of the disasters that have resulted from such events, and we discuss the potential for reducing such disasters by education and warning systems. 相似文献
297.
Impact of land use covers upon karst processes in a typical Fengcong depression system of Nongla, Guangxi, China 总被引:2,自引:0,他引:2
Cheng Zhang Jianguo Pei Yunqiu Xie Jianhua Cao Lanling Wang 《Environmental Geology》2008,55(8):1621-1626
The direction and intensity of karst processes can be deeply affected by soil physical and chemical variations which were
resulted from land use. Taking Nongla Fengcong depression area, Mashan County, Guangxi as an example, authors discussed the
impact of land use on karst processes based on the data of field limestone tablet. The results showed that the corrosional
rates at varied soil depth are quite different. Corrosional rate in woodland and orchard is mostly bigger than 20 mg/a, which
is much higher than that in tilled land and shrub. Generally, corrosional rate decreased from orchard, woodland, tilled land,
fallow land and shrub successively, in which soil organic matter (OM) and soil pH are two major controlling factors: corrosion
process is controlled remarkably by soil OM in woodland and orchard. The higher the organic matter content is and the less
the pH value is, the higher the corrosional rate is. Owing to lower organic matter content, the corrosional rate is mainly
affected by soil CO2 in tilled land and shrub. 相似文献
298.
Groundwater study using remote sensing and geographic information systems (GIS) in the central highlands of Eritrea 总被引:3,自引:1,他引:3
Remote sensing, evaluation of digital elevation models (DEM), geographic information systems (GIS) and fieldwork techniques were combined to study the groundwater conditions in Eritrea. Remote sensing data were interpreted to produce lithological and lineament maps. DEM was used for lineament and geomorphologic mapping. Field studies permitted the study of structures and correlated them with lineament interpretations. Hydrogeological setting of springs and wells were investigated in the field, from well logs and pumping test data. All thematic layers were integrated and analysed in a GIS. Results show that groundwater occurrence is controlled by lithology, structures and landforms. Highest yields occur in basaltic rocks and are due to primary and secondary porosities. High yielding wells and springs are often related to large lineaments, lineament intersections and corresponding structural features. In metamorphic and igneous intrusive rocks with rugged landforms, groundwater occurs mainly in drainage channels with valley fill deposits. Zones of very good groundwater potential are characteristic for basaltic layers overlying lateritized crystalline rocks, flat topography with dense lineaments and structurally controlled drainage channels with valley fill deposits. The overall results demonstrate that the use of remote sensing and GIS provide potentially powerful tools to study groundwater resources and design a suitable exploration plan.The online version of the original article can be found at 相似文献
299.
The influence of topography and land use on water quality of Xiangxi River in Three Gorges Reservoir region 总被引:5,自引:0,他引:5
A self-organizing map (SOM) was used to cluster the water quality data of Xiangxi River in the Three Gorges Reservoir region.
The results showed that 81 sampling sites could be divided into several groups representing different land use types. The
forest dominated region had low concentrations of most nutrient variables except COD, whereas the agricultural region had
high concentrations of NO3N, TN, Alkalinity, and Hardness. The sites downstream of an urban area were high in NH3N, NO2N, PO4P and TP. Redundancy analysis was used to identify the individual effects of topography and land use on river water quality.
The results revealed that the watershed factors accounted for 61.7% variations of water quality in the Xiangxi River. Specifically,
topographical characteristics explained 26.0% variations of water quality, land use explained 10.2%, and topography and land
use together explained 25.5%. More than 50% of the variation in most water quality variables was explained by watershed characteristics.
However, water quality variables which are strongly influenced by urban and industrial point source pollution (NH3N, NO2N, PO4P and TP) were not as well correlated with watershed characteristics. 相似文献
300.
A.G. Brown L.S. Basell R.C. Scrivener 《Proceedings of the Geologists' Association. Geologists' Association》2009,120(4):275-281
This paper presents a first approach to using a sediment budget methodology for paired terrace staircase sediments in SW England. Although a budget approach has become firmly established in Holocene fluvial studies, it has not been used in Pleistocene sequences due to the problems of temporal resolution, catchment changes and downstream loss from the system. However, this paper uses a budget approach in a paired non-glaciated basin, primarily as a method of interrogating the terrace record concerning the degree of reworking and new sediment input required to produce the reconstructed terrace sequences. In order to apply a budget approach a number of assumptions have to be made and these are justified in the paper. The results suggest that the Exe system can most parsimoniously be explained principally by the reworking of a Middle Pleistocene floodplain system with relatively little input of new resistant clasts required and a cascade-type model in geomorphological terms. Whilst this maybe partially a result of the specific geology of the catchment, it is likely to be representative of many Pleistocene terrace systems in NW Europe due to their litho-tectonic similarities. This cascade-type model of terrace formation has archaeological implications and sets the context for the Palaeolithic terrace record in the UK. Future work will involve the testing of this and similar budget models using a combination of landscape modelling and chronometric dating. 相似文献