SEDIMENT RETENTION AND WATER QUALITY ENHANCEMENT IN DISTURBED WATERSHEDS     

C. M. Cooper 《国际泥沙研究》2000,(1)

lPRoBLEMSTATEMENTANDOVERVIEWQualitywateriswithoutdoubtalimitingsubstance,notonlyforhumansbutforalllife.Yet,ashumanpopulation,activity,andpollutioncontinuetoincrease,naturalsourcesofreadilyuseablewateraredecliningatanalarmingfate.Humanscurrentlydiveftorregulatemorethanhalfofgloballyavailablefreshwaterrunofffortheirownpurposes(Posteletal.,l996),includingtheuseoflargedamsordiversionsonriversandthewidespreadcreationofotherartificialcatchments.Additionally,groundwatersourcesarebecomingin…  相似文献   

地理信息系统的模型库研究   总被引：25，自引：1，他引：24  

宫辉力  李京  陈秀万  肖劲锋 《地学前缘》2000,(Z2)

地理信息系统在理论上应该具有强大的空间分析功能 ,但在实际应用中由于缺少空间分析模型及其管理系统 ,严重地制约了地理信息系统强大空间分析功能的发挥。因此 ,对模型与模型库管理子系统的开发研究 ,已成为地理信息系统深入应用的关键之所在。模型库管理子系统应在独立于具体应用领域的前提下 ,对模型进行分类和维护 ,支持模型的生成、存储、查询、运行和分析应用的软件系统。文中对模型库管理子系统的概念、功能与研究内容以及模型字典进行了比较系统的论述 ,提出了模型库管理系统的设计思想与总体框架 ,并给出了模型库系统平台在郑州水资源水环境管理决策支持系统中的应用实例分析  相似文献   

松嫩平原西部盐沼的形成与演化   总被引：21，自引：5，他引：16  

李取生  邓伟  钱贞国 《地理科学》2000,20(4):362-367

本文运用环境变迁的理论和方法,较系统地分析了松嫩平原西部盐沼的形成与演变机制。本区沼泽形成的主要控制因素是古河道变迁、新构造运动、风力作用、古气候变化。沼泽残余盐碱化与晚更新世松辽大湖的消亡、河道变迁有关,现代盐碱化则主要是水利工程、植被破坏和气候变化引起的,而且呈迅速加剧的趋势。防治沼泽盐碱化的主要措施是实施水稻和芦苇开发、大规律建立蓄洪区和自然保护区。  相似文献   

地理空间数据网络服务体系研究     

温伯威  陈换新  张巍 《地理信息世界》2013,(5)

地理信息服务是地理信息产业从“专业化”发展到“公众化、社会化”的必然,地理空间数据网络服务是开展地理信息服务的基础和前提。本文系统总结了网络环境下地理空间数据服务的特点,即规范化,大众化,多元化,个性化,实时化,动态化;提出了地理空间数据网络服务的关键技术,地理空间数据可用性评价,地理空间数据共享与互操作,地理空间数据网络服务的安全管理。  相似文献   

基于“投资—效益”准则的结构全寿命总费用模型     

唐玉  郑七振  楼梦麟 《地震工程与工程振动》2012,32(4):188-194

作为基于结构性能抗震设计的重要原则,“投资—效益”准则反映了抗震设计思想由只注重结构安全到综合考虑技术、经济、社会等诸多因素影响的转变,而结构性能水平和抗震性能目标是实现这一准则的前提和基础.采用五级结构性能水平细化现行规范给出的三水准设防,以层间位移角为定量指标,建立了结构性能水平与层间位移角限值之间一一对应的关系.提出抗震性能目标优化决策,根据最优设防烈度并引入地震危险性分析,建立了基于“投资—效益”准则的结构全寿命总费用模型.该模型规避了直接求解体系可靠度的复杂过程,将问题转化为求解结构的失效概率.其优点在于既能考虑结构的初始造价,又充分根据结构性能失效的特点考虑结构在各级性能水平下的损失期望,全面注重了结构性能、安全及经济等条件,体现了基于性能的抗震设计理念.  相似文献   

Management rules for marine mammal populations: A response to Lonergan     

Justin Cooke  Paul Wade 《Marine Policy》2012,36(2):389-392

  相似文献   

南四湖人工湿地建设与管理   总被引：1，自引：0，他引：1  

刘继凯  马慧 《湿地科学与管理》2010,6(2):37-39

采用生态滞留塘+多级表面流湿地系统的工艺方案建设南四湖人工湿地,使出水水质基本达到《地表水环境质量标准》Ⅲ类水质要求。利用人工湿地的生态经济价值,采取市场化运营的模式,探索"以湿养湿,以收养管"的管理机制,使南四湖人工湿地既能保障南水北调安全顺利进行,又能自身循环发展,取得"保水创收"的双赢效果。  相似文献   

The red swamp crayfish Procambarus clarkii in Europe: Impacts on aquatic ecosystems and human well-being     

《Limnologica》2016

Procambarus clarkii is currently recorded from 16 European territories. On top of being a vector of crayfish plague, which is responsible for large-scale disappearance of native crayfish species, it causes severe impacts on diverse aquatic ecosystems, due to its rapid life cycle, dispersal capacities, burrowing activities and high population densities. The species has even been recently discovered in caves. This invasive crayfish is a polytrophic keystone species that can exert multiple pressures on ecosystems. Most studies deal with the decline of macrophytes and predation on several species (amphibians, molluscs, and macroinvertebrates), highlighting how this biodiversity loss leads to unbalanced food chains. At a management level, the species is considered as (a) a devastating digger of the water drainage systems in southern and central Europe, (b) an agricultural pest in Mediterranean territories, consuming, for example, young rice plants, and (c) a threat to the restoration of water bodies in north-western Europe. Indeed, among the high-risk species, P. clarkii consistently attained the highest risk rating. Its negative impacts on ecosystem services were evaluated. These may include the loss of provisioning services such as reductions in valued edible native species of regulatory and supporting services, inducing wide changes in ecological communities and increased costs to agriculture and water management. Finally, cultural services may be lost. The species fulfils the criteria of the Article 4(3) of Regulation (EU) No 1143/2014 of the European Parliament (species widely spread in Europe and impossible to eradicate in a cost-effective manner) and has been included in the “Union List”. Particularly, awareness of the ornamental trade through the internet must be reinforced within the European Community and import and trade regulations should be imposed to reduce the availability of this high-risk species.  相似文献   

Three‐dimensional vibration control of high‐tech facilities against earthquakes and microvibration using hybrid platform     

Xiao‐Jian Hong  Songye Zhu  You‐Lin Xu 《地震工程与结构动力学》2010,39(6):615-634

High‐tech equipments engaged in the production of ultra‐precision products have very stringent vibration criteria for their functionality in normal operation conditions and their safety during an earthquake. Most previous investigations were based on simplified planar models of building structures, despite the fact that real ground motions and structures are always three‐dimensional. This paper hence presents a three‐dimensional analytical study of a hybrid platform on which high‐tech equipments are mounted for their vibration mitigation. The design methodology of the hybrid platform proposed in this study is based on dual‐level performance objectives for high‐tech equipments: safety against seismic hazard and functionality against traffic‐induced microvibration. The passive devices (represented by springs and viscous dampers) and the active actuators are designed, respectively, to meet vibration criteria corresponding to safety level and functionality level. A prototype three‐story building with high‐tech equipments installed on the second floor is selected in the case study to evaluate the effectiveness of the hybrid platform. The optimal location of the platform on the second building floor is determined during the design procedure in terms of the minimal H ₂ cost function of absolute velocity response. The simulation of the coupled actuator‐platform‐building system subjected to three‐dimensional ground motions indicates that the optimally designed hybrid platform can well achieve the dual target performance and effectively mitigate vibration at both ground motion levels. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

国外测绘产品及其分发模式综述     

牛汝辰  周德军  周琪 《地理信息世界》2001,(2)

简要叙述了主要发达国家 ,如美国、英国、澳大利亚、捷克、芬兰等国的测绘产品及其管理和分发模式 ,这将为我国从事测绘生产和测绘产品的管理分发提供借鉴。同时还介绍了近年美国、英国、加拿大、印度四国数字产品在测绘产品中所占的比例 ,由于各国测绘机构在网上公布的这些产品都是其主流数字产品 ,故有一定参考价值。  相似文献