首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 343 毫秒
1.
Combating desertification in natural rangelands has recently become a priority in large parts of southern Africa. Rangeland managers, farmers, scientists, conservationists and land users have been applying a variety of restoration technologies to address this problem. Bush encroachment, as part of the desertification process, involves the natural replacement of the herbaceous plant cover by undesirable problem woody species. The active and passive restoration technologies that are applied, are mainly based on indigenous knowledge and include the chemical, mechanical or manual reclamation of unproductive rangelands, as well as the combating of woody and alien species encroachment. Indigenous practices and knowledge play a major role in the effectiveness and success rate of these technologies. This project faces the challenge of bringing together both local and scientific knowledge in a single user-friendly, computerised Decision Support System (DSS) which is directly accessible by land users to support them in the process of decision making, concerning the combating of desertification. Case studies from central and northern Namibia were used to combine qualitative and quantitative data to develop this Decision Support System. The DSS currently consists of two databases and an expert system, which evaluates the results of land users’ management practices, and provides easily accessible information and advice for participants in the system, based on the incorporated data. The DSS is also linked to national and international web sites and databases to offer a wider range of information on technologies concerning agricultural and conservation practices.  相似文献   

2.
Many organizations in the USA collect aquatic bioassessment data using different sampling and analysis methods, most of which have unknown performance in terms of data quality produced. Thus, the comparability of bioassessments produced by different organizations is often unknown, ultimately affecting our ability to make comprehensive assessments on large spatial scales. We evaluated a pilot approach for determining bioassessment performance using macroinvertebrate data obtained from several states in the Southeastern USA. Performance measures evaluated included precision, sensitivity, and responsiveness to a human disturbance gradient, defined in terms of a land disturbance index value for each site, combined with a value for specific conductance, and instream habitat quality. A key finding of this study is the need to harmonize ecoregional reference conditions among states so as to yield more comparable and consistent bioassessment results. Our approach was also capable of identifying potential areas for refinement such as reevaluation of less precise, sensitive, or responsive metrics that may result in suboptimal index performance. Higher performing bioassessments can yield information beyond “impaired” versus “unimpaired” condition. Acknowledging the limitations of this pilot study, we would recommend that performance evaluations use at least 50 sites, 10 of which are ecoregional reference sites. Efforts should be made to obtain data from the entire human disturbance gradient in an ecoregion to improve statistical confidence in performance measures. Having too few sites will result in an under-representation of certain parts of the disturbance gradient (e.g., too few poor quality sites), which may bias sensitivity and responsiveness estimates.  相似文献   

3.
One of the main goals in pursuing sustainable development is to provide universal access to modern energy services, notably through the use of off-grid renewable energy technologies. To date, integrated assessment models (IAMs) poorly address energy access targets. In the context of research dedicated to energy scenarios and climate change mitigation in Africa, we attempt to advance the representation of energy access in one such IAM by using GIS data. In a case study for Ethiopia with the TIAM-ECN model, we demonstrate that by enriching an IAM with information derived from GIS databases, insights are obtained that better capture the dynamics of energy access developments, in comparison to conventional IAM analysis of energy technology deployment pathways. When duly accounting for the geographical spread in demography and technology costs in a developing country, we find that many people may gain access to electricity in remote areas thanks to the availability of affordable off-grid power production options that render expensive grid extensions unnecessary. This effect is not explicitly accounted for in most traditional IAMs. By the middle of the century, off-grid technologies could provide affordable electricity to 70% of the Ethiopian population, based almost entirely on renewable sources such as wind, solar and hydropower.  相似文献   

4.
Scholars have been exploring the social impacts of dams for over 50 years, but a lack of systematic approaches has resulted in many research gaps remaining. This paper presents the first systematic review of the literature on the social impacts of dams. For this purpose, we built a sample of 217 articles published in the past 25 years via key word searches, expert consultations and bibliography reviews. All articles were assessed against an aggregate matrix framework on the social impact of dams, which combines 27 existing frameworks. We find that existing literature is highly biased with regard to: perspective (45% negative versus 5% positive); dam size (large dams are overrepresented); spatial focus (on the resettlement area); and temporal focus (5–10 years ex-post resettlement). Additionally, there is bias in terms of whose views are included, with those of dam developers rarely examined by scholars. These gaps need to be addressed in future research to advance our knowledge on the social impact of dams to support more transparency in the trade-offs being made in dam development decisions.  相似文献   

5.
In this paper, we use a stochastic integrated assessment model to evaluate the effects of uncertainty about future carbon taxes and the costs of low-carbon power technologies. We assess the implications of such ambiguity on the mitigation portfolio under a variety of assumptions and evaluate the role of emission performance standards and renewable portfolios in accompanying a market-based climate policy. Results suggest that climate policy and technology uncertainties are important with varying effects on all abatement options. The effect varies with the technology, the type of uncertainty, and the level of risk. We show that carbon price uncertainty does not substantially change the level of abatement, but it does have an influence on the mitigation portfolio, reducing in particular energy R&D investments in advanced technologies. When investment costs are uncertain, investments are discouraged, especially during the early stages, but the effect is mitigated for the technologies with technological learning prospects. Overall, these insights support some level of regulation to encourage investments in coal equipped with carbon capture and storage and clean energy R&D.  相似文献   

6.
An expert system for water quality modelling   总被引:1,自引:0,他引:1  
The RAISON-micro (Regional Analysis by Intelligent System ON a micro-computer) expert system is being used to predict the effects of mine effluents on receiving waters in Ontario. The potential of this system to assist regulatory agencies and mining industries to define more acceptable effluent limits was shown in an initial study. This system has been further developed so that the expert system helps the model user choose the most appropriate model for a particular application from a hierarchy of models. The system currently contains seven models which range from steady state to time dependent models, for both conservative and nonconservative substances in rivers and lakes. The menu driven expert system prompts the model user for information such as the nature of the receiving water system, the type of effluent being considered, and the range of background data available for use as input to the models. The system can also be used to determine the nature of the environmental conditions at the site which are not available in the textual information database, such as the components of river flow. Applications of the water quality expert system are presented for representative mine sites in the Timmins area of Ontario.  相似文献   

7.
In this paper we show the possibility of using expert system tools for environmental data management. We describe the domain indenpendent expert system shell SAK and Knowledge EXplorer, a system which learns rules from data. We show the functionality of Knowledge EXplorer on an example of water quality evaluation.  相似文献   

8.
The purpose of this paper is to study the impacts of the vagueness about the transfer of the harvest right on the use of a natural resource. We develop one-period non-cooperative game frameworks to examine whether the choice of the resource owner to be hazy about the transmission of the harvest contract is optimal. In the perfect information situation, we show that it is optimal for the resource owner to forbid the transfer of the harvest right instead of being hazy about it when the transfer fees are lesser than the collected net punishment fines of the monitoring costs even though the resource would be inefficiently used. In particular, we find in this case that the government’s announcement to forbid the transfer of the right should be public. We further show that there are subgame Nash equilibria in the perfect information context and a unique Nash equilibrium in the imperfect information setting. Specifically, we show that, when the transfer fees are greater or equal to the (net) punishment fines, there is a Nash equilibrium both in perfect and imperfect information situations, precisely when the owner chooses to allow the transfer of harvest title and the resource harvester transfers it.  相似文献   

9.
Many governments use technology incentives as an important component of their greenhouse gas abatement strategies. These carrots are intended to encourage the initial diffusion of new, greenhouse-gas-emissions-reducing technologies, in contrast to carbon taxes and emissions trading which provide a stick designed to reduce emissions by increasing the price of high-emitting technologies for all users. Technology incentives appear attractive, but their record in practice is mixed and economic theory suggests that in the absence of market failures, they are inefficient compared to taxes and trading. This study uses an agent-based model of technology diffusion and exploratory modeling, a new technique for decision-making under conditions of extreme uncertainty, to examine the conditions under which technology incentives should be a key building block of robust climate change policies. We find that a combined strategy of carbon taxes and technology incentives, as opposed to carbon taxes alone, is the best approach to greenhouse gas emissions reductions if the social benefits of early adoption sufficiently exceed the private benefits. Such social benefits can occur when economic actors have a wide variety of cost/performance preferences for new technologies and either new technologies have increasing returns to scale or potential adopters can reduce their uncertainty about the performance of new technologies by querying the experience of other adopters. We find that if decision-makers hold even modest expectations that such social benefits are significant or that the impacts of climate change will turn out to be serious then technology incentive programs may be a promising hedge against the threat of climate change.  相似文献   

10.
We have implemented a diagnostic system designed to advise on the likely causes of sanitary problems with public water sources. The approach to the problem makes extensive use of rule based expert systems and multi media information (maps, data, text, expert knowledge). The rules were based on actual water survey data, with a weighting scheme designed to highlight causes of health risks approximately in reverse order of importance (where such order may be presumed to exist). Out put is a vailable in one of several languages.  相似文献   

11.
Anthropogenic threats and their impacts on aquatic ecosystems have traditionally been evaluated only through literature reviews. Within the last decade, however, expert opinions have become an increasingly popular alternative for gaining complementary information to literature reviews. This study employed a standardized method for collecting bibliographic data combined with synthesize expert opinions to establish a current knowledge baseline on threats to Mediterranean freshwater ecosystems in Chile.We revised 79 scientific articles that included a variety of taxonomic groups containing fish (n = 32); macroinvertebrates (n = 17); amphibians (n = 18); freshwater plants (n = 8); and two taxonomic groups simultaneously (n = 4). From this review, we identified 14 threats, with land-use change, species introductions, and industrial/domestic effluents as salient factors. These findings were in agreement with results from expert opinion surveys (n = 46 researchers). An analysis by taxonomic group indicated freshwater fishes as most threatened by hydropower plants. Aquatic plants were most threatened by mining. Amphibians were most threatened by changes in soil use whereas aquatic macroinvertebrates by industrial/domestic effluents. Remarkably, the magnitude of threats identified in the literature review was of similar order than those catalogued by experts. Moreover, the primary threats identified here align with those reported in other Mediterranean regions of the world. Our combined approach using literature review and expert opinion was useful in determining the consistency of the main threats to each taxonomic group. Our findings can be used as a baseline to further research and in prioritizing management strategies for threatened Mediterranean ecosystems worldwide.  相似文献   

12.
We developed an integrated assessment (IA) using models for energy systems analysis and life-cycle assessment (LCA). Based on this assessment framework, we developed cost-benefit analysis (CBA) case studies for a hypothetical project designed to introduce advanced fossil-fired power generation technologies in China. Our MARKAL model for Japan confirmed that radical reductions (i.e., 80 % by 2050) of carbon dioxide (CO2) could be attained from energy systems alone and that credit for emission allowances was required. We evaluated life-cycle costs and emissions of carbon dioxide, sulfur oxide, and nitrogen oxide gases for the energy technologies using an LCA model. Further, we applied a power generation planning model for six Chinese grids to provide a power mix structure, potentially producing credit by installing fossil-fired power generation technology and by using baseline grid emission factors with an average cost of electricity. Finally, by using dynamic emission reductions and additional costs from the two models, we conducted case studies of CBA for a hypothetical project to install the technologies in China. This was accomplished by evaluating emission reductions in monetary terms and by applying a life-cycle impact assessment model. A unique feature of our IA is its dynamic (time-varying) assessment of costs and benefits.  相似文献   

13.
中国生态监测存在问题及发展趋势   总被引:1,自引:1,他引:0  
在生态学的基本理论基础上,探讨了生态监测的科学内涵,明确了生态监测对象就是生态系统,目标是认识反映生态系统的状态和演变趋势,为管理和决策提供科学依据。深入分析了中国生态监测存在的5个问题:生态监测缺乏统一管理,部门间任务存在交叉和重复;生态监测技术不够规范,信息整合与利用困难;生态监测网络松散,国家级生态监测网络建立缓慢;环境监测法律依据不足,法制保障力度亟待加强;生态监测能力水平普遍较低,亟待建设。最后,从国家现实需求、生态监测现状以及监测技术发展的历史规律,探讨了未来中国生态监测的总体发展趋势。  相似文献   

14.
Groundwater and soil contamination caused by light nonaqueous phase liquids (LNAPLs) spills and leakage in petroleum industry is currently one of the major environmental concerns in North America. Numerous site remediation technologies, generally classified as ex situ and in situ remediation techniques, have been developed and implemented to clean up the contaminated sites in the last two decades. One of the problems associated with ex situ remediation is the cost of operation. In recent years, in situ techniques have acquired popularity. However, the selection process of the desired techniques needs a large amount of knowledge. Insufficient expertise in the process may result in unnecessary inflation of expenses. In this study, petroleum waste management experts and Artificial Intelligence (AI) researchers worked together to develop an expert system (ES) for the management of petroleum contaminated sites. Various AI techniques were used to construct a useful tool for site remediation decision-making. This paper presents the knowledge engineering processes of knowledge acquisition, conceptual design, and system implementation in the project. The expert system was applied to a real-world case study and the results show that the expert system can generate desired remediation alternatives to assist decision-makers. The application case study constitutes partial validation of the prototype expert system.  相似文献   

15.
The expert system described here is designed to aid regulatory personnel in their assessment of the potential for pesticides to contaminate the soil and groundwater environment. The expert system, known as EXPRES (EXpert system for Pesticide Regulatory Evaluation Simulations), consists of existing numerical models which are used to simulate the transport and transformation of pesticides in the unsaturated zone, coupled with a knowledge-based system that guides the user through the choice of all the necessary information for characterizing the physical, meteorological, hydrogeological, pedological and agricultural settings of typical agricultural regions across Canada, as required by the pesticide model. The expert system is designed to be used as a management tool to aid in policy decisions. Thus, its purpose is to provide an assessment of the potential hazards and to identify if further study is warranted.  相似文献   

16.
Aquatic ecoregion, as one type of ecoregions, is a unit of land of relative homogeneity in aquatic ecosystems or in relationships between organisms and their environments. It is the base of establishing the trophic state standard for the lakes and reservoirs, and that of controlling the eutrophication. In this paper, we put forward the principles and assessment index of trophic state divisions for the lakes and reservoirs in China. Based on the assessment index and with the help of spatial analysis of geographic information system, expert judgment and qualitative analysis, we suggest that all the lakes and reservoirs in China be divided into three Level I and six Level II ecoregion divisions. Moreover, the trophic state characteristics of each ecoregion division are summarized.  相似文献   

17.
The management of swine manure is becoming an important environmental issue in Chile. One option for the final disposal of manure is to use it as a biofertilizer, but this practice could impact the surrounding environment. To assess the potential environmental impacts of the use of swine manure as a biofertilizer, we propose a method to identify zones of environmental risk through indices. The method considers two processes: nutrient runoff and solute leaching, and uses available information about soils, crops and management practices (irrigation, fertilization, and rotation). We applied the method to qualitatively assess the environmental risk associated with the use of swine manure as a biofertilizer in an 8,000-pig farm located in Central Chile. Results showed that the farm has a moderate environmental risk, but some specific locations have high environmental risks, especially those associated with impacts on areas surrounding water resources. This information could assist the definition of better farm-level management practices, as well as the preservation of riparian vegetation acting as buffer strips. The main advantage of our approach is that it combines qualitative and quantitative information, including particular situations or field features based on expert knowledge. The method is flexible, simple, and can be easily extended or adapted to other processes.  相似文献   

18.
The combined effects of human activities and natural variability present significant challenges to the goals of protecting, restoring, and sustaining coastal ecosystems. Meeting these challenges and resolving conflicts in an informed fashion will require: (1) more timely detection and prediction of environmental changes and their consequences; and (2) more timely access to relevant environmental information. The achievement of these goals depends on the development of a sustained and integrated coastal ocean observing system (ICOOS) that insures timely access to the data and information required to improve: (1) climate predictions and the effects of changes in the weather on coastal populations; (2) efforts to sustain and restore healthy coastal marine ecosystems and living marine resources; and (3) compliance monitoring and evaluations of the efficacy of environmental policies. Although the responsible federal and state agencies all require similar environmental information, many separate programs have evolved for collecting, managing, and analyzing data for various purposes. Consequently, there is too much redundancy; access to diverse data from disparate sources is limited and time consuming; and individual programs are inevitably underfunded and too limited in scope. A system is needed that coordinates and integrates many of the elements of these programs to minimize redundancy, be more comprehensive, provide more timely access to data and information, and satisfy the information needs of a greater number of user groups in a more cost-effective fashion. This is the purpose of the ICOOS.  相似文献   

19.
The residential sector presents a great potential for greenhouse gases (GHG) mitigation. We perform an integrated assessment of different mitigation policies for Switzerland focusing on the residential sector. We analyze the case of pure incentive taxes and technical regulations. For our analysis, we have coupled a general equilibrium model with a Swiss residential energy model. We find that a progressive GHG tax of more than 200 USD2000/tCO2 eq is necessary to reach a target of 50% reduction of GHG emissions in 2050. Finally, we also find that efficiency-based technical regulations provide limited additional abatement incentives.  相似文献   

20.
Assessments of watershed condition for aquatic and riparian species often have to rely on expert opinion because of the complexity of establishing statistical relationships among the many factors involved. Such expert-based assessments can be difficult to document and apply consistently over time and space. We describe and reflect on the process of developing a computer-based decision support application from expert judgments for assessing aquatic and riparian conditions over the 100,000?km2 managed by the US federal government under the Northwest Forest Plan. The decision support system helped structure and document the assessment process and provided consistency and transparency to the evaluation methodology. However, many decisions and trade-offs were required in the expert engagement and model-building processes. Knowledge elicitation in an interactive group had a number of benefits over nominal group or Delphi processes, but efficient knowledge capture required considerable planning and expertise in the subject matter and modeling process. Communicating model results for validation was problematic and only effectively accomplished via in-person workshops. The choice to use different expert groups for each biophysical province provided more opportunities for participation and promoted greater ownership in the assessment, but it also led to increased variation among the resulting model structures. We propose three possible approaches for better managing the consistency of assessment models when multiple expert groups are involved.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号