下凹式绿地运行效率的概率分析及其应用

在降雨特性参数统计的基础上,提出了下凹式绿地蓄渗效率的概率分析方法,并结合上海市1985年-2004年的降雨特性参数统计结果,对上海市下凹式绿地的设计运行状况进行了探讨.鉴于下凹式绿地巨大的蓄渗效率,建议上海地区广泛使用下凹式绿地;当下凹式绿地的外排率达到2.5%时,其下凹深度宜为50～100 mm.     

不同降雨条件下低冲击开发的水文效应分析

以深圳市光明新区低冲击开发(LID)示范区为研究区域,采用暴雨雨水管理模型(SWMM)模拟了下凹式绿地、渗透铺装和绿色屋顶等3种LID模式下的雨洪控制效果,分析了降雨量、降雨历时和雨峰位置对LID水文效应的影响。结果表明,当降雨量<100 mm时,随着降雨量的增加,渗透铺装和绿色屋顶的径流削减量也相应增加,下凹式绿地的径流削减量变化不大,但其削减量大于其他两种LID控制措施;随着降雨历时的延长,下凹式绿地的径流削减量增加,而渗透铺装和绿色屋顶的径流削减量变化较小;雨峰位置变化时,3种LID控制措施的径流削减量均变化不大,对峰值流量的削减效果随着雨峰后移而减弱。3种LID控制措施对降雨量少、降雨历时长并且雨峰位置靠前的降雨控制效果较好。     

绿色屋顶与下凹式绿地串联对洪峰的削减效应分析

为考察绿色屋顶与下凹式绿地这两种低影响开发(LID)措施的雨洪控制效果,对二者的产汇流模型进行了研究,并采用InfoWorks CS软件建立了天津某大学生活区的雨水系统排洪模型,模拟分析了不同降雨频率、两种排洪模式下二者对城市雨洪的影响。结果表明:当屋面与绿地各自排洪(屋顶径流不接入绿地)时,将不透水平屋面改为绿色屋顶、平式绿地改为下凹式绿地后,洪峰流量的降低幅度高达41.1%,径流系数降低至0.279,降低幅度高达49.9%,峰现时刻有效延迟,显著降低了城市化开发对水文效应的影响;当绿色屋顶与下凹式绿地串联(绿色屋顶径流接入下凹式绿地)时,与二者各自排洪相比,削峰和滞留效果更加显著,且随着降雨频率的增大,串联的优势越加明显。可见,绿色屋顶与下凹式绿地串联使用能更大限度发挥这两种LID措施的削峰效应,实现低影响开发的目标。     

城市公园绿地雨水径流利用研究

在暴雨或较大降雨强度的条件下城市绿地也会产生地面径流,在建设公园绿地的同时要考虑对公园绿地上雨水径流的收集,并回用于绿地灌溉,而不是简单排入城市排水系统。结合北京市丰台区绿源公园绿地径流的现场试验观测,提出了城市草坪绿地降雨量、降雨强度与径流量的关系,以及不同地面坡度条件下的降雨径流关系,为北京城市绿地雨水径流利用提供了基本依据和基础参数。试验结果表明,降雨量小于9mm时试验坡度的草坪绿地均不产流;次降雨量大于9mm时,绿地的径流效率与次降雨量成正比,而坡地上二者的相关性比平地更加显著。     

城市雨水截留调控措施的截污减排效益评价

根据城区雨水系统特征,采用SWMM5.0平台建立某新城区雨水管网模型,利用LID控制模块对设置透水铺设、下凹式绿地、雨水花园和雨水桶等截留调控措施进行模拟,进而运用层次分析法对布设措施的截污减排效益进行评价,结果表明:各种措施均能对地表径流和排水水质起到削减作用,其中雨水花园的截污减排效益最高,下凹式绿地其次,雨水桶效益最小;面积相同时,雨水花园的截留调控效果优于下凹式绿地;在强降雨时雨水桶不能达到很好的截污减排效果.     

上海城市绿地系统对雨水径流的调蓄效应初探

针对上海雨水排放系统的现状,采用实验室小试、绿地现场测试、实例选取与计算分析等方法,就城市绿地系统对雨水径流的调蓄效应进行了探索。提出合理配置土地利用类型、保持适宜的水面率、适当增加绿化覆盖率、倡导铺设渗透性路面、建设下凹深度为10～30cm、面积比为10%～30%的下凹式绿地等是调蓄雨水径流的有效手段;可逐步实现"生态排水"。     

下凹式绿地调蓄净化城市径流

城市地表径流污染是指地表沉积物与大气沉降物等在降雨的淋溶和冲刷作用下,扩散性进入水体造成城市水环境质量下降的过程。地表径流是城市水体的主要面源污染之一,是造成城市内河环境问题的重要原因。有研究表明．美国湖泊中氮磷沉积物有76％来自非点源污染。对于污水（点源）采用二级处理的城市,BOD年负荷40％-90％来自暴雨所产生的径流．悬浮固体、重金属及碳氢化合物浓度在数量级上与未经处理的城市污水基本相同。下凹式绿地利用下凹空间充分蓄集雨水．显著增加了雨水下渗时间。具有渗蓄雨水、削减洪峰流量负荷、减轻污染浓度负荷．改善区域生态气候水文环境等多种等作用,是从中间过程控制城市雨水径流污染的有效措施。     

上海市降雨特性统计与雨水存储池容积计算

介绍了雨水利用系统存储池容积的设计方法.通过统计分析上海市近20年的降雨资料,获得了独立降雨事件的降雨量、降雨历时和降雨间隔的平均值以及各降雨特性参数的概率密度函数,在此基础上运用概率统计方法进行了雨水存储池集蓄效率的分析计算.通过对概率密度函数的积分,获得了不同容积下存储池的集蓄效率及相应的年均集蓄水量.结合雨水利用系统的投资、运行费用与预期水价,可确定相关存储池的合理容积.应用该方法评价了上海世博园区屋面雨水集蓄工程存储池的合理容积.该方法对雨水集蓄利用工程的设计具有普遍意义.     

图解法用于雨水渗透下凹式绿地的设计

下凹式绿地是一种生态型的雨水渗透设施,目前还没有相关设计规范。综合绿地服务汇水面面积、土壤渗透系数、设计暴雨重现期、周边设施的布置情况等多种影响因素,提出了下凹式绿地的设计方法,合理确定了下凹式绿地的设计控制参数——绿地下凹深度及绿地面积。为了简化设计计算过程,建议用下凹式绿地设计计算图取代数值计算,并以邯郸为例介绍下凹式绿地设计计算图的绘制方法及应用。各地区均可依据当地的雨水排放设计标准、地质条件等因素绘制设计计算图,以便于下凹式绿地的推广应用。     

透水砖和下凹式绿地对城市雨洪的影响

为考察不同雨洪措施对防洪和增加雨洪资源利用量的贡献,采用城市暴雨雨水管理模型(SWMM),对北京某区域内铺设透水砖和采用下凹式绿地措施的排水管道主要断面洪峰流量的变化进行了计算分析。结果表明,铺设透水砖和采用下凹式绿地均可有效削减洪峰流量,减小径流系数,从而增加雨洪资源的利用量。但对于不同降雨频率的地区,下凹式绿地在降雨频率较大的地区,雨洪利用效果较好;透水砖则在降雨频率较小的地区,雨洪利用效果较好。该研究成果可以用来评价不同雨洪措施在不同降雨频率下对城市雨洪的利用效果,为防洪排涝工程提供了一定的技术支持。     

下沉式绿地新型截污功能层材料对路面径流COD#br# 和重金属的吸附动力学研究

道路中下沉式绿地截污功能层能够在有效净化路面径流污染的同时削减路面径流强度。研究通过吸附等温试验研究不同材料对COD和重金属Pb，Zn，Cd，Ni的吸附特性，确定复合吸附材料的优化质量配比为，煤质活性炭：钢渣=9∶1。吸附动力学试验中，在复合污染下各污染物达吸附平衡的时间先后依次为：Pb，COD，Ni，Zn，Cd，且各污染物的伪二级动力学方程拟合效果最好。变水头渗透试验明确了截污功能层填料的最佳质量配比为中粗砂：煤质活性炭：钢渣=80∶18∶2，在90%压实度下其饱和渗透系数为1.60×10?6m/s，满足截污功能层的设计要求。     

处理生态住宅区雨水径流的人工湿地运行特性研究

结合重庆市某生态住宅区的雨水资源化利用工程,分析了雨水径流的水质、水量特征,并对处理该雨水径流的人工湿地的运行特性及不同运行方式下的除污效果进行了研究,以期为类似住宅区人工湿地的设计、运行管理提供参考.结果表明,在降雨量较大的南方城市,建有分流制管网的新开发住宅区的雨水水质较好,具有资源化利用优势;在恒定流量下,人工湿地系统对雨水的净化效果良好,出水水质能达到<城市污水再生利用景观环境用水水质>(GB/T 1892l-2002)的要求;人工湿地系统能够承受短期的高强度冲击负荷;在设计调蓄池时,其调蓄容积宜大于或等于所汇集的初期雨水水量,以便最大程度地消除溢流对环境的影响和初始冲刷效应对构筑物造成的冲击.     

生物滞留设施对城市雨水径流热污染的削减效应

径流热污染是水污染的重要方面,也是城市水体生态环境破坏的重要原因,生物滞留是缓解城市雨水径流热污染最有效的措施之一。通过不同填料的生物滞留实验,在人工模拟均匀降雨的条件下,探究了在不同降雨特征下不同填料生物滞留设施对城市雨水径流热污染的削减效果。结果表明,不同填料生物滞留设施热负荷削减效果从大到小依次为:炉渣、石英砂、陶粒、沸石;径流温度越高,所携带的热量越大,生物滞留设施的径流热污染负荷削减率也越高;体积削减对生物滞留设施削减雨水径流热污染的贡献大于热交换。     

Evaluation of a first‐flush capture and detention tank receiving runoff from an asphalt‐paved road

In this article, we propose and examine a first‐flush capture and detention tank (FCDT) working as a first flush capture device and pretreatment unit receiving stormwater runoff from an asphalt‐paved road. We design the FCDT to completely capture all the stormwater including a first flush generated by an initial 5 mm effective rainfall depth, and to bypass the exceeding part. According to our analysis based on the data from field monitoring and SWMM simulation for 27 events from April to June, 2015, the tank captured 35% of total runoff, which resulted in catching 74% of the TSS load. The TSS mass detention attained in this study by capturing the first 35% of the total runoff is close to the typical definition of a first flush, and also justifies the need for a first‐flush friendly treatment.     

In Situ Performance Monitoring of an Infiltration Drainage System and Field Testing of Current Design Procedures

Sustainable urban drainage systems offer a sustainable option for the disposal of stormwater runoff - reducing the risks of flooding and pollution of receiving watercourses. However, the adoption of such systems has been slow, with a lack of performance data identified as being one barrier. This paper presents in situ performance data from a perforated concrete ring soakaway which was installed to collect stormwater runoff from a school roof and paved area. Data on rainfall at the site and water depth in the soakaway were collected for a period of twenty months, and a number of rain events were studied in detail. Data from the soakaway were used to test the most recent design procedures for infiltration drainage systems, and it was found that the design equations gave reasonable predictions of system response to rainfall - especially when the observed runoff coefficients were taken into account.     

基于污染负荷控制的屋面初期径流弃除量探讨

初期径流污染是城市面源污染的主要组成部分,但目前对初期径流的定义、弃除量等都没有统一的说法,而且影响初期效应的因素多而复杂,并与地区特性紧密相关。通过对北京雨水利用示范区降雨及屋面径流水质监测数据的分析,初步探讨了不同初期径流弃除量对污染负荷的削减效果。在不同降雨特性下,屋面产流后弃除2 mm雨量可削减20%～45%的污染负荷,故建议北京市屋面初期径流弃除量标准按2 mm雨量考虑。     

Advancing assessment and design of stormwater monitoring programs using a self-organizing map: characterization of trace metal concentration profiles in stormwater runoff

Stormwater runoff poses a great challenge to the scientific assessment of the effects of diffuse pollution sources on receiving waters. In this study, a self-organizing map (SOM), a research tool for analyzing specific patterns in a large array of data, was applied to the monitoring data obtained from a stormwater monitoring survey to acquire new insights into stream water quality profiles under different rainfall conditions. The components of the input data vectors used by the SOM included concentrations of 10 metal elements, river discharge, and rainfall amount which were collected at the inlet and endpoint of an urban segment of the Yeongsan River, Korea. From the study, it was found that the SOM displayed significant variability in trace metal concentrations for different monitoring sites and rainfall events, with a greater impact of stormwater runoff on stream water quality at the upstream site than at the downstream site, except under low rainfall conditions (≤4 mm). In addition, the SOM clearly determined the water quality characteristics for “non-storm” and “storm” data, where the parameters nickel and arsenic and the parameters chromium, cadmium, and lead played an important role in reflecting the spatial and temporal water quality, respectively. When the SOM was used to examine the efficacy of stormwater quality monitoring programs, between 34 and 64% of the sample size in the current data set was shown to be sufficient for estimating the stormwater pollutant loads. The observed errors were small, generally being below 10, 6, and 20% for load estimation, map resolution, and clustering accuracy, respectively. Thus, the method recommended may be used to minimize monitoring costs if both the efficiency and accuracy are further determined by examining a large existing data set.     

Climate,land use and hydrologic sensitivities of stormwater quantity and quality in a complex coastal-urban watershed

We determined reference hydro-climatic and land use/cover sensitivities of stormwater runoff and quality in the Miami River Basin of Florida by developing a dynamic rainfall-runoff model with the EPA Storm Water Management Model. Potential storm runoff in the complex coastal-urban basin exhibited high and notably different seasonal sensitivities to rainfall; with stronger responses in the drier early winter and wetter late summer months. Basin runoff and pollutant loads showed moderate sensitivities to the hydrologic and land cover parameters; imperviousness and roughness exhibited more dominant influence than slope. Sensitivity to potential changes in land use patterns was relatively low. The changes in runoff and pollutants under simultaneous hydro-climatic or climate-land use perturbations were notably different than the summations of their individual contributions. The quantified sensitivities can be useful for appropriate management of stormwater quantity and quality in complex urban basins under a changing climate, land use/cover, and hydrology around the world.     

Stormwater runoff quality and quantity from asphalt, paver, and crushed stone driveways in Connecticut

This study compared the quality and quantity of stormwater runoff from replicated asphalt, permeable paver, and crushed-stone driveways. Rainfall was measured on-site and runoff was recorded using tipping buckets. Flow-weighted composite runoff samples were analyzed weekly for total suspended solids, total Kjeldahl nitrogen, nitrate-nitrogen, ammonia-nitrogen, total phosphorus (TP), zinc, lead, and copper. Infiltration rate was determined on each driveway annually. Repeated measures analysis of variance indicated that stormwater runoff was significantly different among each driveway type; the order of decreasing runoff was asphalt> paver> stone. Average infiltration rates were 0, 11.2 and 9.0 cm/h for asphalt, paver, and crushed stone driveways, respectively. Both paver and crushed stone driveways reduced stormwater runoff as compared to asphalt driveways. Runoff from paver driveways contained significantly lower concentrations of all pollutants measured than runoff from asphalt driveways. However, runoff from crushed stone driveways was similar in concentrations to runoff from asphalt driveways, except for TP concentrations, which were lower in runoff from crushed stone driveways than runoff from asphalt driveways. The mass export of measured pollutants followed the relative differences in stormwater runoff, rather than differences in concentrations.