城市雨洪资源利用经济价值评价研究

对城市雨洪的合理利用,有助于城市防止内涝、减少灾害、改善水环境,同时能够解决城市水资源短缺,有助于实现水资源可持续利用。文章通过对西安市雨洪资源量的分析,建立了雨洪资源利用的经济效益评价指标,同时,通过分析雨洪资源的利用对国民经济的促进作用,构建了雨洪资源利用的经济价值评价模型,确定了1998～2007年西安市雨洪资源利用对国民经济的贡献量,为下一步建立系统动力学模型分析资源与经济的相互影响奠定了基础。同时,利用该模型测算出2007年西安市雨水利用量约为234万m3,2006年雨洪资源的合理利用推动GDP增长104607.9万元,2007年雨洪资源的合理利用推动GDP增长125787.2万元,但同时尚有76556.61万m3的雨洪资源未得到合理利用。     

Two alternative modes for di use pollution control in Wuhan City Zoo

Pollution in urban zoos arises from diffuse and small point sources. However, its control has received little attention in past decades. Online and ofttine modes of ecological engineering technology were designed to control pollution from small point and diffuse sources in Wuhan City Zoo, China. Their characteristics and performances were investigated in sixteen runoff events from 2003 to 2005. The results showed that the two modes both improved runoff water quality and had high retention rates for water and pollutants. In the outflows, the event mean concentrations （EMCs） of total suspended solids （TSS）, chemical oxygen demand （COD）, total nitrogen （TN） and total phosphorus （TP） were reduced by 88%, 59%, 46% and 71% for the online mode, and those were 77%, 42%, 50% and 66% for the ofttine mode. The annual retention rates of pollutant loads for the online mode were 94.9%-98.5% in the three study years; those for the ofitine mode were 70.5%-86.4%. Based on calculation, the online mode was able to store the runoff of 66.7 mm rainfall completely, and the ofttine mode could store that of 31.3 mm rainfall. In addition, the online mode can provide an effective way for rainwater utilization and good habitats for aquatic wildlives, and has an excellent aesthetics value for recreationsal pastimes. The ofiline mode can save land resources and may be an effective and economical measure for diffuse pollution control in urban areas.     

Pollutant loads of surface runo inWuhan City Zoo, an urban tourist area

The pollutant loads of surface runoff in an urban tourist area have been investigated for two years in the Wuhan City Zoo, China. Eight sampling sites, including two woodlands, three animal yards, two roofs and one road, were selected for sampling and study. The results indicate that pollutants ranked in a predictable order of decreasing load （e.g. animal yard〉roof〉woodland〉road）, with animal yards acting as the key pollution source in the zoo. Pollutants were transported mainly by particulate form in runoff. Particulate nitrogen and particulate phosphorous accounted on average for 61%, 78% of total pollutant, respectively, over 13 monitored rainfall events. These results indicate the treatment practices should be implemented to improve particulate nutrient removal. Analysis of the M（V） curve indicate that no first flush effect existed in the surface runoff from pervious areas （e.g. woodland, animal ground yard）, whereas a first flush effect was evident in runoff from impervious surfaces （e.g. animal cement yard, roof, road）.     

城市生态恢复规划的国外优秀案例借鉴

通过美国金郡的湿地恢复经验、普吉特海湾的雨水管理系统以及加拿大汤姆逊公园废弃地恢复规划案例借鉴国外城市生态恢复规划的重点环境生态策略、措施与后续维护方法、管理等,以国外经验启示我国生态恢复工作中应关注的重点.     

Rapid Assessment of Hydrologic Performance of Low Impact Development Practices under Design Storms

Low impact development (LID) practices are often applied to compensate for surface imperviousness caused by urban development. These practices can mitigate flood risk by reducing runoff volume and peak flow and by delaying the time to peak flow. To select a suitable LID practice type and its surface area during the preliminary design process, it is necessary to rapidly estimate the hydrologic performance of various LID designs under design storms. This study provides a method and a toolbox for rapid assessment of the hydrologic performance of various LID practices, which can be useful to developers for establishment of preliminary LID designs. The hydrologic performance of three common types of LID practices (i.e., green roofs, bioretention cells, and infiltration trenches) under various design storms is first simulated using the Storm Water Management Model (SWMM). The results are then presented as performance curves on a unit storage basis. Look‐up tables are further developed to assist the comparison and selection of the LID alternatives for various hydrologic performance targets. To facilitate SWMM modeling, a MATLAB toolbox is developed to automate the process of input modification, model simulation, result extraction, and postprocessing. Finally, the sensitivity of the look‐up curves to design storm types and design specifications of bioretention cells is also analyzed, and the assumptions used in the development of these look‐up curves are validated.     

利用生态混凝土控制城市坡面暴雨径流污染试验研究

利用生态混凝土作为护坡材料,研究暴雨条件下生态混凝土控制山坡降雨径流污染的机理,以期对生态混凝土在城市护坡和护岸中的应用提供理论依据.研究结果表明,生态混凝土改变了雨水在坡面上的水文过程,阻延径流作用十分明显,有效地降低了污染物的负荷输出.生态混凝土试验小区(T2)与裸地(CK)和改良土壤小区(T1)相比,径流量分别减少了48%和24%,TN年度污染负荷(UPLRs)分别减少了53%和45%,溶解态氮(DN)减少了26%和28%,TP减少了57%和30%,溶解态磷(DP)降低了80%和33%,COD降低了62%和40%,TSS降低了56%和43%,产流时间和流量峰均明显滞后.另外,同植被覆盖良好的小区(T3)相比,生态混凝土对各种污染指标的控制效果没有明显差异,但其抗冲刷能力较强,更能适应城市护坡和护岸的需要.     

Nitrogen Removal by Stormwater Management Structures: A Data Synthesis

A comprehensive synthesis of data from empirically based published studies and a widely used stormwater best management practice (BMP) database were used to assess the variability in nitrogen (N) removal performance of urban stormwater ponds, wetlands, and swales and to identify factors that may explain this variability. While the data suggest that BMPs were generally effective on average, removal efficiencies of ammonium (NH₄), nitrate (NO₃), and total nitrogen (TN) were highly variable ranging from negative (i.e., BMPs acting as sources of N) to 100%. For example, removal of NO₃ varied from (median ±1 SD) ?15 ± 49% for dry ponds, 32 ± 120% for wet ponds, 58 ± 210% for wetlands, and 37 ± 29% for swales. Across the same BMP types, TN removal was 27 ± 24%, 40 ± 31%, 61 ± 30%, and 50 ± 29%. NH₄ removal was 9 ± 36%, 29 ± 72%, 31 ± 24%, and 45 ± 34%. BMP size, age, and location explained some of the variability. For example, small and shallow ponds and wetlands were more effective than larger, deeper ones in removing N. Despite well‐known intra‐annual variation in N fluxes, most measurements have been made over short time periods using concentrations, not flow‐weighted N fluxes. Urban N export is increasing in some areas as large storms become more frequent. Thus, accounting for the full range of BMP performance under such conditions is crucial. A select number of long‐term flux‐based BMP studies that rigorously measure rainfall, hydrology, and site conditions could improve BMP implementation.     

Flow,Organic, and Inorganic Sediment Yields from a Channelized Watershed in the South Carolina Lower Coastal Plain

Many small streams in coastal watersheds in the southeastern United States are modified for agricultural, residential, and commercial development. In the South Carolina Lower Coastal Plain, low‐relief topography and a shallow water table make stream channelization ubiquitous. To quantify the impacts of urbanization and stream channelization, we measured flow and sediment from an urbanizing watershed and a small forested watershed. Flow and sediment export rates were used to infer specific yields from forested and nonforested regions of the urbanizing watershed. Study objectives were to: (1) quantify the range of runoff‐to‐rainfall ratios; (2) quantify the range of specific sediment yields; (3) characterize the quantity and quality of particulate matter exported; and (4) estimate sediment yield attributable to agriculture, development, and channelization activities in the urbanizing watershed. Our results showed that the urban watershed exported over five times more sediment per unit area compared with the forested watershed. Sediment concentration was related to flow flashiness in the urban watershed and to flow magnitude in the forested watershed. Sediments from the forested watershed were dominated by organic matter, whereas mineral matter dominated sediment from the urban stream. Our results indicated that a significant shift in sediment quality and quantity are likely to occur as forested watersheds are transformed by urbanization in coastal South Carolina.     

The Comparative Accuracy of Two Hydrologic Models in Simulating Warm‐Season Runoff for Two Small,Hillslope Catchments

This article assesses the performance of two hydrologic models in simulating warm‐season runoff for two upland, low‐yield micro‐catchments near Coshocton, Ohio. The two models, namely the Storm Water Management Model (SWMM) and the Gridded Surface‐Subsurface Hydrologic Analysis (GSSHA), were implemented with contrasting levels of complexity, with the former representing the catchments as lumped spatial units and computing evaporation only from standing water, and the latter incorporating fine‐scale variation in topography and soil properties and computing evapotranspiration from soil based on weather data. Our investigation began with uncalibrated model runs for 1990‐2003 except for 1994 using a priori parameter values. Then a set of calibration experiments were performed wherein the sensitivity of model performance to the length of calibration records was examined. Our results pointed to large errors associated with simulations from both models: even the calibrated models were unable to reproduce the seasonal and between‐catchment contrasts in runoff response. Using a priori parameter values, SWMM attained better results than GSSHA. However, with simple calibration, GSSHA outperformed SWMM in several respects. It was also found that extending the record of calibration rendered relatively minor changes to model performance. The practical and scientific implications of the findings are discussed.     

An interval joint-probabilistic programming method for solid waste management: a case study for the city of Tianjin, China

Currently, environmental protection and resources conservation continue to be challenges faced by solid-waste managers in China. These challenges are being further compounded by rapid socioeconomic devel- opment and population growth associated with increased waste generation rates and decreased waste disposal capacities. In response to these challenges, an interval joint-probabilistic mixed-integer programming （IJMP） method is developed for supporting long-term planning of waste management activities in the city of Tianjin, which is one of the largest municipalities in the northern part of China. In the IJMP, joint probabilistic constraints are introduced into an interval-parameter mixed-integer programming framework, such that uncertainties presented in terms of interval values and random variables can be reflected. Moreover, a number of violation levels for the waste-management-capacity constraints are examined, which can facilitate in-depth analyses of tradeoffs among economic objective and system-failure risk. The results indicate that reasonable solutions have been generated. They are valuable for supporting the adjustment of the city＇s existing waste-management practices and the long- term planning of the city＇s waste-management facilities.