论喀斯特环境的脆弱性   总被引：71，自引：0，他引：71  

杨明德 《云南地理环境研究》1990,2(1):21-29

占全球陆地面积15%,居住着近10亿人口的喀斯特区域,是一个特殊的自然环境。在环境科学和喀斯特学间的互相渗透和交叉,产生了喀斯特环境学这一边缘分支学科。本文从系统论的观点、人地关系角度简要地论述了喀斯特环境的结构、功能和特性,并以贵州为例,对喀斯特环境脆弱性问题进行了分析,笔者认为:环境生态系统变异敏感度高,环境容量低,灾变承受阈值弹性小,是喀斯特环境脆弱性的最本质特征。  相似文献   

From adoption to implementation? An academic perspective on Sustainable Fisheries Management in a developing country     

《Marine Policy》2015

Despite the fact that Sustainable Fisheries Management (SFM) has long been proposed internationally, it remains controversial. Practical and successful applications are scarce, especially in developing countries with a recent history of massive overfishing, such as Mexico. Although SFM has been adopted at the highest level of the Mexican legal framework during the last two decades, its successful implementation still faces a series of complex challenges. At present, important changes in the Mexican political regime are at a breaking point, motivating the academic discussion about the national implications of adopting SFM approaches. Through the analysis of a series of deep interviews of key actors, combined with published material, the article illustrates how the fast-track adoption of SFM approaches has fared in a national fisheries context, the current situation being largely dysfunctional with regard to the challenges of SFM. A complicated mixture between unbeaten management and academic vestiges caused the present circumstances of an enhanced but limited fisheries system. The article proposes academic initiatives required to improve the implementation of SFM in Mexico based on an enhanced understanding of domestic historic conditions and challenges.  相似文献   

The Coral Triangle Initiative and regional exchanges: Strengthening capacity through a regional learning network     

《Global Environmental Change》2015

Natural resource management and conservation programs that promote building capacity and social learning among participants often lead to the formation of learning networks: a type of social network where learning is both a goal and potential outcome of the network. Through forming relationships and sharing information, participants in a learning network build social capital that can help a network achieve social and environmental goals. In this study, we explored social capital in a learning network that emerged through a large-scale marine governance effort, the Coral Triangle Initiative on Coral Reefs, Fisheries, and Food Security. Through a mixture of social network analysis and key informant interviews, we examined the major patterns of information exchange among individuals who had participated in regional learning exchanges; evaluated whether the network's structure resulted in information sharing; and considered implications for strengthening network sustainability, capacity building, and learning. We found that the Regional Exchange network fostered information sharing among participants across national and organizational boundaries. While the network had individuals who were more central to information sharing, the network structure was generally decentralized, indicating potential resilience to changes in leadership and membership. Participants stressed the importance of the knowledge and connections they had acquired through the learning network; however, they expressed doubts regarding its sustainability and stressed the need for a strong coordinating entity. Our findings suggest that conservation learning networks have the ability to bridge cultural divides and promote social learning; however, a strong network coordinator and continuing efforts to support information sharing and learning are crucial to the network's strength and sustainability. The tangible learning and capacity development outcomes cultivated through Regional Exchange network underscore the value of and need to invest in conservation networks that support peer-to-peer learning.  相似文献   

Marine debris review for Latin America and the wider Caribbean region: from the 1970s until now, and where do we go from here?   总被引：1，自引：1，他引：0  

Ivar do Sul JA  Costa MF 《Marine pollution bulletin》2007,54(8):1087-1104

The available literature on marine debris from Latin America and the Wider Caribbean Region was collected and linked, reviewing their methodologies and principal results (quantities, composition and spatial-temporal patterns). The study region comprises 52 coastal countries of which only 14 had registers of works on marine debris. A total of 70 works were available and 69 had their full contents accessed. Brazil dominated the available literature with 70% of the documents. Beaches were the most studied environment, and plastics the prevalent form of contamination in the whole region. The exposure of marine biota (species, type of contact, consequences) was highlighted. The studied region, although still little exploited by this sort of research, shows the same contamination patterns observed world-wide. We also contacted 40 researchers in the area, collecting scientific contributions, opinions and suggestions for improvement of this research field. Further advances and new (urgently needed) lines of research are also discussed.  相似文献   

Numerical analysis on post-grouted drilled shafts: A case study at the Brazo River Bridge,TX   总被引：1，自引：0，他引：1  

Heejung Youn  Fulvio Tonon 《Computers and Geotechnics》2010

This paper investigates the effects of post-grouting on the behavior of drilled shafts using a case study carried out at the Brazo River, Texas. Commercial finite element software, PLAXIS, was used to quantify the improvement of the tip resistance and side shear resistance of post-grouted drilled shafts (PGDS). The input material parameters of PLAXIS were initially estimated using CPT sounding results, and then the parameters were updated by calibrating the numerical results against full-scale STATNAMIC load test results. Based on the numerical analysis, the authors concluded that (1) the increase in total resistance of PGDS resulted from soil improvement at the shaft tip, (2) the apparent increase in side shear resistance resulted from side shear reversal that occurred during post-grouting, and (3) the apparent increase in the tip resistance of PGDS may be caused by stress relief of the grout. In addition, two approaches to estimate the resistance of PGDS were compared against numerical results. In this case study, the Axial Capacity Multiplier (ACM) approach over-predicted the total resistance whereas the Tip Capacity Multiplier (TCM) approach reasonably predicted the increase in total resistance.  相似文献   

Introduction to systems approaches in coastal management—The legacy of the SPICOSA project     

《Marine Policy》2014

This Special Issue reflects work developed during and following the execution of the Science and Policy Integration for Coastal System Assessment project. Theoretical and practical outcomes of case studies have been of direct relevance to coastal management not only at local but also at a European scale. Papers included here consider the long term legacy of the project for academics and practitioners involved specifically in integrated coastal zone management. These align to two themes, the first focussing on the generic application of the Systems Approach Framework to coastal management and the second focussing on the specific application of the approach at case study sites.  相似文献   

Understanding climate coping as a basis for strategic climate change adaptation – The case of Queenstown-Lake Wanaka,New Zealand     

《Global Environmental Change》2014

Weather conditions that influence natural resource-based tourist destinations are likely to be affected by climate change, but our understanding of how businesses and destinations manage for present and future conditions is limited. In this study we report on the relationships between weather and tourism activities in the Queenstown-Lake Wanaka region, South Island, New Zealand. Key stakeholder interviews and a workshop form the empirical basis of this paper. Coping range application ideas derived from ecological management literature are used to develop a framework to understand and inform thinking and strategies around how tourism businesses and destinations are currently responding to the weather and perhaps could in future respond to climate change. Results show that within a destination individual businesses have widely varying relationships with the weather, with each type of activity operating within its own coping range to particular environmental gradients, for example temperature. Coping, which can be observed outside the ‘ideal’ range of a particular environmental gradient, requires business adjustments so as to cope with increasingly marginal conditions, up to a Critical Stop Point – the ultimate threshold. The data suggest that increased need for adjustments impacts on business viability, and more planned adaptation measures would be necessary to increase viability under increasingly detrimental climatic conditions. Discussion at a destination level workshop indicates that at and beyond thresholds, keystone industry and destination level strategic adaptation planning is required to ensure the viability of the destination as a whole.  相似文献   

Differentiating capacities as a means to sustainable climate change adaptation     

《Global Environmental Change》2014

There are two forms of capacity to adapt to global change: those associated with fundamental human development goals (generic capacity), and those necessary for managing and reducing specific climatic threats (specific). We argue that these two domains of capacity must be addressed explicitly, simultaneously and iteratively if climate change adaptation and sustainable development goals are to be attained. We propose a simple heuristic to understand the four main ways these two capacities interact, leading to more or less desirable outcomes. Drawing from three case studies of agricultural adaptation to climatic risk (Phoenix, AZ; Northeast Brazil; Chiapas, Mexico) we argue that the institutional context of adaptation can implicitly or explicitly undermine one form of capacity with repercussions for the development of the other. A better and more strategic balance of generic and specific capacities is needed if the promised synergies between sustainable development and adaptation are to be achieved.  相似文献   

Numerical study of the 3D failure envelope of a single pile in sand     

《Computers and Geotechnics》2014

The paper presents a comprehensive study of the failure envelope (or capacity diagram) of a single elastic pile in sand. The behavior of a pile subjected to different load combinations is simulated using a large number of finite element numerical calculations. The sand is modeled using a constitutive law based on hypoplasticity. In order to find the failure envelope in the three-dimensional space (i.e. horizontal force H, bending moment M and vertical force V), the radial displacement method and swipe tests are numerically performed. It is found that with increasing vertical load the horizontal bearing capacity of the pile decreases. Furthermore, the presence of bending moment on the pile head significantly influences the horizontal bearing capacity and the capacity diagram in the H–M plane manifests an inclined elliptical shape. An analytical equation providing good agreement with the 3D numerical results is finally proposed. The formula is useful for design purposes and the development of simplified modeling numerical strategies such as macro-element.  相似文献   

Towards identifying sources of subsurface flow: A comparison of components identified by a physically based runoff model and those determined by chemical mixing techniques     

Alice Robson  Keith Beven  Colin Neal 《水文研究》1992,6(2):199-214

A physically-based semidistributed model, TOPMODEL, is applied to a 340 hectare spruce forested catchment in mid-Wales. the model is calibrated to runoff and the subsurface flow is divided into components of flow identified by depth of origin. in addition, chemical mixing techniques are used to provide a hydrograph separation between acidic soil waters and well buffered deep waters. the short-term variations in the components of flow identified by these two approaches compare well.  相似文献