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1.
利用1989-1999年近11年的水文、气象资料分析了福建省6个主要流域主控站水位与降水量的关系和洪涝的时间变化规律,进而分析了暴雨致洪的特征,结果表明:(1)福建省6个主要流域洪峰水位与上游有关气象站前期平均总降水量相关显著,暴雨是福建省洪涝发生的主要原因;(2)根据闽江(竹歧站)、九龙江(浦南)、交溪(白塔)、木兰溪(濑溪)4个站的达警戒水位或危险水位的降水指标,可利用暴雨预报作为洪涝预警预测的依据。(3)上世纪80年代后,洪水的高低变化有增大的趋势,应进一步完善抗洪防洪预警系统,提高抗洪防洪的应变能力。  相似文献   
2.
Soil and water conservation (SWC) contests among farmer groups were organized in five rural villages in the Bolivian mountain valleys. The contests were aimed at quickly achieving widespread sustainable results. This article analyzes the effectiveness of these contests as an extension tool. Mixed results were obtained. In three villages, participation rates in the SWC activities introduced in the contests were still high even 2 years after project withdrawal. These were all villages where a solid foundation for sustainable development had been laid before the contests were held. Two years later, most families were still involved in maintenance of the SWC practices introduced in the contests, and many farmers had started to experiment with different soil management practices. However, replications of these SWC practices were not widespread, Conservation Leaders did not continue with their training activities, and the quality of maintenance of the practices was often not satisfactory. In order to become a more effective extension tool and achieve widespread impact, SWC contests must receive continued support by a catalyst agency. Moreover, other SWC contests should also be organized in which practices are not predefined. Given that SWC contests are a low-budget extension tool, local municipalities could become more actively involved.  相似文献   
3.
Stream tributaries in the Des Moines River basin have been classified according to the glacial terrain through which they flow. Three stream types were categorized as follows: (1) streams that flow entirely on Wisconsin drift, (2) streams that flow entirely on Kansan drift, and (3) streams that have their headwaters located on new drift but have their lower reaches flowing on older drift. Selected channel and valley characteristics were measured and used to verify the stream type classification. Five variables were chosen for use in a multiple linear discriminatory analysis, which is a statistical technique developed for the purpose of classifying observations into one of several categories which have been predetermined. The streams in each group were verified with the exception of three anomalies based on the probability associated with the largest linear discriminant function. The rationale for the three anomalous streams is not easily determined. But, they are considered to be associated with pre-glacial drainage or at least pre-Wisconsin age drainage. Otherwise, the analysis shows that the major channels and valleys in the Des Moines River basin tend to reflect the glaciated upland surface.  相似文献   
4.
江河流域综合开发应以土地资源,水资源的利用保护为基础,与其他资源的开发相结合,从深度和广度两方面进行,而且必须与环境保护相协调。  相似文献   
5.
We propose a geomorphic basis for defining riparian areas using the term: riparian ecotone, discuss how past definitions fall short, and illustrate how a linked sequence of definition, delineation, and riparian sampling are used to accurately assess riparian resources on the ground. Our riparian ecotone is based on the width of the valley (its floodprone area width) plus 30 meters on each side to encompass the important adjacent riparian functions, and 15 meters around obvious landslides. A functionally consistent riparian definition and delineation does not derive from land adjacent to a stream, rather it derives from the valley the stream runs through.  相似文献   
6.
黑水河干旱河谷沿程土壤物理参数梯度变化特征研究   总被引:1,自引:0,他引:1  
黄雪菊  孙辉  唐亚 《四川环境》2007,26(6):32-35,39
横断山区干旱河谷是具有典型的旱季和雨季的特殊气候特征的区域,本区域土壤退化和荒漠化极大制约了区域农业的发展。本文研究了金沙江干热河谷区支流黑水河从源头到河口未扰动土壤的物理参数变化特征。结果表明,沿河土壤物理呈现不同变化趋势,砾石在中游部分河段和河口段高,而〉5mm团聚体的变化则相反;5~1mm的团聚体变化不大;〈1mm团聚体河口和源头段高于其余地段;土壤容重沿程增大,非饱和导水率源头地段土壤最高。本研究初步揭示了干旱河谷土壤不均匀,不同水热条件及其组合可能对退化程度有至关重要的影响。这表明横断山区不同的干旱河谷地段土壤和植被退化途径、退化特征和退化过程不同,开发和治理途径与方式也应当不同。  相似文献   
7.
利用横断山区干旱河谷内24个气象站逐月降水、气温等观测资料,依托高桥浩一郎陆面蒸发公式,计算了干旱河谷区陆面蒸发、可利用降水等水资源分量,并分析了各分量的未来演变趋势。结果表明:干旱河谷区年均降水量723.7mm,而年均蒸发量高达479.5mm,降水量中有超过84.89%因蒸发而损耗;大气水资源分量P、E及PE季节变化非常明显,夏季各分量最大,多年平均值达404.9mm、239.9mm和164.8mm,各占全年的55.94%、50.04%和67.51%,而冬季各分量最小,占全年的比例也相应最小,仅为2.96%、4.06%和0.79%;大气水资源各分量年代际差异很大,20世纪60年代可利用水资源丰富,70年代相对偏少,80和90年代逐渐增加,进入21世纪后又呈现为偏少特征;未来干旱河谷区的降水量维持减少的概率较转向增加的概率要小,蒸发量将依然维持增加的趋势,而可利用水资源量会继续维持减少的倾向。  相似文献   
8.
Alpine valleys are sensitive to anthropogenic emissions. Local atmospheric dynamics are a key factor that may lead to an accumulation of pollutants in the bottom of the Chamonix and Maurienne valleys. Assessment of 2010 pollutant concentrations variability needs to take these specificities into account. A meteorological data classification is combined with different emission scenarios in order to run an air quality model. Using simulations of representative scenarios rather than complete years allows for a fine spatial and temporal representation of local atmospheric dynamics and gives access to detailed chemical breakdowns. Results demonstrate the variability of primary and secondary species due to emissions and the predominance of local effects on pollutant concentrations.  相似文献   
9.
Academic arguments present a critique of representative democracy and suggest that enhanced participation of communities in the management, governance and regulation of their local environments is required. Similarly, theorists of environmental democracy suggest the possibility and desirability of community involvement. In this paper, we argue that theories of environmental democracy lack the explanatory power to address real-life relations between people and their environment. Drawing on empirical material from recent research in the forested communities of the former coalfields of the South Wales Valleys, we identify significant rigidities, inertia and barriers that stand in the way of community participation in environmental democracy. We do this by constructing a framework for critical analysis that postulates a connection between recent shifts towards post-productivism in British forestry policy and theories of environmental democracy. Our findings point to a dissonance between, on the one hand, post-productivist forestry policy and theoretical discourses of governance, participation and environmental democracy, and, on the other hand, the actual situation of people living in the communities of the Valleys forest in South Wales. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   
10.
四川省重点流域浮游植物群落调查研究   总被引:1,自引:0,他引:1  
首次对四川省纳入省控以上地表水、重点湖库及饮用水源地154个水质断面进行了浮游植物优势种、藻类密度及叶绿素a同步调查监测,分析了全省重点流域浮游植物群落特征,建立了四川省地表水环境藻类数据库。  相似文献   
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