Lucas1-5暴雨控制措施过程

1、Watershed Modeling and Hydrologic ProcessesoPrecipitation- Rain & snow （降水雨雪）oInterception- Plant leaf storage （截留植物树叶存储）oSurface Runoff- Net of interception, not infiltrated（地表径流不下渗的总截留量）oInfiltration- Net of interception, infiltrated（下渗下渗的总截留量）oInterflow (subsurface flow) shows as recession li

2、mb（壤中流，或潜流可视为退水分支）oEvapotranspiration (ET)- Most of infiltrated flow（蒸发蒸腾作用(ET)下渗流的大部分）oRecharge- Rest of Infiltrated after Interflow and ET（补给经过壤中流和蒸腾后剩余的下渗部分）oGroundwater discharge-Base flow（排放形成的地下水水流）Source: VDEQ (2009) Virginias Water Resources, http:/ 降水下渗地表径流蒸发蒸腾地下水水流地表径流地下水水流河流蒸发降水壤中流不饱和区土壤水

3、（地下水）补给重力疏干地下水位Precipitation and Interception降水和截留作用Precipitation is the important factor affecting the amount and spatial distribution of water through a watershed降水是一个影响流域中的水空间数量分布的重要因素Interception is the process which may alter the pattern and the amount of water reaching the soil surface by the

4、vegetative cover截留作用可以改变水通过植被覆盖到达土壤表面的模式和数量Factors affecting interception:影响截留的因素Type of land cover土地覆盖类型Extent of land cover土地覆盖程度Condition of land cover土地覆盖条件Source: /wiki/Interception_(water) 降水树干茎流穿透降雨树冠截留下渗森林地面截留Infiltration下渗作用Rainfall reaches the ground surface fills dep

5、ressions, then enters the soil or runs off. 降雨到达地表填满洼地，然后进入土壤或流走Infiltration is the process which rainfall enters the soil layer下渗就是降雨进入土层的过程Factors affecting infiltration:影响下渗的因素Soil Characteristics: Suction Head and Saturated Hydraulic Conductivity土壤特点：吸入水头和饱和的水力传导率Soil saturation: Suction Head土壤饱

6、和度：吸入水头The amount and characteristics of precipitation: intensity and depth降水量和降水特点：强度和雨量Land cover: vegetated vs. bare土地覆盖：植被 vs. 裸露Slope of the land: Less important 土地坡度：相对次要Source: http:/ 降雨下渗渗漏非饱和带地下水位Surface Runoff地表径流Surface Runoff is the rainfall reaching ground surface that does not infiltra

7、te.地表径流是降雨到达地表且不下渗的部分Factors affecting runoff:影响径流的因素：Soil Characteristics: Suction Head and Saturated Hydraulic Conductivity. 土壤特点：吸入水头和饱和的水力传导率。Rainfall characteristics: intensity, duration.降雨特点：强度，持续时间。Vegetation: Rooting density, roughness植被：根密度，粗糙度。Watershed characteristics: overland flow type,

8、 length and slope.流域特点：地面水流类型，长度和倾斜度。Attenuating features: depression storage, reservoir storage.衰减特征：洼地存储，蓄水池存储。Evapotranspiration蒸发蒸腾作用Evapotranspiration is the process of evaporation from soils and transpiration through leaves. 蒸发蒸腾是通过土壤蒸发和树叶蒸腾的过程。Factors affecting Evapotranspiration:影响蒸发蒸腾的因素：En

9、ergy availability 能量可用性Vapor pressure 蒸汽压Wind speed 风速Water availability 水可用性Vegetative cover 植被覆盖Plant type and height 植物类型和高度Soil characteristics such as heat capacity, soil chemistry, and albedo土壤特点如比热容，土壤化学性质和反射率Source: /wiki/Evapotranspiration.蒸发蒸腾=蒸腾+蒸发蒸腾草地树蒸发径流地下水补给Soil

10、Moisture Storage土壤降雨贮水量Soil moisture storage is the amount of water stored in the soil within the plants root zone土壤降雨贮水量是土壤中植物根部区域的存水量Factors affecting soil moisture storage:影响土壤降雨贮水量的因素：Soil texture土壤结构Crop rooting depth作物扎根深度Water Balance in soil can be similar to reservoir storage土壤中的水平衡可以类比于储水池

11、贮水量Infiltration increases moisture下渗提高湿度Evapotranspiration removes moisture upward蒸发蒸腾向上带走湿度Interflow removes moisture laterally壤中流横向带走湿度Drainage to groundwater removes moisture downward排放进入地下水向下带走湿度Source: Allen, R.G., Pereira, L.S., Raes, D., and Smith, M. (1998) Crop Evapotranspiration: Guideline

12、s for Computing Crop Water Requirements. United Nations Food and Agricultural Organization (FAO), Irrigation and Drainage Paper 56, Rome, Italy. 蒸发蒸腾雨灌溉径流毛细上升深层渗透饱和田间保水量阈值萎蔫点亏水Groundwater地下水Groundwater is the permanently saturated zone under the vadose zone. 地下水是处于包气带下面的永久饱和带Recharged from vadose zo

13、ne as net infiltration after evapotranspiration and interflow补给来自包气带的经过蒸发蒸腾和壤中流之后的下渗总量Discharges as base flow into streams, maintaining flow between events. 随着水流进入河流排放，保持着两者之间的水流。Factors affecting groundwater flow movement:影响地下水流动的因素：Topography地形学Subsoil/Bedrock characteristics 下层土/基岩特点Riparian zone

14、 evapotranspiration河岸地区的蒸发蒸腾Source: USGS - GROUND WATER ATLAS of the UNITED STATES: Delaware, Maryland, New Jersey,North Carolina, Pennsylvania, Virginia, West Virginia, HA 730-L 包气带饱和带毛细上升区水位地下水流动Water Budget水量平衡The relationship between input and output of water through a region.一个地区水量输入与输出的关系。Requ

15、ires estimating the amount of water in each component.要求预测在每一个部分的水量。Requires calculating movement of water through different components.要求计算每一个部分之间的水流动。Key components of water budget:水平衡的关键部分Precipitation 降水Surface-Runoff 地表径流Evapotranspiration 蒸发蒸腾Groundwater flow 地下水水流Change in surface-water and g

16、roundwater storage 地表水与地下水贮水的交换Change in snow and ice storage 冰贮水和雪的交换Human withdrawals 人类开采Source: /watercensus/water-budgets.html Water Budget水量平衡Surface Water Budgets:地表水平衡：o Streamflow R= SRO+SSF+B河流量 R=SRO+SSF+Bo Evapotranspiration ET = E+I+T蒸发蒸腾 ET=E+I+To Precipitation P=ET

17、+R降水 P=ET+R Where:Stream Flow (R), Surface Runoff (SR0), Subsurface flow or interflow (SSF), Base Flow (B), Evapotranspiration (ET), Evaporation (E), Transpiration (T), Interception (I), Precipitation(P). 其中：河流流量(R)，地表径流(SRO)，地下径流流或壤中流(SSF)，基流(B)，蒸发蒸腾(ET)，蒸发(E)，蒸腾(T)，截留(I)，降水(P)。Infiltration- Mechan

18、isms下渗机制Effects of Vegetation (Ralston, 2004, Rachman et al 2004). 植被作用（罗尔斯顿，2004，拉赫曼等人，2004）Vegetation restores/enhances infiltration rates. Up to several orders of magnitude higher. 植被恢复/ 提高下渗速率。可提高几个量级。Roots penetrate confining layers, open up soil structure. Root turnover forms macropores.根穿透隔水层

19、，打开土壤结构。根翻过来形成大孔隙。Native grasses in crops infiltrate an order of magnitude higher than adjacent cropped area. 作物中天然草地的下渗比周边作物区下渗大一个量级。Even in deposition setting, infiltration outside the grasses were half that of crops. 即使在沉积作用的设定下，草地以外的作物的下渗是草地的一半。Effects of Organic Matter (Saxton and Rawls, 2004).

20、 有机物质的作用（萨克斯顿和罗尔斯，2004）。Organic matter (OM) content substantially increases infiltration rates.有机物质(OM)含量极大地提高下渗速率Primarily due to decreased bulk density. Soils high in OM cannot be compacted 主要因为体密度的降低。高有机物质含量的土壤无法有紧密的状态Intact mineral topsoil typically 1-2% OM, but substantially less if disturbed.

21、完整的矿物表土一般含有1-2%有机物质，但一旦被扰乱，会极大的降低。Soils can be amended to an OM content of 5-10% (w/w).土地可以修复成含有5-10%(重量/重量)的有机物质含量。OM increases field capacity in sandy soils by approximately 10%.有机物质提高场地约10%的砂土能力含量。OM also promotes the microbial community, contributing to soil aggregate formation. 有机物质也可以增进微生物群落，为

22、土壤聚集形成做贡献。Infiltration- Mechanisms下渗机制Effects of Compaction (Pitt 1987, OCSCD, 2001, Saxton and Rawls, 2004). 紧密结构的作用（皮特 1987，海洋郡水土保护区，2001，萨克斯顿和罗尔斯，2004）Compaction can substantially reduce infiltration rates.紧密结构可以极大地减少下渗速率。Especially in sandy soils, where rates have been shown to decline from HSG

23、“A” to “D”.特别是在砂土中，速率被证明可以从HSG的A降到DThis is primarily due to increased bulk density. 这主要是因为体密度的提高。Compaction greatly inhibits the growth of plants, since roots cannot extend through the soil.紧密结构大大地抑制了植物的生长，由于根不能伸展穿透土壤。Compaction not alleviated by freeze/thaw cycles- Roman wheel tracks still visible

24、in England.结冰/解冻循环不会减轻紧密结构罗马轮距在英格兰依然可见Pedotransfer Functions (PTFs) (Saxton and Rawls, 2004) . 土壤传递函数(PRFs)（萨克斯顿和罗尔斯，2004）。Compaction and OM greatly affect the underlying textural class properties of the mineral soils.紧密结构和有机物质极大地影响无机土壤的基本结构类型特点PTF equations predict saturated hydraulic conductivity

25、(Ksat), suction wetting head (), field capacity, and wilting point.土壤传递函数(PTF)等式预测饱和水力传导率，吸入水头，土壤毛细含水量，和萎蔫点。The SPAW model at Saxtons web site recommended to be used to obtain Ksat. 推荐使用在萨克斯顿网站上的SPAW模型来获得Ksat值。SPAW provides conservative results without having to use a safety factor (typically 2).SPA

26、W模型能在非必须使用安全因子的情况下提供保守的结果(类型2)Soil Properties- SPAW Model Guidance土壤特点SPAW模型指导SPAW used to estimate saturated and unsaturated hydraulic conductivities as function of soil properties and moisture. Very useful for model parameters. SPAW曾用来预估饱和与不饱和水力传导率，将其作为土壤特点和湿度的函数。这些是非常有用的模型参数。Infiltration Computat

27、ions下渗计算)()(1)(0tFhKtfsatIn the Green-Ampt (G-A) formulation, infiltration rate is computed as follows: 在格林安姆特方程式中，下渗速率的计算如下：where F(t) is volume infiltrated t, Ksat is saturated hydraulic conductivity, h0 is the ponding depth, is the capillary suction head at the wetting front, and is initial moist

28、ure deficit. 其中F(t)是下渗体积t, Ksat是饱和水力传导率，h0是积水深度，是在湿润界面的毛细吸入水头，是初始湿度差。G-A accurate for each location for Ksat and , but pervious areas have very wide range of values.格林安姆特对于每一个地点的Ksat和都是准确的，但透水区域的值范围非常广。So runoff flows from areas with low Ksat and to areas with higher Ksat and 所以各区域的径流会从Ksat和的低值区流向Ks

29、at和的高值区。As a result, infiltration rates actually increase as rainfall intensity increases. 结果是，由于降水强度的提高，下渗速率实际上提高了。This is what the Curve Number (CN) method simuates as an exponential distribution of infiltration parameters over space subjected to an exponential distribution of rainfall over time (

30、Yu, 1998). 这是曲线数(CN)法模拟下渗参数在空间上的一个指数分布的结果。这个分布受制于降雨在时间上的指数分布。(Yu,1998)Most common method in USA used for designing flood control facilities. 在美国用来设计洪水控制的最普遍方式是控制市政管线。Curve Number Hydrology曲线数水文Based upon observations of thousands of events in mostly rural watersheds, Victor Mockus generated the foll

31、owing equation:基于对数以千计大多数发生在乡间流域事件的观测，维克多莫卡斯发明了以下等式：Where Q is runoff in 24 hour event, P is precipitation depth, S is storage depth (the amount that infiltrates over 24 hours) and Initial abstraction Ia (the amount that doesnt runoff) is 20% of S. 其中Q是24小时事件径流，P是降雨量，S是贮水量（超出24小时的下渗量）和初损量Ia（没有流走的量）是

32、S的20%。Note that Ia (initial abstraction) is a large proportion of small events. Should be lower. 注意Ia（初损量）占小事件很大的一部分。应该稍微降低。The following equation relates S to Curve Number (CN):通过以下等式将S与曲线数(CN)联系起来：The higher the CN, the lower S, and Ia will be.CN越大，S越小，Ia也越小。SPIPQa8 . 0)(2101000CNSCurve Number Hyd

33、rology曲线数水文(Pitt, 1987)Due to Ia being too big in small events, “effective” CN in small events has to increase. 由于Ia在小事件中比例太大，必须增大小事件中的“有效”的曲线数。Current thinking is that Ia should be closer to 5% of S, not 20%. 现行的想法是Ia应该更接近S的5%，而不是20%。Ia is really the suction term in the Green-Ampt equation, not dep

34、ression storage.Ia是格林安姆特等式中真正的吸入量，而不是洼地贮水量。LID HydrologyLID 水文RAINFALL- RUNOFF RESPONSE- OBSERVED, DURMM & TR-20 025500255075100125RAINFALL (mm)RUNOFF (mm)PerviousC/DDURMM 73.5TR-20 73.5Urban SoilsDURMM 67.5TR-20 67.5Pervious BDURMM 59.0TR-20 59.02.0 INCHQUALITYEVENT3.3 INCHBANKFULLEVENT(Lucas,

35、2004)（卢卡斯，2004） Pitt (1987) developed response for disturbed urban soils confirmed by observations. 皮特（1987）为受扰城市土壤开发出了受观测限制的曲线。 Pitt equations used in DURMM model for Delaware in USA (Lucas, 2004). 皮特等式在美国DURMM模型中被用于特拉华州。 This allowed use of extensive NRCS CN dataset for small storm responses. 这使得大

36、规模地运用国家自然保护服务的CN数据集作用于小型暴雨曲线得到了允许。LID HydrologyLID 水文Remember, it is runoff captured that is what really matters, not precipitation falling. 记住，起到作用的是径流收集而不是降水下落。Percentage of runoff is function of mix between impervious and pervious, and pervious CN.径流的百分比是不透水率和透水率混合与透水CN之间的函数。Table shows 50% pervi

37、ous at CN of 61, like tower project with landscaping. 表格显示了在61CN处有50%透水率，比如景观美化的塔工程。If all rainfall up to 30mm (1.18 inch) intercepted, represents capturing 80% of annual runoff.如果截留的降雨达到30毫米(1.18英寸)，代表收集了80%的径流。If all rainfall up to 51mm (2.00 inch) intercepted, represents capturing 93% of annual r

38、unoff.如果截留的降雨达到51毫米(2.00英寸)，代表收集了93%的径流。As impervious increases, capture percentage goes down. 随着不透水率的增加，收集的百分比降低。INFILTRATION 下渗:Positively affected by high organic matter, low compaction, and presence of plants.正比于高含量的有机物质，低紧密性，和植物存在度。Methods to improve these factors can have very large effect on

39、infiltration rates. 提高这些因素的方法可以极大地作用于下渗速率。HYDROLOGY 水文:Runoff from disturbed pervious soils often much higher than CN method predicts. 来自受扰透水土壤的径流常常比CN法预测的更多。Runoff from small events dominated by impervious cover. 来自小事件的径流主要由不透水覆盖面控制。Typical application of composite CN method not appropriate for LID

40、 hydrology.综合CN法的典型应用并不适合LID水文。Must segregate connected impervious from disconnected impervious. 必须把连接的不透水区和分散的不透水区分离开。Must use design storm (DS) that is more representative than flood storm. 必须使用暴雨设计(DS)，比暴雨洪水更有代表性。LID HydrologyLID 水文LID ModelingLID 模型All approaches intend pre-development hydrology

41、 to be replicated by the provision of BMPs.所有想要通过BMPs的提供复制开放前水文的方式。Rational Method is useless, since does not route or attenuate by detention or infiltration.推算方式是没有作用的，因为它不能演算，也不能被滞留或者下渗衰减。Specific discharge rate oversimplifies, since same even though soils and vegetation very different. 特定排放速率过度简化

42、，因为即使是同样的土壤和植被，下渗速率还是很不一样的。Specific detention volume is also inadequate for same reasons. But useful for initial screening. 同样的理由，特定的滞留量也是不够的。但对于初步筛选还是有用的。Must use routing approach so BMPs determined by initial screening meet discharge criteria.必须使用演算的方法，因此经由初步筛选决定的BMPs可以达到排放标准。The CN approach is us

43、ed nationally throughout USA for both for screening and for routing. CN法在整个美国范围内被用于筛选和演算。It is the basis for many models such as TR-20, HEC-1. We discuss TR-20 (simplified as TR-55).它也是很多模型如TR20，HEC1的基础。我们讨论一下TR20（简化成TR55）。LID ModelingLID 模型For initial screening, can use the overall composite CN app

44、roach. 对于初期筛选，可以使用总体综合CN法。Volume required is difference in runoff depths from pre-development to post-development. 要求的体积在不同径流量中从开发前到开发后都是不同的。Multiplied by area, this gives total volume required. 乘上面积，这可以算出要求的总体积。BMPs then computed according to volume provided in surface storage and in media/stone vo

45、ids. BMPs之后可以依据在地表贮存提供的体积和媒介/石头间的缝隙计算。For detailed design, segregate various types of source areas to determine contribution of each. 对于详细的设计，分离不同类型的源头区域来决定每一样对设计的贡献。Segregate directly connected effective impervious area (EIA), since generates runoff every event.分离直接连接的有效不透水区域(EIA)，因为每一项都会产生径流。Compo

46、site disconnected impervious areas (DIA) and adjacent pervious to generate their runoff . 综合分离的不透水区域(DIA)和邻近的透水面来生成他们的径流。Natural pervious areas will generate very little runoff at all.天然透水区域会几乎不产生径流。Multiply source areas by their depths to get loads. 将源头面积乘上他们的深度可以得到载量。LID ModelingLID 模型Design Storm

47、 (DS) Summary 暴雨设计(DS)方式?Design storms (DS) are very common way to design hydraulic structures. 暴雨设计(DS)是非常普遍的设计水力结构的方式。Average recurrence interval (ARI, or frequency) depths are based on long term rainfall records. 平均重复周期(ARI,或频率)深度是基于长期降雨记录的。DS synthetic hyetographs often accentuate peak flows sin

48、ce directed toward flooding. 暴雨设计(DS)合成雨量图常常会削弱水流峰值因为将其直接导向洪水。So design storms may not represent any actual events, but useful for initial design. 所以暴雨设计一般不会代表任何真实事件，但对初期设计很有用。DS models can rapidly audit capacity and performance, and optimize design.暴雨设计(DS)模型可以快速的审查设计的能力和性能并优化设计。TR-20 is most used

49、model in USA, based on CN methods. Here used with HydroCAD.TR-20是在美国最常用的基于CN方法的模型。这里讲其与HydroCAD一起使用。While DS models are very useful, more information is needed to evaluate SCMs. 当暴雨设计(DS)模型非常有用时，需要更多信息来评估雨水管理措施。Continuous Simulation vs. Design Storm连续性模拟 vs. 暴雨设计Design storms (DS) do not represent a

50、ny actual events, so useful only for initial design. 暴雨设计(DS)并不代表任何真实事件，所以只适用于初期设计。Continuous simulation (CS) simulates response using long term rainfall and flow records. 连续性模拟(CS)可将长期降雨和水流记录用于模拟结果。Flow Duration Curve (FDC) is much better indicator of performance than a DS analysis流量历时曲线(FDC)是比暴雨设计

51、(DS)分析更好的性能指标The FDC compares the duration of flows of differing magnitudes, so all events represented. 把流量历时曲线与不同量级水流的持续时间作比较，因此可以代表所有事件。The FDC is the fundamental metric of how well LID SCMs work.流量历时曲线是LID雨水控制措施有效程度的基本度量。CS data can also define DS depth. If enough data available, DS hyetograph al

52、so derived. 连续性模拟可以定义暴雨设计深度。如果有足够的可用数据，暴雨设计雨量图也可以推导得出。CS Models-SWMMEPA SWMM is very comprehensive CS model. SWMM now includes useful modules for LID BMPs so they can be modeled quite well. SWMM also includes aquifers, which can mimic overland flow hydrology quite well Details of SWMM operation and

53、examples are focus of the afternoon session. First, must address how both DS and CS models should address vertical and lateral flow in layered systems. This element is critical in modeling LID BMPs, and often overlooked. Following section presents how flows in layered systems such as bioretention ar

54、e modeled. Flow Duration Curve comparison between Urban and Forest Streams. 城市和森林河流的流量历时曲线比较Urbanization greatly increases both discharge and duration of erosive flows over bankfull. 城市化极大地增加了超出满槽流的水流排放和侵蚀流的维持。Due to logarithmic scale, these differences are even greater actual magnitude. 由于是在对数尺度下，这

55、些差别会变得比实际量级更大。Urban Stream城市溪流Forest Stream森林溪流Discharge Increases 10 x排放提高10倍Flow Duration Increases 10 x水流持续时间10倍“Normal” Flow Rate“正常”流速Bankfull Flow Rate满槽流速Base Flow Decreases 基础流量减少Continuous Simulation 连续性模拟流量历时曲线Why FDCs?- Physical and Chemical为什么用流量历时曲线(FDCs)？物理的和化学的(原因)Impervious FDC impli

56、cations for Flooding :All runoff events have much higher flows compared to natural.So many more bankfull flow events (from 10/yr).Such “flashy” streams result in frequent nuisance flooding. Impervious FDC implications for Bank Stability:Resultant higher bankfull flow vastly increases erosive energy.

57、So bank erosion, downcutting and channel incision accelerated.Resulting erosion major source of sediments in streams.Impervious FDC implications for Base Flow:Decreased base flow due to diversion to runoff.Base flow temperatures higher, and dissolved oxygen lower.不透水流量历时曲线(FDC)对洪涝的含义 :所有径流事件都有比天然径流高

58、得多的流量所以有更多的漫灌流事件（从少于1次每年到多余10次每年）。比如“瞬间的”潮流导致频繁的洪涝灾害。不透水流量历时曲线(FDC)对河岸稳定性的含义:因此产生的更多的漫灌流极大地提高了侵蚀能量。所以河岸侵蚀，向下侵蚀和河道切削加速。导致侵蚀河流中沉积物的主要源头。不透水流量历时曲线(FDC)对基流的含义:由于径流分散从而减低基流.基流温度更高，溶解的氧气更少。Why FDCs?- Biological为什么用流量历时曲线(FDCs)？生物的（原因）Impervious FDC effects upon Benthic Macroinvertebrates:Increased flow di

59、srupts breeding cycles and feeding.Increased flow eliminates many individuals.Sediments smother breeding and refuge sites.Floods wash away woody debris habitat. Loss of habitat eliminates many species.Impervious FDC effects upon Fish:Most macroinvertebrate food sources eliminated.Increased flow disr

60、upts breeding cycles and feeding.Sediments smother breeding and refuge sites.Floods wash away woody debris habitat. Low flow conditions elevate temperature and reduce oxygen.Loss of habitat eliminates many species.不透水流量历时曲线(FDC)对海底大型无脊椎动物的影响:提高的水流扰乱繁殖周期和觅食。提高的水流消除许多的个体。沉积物抑制繁殖和避难场所。洪水冲刷掉栖息地的木质碎屑。 栖息地的失去会消除许