QUANTIFYING URBAN INTENSITY IN DRAINAGE BASINS FOR ASSESSING STREAM ECOLOGICAL CONDITIONS1

ABSTRACT: Three investigations are underway, as part of the U.S. Geological Survey's National Water‐Quality Assessment (NAWQA) Program, to study the relation between varying levels of urban intensity in drainage basins and in‐stream water quality, measured by physical, chemical, and biological factors. These studies are being conducted in the vicinities of Boston (Massachusetts), Salt Lake City (Utah), and Birmingham (Alabama), areas where rapid urbanization is occurring. For each study, water quality will be sampled in approximately 30 drainage basins that represent a gradient of urban intensity. This paper focuses on the methods used to characterize and select the basins used in the studies. It presents a methodology for limiting the variability of natural landscape characteristics in the potential study drainage basins and for ranking the magnitude of human influence, or urbanization, based on land cover, infrastructure, and socioeconomic data in potential study basins. Basin characterization efforts associated with the Boston study are described for illustrative purposes.     

SIZING OF SURFACE WATER RUNOFF DETENTION PONDS FOR WATER QUALITY IMPROVEMENT1

ABSTRACT: Historically, storm water management programs and criteria have focused on quantity issues related to flooding and drainage system design. Traditional designs were based on large rainfall‐runoff events such as those having two‐year to 100‐year return periods. While these are key criteria for management and control of peak flows, detention basin designs based on these criteria may not provide optimal quality treatment of storm runoff. As evidenced by studies performed by numerous public and private organizations, the water quality impacts of storm water runoff are primarily a function of more frequent rainfall‐runoff events rather than the less frequent events that cause peak flooding. Prior to this study there had been no detailed investigations to characterize the variability of the more frequent rainfall events on Guam. Also, there was a need to develop some criteria that could be applied by designers, developers, and agency officials in order to reduce the impact of storm water runoff on the receiving bodies. The objectives of this paper were three‐fold: (1) characterize the hourly rainfall events with respect to volume, frequency, duration, and the time between storm events; (2) evaluate the rainfall‐runoff characteristics with respect to capture volume for water quality treatment; and (3) prepare criteria for sizing and designing of storm water quality management facilities. The rainfall characterization studies have provided insight into the characteristics of rainstorms that are likely to produce non‐point source pollution in storm water runoff. By far the most significant fmdings are the development of a series of design curves that can be used in the actual sizing of storm water detention and treatment facilities. If applied correctly, these design curves could lead to a reduction of non‐point source pollution to Guam's streams, estuaries, and coastal environments.     

Century Perspective of Heavy Metal Use in Urban Areas. A Case Study in Stockholm

The inflow and stock (amount in use) of heavy metals (cadmium(Cd), chromium (Cr), copper (Cu), lead (Pb), mercury (Hg), nickel (Ni) and zinc (Zn)) in goods in 1995 have been quantifiedin the anthroposphere of Stockholm, Sweden. Statistics on national, regional and local level were used. Contacts were established with representatives from production and constructionin the industrial sector and with authorities. The results show that the stock of Cd is 0,2 kg per capita. For the other heavymetals the corresponding result per capita is: Cr 8, Cu 170, Hg 0,01, Ni 4, Pb 73 and Zn 40 kg. The inflow varies between2–8%of the stock indicating the importance of the stock. The lowestlevels are for Cu and Pb. Heavy metal levels in solid waste are high, between 15–45% of the amount in the inflow (Hg excluded), the lowest values were for Cu and Pb. Thus, recyclingis incomplete. Long life expectancy goods form the majority of the stock but there is a tendency that short life expectancy goods increase their importance in the inflow. Concealedgoods are also more frequent in inflow than in the stock.     

党校的城市生态环境教育

本文论述了党校开展城市生态环境教育的重要意义,城市生态环境的特点,与城市发展的关系,提出了加强城市生态环境管理的对策。     

MANAGEMENT OF FLOOD CONTROL SUMPS AND POLLUTANT TRANSPORT1

ABSTRACT: Levee sump systems are used by many riverine communities for temporary storage of urban wet weather flows. The hydrologic performance and transport of stormwater pollutants in sump systems, however, have not been systematically studied. The objective of this paper is to present a case study to demonstrate development and application of a procedure for assessing the hydraulic performance of flood control sumps in an urban watershed. Two sumps of highly variable physical and hydraulic characteristics were selected for analysis. A hydrologic modeling package was used to estimate the flow hydrograph for each outfall as part of the flow balance for the sump. To validate these results, a water balance was used to estimate the total runoff using sump operational data. The hydrologic model calculations provide a satisfactory estimate of the total runoff and its time‐distribution to the sump. The model was then used to estimate pollutant loads to the sump and to the river. Although flow of stormwater through a sump system is regulated solely by flood‐control requirements, these sumps may function as sedimentation basins that provide purification of stormwater. A sample calculation of removals of several conventional pollutants in the target sumps using a mass balance approach is presented.     

基于GIS的城市最小生态用地空间分析模型研究——以深圳市为例

21世纪,全球范围内城市化已经成为人类社会发展的必然趋势,城市扩张不可避免地将大量的森林、农田、草地、湿地和水域等发挥着重要生态服务功能的生态用地转化为城市建设用地,对城市、区域乃至全球的生态系统造成较大的影响。在未来快速城市化过程中,保护必需的生态用地对于维持城市自身生态系统健康、改善城市居民生活质量和城市可持续发展有着重要意义。研究以中国经济特区深圳市为例,将景观生态概念模型与生态系统服务功能价值评估方法结合起来,在GIS技术的支持下,构建了城市最小生态用地空间分析模型,并分别按照保留城市面积30%、40%、50%和60%生态用地的4种情景,分析最小生态用地空间分布的合理性,结果表明论文所构建的最小生态用地模型能够很好地将城市当中具有重要生态系统服务功能的土地提取出来。     

北京工业废水和城市污水环境激素污染状况调查

利用固相萃取前处理技术和高效液相色谱、气相色谱方法,分析研究北京地区重点污染源排水(包括工业废水和城市污水)中主要环境激素(邻苯二甲酸酯、有机氯农药、有机氮农药、有机磷农药、菊酯类农药、烷基酚和双酚A)的残留状况. 调查分析了分布在北京市10个区县的污水处理厂、化工行业、冶金焦化行业、医院及其洗涤中心、印钞行业、食品加工行业和制药行业等7类22个单位排水中的8种邻苯二甲酸酯,17种有机氯农药,7种有机氮和有机磷农药,4种菊酯类农药,4种烷基酚及双酚A共40种环境激素类物质的质量浓度. 并着重分析了污水处理厂进、出水中的环境激素的浓度水平. 结果表明,北京地区工业废水和城市污水中广泛存在着环境激素污染,但其质量浓度并未超过现行排放标准.      

城市用地扩展与耕地保护

中国耕地资源不足,人均耕地不足世界水平的一半。由于快速城市化,城市用地扩展(占用耕地)和耕地保护间的矛盾已引起了国内外学者的广泛关注。对此矛盾存在两种看法,一种观点认为城市用地远比农村居住用地节约,城市化有助于减少耕地的流失;另一种观点认为中国城市用地扩张和耕地资源稀缺之间矛盾尖锐,城市用地的蔓延极可能造成耕地资源的紧张。论文针对国外城市发展水平较高的国家和我国城市发达地区的城市发展历程,探讨了在城市发展过程中,这些国家或地区的耕地资源总量的变化趋势。然后,利用由遥感解译的土地利用数字化图,分析了我国部分地区城镇人均用地和农村人均居住用地的差距。结果认为,中国城镇人均用地并不像人们想象的那样远低于人均农村居民点用地,而是较为接近;中国城市用地的扩展可能导致耕地资源的紧张。     

Coupling urban 3-D information and circuit theory to advance the development of urban ecological networks

Ongoing, rapid urban growth accompanied by habitat fragmentation and loss challenges biodiversity conservation and leads to decreases in ecosystem services. Application of the concept of ecological networks in the preservation and restoration of connections among isolated patches of natural areas is a powerful conservation strategy. However, previous approaches often failed to objectively consider the impacts of complex 3-D city environments on ecological niches. We used airborne lidar-derived information on the 3-D structure of the built environment and vegetation and detailed land use and cover data to characterize habitat quality, niche diversity, and human disturbance and to predict habitat connectivity among 38 identified habitat core areas (HCAs) in Nanjing, China. We used circuit theory and Linkage Mapper to create a landscape resistance layer, simulate habitat connectivity, and identify and prioritize important corridors. We mapped 64 links by using current flow centrality to evaluate each HCA's contribution and the links that facilitate intact connectivity. Values were highest for HCA links located in the west, south, and northeast of the study area, where natural forests with complex 3-D structures predominate. Two smaller HCA areas had high centrality scores relative to their extents, which means they could act as important stepping stones in connectivity planning. The mapped pinch-point regions had narrow and fragile links among the HCAs, suggesting they require special protection. The barriers with the highest impact scores were mainly located at the HCA connections to Purple Mountain and, based on these high scores, are more likely to indicate important locations that can be restored to improve potential connections. Our novel framework allowed us to sufficiently convey spatially explicit information to identify targets for habitat restoration and potential pathways for species movement and dispersal. Such information is critical for assessing existing or potential habitats and corridors and developing strategic plans to balance habitat conservation and other land uses based on scientifically informed connectivity planning and implementation.     

中国北方城市内河水资源综合利用与调配方案研究——以胶州市城市内河为例

内河是城市的重要组成部分,而伴随着快速城镇化进程,城市内河原有的水文、生态节律都受到很大的扰动。针对胶州市水资源量相对有限、水环境质量较差的现状,以河道生态需水量理论为指导,以期通过实施科学的生态补水,逐步恢复城市内河的生态功能与城市景观功能。结果表明,胶州市城市内河以景观功能为主,经测算其生态需水量为36 486.9m3/d,而根据胶州市的相关发展规划,其污水处理厂中水回用能力为5万m3/d,可以满足生态补水工程的需求;根据生态补水工程实施后的污染物入河情况预测,实施生态补水后,胶州市城市内河水质基本达到《地表水环境质量标准》(GB 3838—2002)Ⅳ类标准,基本可消除水体黑臭等现象。