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541.
This paper presented a thermodynamic synthesis that involved resource accounting, evaluation and modeling of urban ecosystems based on embodied cosmic exergy (EcE), which redefined embodied exergy with the cosmic microwave background radiation (CMBR) as the reference for solar exergy. In a case study of the Beijing urban ecosystem, the major resources supporting the urban ecosystem, both from free natural resources and from the economy, were accounted for, analyzed and evaluated in the same units, Cosmic Joules (Jc). These indicators revealed the current performance of the Beijing urban ecosystem by considering five aspects of the system: EcE sources, EcE intensity, EcE welfare, environmental impacts and economic efficiency. Moreover, through the combination of the EcE synthesis with a systems dynamics, this research constructed an embodied cosmic exergy-based urban system model (EESM) using Beijing as an example of urban development. The results show that the 10 years from 2010 to 2020 will be very critical for the sustainable development of Beijing because many key factors, such as water resources, wastes and urban assets, might be confronted with great changes during this period. These changes will inevitably transform the urban system not only in its external circumstances but also in its inner structure and may lead to serious consequences. Of all the necessary resources, the most sensitive factor is water supply.  相似文献   
542.
543.
对我国生态市(县)建设的几点思考   总被引:1,自引:0,他引:1  
通过对我国生态市(县)的建设现状、建设指标的修订情况及建设意义进行深入分析,从组织领导、建设规划、建设机制等方面提出了建设生态市(县)的可行性措施。  相似文献   
544.
耕地质量指标体系的构建   总被引:8,自引:0,他引:8  
根据土地质量的概念及其影响因素,构建了耕地质量指标体系。认为耕地质量的影响因素包括自然、社会和经济因素,而PSR(压力——状态——响应)框架则是构建耕地质量指标体系的最佳思路。在此基础上提出具体评价指标,其中生态功能指标体系包括土壤质量、气候质量、生物多样性质量和景观生态质量,生产功能指标体系(即耕地生产力)则通过耕地生产潜力、耕地基础地力和耕地现实生产力进行评价。  相似文献   
545.
This paper estimates the true economic income for the Chilean mining sector, using the welfare foundations for the usual net domestic product (NDP) income measure of the traditional National Accounts System (NAS) provided by [Weitzman, M., 1976. On the welfare significance of national product in a dynamic economy. Quarterly Journal of Economics. 90, 156–162; Weitzman, M., 2000. The linearised Hamiltonian as comprehensible NDP. Environment and Development Economics. 5, 55–68]. The total depletion of natural capital caused by mining is calculated by estimating, on the one hand, the depreciation of resources (using the net price approach) and, on the other, the environmental costs provoked by mining activity. The results show that, correcting the usual GDP measure for man-made capital depreciation plus the total loss of natural capital, the standard mining GDP measure of the NAS overestimates by 31–36% the economic income generated by Chile's mining sector during the period 1985–1996.  相似文献   
546.
1 INTRODUCTION Growing pressure on the land of North China Plain (NCP - a food bowl of the country, has made many of th traditional farming practices increasingly difficult to sustain such as manuring, composting, mulching, legume-based rotations, field levelling and fertilizing with mud from rivers and canals. The pressure on the farmlands has also led to a decrease in farm sizes and shortened fallow periods To cope with this pressure on the land and to maintain its fertility, farmers …  相似文献   
547.
ABSTRACT: In this paper we seek to identify historical indicators of international freshwater conflict and cooperation and to create a framework to identify and evaluate international river basins at potential risk for future conflict. We derived biophysical, socioeco‐nomic, and geopolitical variables at multiple spatial and temporal scales from GIS datasets of international basins and associated countries, and we tested these variables against a database of historical incidents of international water related cooperation and conflict from 1948 to 1999. International relations over freshwater resources were overwhelmingly cooperative and covered a wide range of issues, including water quantity, water quality, joint management, and hydropower. Conflictive relations tended to center on quantity and infrastructure. No single indicator—including climate, water stress, government type, and dependence on water for agriculture or energy—explained conflict/cooperation over water. Even indicators showing a significant correlation with water conflict, such as high population density, low per capita GDP, and overall unfriendly international relations, explained only a small percentage of data variability. The most promising sets of indicators for water conflict were those associated with rapid or extreme physical or institutional change within a basin (e.g., large dams or internationalization of a basin) and the key role of institutional mechanisms, such as freshwater treaties, in mitigating such conflict.  相似文献   
548.
ABSTRACT: Drought management depends on indicators to detect drought conditions, and triggers to activate drought responses. But determining those indicators and triggers presents challenges. Indicators often lack spatial and temporal transferability, comparability among scales, and relevance to critical drought impacts. Triggers often lack statistical integrity, consistency among drought categories, and correspondence with desired management goals. This article presents an approach for developing and evaluating drought indicators and triggers, using a probabilistic framework that offers comparability, consistency, and applicability. From that, a multistate Markov model investigates the stochastic behavior of indicators and triggers, including transitioning, duration, and frequency within drought categories. This model is applied to the analysis of drought in the Apalachicola‐Chattahoochee‐Flint River Basin in the southeastern United States, using indicators of the Standardized Precipitation Index (for 3, 6, 9, and 12 months), the Palmer Drought Severity Index, and the Palmer Hydrologic Drought Index. The analysis revealed differences among the performance of indicators and their trigger thresholds, which can influence drought responses. Results contribute to improved understanding of drought phenomena, statistical methods for indicators and triggers, and insights for drought management.  相似文献   
549.
Challenges for a sustainable urban development are increasingly important in cities because urbanization and related land take come up with negative challenges for the environment and for city residents. Searching for successful solutions to environmental problems requires combined efforts of different scientific disciplines and an active dialogue between stakeholders from policy and society. In this paper, we present a comparative assessment of the way policy-science dialogues have achieved knowledge co-production about strategic urban environmental governance action using the cities of Berlin in Germany and Rotterdam in the Netherlands as case studies. The ecosystem services framework is applied as a lens for policy–science interaction and a ‘knowledge co-production operating space’ is introduced. We show how policy officers, urban planners, practitioners and scientists learned from each other, and highlight the impact of this knowledge co-production for governance practice. We found that the concerted collaboration and co-creation between researchers and policy officers have led to mutual learning and establishment of relationships and trust in both cities. Not only the policy-relevance of research and its policy uptake were achieved but also new insights for research blind spots were created. In our conclusions we reflect on co-production processes with two types of conditions that we introduced to be most influential in the way knowledge can be co-created. These are conditions that relate to the way knowledge co-production processes are set-up and, conditions that relate to the expected value or benefit that the co-produced knowledge will bring across society, policy and practice.  相似文献   
550.
中国生态修复成效评估方法研究   总被引:2,自引:0,他引:2  
目前已有很多的生境、自然资源以及水质修复措施被开发出来,而生态修复后的监测、成效评估等研究内容相对较少。在分析国内外生态修复概念的研究进展基础上,从生态修复目标、评价指标体系、评估方法以及数据获取方法等4个方面对生态修复后的效果评估的当前研究进行了分析,探讨了国内现有研究中存在的问题,指出应加强生态修复成效评估的理论和方法研究,并对今后中国生态修复成效评估研究进行了展望。  相似文献   
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