IMPACT OF WATERSHED URBANIZATION ON STREAM INSECT COMMUNITIES1

ABSTRACT: The impact of urbanization on stream insect communities was determined by sampling 22 sites in northern Virginia representing a range of human population densities. Watershed development had little effect on the total insect numbers (no./m²), but shifted the taxonomic composition markedly. Relative abundance of Diptera (mainly chironomids) increased at more highly urbanized sites, while most other insect orders including Ephemeroptera (mayflies), Coleoptera (bettles), Megaloptera (dobsonflies), and Plecoptera (stone-flies) decreased. Trichoptera (caddisfiles) exhibited a variable response. Genus diversity and richness (number of genera) were significantly higher in less urbanized streams. Two genera of chironomids were positively correlated with increased urbanization, while 14 other genera (scattered through several orders) were negatively related to human population density. Principal components analysis demonstrated a gradient from more urbanized to less urbanized stations based on generic and order level biological data. Results of this study indicate that watershed urbanization has a major impact on benthic insect communities even in the absence of point source discharges.     

MODELING THE EFFECTS OF URBANIZATION ON BASIN WATER YIELD AND RESERVOIR SEDIMENTATION1

ABSTRACT: The dam impounding White Rock Lake was completed in 1910 to provide water for the City of Dallas. Since then, land use on the watershed has changed from entirely rural to over 77 percent urban. A model called SWRRB (Simulator for Water Resources in Rural Basins) was utilized to determine the effect of urbanization on water and sediment entering the lake. The simulation results show that, if urbanization had not occurred, then the annual surface runoff would be 135 mm rather than 151 mm and the annual sediment yield would be 4.4 t/ha rather than 4.1 t/ha. Also, the effect of urbanization on delivery ratios was shown and a positive linear correlation was found. Finally, the weather generator in SWRRB was utilized to estimate the loss of reservoir capacity until 2050 for three different land use management scenarios.     

城镇化、居民生活能源消费与生活碳排放之间关系的实证研究

利用中国1995年－2012年居民生活能源消费数据,通过协整检验、格兰杰因果关系检验等方法对城镇化、居民生活能源消费与碳排放之间关系进行了实证研究,结果发现：城镇化、居民生活能源消费与碳排放存在长期均衡关系;城镇化程度的提高会降低CO2排放;生活能源消费的增加是CO2排放提高的重要原因。居民生活能源消费与CO2排放之间存在着双向格兰杰因果关系。提出稳步推进新型城镇化进程、合理进行生活能源消费、调控城乡居民生活能源消费等建议。     

江苏省人口数据空间离散化研究及其精度分析

针对传统人口数据表达方法在表达人口空间分布上的不足,设计了人口数据离散化模型,通过分析人口数据与土地覆被信息之间的关系,将分县统计的人口数据分配到空间1 km×1 km栅格单元上。在江苏省的研究表明,利用该方法能获得比较高的精度。基于离散化后的人口数据,发现江苏省人口空间分布有两大特点：(1)人口分布自城市中心向城市外围由密集渐变为分散;(2)苏南的城市人口规模显著大于苏中和苏北,苏南、苏中、苏北三大区域的人口城镇化水平呈现由高到低排列。江苏省人口空间分布的上述特点与江苏省三大区域的经济发展状况及各个区域的城镇化水平相一致。离散化后生成的1 km×1 km栅格人口数据,能够精确表达人口分布的区域差异,可以作为制订资源开发、环境规划、区域发展战略等重要参考依据。     

城市环境熵模型的建立及其在城市化环境影响评价研究中的应用

城市化是20世纪以来的一个全球性进程,与此同时,城市化对环境的影响也日益明显,并逐渐成为社会各界关注的焦点之一。文章在简单介绍热力学原理的基础理论、城市化概念特别是城市化对环境影响的基础上,从系统的角度深入分析了城市化对环境的影响与热力学熵原理的相似性。由此提出在城市化环境影响评价研究中借鉴热力学方法,提出了城市化环境影响评价的新概念和新方法——"城市环境熵"模型。最后,以珠江三角洲经济区城市化河水质量影响评价为例,运用"城市环境熵"模型进行了具体计算,结果表明,用此模型的评价结果与用均值化综合污染指数法的评价结果基本一致,相对误差为6.67%。可以认为用城市环境熵模型法来评价城市化对城市环境的影响是可行的。     

人为活动对城市湖泊沉积物重金属污染的影响——以武汉墨水湖为例

人类活动使得大量的重金属向水环境中排放,导致了城市湖泊严重的重金属污染.为了研究中国的工业化、城市化发展对城市水体重金属污染的影响,以武汉墨水湖为例,测定了沉积物中几种常见痕量重金属Zn、Pb、Ni、Cu、Cr的含量和富集系数,并运用主成分分析对重金属的污染来源进行了初步探讨.结果表明,墨水湖表层沉积物重金属污染程度较重,主要受人为输入的影响;5种重金属在全湖区域上具有比较高的富集系数,尤以排污口为甚,排污口是重金属富集的主要区域.主成分分析表明,Pb可能主要来自于暴雨径流面源,而Cr可能主要来自于工矿企业的点源排放,其他3种金属则有着大小相当的点、面源输入贡献。以上结果表明,城市化和工业化进程已经给城市湖泊带来了很高的重金属污染负荷.     

仙居县城乡居民消费差异的生态足迹分析

根据生态足迹理论，以浙江省仙居县为例，利用统计调查和问卷调查资料，分别计算了城乡居民生活消费的生态系统占用情况。计算结果表明，该地城市居民的生活消费所占用的生态系统是农村居民所占用的1．73倍，差异最大的是草地，其次是水域、建筑用地、化石能源和耕地，对于林地的占用则是农村居民大于城市居民。     

中国乡村城市化过程中的景观生态学问题与对策研究

城市和乡村的发展共同构成了社会-经济-自然复合生态系统的可持续发展,然而长期以来,重城市轻乡村的发展思想导致了城乡二元结构矛盾不断尖锐。随着经济的高速发展和加入WTO后的国际化冲击,未来的10~20年间,中国将进入一个乡村城市化快速发展的时期,这将使得中国本来紧张的人地关系变得更加严重,资源消耗与环境污染问题日益突出,乡村发展将面临更大的挑战,同时也将是中国乡村发展的重要契机。本文依据景观生态学原理与方法,通过研究乡村城市化进程中乡村景观的组合、结构、功能以及变化中存在的问题,提出了城乡协调、全盘布局和保留自身特色等相应的生态规划治理措施和对策,尽可能使乡村景观格局呈现多样性、异质性,并在功能上表现出稳定性和连续性,最终实现城乡景观和谐发展的局面。     

论现阶段我国城市化的道路选择及政策取向

通过我国城市化现状的分析，结合我国具体国情，具体提出相当一段时期内我国城市化道路的选择：大、中、小不同城市协调发展、整体推进；东、中、西不同经济发展地带区别对待，体现层次．同时，还要求相应的政策、制度、法规等及时跟上，加快城市化步伐．     

THE EFFECTS OF URBAN AREAS ON BENTHIC MACROINVERTEBRATES IN TWO COLORADO PLAINS RIVERS

Water demands in arid and semi-arid areas, coupled with increased human populations and concomitant changes in land use, can greatly alter aquatic ecosystems. A good example of this type of system occurs along the eastern slope of the Colorado Rocky Mountains, U.S.A. Long-term macroinvertebrate metric data from the Big Thompson and Cache la Poudre Rivers, Colorado, were collected at one site above, and three sites in and downstream from urban areas. These data were compared both with regional reference and single reference sites in the respective rivers. Using the surrogate variables of potential urban impact (population and housing units), and the environmental gradient represented primarily by chemical factors, it was determined that there was an effect of urban land use that was reflected in the macroinvertebrate assemblages in both rivers. The most robust results were usually seen when regional reference data were used. However, even using only the upstream reference site in either river indicated some negative impacts from the urban areas. The long-term data, particularly in the Cache la Poudre River, showed that water quality has not been getting worse and there is some evidence of a slight improvement in downstream reaches, even with increased urban development.