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501.
William J. McElroy 《Journal of the American Water Resources Association》1977,13(6):1153-1164
ABSTRACT: Since the early 1900's the Upper St. Johns River Basin, Florida, has been experiencing rapid agricultural development, through reclamation of the low-lying marshland by organized drainage districts, private land owners and corporations. These low-lying marsh areas, which constitute the floodplain, have been altered by the creation of levees, thereby reducing the natural storage capacity and permanently altering the regime of the system. This floodplain encroachment has resulted in both higher and lower water levels occurring in the upper basin area, and an increase in hydroperiod. This paper discusses the history and background of the basin accompanied by a hydrologic discussion, and suggests recommendations for a water management plan that could improve the overall operation and management of the Upper St. Johns River basin. 相似文献
502.
Atmospheric reaeration is a natural mechanism of oxygen transfer from the atmosphere to a water body. In practice, stream water quality models are developed with reaeration coefficients (K2) estimated by predictive equations. This leads to uncertainties in modeling analysis because these equations are empirical in nature and may yield greatly different K2 values for the same stream. Values of K2 may be adjusted in model calibration, but unfortunately, values of other model parameters are no less easy to identify and require adjustment in model calibration as well. Therefore, validity of a stream model would be enhanced significantly if K2 could be determined directly and reliably. In this research, values of K2 in the Canandaiqua Outlet in Central New York have been measured by using a gas tracer method. A successful modeling analysis was conducted using these K2 values. As a result, effluent limitations of several waste water discharges into the Outlet were established. It was concluded that field measurements of reaeration rate would improve modeling results significantly, and that the gas tracer method can be easily incorporated into intensive water quality surveys normally required for stream modeling. 相似文献
503.
Preventing groundwater contamination is vastly cheaper than remediation. Recognizing this, attention in water and land management
agencies in North America increasingly turn to groundwater protection. Local agencies, such as municipalities and watershed
management districts, are vital to successful groundwater protection, but they face daunting challenges. In the United States,
senior governments have recognized these challenges and provide considerable support for local agencies. In Ontario, Canada,
local agencies are, to a much greater extent, on their own. The aims in this paper are to analyze factors that shape local
capacity for groundwater protection, focusing on Ontario, and to recommend avenues for capacity building. Interrelationships
among five dimensions of capacity (technical, financial, institutional, social, and political) are explored through an analysis
of three smaller Ontario communities: City of Guelph (population 93,400), Town of Orangeville (population 22,188), and Town
of Erin (population 11,000). Size clearly influences capacity for groundwater protection. However, other considerations unrelated
to size appear to be as important. These other factors include the ability to form horizontal and vertical linkages with external
agencies, political leadership and commitment, and citizen involvement. Thus, smaller communities in Ontario (and other jurisdictions
with limited senior government support) would do well to focus on these areas at the same time as they develop their technical,
financial, and institutional capacity. 相似文献
504.
本文提出了土地人口容力,即单位面积土地的人口容量的概念,建立了描述和测算开放区域人口容力的模型,确立了模型对多种人口容力定义,揭示了不同人口容力模型的内在联系性,并将它用于沪苏锡常城市群的土地人口容力测算和分析。 相似文献
505.
506.
507.
Oettlé N Arendse A Koelle B Van der Poll A 《Environmental monitoring and assessment》2004,99(1-3):115-125
Community knowledge exchanges have played a key role in developmental processes in the Suid Bokkeveld community of South Africa.
Two exchange visits were undertaken with the support of the Department of Agriculture and an NGO, the Environmental Monitoring
Group, which have led to local economic development and enhanced capacity to manage natural resources in a sustainable manner.
These pilot projects were undertaken within the framework of the Community Exchange and Training Programme of the Global Mechanism
of the United Nations Convention to Combat Desertification (UNCCD). The methodology applied included facilitation to develop
a community-based vision for development, in terms of which the community exchange process was designed. A Facilitation Team
of service providers conducted preparatory workshops, and identified potential partner communities. Two exchange visits were
carried out, one focused on Rooibos production and marketing, and the other on community-based eco-tourism. Following report-back
and planning workshops, emerging community-driven initiatives were supported through their formative stages. The initiatives
have not only resulted in enhanced livelihoods, but the methodology has also been applied widely in a number of different
contexts. 相似文献
508.
Combating desertification requires the involvement of many people ranging from communities who experience the effects on a
daily basis and scientists attempting to understand the biophysical and socio-economic causes and consequences of desertification,
to developers and policy makers on all levels. In many instances, however, the understanding, approaches and actions of these
different groups contradict rather than support one another. Over the period 2000 to 2002, a conference process undertaken
in southern Africa brought together communities, scientists, and development workers to test the concept that they could connect
and work together to combat desertification, given an appropriate framework. The conference was a success, and communities,
scientists and developers did exchange experience, knowledge and information. Many lessons were learned, although some pitfalls
were experienced. Time, funding, enhanced communication, and good will are the primary ingredients for ensuring that different
sectors complement one another in their efforts to combat desertification. 相似文献
509.
在建立空气污染物排放清单的基础上,利用ADMS-城市多元扩散模型,采用城市空气质量管理战略初步成果,测算了抚顺市二氧化硫、颗粒物的容量。 相似文献
510.