Global analysis of sensitivity of bioretention cell design elements to hydrologic performance

Analysis of sensitivity of bioretention cell design elements to their hydrologic performances is meaningful in offering theoretical guidelines for proper design. Hydrologic performance of bioretention cells was facilitated with consideration of four metrics: the overflow ratio, groundwater recharge ratio, ponding time, and runoff coefficients. The storm water management model (SWMM) and the bioretention infiltration model RECARGA were applied to generating runoff and outflow time series for calculation of hydrologic performance metrics. Using a parking lot to build a bioretention cell, as an example, the Morris method was used to conduct global sensitivity analysis for two groups of bioretention samples, one without underdrain and the other with underdrain. Results show that the surface area is the most sensitive element to most of the hydrologic metrics, while the gravel depth is the least sensitive element whether bioretention cells are installed with underdrain or not. The saturated infiltration rate of planting soil and the saturated infiltration rate of native soil are the other two most sensitive elements for bioretention cells without underdrain, while the saturated infiltration rate of native soil and underdrain size are the two most sensitive design elements for bioretention cells with underdrain.     

Hydrological simulation approaches for BMPs and LID practices in highly urbanized area and development of hydrological performance indicator system

Urbanization causes hydrological change and increases stormwater runoff volumes, leading to flooding, erosion, and the degradation of instream ecosystem health. Best management practices （BMPs）, like detention ponds and infiltration trenches, have been widely used to control flood runoff events for the past decade. However, low impact development （LID） options have been proposed as an alternative approach to better mimic the natural flow regime by using decentralized designs to control stormwater runoff at the source, rather than at a centralized location in the watershed. For highly urbanized areas, LID stormwater management practices such as bioretention cells and porous pavements can be used to retrofit existing infrastructure and reduce runoff volumes and peak flows. This paper describes a modeling approach to incorporate these LID practices and the two BMPs of detention ponds and infiltration trenches in an existing hydrological model to estimate the impacts of BMPs and LID practices on the surface runoff. The modeling approach has been used in a parking lot located in Lenexa, Kansas, USA, to predict hydrological performance of BMPs and LID practices. A performance indicator system including the flow duration curve, peak flow frequency exceedance curve, and runoff coefficient have been developed in an attempt to represent impacts of BMPs and LID practices on the entire spectrum of the runoff regime. Results demonstrate that use of these BMPs and LID practices leads to significant stormwater control for small rainfall events and less control for flood events.     

山区水土保持措施防洪效果评价

以门头沟区赵家台小流域为研究对象,运用MIKE系列模型软件,将水文模型与一维河流水动力学模型进行耦合,模拟了该流域在"7·21"及10年一遇降雨情况下的降雨径流及不同下垫面状况影响下的坡面汇流入河等过程。模拟结果表明:坡面措施能够有效削减洪峰及洪量,防洪效果显著;沟道措施可在一定程度上提高过水能力,有效缩减淹没范围,减少洪灾损失,但对径流量无明显影响。     

清流河流域场次暴雨洪水特征及其对降水的响应关系

暴雨洪水是主要的自然灾害,分析暴雨洪水特性及其与气候要素的响应关系对流域防洪减灾和水资源可持续利用等方面具有重要意义。根据清流河流域102场暴雨洪水资料,系统分析了场次暴雨洪水过程特征、径流组成以及洪水特征要素与降水指标之间的响应关系。结果表明:场次降雨特征在一定程度上决定了洪水过程变化,水利工程修建和下垫面变化等人类活动对暴雨洪水过程特征有一定影响;场次暴雨洪水的产流系数总体具有递减趋势,但地表径流占径流总量的比率有增大趋势;场次径流量及洪峰流量与场次降水量之间具有较好的相关性,雨强对清流河流域暴雨洪水特征影响相对较小,蓄满产流是清流河流域主要的产流机制。     

Multiple-event study of bioretention for treatment of urban storm water runoff.

Bioretention is a novel best management practice for urban storm water, employed to minimize the impact of urban runoff during storm events. Bioretention consists of porous media layers that can remove pollutants from infiltrating runoff via mechanisms that include adsorption, precipitation, and filtration. However, the effectiveness of bioretention in treating repetitive inputs of runoff has not been investigated. In this study, a bioretention test column was set up and experiments proceeded once every week for a total of 12 tests. Through all 12 repetitions, the infiltration rate remained constant (0.35 cm/min). All 12 tests demonstrated excellent removal efficiency for TSS, oil/grease, and lead (99%). For total phosphorus, the removal efficiency was about 47% the system removal efficiency ranged from 2.3% to 23%. Effluent nitrate concentration became higher than the influent concentration during the first 28 days and removal efficiency ranged from 9% to 20% afterward. Some degree of denitrification was apparently proceeding in the bioretention system. Overall, the top mulch layer filtered most of TSS in the runoff and prevented the bioretention media from clogging during 12 repetitions. Runoff quality was improved by the bioretention column.     

基于SWMM的生物滞留池布置水文时空效应

利用SWMM中的低影响开发模块,根据汇流时间将研究区的子汇水区划分为上游和下游,生物滞留池按照不同位置(上游和下游)和不同规模布设,研究其遭遇不同重现期降雨下的水文时空效应。结果表明:在低降雨重现期下,生物滞留池的雨洪控制效果较好;相同重现期时,规模较大的生物滞留池效果较好,而布设的越分散,其降低径流系数的效果越好,但削减洪峰的效果较差。     

基于分项调查法和SWAT模型的水资源评价方法

现状下垫面条件下长系列天然径流资料是水资源评价的基础,但下垫面变化以及人类活动常常改变了水文循环过程,给水资源评价带来系统性偏差与较大的不确定性。以浠水流域为实例,提出将分项调查法和SWAT模型相结合的水资源评价方法,即根据水文站与水库位置关系建立不同水量平衡方程进行径流还原,利用与现状下垫面条件相近年份的还原后的径流数据进行参数率定与验证,并将构建的模型应用于长系列天然径流过程模拟计算。结果表明：仅采用分项调查法还原后的水文站降水-径流关系的一致性存在明显偏差;而通过构建基于现状下垫面条件下的SWAT模型,各水文站径流模拟值的降水-径流相关性优于还原值,且不同时期降水-径流关系一致性得到显著改善,表明该方法能够有效修正下垫面变化对径流的影响,有助于进一步开展水资源规划、水旱灾害风险评估等工作。     

西控工程对望虞河西岸地区防洪的影响

为了评估西控工程对望虞河西岸地区造成的防洪影响,以望虞河西岸为研究区域并结合其水文特性,构建了适合于模拟平原河网地区产汇流过程的MIKE11水文水力模型并利用当地降雨、水位等实测资料进行了率定。通过模拟50年一遇设计暴雨情况下的不同工况,得到研究区域内水系各节点的水位等要素变化情况,并依此分析了西控工程对望虞河西岸地区造成的防洪影响。结果表明:西控工程运行后,研究区域内重要节点的最高水位抬升明显,部分地区有遭受洪水淹没的风险;MIKE11水文水力模型对于分析平原河网地区河流沿线闸控影响具有较高的应用价值。     

小流域暴雨山洪水文模型与水动力学方法计算比较分析

针对小流域暴雨山洪精细模拟问题,提出了小流域时空变源混合产流模型,以小流域为单元构建了暴雨山洪分布式模拟模型,开发了可视化时空变源分布式水文模型软件FFMS和水动力学计算软件FHMS。以宝盖寺小流域场次暴雨洪水计算为例,分别采用水文学和水动力学方法计算了小流域暴雨山洪过程,并分析了两种方法的计算精度、效率、实用性等。案例研究结果表明:(1)水文与水动力学方法均可实现小流域暴雨山洪的模拟,模拟结果与实测基本一致;(2)对于无资料小流域暴雨洪水计算,水文学建模速度快,计算效率更高,水动力学方法建模和计算效率更低;(3)在复杂地形条件下暴雨洪水形成机理、演进过程模拟方面,水动力学计算结果更加精细和准确;在山区中小流域洪水预报预警方面,水文学方法更加实用。     

桂江流域水文特性分析

根据桂江流域代表站点历年水文资料和结合相关成果,分析流域降水、径流、暴雨洪水、泥沙、蒸发等水文特征的变化规律,为合理开发利用桂江流域水资源,解决水环境及水资源问题提供分析依据。     

瑞士RS模型在金沙江流域洪水预报中的应用

为更好地服务于长江流域防汛抗旱及水资源综合管理工作,依托中瑞合作"气候变化下金沙江流域水资源与风险综合管理项目",引进瑞士RS洪水预报模型及系统,以金沙江流域作为试验区,构建了长、中、短期多尺度的RS分布式水文模型。试验应用成果表明:瑞士RS模型对高跨度、多水库、多方式径流补给的金沙江流域具有较强的适用性,模型可运用气象数值产品中降雨、蒸发、气温等数据源完成多尺度洪水预报。预报成果合理可靠,可为电力生产、水资源调配及防汛决策提供技术支撑,同时为该模型扩展至其他流域提供了重要参考。     

赣江赣东大堤水文特征浅析

根据赣江赣东大堤气象、径流、泥沙、暴雨洪水等水文气象特征，分析计算了设计洪水、设计枯水、分期设计水位等，为大堤设计、施工及管理提供了重要的基础资料。     

Short-Term Predictions of Hydrological Events on an Urbanized Watershed Using Supervised Classification

Many tasks of operational watershed management at the local level require stream flow predictions delivered to decision makers in a timely manner. In highly urbanized watersheds with an impermeable surface, stormwater runoff can cause rapid increases in water levels in streams leading to flood and even flash flood events. Usually, such rapid increases in water flow characteristics are predicted by process-based models with high levels of uncertainty. In this study, the prediction of magnitudes of the stream hydrological characteristics is replaced by the forecasting of an event (i.e., flood or no-flood) using data collected by stream and rain gauges at the watershed. The proposed approach is based on a black box model developed as an ensemble of classifiers generated by independent inducers to predict the class of a future hydrological event in a small highly urbanized watershed. Eight inducers were investigated in the phase space reconstructed from observation data using time-delay embedding extended to multiple observation sites. Five inducers were selected for the ensemble, where the final decision is made by majority vote. The developed model generates 45-minute and hourly predictions of high-flow events with more than 80 % precision – a threshold used in operational flood management. Model site-specific parameterization is replaced by the training step using observation data on water levels and precipitation which are collected at 15-minute intervals and are readily available. The proposed approach to developing a prediction tool can be used by local authorities as one of the methods for flood management.     

GIS在三峡流域水文模拟中的应用

本文在三峡区间6个小流域上由人工率定了新安江模型参数，在地理信息系统平台上推求了流域地理地貌特征值。采用相关分析的方法，对自由水蓄水容量SM、地下水出流系数KG、壤中流出流系数KI、马斯京根法汇流系数X等模型参数和下垫面地形、地质、植被等特征值建立了相关关系。由相关关系和特征值采用反演的方法推求上述参数的反演值。经小流域模拟验证，相关关系是可靠的，在实际降雨径流模拟中能达到一定的精度。因此，由特征值反演参数的方法可移用于无资料地区，解决此类地区模型参数的率定问题。本文提出的方法已应用于长江三峡区间实时洪水预报中。     

区域降雨径流水质特性及控制对策探讨

探讨了降雨径流对城市内涝和区域水环境的影响,分析了径流污染和洪涝灾害的原因,提出了降雨径流污染控制措施。分别从控源截污、暴雨径流污染控制、海绵城市建设、防洪排涝体系建设和完善管理措施等方面,探讨了降雨径流污染控制对策,为区域洪灾预防和水环境治理提供科学依据。     

湖北平原水网区水文水资源系统模拟研究

本文以湖北汉川洪西垸径流试验区为对象，探讨了水网地区水量转化的系统模拟问题，通过单元系统的水均衡分析，提出一种能反映平原湖区水文基本特征的水资源系统模型，它能够定量描述降水、灌溉水、流域产水量、入渗补给理、潜水蒸发量以及地下水动态变化；可进行日径流长序序操作，由系统输入自动实现地表和地下水动态过程分割和水资源总量评价。该模型用洪西垸径流试验区实测资料做了验证与分析。     

资料匮乏地区中小流域设计洪水计算方法的研究

因缺乏实测流量资料,中小流域常采用暴雨资料推求设计洪水。文章以乌托水电站近坝支流--谟章河为例,首先基于数字高程模型（DEM）和ArcGIS平台提取流域特征信息,为谟章河设计洪水推求提供基础条件;然后利用反距离权重插值法计算谟章河流域设计暴雨;接着利用SCS模型进行产流计算,利用推理公式法进行汇流计算。计算结果表明,推荐的中小流域设计洪水计算方法是可行的,对解决资料匮乏地区具有一定的参考价值。     

水土保持对清涧河流域洪水径流的影响

采用时间序列对比分析方法，分析了黄土高原清涧河流域水土保持对流域暴雨洪水过程及径流量的影响，结果表明了水土保持使该流域产洪次数减少、地表径流模数和径流系数减小、流域产流起始时间滞后，径流持续时间缩短，洪峰流量降低．     

生物滞留池水文水质效应模拟分析

为研究生物滞留池措施对雨水水文水质的调控作用,以宜兴市城区某试验区为研究区域,利用SWMM模拟软件,在5年、10年、100年设计重现期下,分别模拟城市化后有无生物滞留池措施的水文水质状况,并将两者比较分析。研究发现:占研究区域总面积10.75%的生物滞留池措施下,雨水径流量减少了12%左右,峰值流量降低了8%左右,入渗量增加了22%左右;污染物SS、COD、TN、TP总负荷量的削减率分别在10%、7%、9%、8%左右。结果表明:随着城市化进程日益加快,生物滞留池可有效地降低雨水径流量、增加雨水入渗量,削减雨水径流的峰值流量;同时还可以拦截一定量的颗粒悬浮物、营养物质、重金属等污染物。研究成果对海绵城市建设和雨水资源调控利用具有参考价值,对城市水生态建设具有重要意义。     

低碳生态城区地表雨水管理的综合性指标研究

雨水综合利用是低碳生态城区水资源管理的重要方面,有助于解决城市河流行洪压力和径流污染等问题.调研分析了国内绿色建筑雨水管理现状及低碳生态城区建设中已采取的雨水管理措施.以场地综合径流系数作为衡量低碳生态城区雨水管理的控制指标,分析了各类雨水利用措施对场地综合径流系数的影响.根据多年平均降雨量进行全国区域划分,通过计算分析确定了适用于不同区域的低碳生态城区雨水利用措施及对应的场地综合径流系数范围.