THE STRUCTURE AND PRACTICE OF WATER QUALITY TRADING MARKETS1

ABSTRACT: The use of transferable discharge permits in water pollution, what we will call water quality trading (WQT), is rapidly growing in the U.S. This paper reviews the current status of WQT nationally and discusses the structures of the markets that have been formed. Four main structures are observed in such markets: exchanges, bilateral negotiations, clearinghouses, and sole source offsets. The goals of a WQT program are environmental quality and cost effectiveness. In designing a WQT market, policy makers are constrained by legal restrictions and the physical characteristics of the pollution problem. The choices that must be made include how trading will be authorized, monitored and enforced. How these questions are answered will help determine both the extent to which these goals are achieved, and the market structures that can arise. After discussing the characteristics of different market structures, we evaluate how this framework applies in the case of California's Grassland Drainage Area Tradable Loads Program.     

洪水多站峰量同时模拟的随机模型

洪水过程是一复杂的随机动力系统，随机模拟技术至今仍是研究洪水过程时空统计特性的有力工具。该文以同时模拟上游站、下游站及其区间的最大洪峰流量、最大五日洪量和最大十二日洪量为例，建立了一种简便而适用的随机模型。实例结果表明，该随机模型是可行而有效的，在水资源系统工程的理论与实践中具有重要价值。     

关中盆地地-气系统灾变的节律性及耦合关系

依据丰富而系统的历史资料，建立了关中盆地历史地震与旱涝灾害两个数据库，分析了近2000a来地-气系统环境灾变的节律性及耦合关系。结果发现：(1)地震活动具有一定的节律性，并先后经历了3个平静期和3个活跃期，平静期与活跃期呈交替出现，具有3～4个世纪的周期；(2)较为严重的干旱、洪涝灾害亦具有一定的周期性，先后经历了2个洪涝期和3个干旱期，其较长尺度的转换周期亦为3～4个世纪；(3)在世纪尺度上，地震活动与旱涝灾害具有某种耦合关系，表现为在地震活动的活跃期，旱涝灾害呈多发性，而在地震活动的平静期，旱涝灾害较为稀少；(4)以较大级别的地震群发为节点，地气系统环境灾变的耦合关系具有先旱→后震→再涝的演替特征。基于上述事实，提出了一个地-气系统环境灾变的概念模型，对地震与旱涝灾害的耦合关系给出了确定性解释。为关中盆地世纪尺度的环境灾变群发性预测提供了新的依据。     

基于GIS技术的县市级防汛信息系统

防汛减灾是县市水利部门的重点工作。以临海市防汛决策指挥系统为实例，探讨了基于GIS技术，采用Client／Server模式的防汛信息系统的解决方案。根据防汛业务管理工作的实际要求，分析了系统的属性和空间数据库的存储结构和建库方法，实现了防汛信息系统的各主要模块及其功能。     

USE OF THE DELPHI METHOD IN RESOLVING COMPLEX WATER RESOURCES ISSUES1

ABSTRACT: The tri‐state river basins, shared by Georgia, Alabama, and Florida, are being modeled by the U.S. Fish and Wildlife Service and the U.S. Army Corps of Engineers to help facilitate agreement in an acrimonious water dispute among these different state governments. Modeling of such basin reservoir operations requires parallel understanding of several river system components: hydropower production, flood control, municipal and industrial water use, navigation, and reservoir fisheries requirements. The Delphi method, using repetitive surveying of experts, was applied to determine fisheries' water and lake‐level requirements on 25 reservoirs in these interstate basins. The Delphi technique allowed the needs and requirements of fish populations to be brought into the modeling effort on equal footing with other water supply and demand components. When the subject matter is concisely defined and limited, this technique can rapidly assess expert opinion on any natural resource issue, and even move expert opinion toward greater agreement.     

MARSH DEVELOPMENT AT RESTORATION SITES ON THE WHITE MOUNTAIN APACHE RESERVATION,ARIZONA1

ABSTRACT: To prioritize sites for riparian restoration, resource managers need to understand how recovery processes vary within landscapes. Complex relationships between watershed conditions and riparian development make it difficult to predict the outcomes of restoration treatments in the semiarid Southwest. Large floods in 1993 scoured riparian areas in the Carrizo watershed on the White Mountain Apache Reservation in east‐central Arizona. We evaluated recovery at three of these sites using repeated photographs and measurements of channel cross sections and stream‐side vegetation along permanent transects. The sites were mapped as lying on the same soil type, had similar streamside vegetative communities, and were similarly treated through livestock exclusion and supplemental seeding. However, the sites and individual reaches within the sites followed strikingly different development paths. Dramatic recovery occurred at a perennial reach where cover of emergent wetland plants increased from 4.7 percent (standard error = 0.8 percent) in October 1995 to 55.5 percent (standard error = 2.7 percent) in September 2001. At several other reaches, geologic and hydro geomorphic characteristics of the sites limited inputs of fine sediment or surface water, resulting in modest or negligible increases in emergent cover. Recovery efforts for highly valued marshlands in this region should prioritize perennial reaches in low gradient valleys where salty sediments are abundant.     

一种新型悬浮填料的性能试验研究

本文对生物接触氧化法中的悬浮填料一密度、材质和形状对曝气强度、充氧能力及挂膜能力的影响进行了试验研究.研究中分别采用清水状态的曝气和充氧能力试验以及挂膜的方法.结果表明,悬浮填料的密度在0.95～0.99 g/cma之间比较适合.曝气池内加入填料后,可以提高普通穿孔管的充氧能力,且在一定的投配率范围内,随着填料的增加,氧的传递速率和利用率增加.挂膜试验表明聚丙烯比聚乙烯挂膜快且均匀,膜量大,而且圆柱形填料比空心球填料的挂膜量大.     

用于结构振动控制的电流变阻尼器的设计

地震是一种随机振动 ,一旦发生将影响结构的安全。ER智能材料是一种可控流体 ,它在电场作用下可从牛顿流体变为剪切屈服应力较高的粘塑性体 ,且这种转变连续、可逆、迅速 ,因此 ,可用它来制作可调阻尼器 ,实现对工程结构地震反应的半主动控制。本文在简要介绍了ER电流材料的基本性能和ER可调阻尼器的工作原理的基础上设计了一个具有较大可调范围和较高阻尼力的ER电流变阻尼器     

生物多样性保护规制工具更新——规范层面的分析

生物多样性保护法律的有效执行,应立足于具体规制工具的设计。生物多样性保护立法涉及三个主要法律领域——物种保育法、自然保护地法和生物安全法,从法律规范层面分析,这三个法律领域对规制工具的偏好与选择呈现出"硬者极硬,刑罚优先,软者无力"的整体格局。本文以生物多样性保护原理对现行规制工具进行检验,物种保育法和自然保护地法应以规制领域的去极端化为导向进行规制工具更新,一方面要软化甚至去除极硬规制,与此同时应建立完善行政合同、行政指导、行政奖励等柔性规制工具,赋予其可操作性,使之柔而有力。     

上海市2003年生态足迹计算与分析

本文应用Wackernagel等提出的生态足迹概念和方法对上海区2003年的生态足迹和承载力进行计算和分析。结果表明,2003年上海市人均生态足迹为3．36hm^2,人均生态承载力为0．46hm^2。在此基础上提出了减缓上海市生态赤字的一系列措施,最后对模型的完善作出了展望。