防涝标准下城市道路雨水口排水能力分析

以长沙市某城市道路雨水口设计为例,在常规市政雨水管渠设计的基础上布置雨水口(P=3a),防涝标准降雨强度下(P=50a)道路竖曲线底部处雨水口形成孔口流。复核了雨水口的排水能力,并采用SWMM排水模型进行了验证。结果表明,孔口入流条件下,道路竖曲线底部雨水口可满足路面排涝要求。     

雨水口的流量计算方法探讨

基于水力学理论以及对美国相关规范的研究,提出雨水口设计流量的计算方法。并以计算示例验证了《雨水口》(05S518)标准图集中规定的泄水能力不准确,建议实际工程中应以道路坡度、箅前设计水深、雨水口型式及尺寸等为条件进行具体的设计流量计算,以确定雨水口的设计与布置。     

道路雨水口布设方案对泄流能力影响的模拟研究

雨水口作为城市排水系统的重要组成部分，其布设情况对周边小区及道路积水的消除至关重要。为此，利用耦合了水文和水动力过程的数值模型，研究雨水口在不同道路纵坡坡度、布设数量和径流流量条件下的泄流能力。结果表明，道路纵坡坡度越大，雨水口的泄流能力越差，在小流量、雨水口数量为5个（间距为20 m）的条件下，当道路纵坡坡度从0.3%增至8%时，雨水口泄水率从55.64%降至21.05%；雨水口数量越多，其泄流能力越强，在小流量、道路纵坡坡度为0.3%的条件下，当雨水口数量从2个增至5个（间距由50 m降至20 m）时，雨水口泄水率由25.60%增至55.64%；径流流量越大，雨水口的泄流能力越差，在道路纵坡坡度为0.3%且布设5个雨水口的条件下，小、中、大3种流量下雨水口泄水率分别为55.64%、46.92%、37.28%。     

新型立体涡轮雨水口试验研究与工程示范

通过对上海市雨水口应用现状调查,分析了雨水口堵塞的危害,提出了新型雨水口研究的必要性。结合试验研究及峨山路示范工程相关数据,得出了新型雨水口的相关参数,并进行了相关数据总结,为解决雨水口防堵及实现快速入流、改善城市暴雨积水状况提供解决思路,可为相关工程提供一定的参考。     

基于径流模型的排涝泵站优化设计研究

针对径流模型排涝泵站优化设计中降雨工况的选择问题,以实际工程为例,构建汇水区SWMM暴雨径流模型,由径流模型结合调蓄容积法演算了城市排涝泵站设计流量,对比分析了8种降雨条件下排涝泵站设计流量的差异性.研究发现,采用暴雨强度公式生成的芝加哥雨型是不合适的,应当采用由历年水文资料确定的水利长历时降雨模式;由实测单一降雨事件...     

基于水力模型的城市排水干渠排涝流量计算方法

针对城市排水干渠既承接上游山区洪水,又沿途接纳城市雨水管道涝水的特性,以湖北省黄石市某排水干渠为例,提出了城市干渠排涝流量计算模型。模型将城市干渠汇水区域划分为山地子排区和城市子排区,在子排区层面分别利用单位线法(山区)和MIKE SWMM模型(城区)建立暴雨径流模型,然后在共同的排水通道(城市干渠)层面建立了MIKE11水动力学模型。该模型既考虑了山洪以沟渠为主要排水方式的特点,又考虑了城区涝水以雨水管网为主要排水方式的特点,同时可以模拟排水干渠下游受顶托的情况。相对于传统的单位线法,水力模型法计算的径流总量大、峰值流量小、峰现时间早。该研究可为城市排水干渠排涝流量计算方法的选择及其合理取值提供参考。     

污水管网外水流量与入流位置的模型估算

外水流量的估计和入流点查找是污水管网运行的难题。基于此,首先应用污水管网综合模型,建立了区域内生活和工业用水量、泵站液位、泵站流量和外水流量之间的动态平衡关系,以估计外水流量;再应用污水管网机理模型,在不同外水入侵点假设条件下,计算管网水力状态,并与实际污水管网运行水力状态进行对比,估计污水管网外水入流点的位置。用此方法对某区域进行外水查找,并封堵外水源头后,该区域旱季污水平均流量从2.0×10⁴ m³/d降低到与实际用水量相当的0.5×10⁴ m³/d左右,COD平均浓度从92.4 mg/L提升至290.2 mg/L。其他污染指标如氨氮、TN、TP、SS和VSS等,均获得了3倍以上的提升;污水管网从高液位运行的满管流转变为低液位运行的非满管流。该基于污水管网模型的外水流量和入流位置的估计方法,有助于促进污水管网运行质态的提升和提质增效。     

基于模型评估雨水口过流能力对区域内涝的影响

以某城市立交桥下低洼地区的排水系统为对象建立水力模型,从内涝防治的角度探索了雨水口的设计和校核方法。通过模拟不同情景分别计算了雨水口具备不同过流能力时的水力条件,以及相应的地面积水情况。结果表明,当雨水口过流能力不满足设计标准时,管网的排水能力不能得到充分发挥,地面的内涝风险也会显著增加。此外,基于模拟结果对"雨水口能力不足"与"管道能力不足"这两种内涝原因进行了区分,说明分析内涝原因是解决内涝问题的先决条件。     

山地城市小流域暴雨径流模型的研发及应用

采用ArcEngine二次开发包结合水力学基础算法,建立山地城市暴雨径流模型,以模拟山地城市降雨径流,分析山地城市排水系统的排放能力。应用该模型对重庆市北部新区盘溪河流域排水系统进行了预测和评估,结果表明,模拟结果与实测数据的效率系数Nash-Suttcliffe系数Ens为0.56~0.76,相对误差8.82%~11.8%。模型关键参数率定及敏感性分析表明,最敏感参数为径流宽度、坡度、曼宁系数和不透水面积率。针对排水管道内流量、充满度和溢流检查井个数等方面进行了排水系统排放能力的评估,结果表明,一年一遇暴雨下有0.52%的排水管道长时间处于满流状态,五十年和百年一遇的超载排水管道占排水管道总数5.86%和 8.20%;百年一遇暴雨下有0.72%的检查井发生溢流,一年一遇暴雨下有0.31%的检查井发生溢流。该模型实现了对山地城市暴雨径流的产汇过程模拟以及内涝点位置和数量的识别,为城市雨水管网管理提供决策支持。     

基于LS-SVM的高速列车广义非线性模型子空间辨识

针对高速列车动力建模问题,提出了基于最小二乘支持向量机(LS-SVM)的高速列车广义非线性模型子空间辨识方法。先给出描述高速列车单质点力学行为的随机离散非线性状态空间模型,并进一步构建了高速列车广义非线性模型;采用LSSVM回归方法构造广义非线性函数,并运用子空间辨识方法,直接由增广输入、输出数据得到高速列车广义非线性模型参数矩阵。最后对上述模型进行了数值仿真。结果表明:所提出的基于LS-SVM的子空间辨识方法比常规LS-SVM方法、线性子空间方法对列车模型具有更高的预报性能,用于高速列车的建模是有效的,可用于具有非线性、强耦合的高速列车运行过程数学模型的辨识。     

基于北方平原城市特点的雨水系统优化设计

针对北方平原城市地势平坦、河道水位顶托、夏季降雨集中的特点,对集流时间、汇水面积、径流系数、暴雨重现期、淹没流速、雨水口等几个市政雨水管网设计中的要素进行分析,提出了最佳取值的选取方法,以达到优化设计的目的。     

Evaluation of the EUROSEM model for predicting the effects of erosion-control blankets on runoff and interrill soil erosion by water

The European Soil Erosion Model (EUROSEM, Morgan et al., 1998) is an event-based soil erosion model which predicts runoff and sediment discharge for different environmental conditions. Applying geotextiles or erosion-control blankets (ECB’s) on the soil surface significantly affects surface seal formation and topsoil properties and therefore controls runoff and soil erosion rates during a rainfall event. Since these within-storm changes of soil surface characteristics and hydrological conditions are not incorporated in EUROSEM, errors in runoff and soil erosion predictions may occur for soil surfaces covered with ECB’s.Therefore, the objective of this paper is to evaluate and improve the performance of a research version of the physically-based erosion model EUROSEM (EUROSEM-2010; Borselli and Torri, 2010) for simulating the effects of ECB’s on runoff and interrill soil erosion by water during intense simulated rainfall events. Results of model simulations are compared with experimental results of interrill erosion using biological (i.e. natural) ECB’s and simulated rainfall. Because ECB’s applied on the soil surface retard seal formation, the differences between observed and predicted runoff rates and sediment discharges are rather high during the first 20-30 min of the simulated rainstorm. Therefore, a simple approach is proposed to cope with the dynamic evolution of some soil characteristics, i.e. saturated hydraulic conductivity, soil erodibility and soil cohesion, during an intense rainfall event. This time-dependent approach improves the predictions of runoff rate and sediment discharge during the first 20-30 min of a rainfall event and increases the model efficiency (i.e. a measure for the goodness of fit) from 0.84 to 0.98 and from 0.48 to 0.68 for the total runoff volume and soil loss, respectively. For most conditions, the predicted final sediment discharge is still considerably larger than the observed values, which can be partly attributed to the deposition of sediment in the bare soil patches (i.e. inter-weave open areas) of the ECB’s, which is not simulated by EUROSEM in this study. This model approach increases our understanding of the effects of ECB’s on within-storm changes in hydrological conditions and soil surface characteristics.     

Effect of different land use on soil erosion in the pre-alpine fringe (North-East Italy): Ion budget and sediment yield

Data concerning ion budget from rainfall, runoff and soil loss measurements from two experimental plots located in North-East Italy, under different land cover (beech forest and vineyard, respectively), are reported. The chemical composition of rainfall, soil solution and runoff was determined to study the solute cycle within the soil, and the relationships between water, soil and vegetation. The forest ecosystem is more prone to acidification than the agricultural one; the elemental concentration of runoff water is considerably lower than that of soil solution. Comparing the ion input (rainfall) and output (runoff) at the two sites, it was possible to estimate the ion budget in the two soil-vegetation systems. The runoff amount and the ion balance are related to rainfall volumes and composition; the measured runoff under vineyard is 59% in comparison to the one under beech. The soil loss at the two experimental sites (170 kg/ha and 132 kg/ha, respectively) is quite limited. The measured sediment yield of the two catchments (0.24-0.19 t/ha/year, respectively) is consistent with data reported for native forests of western Europe. Comparing rainfall and soil loss at the two sites proved that maintenance of some form of land cover is advisable if runoff and erosion are to be minimized. In the European context, where the most important consequences of erosion are sedimentation downstream and loss of productivity, this type of data will yield valuable information for the understanding of such processes occurring at catchment scale, and will help policy-makers develop appropriate programs for the territory safeguard.     

北京洪水峪泥石流形成条件探讨

洪水峪泥石流、沟内崩塌、不稳定斜坡等不良地质现象发育。该沟内煤矸石、沟道物源丰富,上游汇水面积大,沟道纵坡降较大,在强降雨沟道径流冲刷作用下,极易发生揭底起动而形成泥石流灾害。在雨季,支沟常有少量泥沙、块石冲出,阻塞进山道路,淤塞河道,引起原有坝体损毁,威胁居民生命财产安全。通过对以往资料的综合整理,结合现场调查,对洪水峪泥石流形成的诸多条件进行了分析,以期对该区泥石流的防治与预测起到参考作用。     

黄土高原的石油类物质坡面径流污染研究

延河流域石油类污染物的暴雨径流污染是当地地表水体的一种重要污染形式。为了探明石油类物质的径流污染规律,进行了室内模拟试验。结果表明：降雨强度、土壤污染强度、受雨坡面的坡度等因素都能明显影响降雨径流污染过程;污染过程中的水相石油类物质是由径流含沙量和径流泥沙石油污染强度共同决定的,在试验条件下,水相污染强度可达１．５６～５．１９ｍｇ／Ｌ,足以对径流造成严重的污染。     

Predicting the existence of stormwater first flush from the time of concentration

Simulations were performed using a one-dimensional kinematic wave model to examine the relationships between the time of concentration (T(c)) and the first flush (FF) for impervious landuses. The model used chemical oxygen demand parameters from a highway runoff site in west Los Angeles for eight storm events. FF indices such as the mass first flush ratio (MFF(n)) and the partial event mean concentration to event mean concentration ratio (PEMC(t)/EMC) were calculated from simulations using various rainfall intensities, rainfall durations, bed slopes, and watershed lengths (L), and matched measured values with an RMS error of 25% for six events. Resulting values of MFF(20) and PEMC(60)/EMC were correlated to T(c) calculated using ASCE's kinematic wave formula, and showed a non-monotone relationship, with very short or long T(c) having low MFF(20) with a maximum for mid-range T(c). Contours of the MFF(20) and PEMC(60)/EMC were created to predict and quantify FF from known T(c), L, and rainfall duration (T).     

Experimental campaign to determine grated inlet clogging factors in an urban catchment of Barcelona

Urban drainage systems have two different drainage layers, one superficial and another underground, that are connected through drain inlets and manholes. Specifically, a collection system is formed by inlets distributed throughout a basin, with the function of collecting and directing the surface runoff into sewers. Generally, the hydraulic characterisation of the inlet system considers the grates in an ideal state, free of dirt and debris obstructions, although often this is not the case. In these cases, clogging effects should be considered as a reduction in terms of hydraulic efficiency. The aim of this paper is to present a methodology to determine, quantitatively, the hydraulic efficiency reduction of partially clogged grated inlets. With this aim, clogging patterns for the most common grated inlets operating in Barcelona (Spain) were defined and experimental tests at real scale were carried out in order to determine the hydraulic efficiency reduction due to clogging phenomena.     

Rainfall intensity and phosphorus source effects on phosphorus transport in surface runoff from soil trays

Phosphorus runoff from agricultural fields amended with mineral fertilizers and manures has been linked to freshwater eutrophication. A rainfall simulation study was conducted to evaluate the effects of different rainfall intensities and P sources differing in water soluble P (WSP) concentration on P transport in runoff from soil trays packed with a Berks loam and grassed with annual ryegrass (Lolium multiflorum Lam.). Triple superphosphate (TSP; 79% WSP), low-grade super single phosphate (LGSSP; 50% WSP), North Carolina rock phosphate (NCRP; 0.5% WSP) and swine manure (SM; 70% WSP), were broadcast (100 kg total P ha-1) and rainfall applied at 25, 50 and 75 mm h-1 1, 7, 21, and 56 days after P source application. The concentration of dissolved reactive (DRP), particulate (PP), and total P (TP) was significantly (P<0.01) greater in runoff with a rainfall intensity of 75 than 25 mm h-1 for all P sources. Further, runoff DRP increased as P source WSP increased, with runoff from a 50 mm h-1 rain 1 day after source application having a DRP concentration of 0.25 mg L-1 for NCRP and 28.21 mg L-1 for TSP. In contrast, the proportion of runoff TP as PP was greater with low (39% PP for NCRP) than high WSP sources (4% PP for TSP) averaged for all rainfall intensities. The increased PP transport is attributed to the detachment and transport of undissolved P source particles during runoff. These results show that P source water solubility and rainfall intensity can influence P transport in runoff, which is important in evaluating the long-term risks of P source application on P transport in surface runoff.     

城市雨水口设计的探讨

在城市雨水排放系统中,设置合理的雨水口可以使雨水迅速排入雨水管网,避免积水产生。分别从雨水口的位置和长直路面雨水口设置间距2个方面介绍了城市雨水口的设置。     

Assessment of gully pot management strategies for runoff quality control using a dynamic model

A gully pot is the first entry point of road runoff into an urban drainage network. Pots are extensively used to trap solids from runoff in order to avoid/minimise the problems associated with sediment deposition in the downstream drainage structures or receiving waters. Here we briefly describe the different modules of a dynamic gully pot model developed to assess the impact of a series of management practice scenarios on the quality of runoff discharged through the pots. Runoff quality was modelled in terms of suspended solids (SS), chemical oxygen demand (COD), dissolved oxygen (DO) and ammonium. The model has the flexibility to represent the impact of various interactions between physical and biochemical processes occurring in a pot during wet and dry weather conditions, respectively. The simulation results show that the pots are effective at retaining solids, but their role with regard to reduction of dissolved pollutants is almost neutral. Model predictions, as against common perception, show that frequent pot cleaning does not significantly improve the runoff quality. However, considerably improved solid retention is possible if larger pots with modified geometry are introduced into the drainage system.