Alternatives to biodiversity offsets for mitigating the effects of urbanization on stream ecosystems

Globally, offset schemes have emerged in many statutory frameworks relating to development activities, with the aim of balancing biodiversity conservation and development. Although the theory and use of biodiversity offsets in terrestrial environments is broadly documented, little attention has been paid to offsets in stream ecosystems. Here we examine the application of offset schemes to stream ecosystems and explore whether they suffer similar shortcomings to those of offset schemes focused on terrestrial biodiversity. To challenge the applicability of offsets further, we discuss typical trajectories of urban expansion and their cascading physical, chemical and biological impacts on stream ecosystems. We argue that the highly connected nature of stream ecosystems and urban drainage networks can transfer impacts of urbanization across wide areas, complicating the notion of like‐for‐like exchange and the prospect of effectively mitigating biodiversity loss. Instead, we identify in‐catchment options for stormwater control, which can avoid or minimize the impacts of development on downstream ecosystems, while presenting additional public and private benefits. We describe the underlying principles of these alternatives, some of the challenges associated with their uptake, and policy initiatives being trialed to facilitate adoption. In conclusion, we argue that stronger policies to avoid and minimize the impacts of urbanization provide better prospects for protecting downstream ecosystems, and can additionally, stimulate economic opportunities and improve urban liveability.     

Resident preferences for augmented rainstorm disasters management strategies: the case of Nanjing in China

In recent years, rainstorm disasters have enormously negative effect on property safety and life safety in Nanjing. In order to achieve the consistency of optimal social supply of rainstorm disasters prevention management strategies and public sector supply, this paper studies citizens’ preferences for augmented strategies in Nanjing. Using a choice experiment approach, we consider willingness-to-pay (WTP) for augmented efforts for non-structural reform strategy of rainstorm runoff control, structural reform strategy of rainstorm drainage and non-structural education. Our results showed that citizens were generally in favor of augmented rainstorm disaster prevention management strategies, but with varying degrees. They were most favorable to increased educational effort that does not physically affect rainstorm, with the WTP of ¥134.29 a year. Followed by improvements in Non-structural Reform Strategy of Rainstorm Runoff Control, its WTP was ¥88.08 a year. The improving Structural Reform Strategy of Rainstorm drainage was less influential, but still significantly affected policy choice with the WTP of ¥55.42 a year. Specifically, the results of latent class model best confirmed the assumption that individual preference is heterogeneous. Furthermore, in order to gain the support of the public, policy-makers should advance publicly linked strategies such as mentioned in this study that appear most useful.     

Geospatial Method to Map Potential Risk of Stormwater Thermal Pollution

Thermal pollution is a growing concern as communities strive to protect and improve the nation's waters. The purpose of this study was to develop and analyze a geospatial model that predicts the relative risk of contribution of thermal energy to surface runoff throughout an urban watershed. A geospatial‐based solution could serve as a screening method or planning element, prior to or instead of the development of a more complex simulation of mass‐load transport of thermal energy. The study's theoretical methodology integrated the thermal potential of land cover and thermal decay due to overland travel to inlets. The resulting thermal pollution potential (TPP) index value was then assigned to individual model grid cells for comparison. Analysis of results from application to a case study watershed in Blacksburg, Virginia, indicated the computational methodology is not very sensitive to changes in spatial resolution. The thermal decay constant used in the analysis was varied, and results indicated a low sensitivity to selection of this parameter. A comparison between methods of watershed delineation also indicated use of infrastructure‐corrected watershed delineation yields better results than derivation from automated techniques. The geospatial method presented may be used to reproduce a TPP risk map to prioritize thermal pollution mitigation efforts.     

城市地面停车场透水铺装使用分析——以南京市为例

南京市在城市化的进程中，各项城市建设使得原先的土壤表面日益被不透水铺装所覆盖，从而引发了一系列环境问题。其中，最受关注的是由于地表径流系数增大而导致的雨水径流量的增加。解决这一问题的关键是在城市建设中因地制宜的选用透水铺装，以控制城市不透水地表的蔓延。现代城市的重要交通设施之一——地面停车场，由于使用的特殊性，是一个可以采用透水铺装的典型区域。根据分析，对南京市地面停车场采用透水铺装能够有效减轻雨水径流量和污染物的排放量．在一定程度上起到优化城市环境的作用。因此，应将地面停车场作为南京市推广透水地表的一个开端，并逐渐带动城市其它区域透水铺装的使用。     

北京城区雨水径流的污染及控制

随着城市化发展，不透水地面面积增加，雨水径流的污染性也相应增长，它已成为不可忽视的污染源。文章分析了北京市雨水径流的污染源，估算了其污染量，并提出了多种控制径流污染的措施。     

城市地面停车场透水铺装使用分析——以南京市为例

南京市在城市化的进程中,各项城市建设使得原先的土壤表面日益被不透水铺装所覆盖,从而引发了一系列环境问题.其中,最受关注的是由于地表径流系数增大而导致的雨水径流量的增加.解决这一问题的关键是在城市建设中因地制宜的选用透水铺装,以控制城市不透水地表的蔓延.现代城市的重要交通设施之一--地面停车场,由于使用的特殊性,是一个可以采用透水铺装的典型区域.根据分析,对南京市地面停车场采用透水铺装能够有效减轻雨水径流量和污染物的排放量,在一定程度上起到优化城市环境的作用.因此,应将地面停车场作为南京市推广透水地表的一个开端,并逐渐带动城市其它区域透水铺装的使用.     

沸石床处理农田暴雨径流氮磷中试研究

对沸石床去除农田暴雨径流中氮磷进行了人工模拟中试研究。结果表明 ,沸石床对暴雨径流有较好的净化作用 ,系统水力负荷介于 0 2 4m3 /m2 ·d和 2 4m3 /m2 ·d之间时 ,暴雨径流中主要氮磷污染物的总去除率可达 :TN 4 5 % ,NH4 N 6 0 % ,NO3 N 2 0 % ,TP 38%。平均去除能力为TN 8 14g/m2 ·d ,NH4 N 3 6 4g/m2 ·d ,NO3 N 1 17g/m2 ·d ,TP 0 5 9g/m2 ·d。茭草床的效果明显好于芦苇床 ,植物床的效果明显好于空白对照床。系统在最大进水能力 31L/min下 ,对氨氮仍然能保持4 0 %以上的去除率     

城市旅游区暴雨径流污染过程中的不透水面效应

选取武汉市动物园4种典型的不透水面暴雨径流污染特征进行了系统的研究，以期为旅游区面源污染危害评价和治理提供基本的依据。结果表明，动物园4种不透水面初期径流污染物浓度很高，COD最大值达1140mg／L，下垫面类型及地表累积污染物是影响径流水质的主要因素。通过无量纲累积曲线的分析，表明旅游区不透水面径流初期冲刷严重，该曲线还为面源治理提供了重要的工程参数。     

COMMUNITY RESPONSE TO STORMWATER POLLUTION IN AN URBANIZED WATERSHED1

ABSTRACT: A model is developed and tested to identify the factors influencing variation in community response to stormwater pollution. Basic constructs of the model use environmental hazard theory, integrated with analysis of community demographic and political forces affecting local government decision processes. Community stormwater response is measured by an index comprised of 12 response indicators. Selection criteria for the response indicators include their effectiveness, variability, and general representation of the spectrum of stormwater response activity. Observable activities are scored progressively based upon their relative ecosystem impacts. Weighted and unweighted indicator scores are computed, with a survey of stormwater experts providing the basis for the weights. Results indicate a wide variation in response levels among the selected communities. Regression analysis identifies four significant predictors of response at the watershed scale: the mean age of householder over 25, the total tax rate, community type (city or township), and the amount of green staff (presence of recycling coordinators, foresters, or environmental planners). This mix of predictors demonstrates the applicability of hazard theory to stormwater response, as community stormwater response is influenced by the capacity and economic means to effect change - two central constructs of hazard theory.     

ECONOMIC FRAMEWORK FOR FLOOD AND SEDIMENT CONTROL WITH DETENTION BASINS1

ABSTRACT: A framework for combining economic factors and the hydrolo of detention basins is provided. The general development of economic production functions for water quality (sediment) and flood control is discussed. Example production functions are generated to compare water quality (sediment control only) and flood control. For the given example, the design of a detention basin for downstream sediment control is economically unwarranted. When compared to on-site detention facilities, regional detention structures appear to be more practical from an economic standpoint for water quality control. Since sediment was the only water quality parameter assessed, it is entirely possible that the design of a detention basin for water quality control would be justified if the effects of all pollutants of concern could be quantified. Policy aspects of detention facilities that relate to the economics of water quality control are also discussed.