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331.
Ton H. Snelder Barry J. F. Biggs 《Journal of the American Water Resources Association》2002,38(5):1225-1239
ABSTRACT: River Environment Classification (REC) is a new system for classifying river environments that is based on climate, topography, geology, and land cover factors that control spatial patterns in river ecosystems. REC builds on existing principles for environmental regionalization and introduces three specific additions to the “ecoregion” approach. First, the REC assumes that ecological patterns are dependent on a range of factors and associated landscape scale processes, some of which may show significant variation within an ecoregion. REC arranges the controlling factors in a hierarchy with each level defining the cause of ecological variation at a given characteristic scale. Second, REC assumes that ecological characteristics of rivers are responses to fluvial (i.e., hydrological and hydraulic) processes. Thus, REC uses a network of channels and associated watersheds to classify specific sections of river. When mapped, REC has the form of a linear mosaic in which classes change in the downstream direction as the integrated characteristics of the watershed change, producing longitudinal spatial patterns that are typical of river ecosystems. Third, REC assigns individual river sections to a class independently and objectively according to criteria that result in a geographically independent framework in which classes may show wide geographic dispersion rather than the geographically dependent schemes that result from the ecoregion approach. REC has been developed to provide a multiscale spatial framework for river management and has been used to map the rivers of New Zealand at a 1:50,000 mapping scale. 相似文献
332.
Robert V. Sobczak Thomas C. Cambareri 《Journal of the American Water Resources Association》2002,38(3):747-757
ABSTRACT: An inverse‐simulation approach is used to determine optimal strategies for developing public water‐supply systems in a shallow, coastal aquifer on the outermost arm of the Cape Cod peninsula in Massachusetts. Typically a forward simulation (or “trial and error”) approach is used to find best pumping strategies, but the chances of finding success with this tact diminish as the number of potential options grows large. Well locations and pumping rates are optimized with respect to: (1) providing sufficient water to areas of water‐quality impairment, (2) minimizing impacts to nearby surface waters, (3) preventing saltwater contamination due to overpumping, and (4) minimizing financial cost of well development. Potential well sites and water‐supply scenarios are separated into “politically‐based” and “resource‐based” categories to gain insight into the degree that pre‐existing political boundaries hinder best management practices. The approach provides a promising tool in transboundary water‐resources settings because it allows stakeholders to find solutions that best meet everyone's goals, as opposed to pursuing options that will create conflict, or are less than optimal. 相似文献
333.
随着工、农业的发展,洞庭湖区域的环境污染日趋严重。本文较详细地研究了洞庭湖区域的环境整治规划,在各环境要素的规划方面进行了探讨。 相似文献
334.
Since the end of the 1970s, the southern European countries have shown an exceptional reduction in fertility rate. From the
highest levels among the developed nations, these countries dropped beneath the substitution rate level: in Greece there is
an average of about 1.5 children per woman, and Italy (starting three to four years ago), with 1.3 children per woman, is
now the country with the lowest fecundity rate in the world. Land-use planning in southern European small islands therefore
requires substantial revision. In the areas where western civilization began, which are highly populated and have a long history,
cultural and ethnic aspects of tradition are fundamental to environmental management and to the defense of historical heritage.
They also place a strong value on sustaining tourism, the most relevant economic activity, that allows them to survive and
maintain a high welfare level. For some decades they have had populations with a marked presence of young people and high
emigration rates, but now they are fast becoming dominated by the elderly and must prepare for a period of fast reduction
in youth of the workforce, while the peripheral areas of Asia and Africa are entering a sudden demographic growth phase.
The demographic structure has also been deeply altered both by previous migrations and by random variations, as usually happens
in all small communities. Social services for younger and older people have had to be adapted rapidly, reorganizing high-school
management, hospital and health-care structures, in-house assistance, and so on. There is a need to rethink the job market
and favor the immigration of highly specialized workers, which is a necessity for technical evolution. Sustainable development
is constrained nowadays not only by the scarcity of natural resources, but also by the quality and quantity of human resources.
Proper policies for population and land-use planning are highly correlated factors; they have to be considered with respect
of these new, rapid demographic changes. 相似文献
335.
It is a common experience that public administrations tend to shy away from the explicit acknowledgment of quantitative risk
levels. Faced with extreme concentrations of population and of industrial activities, including LPG and liquid chlorine storage,
within a very small land area, Hong Kong has faced up to the issue of major man-made hazards by “thinking the unthinkable”
and adopting explicit risk guidelines. This article describes how these guidelines were developed and the arguments that led
to their adoption. It is emphasized that the risk guidelines are not rigid standards but simply a method of focusing decision
making and ensuring that any decision to contravene the guidelines is taken at an appropriately senior level in the administration.
The way in which the guidelines have been incorporated intimately into the planning and decision-making process is described
and details are given on how this has led to the implementation of a variety of measures that have greatly reduced both societal
and individual risk from certain types of chemical storage and chemical processing installations in Hong Kong.
The opinions in this paper represent the views of the authors and not necessarily those of the Hong Kong Government. 相似文献
336.
Timothy Beatley 《Environmental management》1992,16(1):7-19
Habitat conservation plans (HCPs) permitted under Section 10(A) of the federal Endangered Species Act, have been increasingly
used to overcome conflicts between urban development and species conservation. This article profiles one such HCP, the Coachella
Valley (CA) Fringe-Toed Lizard Habitat Conservation Plan. The second HCP officially approved by the US Fish and Wildlife Service,
the Coachella Valley case is frequently cited as a model for resolving conservation and development conflicts. The article
begins with a discussion of the use of HCPs, and then provides a detailed discussion of Coachella Valley experience, its history,
specific provisions, and success to date. A final section examines whether Coachella Valley does in fact represent a positive
model. It is argued that the HCP has been less than fully successful and leaves unresolved a series of fundamental ethical
and policy questions concerning the protection of endangered species.
Funding for this report was provided by the National Fish and Wildlife Foundation. Any opinions, findings, conclusions, or
recommendations are those of the author and do not necessarily represent the views of the Foundation. 相似文献
337.
338.
John Houlahan W. Andrew. Marcus Adel Shirmohammadi 《Journal of the American Water Resources Association》1992,28(3):553-567
ABSTRACT: This paper presents the results of an investigation of the effects of the Maryland Critical Area Act on generation of non-point source loads of phosphorus, nitrogen, and sediment to the Rhode River estuary. The Simple Method model, the Marcus and Kearney regression model, and the CREAMS model were used to estimate annual loads under: (1) present conditions, (2) maximum land use development allowable under the Act, and (3) two sets of future land use conditions that might occur if the Act were not in place. Results indicate that the Critical Area Act can reduce the present generation of nonpoint nutrient and sediment loadings 20–30 percent from the regulated area. These reductions can occur while preserving agricultural lands and allowing limited residential and urban development. The decrease in nutrient loadings is primarily dependent upon implementation and enforcement of agricultural best management practices (BMPs). The BMPs could reduce present agricultural nutrient loadings by 90 percent to a level comparable to loadings from residential areas. The estimated effectiveness of the Critical Area Act is even greater when compared to potential future nutrient loadings if development in the area remains unregulated. Unrestricted residential and urban development could increase nutrient loadings by 200 percent to 1000 percent as compared to controlled development under Critical Area Act guidelines. The Critical Area Act primarily prevents these future increases by severely limiting woodland cutting, with lesser results obtained by requiring urban BMPs. 相似文献
339.
本文在论述土地使用权出让和土地利用总体规划内涵的基础上,研究了两者作用和反作用的关系,提出了两者最终目标一致性的观点,并探讨了实践上相关的问题。 相似文献
340.
根据毕节地区16个主要造林树种的生态生物学特性,结合本区气候和土壤生态条件,运用 Fuzzy 二级评价模型,对各土类水土保持树种的适宜程度进行了综合评价。 相似文献