金沙江流域水土流失与人类活动影响分析

长江三峡水利枢纽工程能否正常发挥效益，泥沙是重要的制约因素之一，而水库的泥沙主要来自上游金沙江，其多年平均输沙量占入库寸滩站的５２７％。因此，本文对金沙江泥沙的地区组成、水土流失及人类活动影响等问题进行了深入的分析，并提出了防治对策。     

Planning for optimisation of outdoor recreational potential in Benin city through a deferred demand approach

This paper attempts to provide an empirical basis for planning the optimisation of public outdoor recreational potential in Benin City, Nigeria. The study is seen as a partial analysis in that it considers only the deferred component of demand, and only with public recreational facilities. It identifies a mismatch between demand for and provision of facilities, due to an inadequate planning system.     

Hydro-abrasive erosion in hydro turbines: a review

The flow of sediment particles in rivers is a big challenge to develop hydropower plants across the sediment-laden rivers. Hard particles such as quartz and feldspar are available in high amount in the Asian mountain range. The abrasive action of these particles causes the hydro turbines to suffer from erosion in particular at high- and medium-head hydroelectric power plants. This has become a serious economic issue due to maintenance costs and production losses. The treatment without prevention is simply unsustainable. Facilities for sediment exclusion, typically sand traps as well as turbine design, and materials have been improved considerably. In the present paper, studies have been discussed extensively undertaken by several investigators in this field. Based on literature survey several aspects related to reducing the sediment load on turbines, useful ways to improve the turbine surface performance and various erosion models to characterize the effect of erosion on the performance of turbines have been discussed. To calibrate and validate the developed erosion models, more measurements from both physical model tests in laboratories and continuous monitoring of sediment parameters and their impact on the operational hydro turbines are required. As well as the state-of-art in the modeling and simulation using computational fluid dynamics (CFD) has made it possible to optimize the hydraulic design of hydro turbines in order to minimize the erosion level without much sacrifice in the efficiency. To mitigate the hydro-abrasive erosion effects on the performance of turbines, significant improvements have been achieved so far and development is ongoing.     

Valuing lagoons using a meta-analytical approach: methodological and practical issues

Lagoons are naturally complex ecosystems whose dynamics are strongly influenced by anthropic factors. Therefore, their value depends not only on their characteristics but also on the nature of the interactions, whether positive or negative, between mankind and nature. Starting from a representative set of 31 original studies exclusively devoted to coastal lagoons valuation, we estimate a meta-analytic function of value transfer. Using a resampling technique, we then determine a transfer value and find a mean transfer error of 87% and a median error equal to 24%, between the predicted value and the original ones. This raises the problem of divergences between individual valuations for natural assets.     

Deteriorated watersheds can be restored: A case study

A project in west-central Colorado demonstrated that a watershed dissected by a dense gully network can be stabilized and rehabilitated. Check dam systems, aided by improved vegetative cover through reduced cattle grazing and plantings, stabilized not only the structurally treated gullies, but also gullies within the network that were not structurally treated. Comparison with untreated gullies located outside of the project area, showed that the outside gullies widened three times as much as the structurally untreated inside gullies. Statistical analysis indicated that precipitation was normal during the treatment and evaluation period.Check dams decreased gully depth by accumulating sediment deposits. In turn, gully bank stabilization was hastened and alluvial aquifer volumes increased. This increase, plus higher infiltration rates as a result of denser vegetation, led to renewed perennial streamflow after 7 treatment years.Within 11 years after treatment, check dam systems and improved vegetation reduced sediment loads in the flows by more than 90 percent, providing a substantial benefit to farmlands and ponds downstream.From this work we are able to conclude that only part of a gully network requires structural treatment. The mainstem gully, and those tributaries controlling the local base levels of others, are the critical segments that should be structurally treated.     

Sediment Source Assessment in a Lowland Watershed Using Nitrogen Stable Isotopes1

Fox, James F., Charles M. Davis, and Darren K. Martin, 2010. Sediment Source Assessment in a Lowland Watershed Using Nitrogen Stable Isotopes. Journal of the American Water Resources Association (JAWRA) 46(6):1192–1204. DOI: 10.1111/j.1752-1688.2010.00485.x Abstract: Sediment sources and transported sediments were sampled in a lowland watershed with pronounced fine sediment storage in the streambed. Sediments were analyzed for carbon and nitrogen content and stable nitrogen isotopic composition. Analysis of the data shows that temporarily stored streambed sediments dominate the sediment load during moderate- and low-flow hydrologic events. Modeling of sediment transport and nitrogen elemental and isotopic mass balance was performed for the watershed for a 12-month time period using a continuous, conceptual-based model. The model results show that during moderate- and low-flow hydrologic events, the streambed is slowly downcutting. During very high-flow hydrologic events, deposition is pronounced in the streambed and sediment is replenished to the bed. Nitrogen model results show that elemental and isotopic nitrogen of streambed sediments vary substantially over the simulation period. In this manner, the streambed in a lowland watershed functions as a temporary storage zone that, in turn, can impact the nitrogen elemental and isotopic signature of sediments. The variation could significantly impact estimates of sediment provenance using nitrogen tracer-based methods. Future work should consider both hydrologic and biogeochemical control on the nitrogen isotopic signature of sediments in small lowland watersheds and streams where a significant portion of deposited fines are temporarily stored.     

Barriers to the enterprise culture: new firm formation in the merchant city area of glasgow

The paper reports the study of a group of twenty‐two new firm founders in the retail sector, in the Merchant City, an historic part of inner Glasgow that has recently undergone a miraculous revitalisation in a vein similar to that of the Docklands areas of London and Liverpool. The principal aim is to indicate how far the long term unemployed will be involved in this particular part of the enterprise culture, whether directly, or indirectly as a result of expanded employment opportunities. The results provide an upper limit of what we could expect this type of economic development to achieve in less attractive areas. The study provides a useful comparison to previous work concentrated on the manufacturing sector and suggests that the results from such work apply across sectors.     

Diffusion of innovative agricultural production systems for sustainable development of small islands: A methodological approach based on the science of complexity

In order to develop small islands, not only must a vital agricultural system be maintained, but the range of opportunities for tourism must be increased with respect to both the seaside and the environmental features of the rural landscape. As an alternative to the traditional and economically declining ones, many innovative production processes can be identified, but their success depends on their interaction with the physical, biological, economic and social environment. In order to identify the main nodes and the most critical interactions, so as to increase the probability of success of a new productive process, a methodological approach based on the science of complexity is proposed for the cultivation of capers (Capparis spinosa L.) on the island of Pantelleria. The methodology encompasses the identification of actors and factors involved. the quantitative evaluation of their interactions with the different stages of the productive process, and a quasiquantitative evaluation of the probability that the particular action will be performed successfully. The study of “traditional,” “modernized,” and “modernized-sustainable” processes, shows that the modernized-sustainable process offers mutually reinforcing opportunities in terms of an integrated development of high-quality agricultural products and the enhancement of environmental features, in conjunction with high-efficiency production techniques, in conjunction with high-efficiency production techniques, in a way that suits the development of Pantelleria. There is a high probability of failure, however, as a result of the large number of critical factors. Nevertheless, the present study indicates which activities will enhance the probability of successful innovation in the production process.     

城市公园湖泊污染治理实践

城市公园湖泊水体保护和水污染治理越来越受到人们的重视。公园内水体往往补充水源不足,自净能力脆弱,当受到污染,湖水会变黑发臭,破坏公园美景。深圳市东湖公园人工湖污染治理过程中结合了水利防洪、环境保护、园林绿化等措施进行综合治理,通过截污、清淤、补充水、湖泊堤岸及拦水橡胶坝的恢复等措施,使湖泊水质得到彻底改善。合理的设计使人工湖具有滞洪防洪功能,还可对公园内地下水起到调节和补充作用,清澈的湖水又使人工湖成为公园内秀丽的景点。该项目为城市公园湖泊污染综合治理进行了一次探索和实践。     

Soil erosion in developing countries: a socio-economic appraisal

Soil erosion is the single most important environmental degradation problem in the developing world. Despite the plethora of literature that exists on the incidence, causes and impacts of soil erosion, a concrete understanding of this complex problem is lacking. This paper examines the soil erosion problem in developing countries in order to understand the complex inter-relationships between population pressure, poverty and environmental-institutional dynamics. Two recent theoretical developments, namely Boserup's theory on population pressure, poverty and soil erosion and Lopez's theory on environmental and institutional dynamics have been reviewed. The analysis reveals that negative impacts of technical change, inappropriate government policies and poor institutions are largely responsible for the continued soil erosion in developing countries. On the other hand, potential for market-based approaches to mitigate the problem is also low due to the negative externalities involved. A deeper appreciation of institutional and environmental dynamics and policy reforms to strengthen weak institutions may help mitigate the problem.     

A hierarchic metric approach for integration of green issues in manufacturing: a paper recycling application

This paper presents a hierarchic framework for environmentally conscious design. The framework integrates both product designers and stakeholders to evaluate not only the product features but also its environmental burden. In evaluating the product's burden, a life cycle assessment of the product is conducted through input-output analysis so that a comprehensive inventory of the product's actions and reactions to the environment could be documented. The analytic hierarchy procedure (AHP) is used to develop priority indices for customer requirements to highlight key features that must be present in the product. Subsequently, the quality function deployment is used to match design requirements to customer requirements. A cost-effective design plan is then finally developed. This framework adopts a systemic approach and ensures that environmentally conscious products are designed and manufactured.     

Monitoring in adaptive co-management: Toward a learning based approach

The recognition of complexity and uncertainty in natural resource management has lead to the development of a wealth of conceptual frameworks aimed at integrated assessment and complex systems monitoring. Relatively less attention has however been given to methodological approaches that might facilitate learning as part of the monitoring process. This paper reviews the monitoring literature relevant to adaptive co-management, with a focus on the synergies between existing monitoring frameworks, collaborative monitoring approaches and social learning. The paper discusses the role of monitoring in environmental management in general, and the challenges posed by scale and complexity when monitoring in adaptive co-management. Existing conceptual frameworks for monitoring relevant to adaptive co-management are reviewed, as are lessons from experiences with collaborative monitoring. The paper concludes by offering a methodological approach to monitoring that actively seeks to engender reflexive learning as a means to deal with uncertainty in natural resource management.     

A process integration approach to industrial water conservation: a case study for a Chinese steel plant

A systematic approach to optimizing water network has traditionally been utilized to exam and plan water conservation in industrial processes. In the present case study, water-pinch technology was used to analyze and optimize the water network of a steel plant near China's Zhangjiakou city. A system design was developed and a limiting constraint (Cl(-) concentration) was identified based on investigations of water quality then the minimum freshwater and wastewater targets were determined without considering water losses. The analysis was then extended by calculating the additional input of freshwater required to balance the actual water losses. A nearest-neighbor algorithm (NNA) was used to distribute the freshwater and recycled water among each of the plant's operations. The results showed that with some reconstruction of the water network, the flow rates of freshwater and wastewater could be decreased by 57.5% and 81.9%, respectively.     

Assessing potential bioavailability of metals in sediments: A proposed approach

Due to anthropogenic inputs, elevated concentrations of metals frequently occur in aquatic sediments. In order to make defensible estimates of the potential risk of metals in sediments and/or develop sediment quality criteria for metals, it is essential to identify that fraction of the total metal in the sediments that is bioavailable. Studies with a variety of benthic invertebrates indicate that interstitial (pore) water concentrations of metals correspond very well with the bioavailability of metals in test sediments. Many factors may influence pore water concentrations of metals; however, in anaerobic sediments a key phase controlling partitioning of several cationic metals (cadmium, nickel, lead, zinc, copper) into pore water is acid volatile sulfide (AVS). In this paper, we present an overview of the technical basis for predicting bioavailability of cationic metals to benthic organisms based on pore water metal concentrations and metal-AVS relationships. Included are discussions of the advantages and limitations of metal bioavailability predictions based on these parameters, relative both to site-specific assessments and the development of sediment quality criteria.     

Soil erosion in developing countries: A politicoeconomic explanation

Soil erosion is accelerating in developing countries of Asia, Africa, and Latin America. It has threatened the livelihood of millions of peasants, for agriculture is their economic mainstay. A probe into the forces causing erosion reveals that the elite’s resolve to accumulate ever more wealth and to maintain, consolidate, or expand their sociopolitical power and the necessity of the poor to fulfill their requirements of food, fuelwood, and fodder are the two major factors accelerating soil erosion. Unless the vast masses of poor people are integrated into the national mainstream through the implementation of equitable and redistributive development policies, it is impossible to control the accelerating rate of soil erosion and thus to achieve the objective of sustainable development. In this article, the phenomenon “soil erosion” is studied with the sol e focus on causation through anthropogenic factors.     

Small towns in the united states: a perspective

Small towns are an important part of the rural settlement fabric in the United States, but there is very little substantive research into their capacity to survive or their intrinsic importance. However, recently there has been increasing interest shown by social scientists in these problems. This paper looks at features of this research from the point of view of the population and economic structure of small towns. It concludes by arguing that the problems of small towns are not indigenous to the towns, and calls for a comprehensive national urban policy.     

Metal capital sustaining a North American city: Iron and copper in New Haven, CT

A detailed inventory shows that an average resident of the City of New Haven depends on a per capita capital stock of 9200 kg/c of iron and 144 kg/c of copper in the city infrastructure, buildings, transportation systems, and equipment. Of the iron stock 28% is in items such as rail cars and ships in ocean trade not permanently within the city, and 22% is devoted to receiving and delivering oil fuel to the city and its surrounding communities. Copper is principally used in the distribution of electric power and in water piping within buildings. The city's 9200 kg/c of iron stock-in-use is less than the 13,000 kg/c national average due to New Haven's lack of heavy industry and relatively small number of large buildings. The 144 kg/c of copper stock-in-use is only 58% of the overall value for the United States, but is comparable to that in cities such as Stockholm, Sweden. Attainment of a level of iron and copper services with contemporary technology in less developed countries to the level enjoyed in New Haven would require consumption of the presently identified world copper resources.     

Towards a systematic approach of effect prediction: A handbook as guide and aid for environmental prediction. A review

Environmental impact assessment (EIA) is based on the results of effect prediction. In general, there is much diversity in the expertise in the field of environmental prediction between the different categories of actors involved in EIA. In practice it became obvious in The Netherlands that the accessibility and comprehensibility of existing relevant information was insufficient. For improvement, a series of systematic handbooks on effect prediction, useful for all categories of actors, has been developed in The Netherlands. In this way, the selection of effect prediction methods to be used in concrete circumstances is improved and speeded up for all parties involved in environmental prediction. After a discussion of the purpose of the handbook, the realization and structure of the series are presented. Finally, the use and (potential) benefits of the handbooks for environmental management are indicated.     

A horizontal merger in the iron ore industry: An event study approach

The purpose of this paper is to analyse the competitive and efficiency impacts of a large merger in the world iron ore industry, using an event study approach. This method builds on an analysis of stock market reactions of the merging firms as well as close rivals at the time of the merger announcement. The event study method allows for the possibility to assess both the motivations behind as well as the welfare effects of the merger. The event study results for the merger announcement of Rio Tinto and North Ltd. show that, according to the market reactions, the main motive behind the merger was either the market power or the efficiency hypothesis. When adjusting the analysis to include several information releases about the merger, the overall result indicates that efficiency improvements were the predominant motives behind the merger. Thus, the event study results suggest that there are positive welfare effects to expect and the European Commission's decision to allow the merger is supported.