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排序方式: 共有229条查询结果,搜索用时 31 毫秒
81.
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). 相似文献
82.
First flush of storm runoff pollution from an urban catchment in China 总被引:13,自引:0,他引:13
Storm runoff pollution process was investigated in an urban catchment with an area of 1.3 km^2 in Wuhan City of China. The results indicate that the pollutant concentration peaks preceded the flow peaks in all of 8 monitored storm events. The intervals between pollution peak and flow peak were shorter in the rain events with higher intensity in the initial period than those with lower intensity. The fractions of pollution load transported by the first 30% of runoff volume (FF30) were 52.2%-72.1% for total suspended solids (TSS), 53.0%-65.3% for chemical oxygen demand (COD), 40.4%-50.6% for total nitrogen (TN), and 45.8%-63.2% for total phosphorus (TP), respectively. Runoff pollution was positively related to non-raining days before the rainfall. Intercepting the first 30% of runoff volume can remove 62.4% of TSS load, 59.4% of COD load, 46.8% of TN load, and 54.1% of TP load, respectively, according to all the storm events. It is suggested that controlling the first flush is a critical measure in reduction of urban stormwater pollution. 相似文献
83.
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. 相似文献
84.
Rapid Assessment of Hydrologic Performance of Low Impact Development Practices under Design Storms 下载免费PDF全文
Yang Yang Ting Fong May Chui 《Journal of the American Water Resources Association》2018,54(3):613-630
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. 相似文献
85.
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. 相似文献
86.
Benjamin J. Koch Catherine M. Febria Muriel Gevrey Lisa A. Wainger Margaret A. Palmer 《Journal of the American Water Resources Association》2014,50(6):1594-1607
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. 相似文献
87.
Anand D. Jayakaran Susan M. Libes Daniel R. Hitchcock Natasha L. Bell David Fuss 《Journal of the American Water Resources Association》2014,50(4):943-962
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. 相似文献
88.
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. 相似文献
89.
Helen Y. Chen Clayton C. Hodges Randel L. Dymond 《Journal of the American Water Resources Association》2021,57(1):109-133
Stream ecosystems are increasingly at risk for thermal impairment as urbanization intensifies, resulting in more heated runoff from impervious cover that is less likely to be cooled naturally. While several best management practices, including bioretention filters, have been able to reduce thermal pollution, success has been limited. The extent of thermal mitigation required to prevent ecological damage remains unknown. A calibrated runoff temperature model of a case study watershed in Blacksburg, VA was developed to determine the cumulative treatment volume of bioretention filters required to reduce thermal impacts caused by runoff from development in the watershed to regulated biologically acceptable levels. A future build out scenario of the study watershed was also analyzed. Results from this study established that runoff thermal pollution cannot be fully reduced to goal thresholds during all storms using bioretention filter retrofits. While retrofitting significantly decreased temperatures and heat exports relative to the controls, increasing treatment volumes did not really enhance mitigation. Alternate thermal mitigation methods that actively remove runoff volume should be considered where more thermal mitigation is required. 相似文献
90.