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871.
Manmade dunes are used to stabilize the barrier islands of the mid-Atlantic coast of the United States so that they are more amenable to development. Although this strategy has stabilized extensive sections of the barrier-island substrate, it has also caused significant ecological changes. The rate and pattern of the resulting vegetation changes along the Outer Banks of North Carolina were determined using sequential aerial photography. Successional trends have been altered in favor of more stable woody communities.  相似文献   
872.
Irreversible environmental changes are occurring along the Colorado River in the Grand Canyon as a result of regulation of the river flow by the Glen Canyon Dam. The questions of primary importance in managing this great natural resource are 1) in what manner and how rapidly are the physical and ecological adjustments taking place, and 2) is the increased use of the river for recreational boating contributing to the degradation? Human use along the Colorado River is limited, for the most part, to the relic, pre-dam fluvial deposits colloquially called “beaches.” With the new river regime these deposits are positioned well above the present high-water stage, 27,000 cubic feet/second (cfs), or 765 cubic meters/second (cms), so they are not replenished periodically as they were prior to construction of the dam in 1963. The dominant natural processes now are aeolian sand transport and mass wasting. The float-trip passengers use the river beaches for hiking, camping, and. lunch stops. At the most desirable sites thirty to forty people camp on the beaches each night over a four to five month season. Human impact includes incorporation of campsite litter, burial of chemically treated waste, and the direct stress associated with people walking on the vegetation and unstable sedimentary deposits. Results of our investigations indicate that the rate of degradation at the most heavily used sites exceeds the capacity of aeolian processes to reestablish natural landscapes. Therefore, careful management of float trjps is needed if these environments are to be maintained in a natural state rather than a “sand-box” state.  相似文献   
873.
ABSTRACT: An important international Niagara River management issue concerns allocation of the average 202,000 cubic feet per second river discharge for hydroelectric power and scenic purposes. Major water diversions from Niagara Falls are necessary for power production. Flow is allocated by the 1950 Niagara Treaty which is intended to maximize power benefits and preserve and enhance the scenic fals spectacle. This paper examines the extent to which the Treaty objectives have been achieved. Based on analyses of government documents, engineering data, and falls-viewing patterns, it is concluded that the 1950 Treaty led to enhancement of the falls spectacle and increased power generation. But significant additional power diversions probably are attainable without adverse effect upon the existing falls spectacle. Reducing daytime summer Horseshoe Falls flow and scheduling spring and autumn flow according to viewing patterns are possible means of increasing power diversions. Existing generating facilities could use considerably more water and the value of additional Niagara hydroelectricity is very high in terms of generation-cost savings over alternative power sources. Because of the cultural importance of the falls, Treaty modifications to permit increased power diversions are not recommended without prior public opinion sampling and on-site viewing experiments. These findings highlight the need for more careful study before long-term international agreements are concluded and illustrate the need for more flexible treaty arrangements to permit periodic adjustments for changing conditions.  相似文献   
874.
ABSTRACT: A nonlinear multilevel transportation model is developed to study large-scale allocations in a water resources system. The model uses a modified transportation matrix formulated with nonlinear cost functions as the basic subregional model and the goal coordination method for multilevel decomposition and optimization of the overall regional system. The model is applied to projected water requirements for Salt Lake County in 1985. Sources of water supply - surface water, ground water, import water, and reuse of reclaimed wastewater on a restricted basis - are available to satisfy water requirements for municipal, industrial, and agricultural sectors in four subregions. The conjugate gradient projection method is used to optimize the first level subregional models having cost functions of the form of C = aXb, and the second level problem is solved using the conjugate gradient method.  相似文献   
875.
ABSTRACT: Water resource development has progressed to the stage where various human factors are now being considered in reservoir design and operation. The introduction of human factor objectives complicates the problem since they are noncommensurate with other objectives and they are difficult to identify quantitatively. Some of the problems that now arise concern the proper methods for consideration of several different, sometimes subjectively identified, objectives in reservoir planning. The classical systems analysis approach to decision making for multiple objective problems is outlined and the inherent difficulties associated with multiple objectives and subjective estimates are identified. Techniques being used in reservoir design and operation are reviewed and discussed. An alternate technique for considering noncommensurate, subjectively identified, objectives, which relates the objectives in terms of real trade-off costs and eliminates the need for a priori estimates of objective worth is then presented. The method is illustrated with three examples, including a reservoir operation problem and a cooling tower design problem.  相似文献   
876.
877.
Disaster risk management, particularly management of climate-related risks, has become central to the international policy agenda. Reducing hazard-related loss and damage relies heavily on scientific inputs. Science, in turn, relies on data—in this case 1) risk-related data on hazards, exposure and vulnerability, and 2) data on associated loss and damage outcomes. The latter, data on losses and damage, are also post-2015 international policy outcome indicators at the highest level, required for countries’ monitoring of progress in reducing disaster risk, adapting to climate change, and achieving sustainable development. Although the quantity and accessibility of loss and damage data are improving, a number of issues continue to constrain their potential. These include needs for more consistent cataloguing of hazards and extreme events, more systematic and accurate documentation of per-event losses and damage, more precise cross-referencing of hazard events with associated loss and damage, and improved standardization and interoperability among databases. We identify measures for improvement in this regard, both for research purposes and for post-2015 international policy implementation.  相似文献   
878.
Vietnam, in the ongoing transition to market economies, has to cope with high rural poverty and a dramatic process of forest loss and environment degradation, particularly in the mountainous regions. The government considers rural poverty as the main cause of environment degradation, associated with slash-and-burn cultivation and to an unclear definition of property rights on forest land. In 1993, the government launched a Forest Land Allocation programme aiming to lease forest lands to individual households and, on this basis, to solve food security problems, halt the increasing environment degradation and preserve the remaining forests.To evaluate the results of this land reform policy, two upland pilot communes have been intensively monitored. The environmental and economic impacts of the forest land reform allocation in the two study areas are presented, after providing a background on the Vietnamese situation of mountain zones. On the basis of these findings, it is discussed as to whether the current forest land allocation process may actually promote local development and natural resources conservation, and under what conditions. Deforestation problems must be tackled also with new macroeconomic policies (e.g. credit programmes to support sustainable agriculture practices) and social policy (e.g. reduction of demographic pressure), together with the reform of the State institutions (e.g. State Forest Enterprises) involved in management of the forest areas.  相似文献   
879.
We propose a suite of actions for strengthening water governance in contexts with complex, multi-tiered arrangements. In doing so, we focus on the collective water policies and approaches of the United Kingdom (UK), including those of devolved governments, which confront a host of serious water-related challenges—from massive flooding of urban areas and agricultural lands, to pressure on aquifers from rising water demand and drought. Further complexity in addressing these challenges has emerged in the wake of the June 2016 vote to leave the European Union (EU), so-called ‘Brexit’, and the ensuing ‘separation process’ with uncertainties for institutional and governance arrangements to follow. We make ten proposals for improving and reinvigorating water policy in complex, multi-layered situations, and comment specifically on their application in the UK setting. These are: put in place a system-wide water policy; fully embrace community-led nested river basin planning and management; fully fund river basin planning and management; re-focus the policy framing; use best-available data and information; create conversational spaces and become a more water-literate society; mobilise people; support and sustain core community networks; underpin river basin plans with regulatory provisions and effective monitoring and enforcement; and address systemic institutional amnesia. Individually and collectively, we contend that these actions will have a marked effect on transforming the planning and management of water resources. A system-wide water policy that maintains and builds on the substantive biophysical and socio-economic benefits delivered through implementation of the EU Water Framework Directive, together with the more recent Floods Directive, will galvanise stewardship of water in the UK. We urge more active engagement with and empowerment of the multiplicity of system ‘actors’, and highlight the role of non-government actors in a post-Brexit world as conduits for reaching out to and connecting directly with a wide range of water-related actors, especially across the EU. While attention to-date has focused on a plethora of specifically water-related projects, initiatives, plans and regulations, what is really needed is a systemic, long-term view of water resource management.  相似文献   
880.
重点论述社会主义市场经济条件下的企业全员安全管理的概念、特点和基本要求,企业开展全员安全管理的重要性,应遵循的原则和实施措施。  相似文献   
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