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951.
Robert Coats Laurel Collins Joan Florsheim Darrell Kaufman 《Environmental management》1985,9(1):35-48
A study on sediment transport and channel change was conducted on Zayante Creek and the lower San Lorenzo River in Santa Cruz County, California. A rainstorm with a recurrence interval locally in excess of 150 years occurred during the study year, 1982 WY. Stream surveys indicated that significant aggradation occurred during and after the peak flood. Upper study reaches were substantially recovered after high flows of early April, but the lower study reaches still had significant filling of pools and burial of riffles by sand. Increases in width-depth ratio were minor and localized in upper reaches, but were significant in lower reaches. Large inputs of sand, primarily from landsliding, altered the sediment transport regime. A higher proportion of the bedload is now transported by lower flows than before the January event. Roads and sand quarries contributed significantly to sediment input to the stream. A proposed dam may alter the sediment transport regime of Zayante Creek. Mitigating the effects of this dam on downstream fish habitat may require occasional bankfull discharges. 相似文献
952.
This article analyzes landscape pattern in the WesternGhats mountain ranges in south-western India at two scales,comparing small-scale, detailed studies of landscapepattern, with broader, regional-scale assessments of theWestern Ghats. Due in large part to their inaccessibility,relatively little is known about the landscapes of thisbiodiverse region, which also supports some of the highestpopulation densities in the world. A broad-scale NDVI-basedIRS 1B satellite image classification is used to analyzenorth-south and east-west trends across the entire WesternGhats and western coast of India, an area over 170 000 km2. Northern and eastern landscapes are morefragmented compared to the southern and western slopes.Western slopes also have greater landscape diversity withland cover types more interspersed compared to the easternslopes. These differences can be related to north-south andeast-west variations in rainfall and plant distribution. Data from thirteen landscapes 10–50 km2 in area, arefurther utilized to analyze trends in landscape pattern, anddescribe the geographical distribution of major natural andmanaged ecotope types. At this scale, very high levels ofintra-ecotope type variability in landscape pattern areencountered for all land cover types. Results at these twoscales are integrated to suggest a hierarchical stratifiedapproach for monitoring land cover and biodiversity in the region. 相似文献
953.
Peter Timmerman 《Environmental monitoring and assessment》1998,49(2-3):111-122
The social and economic implications of atmospheric change on biodiversity need to be seen in a global context of major shifts in the conceptualization and management of our relationship with nature. Traditionally, we have conceptualized the atmosphere and the other creatures of the biosphere as separate from the human, but their quasi-autonomy is now becoming subject to more and more human management. This raises not only economic issues, but social, political, and ethical concerns that will have substantial influence on public policy. Among these are the commodification of genetic material; the privatization of traditional knowledge; and the management of information. In this broader context, the paper examines an array of current and proposed strategies of response to changes in biodiversity as a result of climatic and other stresses. 相似文献
954.
Whitelaw G Vaughan H Craig B Atkinson D 《Environmental monitoring and assessment》2003,88(1-3):409-418
Community-based ecosystem monitoring activities in Canada are increasing in response to a number of factors including: (i) the needs of decision-makers for timely information on local environmental changes; (ii) limited use of government monitoring data and information by decision makers; (iii) government cuts to monitoring programs; (iv) the increasingly recognized need to include stakeholders in planning and management processes; and (v) the desire of citizens to contribute to environmental protection. To date there has been no network coordination of community based monitoring in Canada. This paper reports on the establishment of the Canadian Community Monitoring Network by Environment Canada's Ecological Monitoring and Assessment Network Coordinating Office and the Canadian Nature Federation. Information on research prepared in support of network establishment is presented along with a discussion of the potential of the network. 相似文献
955.
本文利用曲线补偿,变时溶出示差技术提高了测定Cu、Pb、Zn、Cd的灵敏度、精密度和准确度,进一步改变了谱图的分辨率,避免了O2波的干扰 相似文献
956.
分析了濠河水体中非离子氨在不同断面、不同月份、不同年际的变化情况 ,并指出其超标的原因及控制措施 相似文献
957.
Environmental Monitoring in The Netherlands: Past Developments and Future Challenges 总被引:1,自引:0,他引:1
During the past three decades environmental monitoringsystems covering an immense variety of environmentalproblems emerged rapidly throughout the world. In The Netherlands the entire spectrum of monitoring systemsis present. Their development is especially interesting because of the Dutch complex environmental landscape: a result of the combination of a natural setting with a high small-scale variation and an intense use of the available space by both industry and agriculture. This necessitates a well balanced environmental policy wherein monitoring ofboth environmental compartments and environmental policy itself plays an important role. In this article we focus on abiotic systems, whereby the development of monitoring will be related to that of environmental policy in general. Some general lines emerge: from quantity towards quality, from single pollutants towards environmentally harmful processes as a whole, and from a focus on human health and safety towards integrated environmental management. Because The Netherlands is a highly organized and highly educatedsociety, reacting fast and flexible to new problems, this progression has happened quickly. However, still much remains to be desired and flexibility not necessarily guarantees optimal routes of development. Paramount is the development of sophisticated and robust monitoring systems that truly support integrated environmental management. This asks forclear objectives based on solid scientific insights. 相似文献
958.
Integration of Case Studies on Global Change by Means of Qualitative Differential Equations 总被引:2,自引:0,他引:2
We present a novel methodology to integrate qualitative knowledge from different case studies on Global Change related issues
into a single framework. The method is based on the concept of qualitative differential equations (QDEs) which represents
a mathematically well-defined approach to investigate classes of ordinary differential equations (ODEs) used in conventional
modeling exercises. These classes are defined by common qualitative features, e.g., monotonicity, signs, etc. Using the QSIM-algorithm
it is possible to derive the set of possible solutions of all ODEs in the class. By this one can formulate a common, qualitatively
specified cause–effect scheme valid for all case studies. The scheme is validated by testing it against the actually observed
histories in the study regions with respect to their reconstruction by the corresponding QDE. The method is outlined theoretically
and exemplary applied to the problem of land-use changes due to smallholder agriculture in developing countries. It is shown
that the seven case-studies used can be described by a single cause–effect scheme which thus constitutes a pattern of Global Change. As a generally valid prerequisite for sustainability of this kind of land-use the presence of wage labor is shown to represent
a decisive factor.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
959.
Stream discharge of a watershed is affected and altered by climate and landcover changes. These effects vary depending on the magnitude and interaction of the changes, and need to be understood so that local water resource availability can be evaluated and socioeconomic development within a watershed be pursued and managed in a way sustainable with the local water resources. In this study, the landcover and climate change effects on stream discharge from the Jacks Fork River basin in the Ozark Highlands of the south-central United States were examined in three phases: site observation and data collection, model calibration and simulation, and model experiment and analysis. Major results of the study show that climate fluctuations between wet and dry extremes resulted in the same change of the basin discharge regardless of the landcover condition in the basin. On the other hand, under a specified climate condition landcover change from a grassland basin to a fully forested basin only resulted in about one half of the discharge change caused by the climate variation. Furthermore, when landcover change occurred simultaneously with climate variation, the basin discharge change amplified significantly and became larger than the combined discharge changes caused by the climate and landcover change alone, a result indicating a synergistic effect of landcover and climate change on basin discharge variability.
Agricultural Research Division, University of Nebraska-Lincoln, Contribution Number 13437.Qi Hu: Corresponding author: Dr. Qi Hu, Climate and Bio-Atmospheric Sciences Group, School of Natural Resource Sciences, 237 L.W. Chase Hall, University of Nebraska-Lincoln, Lincoln, NE 68583-0728, USA. E-mail: qhu2@unl.edu. 相似文献
960.
We have developed a new version of the MERGE model, called MERGE-ETL, to analyse the dynamics of endogenous technological learning (ETL) in the energy system. This paper describes the basic formulation of MERGE-ETL, the solving techniques used for this model and some first numerical results in the context of policies designed to mitigate global climate changes. 相似文献