SWMM 视觉对象

可视对象可以显示在SWMM工作空间中的地图上。

1 雨量计

雨量计为研究区域的一个或多个子汇水面积提供降水数据。 降雨量数据可以是用户定义的时间序列,也可以来自外部文件。 支持当前使用的几种不同的流行降雨文件格式,以及标准的用户定义格式。

雨量计的主要输入属性包括:

  • 降雨数据类型(例如,强度,体积或累积体积)
  • 记录时间间隔(例如,每小时,15分钟等)
  • 降雨数据来源(输入时间序列或外部文件)
  • 降雨数据源名称

 

2 汇水

子水库是土地的水文单位,其地形和排水系统元素将地表径流引导到单个排放点。 用户负责将研究区域划分为适当数量的子汇水面积,并用于识别每个子汇水面积的出口点。 排放出口点可以是排水系统的节点或其他子汇水面。

子分类分为透水和不透水的子区域。 地表径流可以渗透到透水分区的上部土壤区域,但不会渗透到不透水的分区。 不透水区域本身分为两个子区域 – 一个包含凹陷存储,另一个不包含凹陷存储。 子汇水层中的一个子区域的径流流量可以路由到另一个子区域,或者两个子区域都可以排放到子汇水面出口。

可以使用四种不同的模型描述从子汇水层的透水区域到不饱和上部土壤区域的降雨入渗:

  • Horton
  • Modified Horton
  • Green-Ampt
  • Modified Green-Ampt
  • Curve Number

为了模拟在子汇水面上积雪的积累,重新分布和融化,必须为其分配一个Snow Pack对象。 为模拟子汇水面下的含水层与排水系统节点之间的地下水流量,必须为子汇水面分配一组地下水参数。 子汇水面积的污染物累积和冲刷与分配给子汇水面积的土地利用相关联。 使用不同类型的低影响开发实践(如生物滞留单元,渗透沟,多孔路面,植物洼地和雨桶)捕获和保留降雨/径流可以通过为子汇水面分配一组预先设计的LID控制来建模。

子汇水面积的其他主要输入参数包括:

  • 分配雨量计
  • 出口节点或子汇水面
  • 分配土地用途
  • 支流表面积
  • 不透水
  • 陆地流动的特征宽度
  • 曼宁在透水和不透水区域的陆地流动
  • 凹陷处于透水区和不透水区
  • 没有凹陷储存的不透水区域的百分比。

 

3 连接节点

交汇点是排水系统节点,其中链接连接在一起。 在物理上它们可以代表天然表面通道,下水道系统中的检修孔或管道连接配件的汇合。 外部流入可以在交叉点进入系统。 在连接处的多余水可能变得部分加压,而连接管道是附加的,并且可能从系统中丢失或被允许在连接处顶部并且随后排回到连接处。

结的主要输入参数是:

  • 反转(通道或人孔底部)高程
  • 地面高度
  • 淹水时积水面积(可选)
  • 外部流入数据(可选)。

 

4 排水口节点

排水口是排水系统的终端节点,用于在动态波流路由下定义最终下游边界。 对于其他类型的流路由,它们表现为结点。 只有一个链路可以连接到排污口节点,并且存在将排水口排放到子集水区表面的选项。

排水口的边界条件可以通过以下任何一个阶段关系来描述:

  • 连接导管中的临界或正常流动深度
  • 固定的阶段高度
  • 在潮汐高度与一天中的小时表中描述的潮汐阶段
  • 用户定义的阶段与时间的时间序列。

 

排污口的主要输入参数包括:

  • 反转高程
  • 边界条件类型和阶段描述
  • 挡板门的存在,以防止通过排水口回流。

 

 

5 分流器节点

流量分配器是排水系统节点,以规定的方式将流入物转移到特定的管道。 分流器在其排出侧可以具有不超过两个导管连杆。 分流器仅在稳态流和运动波路由下有效,并在动态波路由下被视为简单的接头。

流量分配器有四种类型,由流入流入的方式定义:

Cutoff Divider:  将所有流入转移到定义的截止值以上。

Overflow Divider:  将所有流入物转移到非转向管道的流量以上。

Tabular Divider:  使用表格表示转移流量作为总流入量的函数。

Weir Divider:  使用堰方程来计算转向流量。

 

通过堰分隔器转移的流量通过以下等式计算

Qdiv = 转移流量, Cw = 堰系数 Hw = 堰高度和f计算为

Qin 是分频器的流入, Qmin是转移开始的流程,

用户指定的堰分隔器参数是Qmin,Hw和Cw。 分流器的主要输入参数是:

  • 结参数(见上文)
  • 接收转移流的链接的名称
  • 用于计算转移流量的方法。

 

6 存储单元

存储单元是提供存储容量的排水系统节点。 从物理上讲,它们可以代表像集水盆一样小的存储设施,也可以像湖一样大。 存储单元的体积特性由表面积与高度的函数或表格描述。 除了接收流入和排放到排水网络中的其他节点的流出物之外,存储节点还可以从表面蒸发和渗入本地土壤中失去水。

存储单元的主要输入参数包括:

  • 反转(底部)高程
  • 最大深度
  • 深度表面积数据
  • 蒸发潜力
  • 渗水参数(可选)
  • 外部流入数据(可选)

 

 

6 Conduits

Conduits are pipes or channels that move water from one node to another in the conveyance system. Their cross-sectional shapes can be selected from a variety of standard open and closed geometries.

Most open channels can be represented with a rectangular, trapezoidal, or user-defined irregular cross-section shape. For the latter, a Transect object is used to define how depth varies with distance across the cross-section. Most new drainage and sewer pipes are circular while culverts typically have elliptical or arch shapes. Elliptical and Arch pipes come in standard sizes that are listed in Appendix A.12 and A.13. The Filled Circular shape allows the bottom of a circular pipe to be filled with sediment and thus limit its flow capacity. The Custom Closed Shape allows any closed geometrical shape that is symmetrical about the center line to be defined by supplying a Shape Curve for the cross section.

SWMM uses the Manning equation to express the relationship between flow rate (Q), crosssectional area (A), hydraulic radius (R), and slope (S) in all conduits. For standard U.S. units,

where n is the Manning roughness coefficient. The slope S is interpreted as either the conduit slope or the friction slope (i.e., head loss per unit length), depending on the flow routing method used.

For pipes with Circular Force Main cross-sections either the Hazen-Williams or Darcy-Weisbach formula is used in place of the Manning equation for fully pressurized flow. For U.S. units the Hazen-Williams formula is:

where C is the Hazen-Williams C-factor which varies inversely with surface roughness and is supplied as one of the cross-section’s parameters. The Darcy-Weisbach formula is:

supplied as one of the cross-section’s parameters. The Darcy-Weisbach formula is:

where g is the acceleration of gravity and f is the Darcy-Weisbach friction factor. For turbulent flow, the latter is determined from the height of the roughness elements on the walls of the pipe (supplied as an input parameter) and the flow’s Reynolds Number using the Colebrook-White equation. The choice of which equation to use is a user-supplied option.

A conduit does not have to be assigned a Force Main shape for it to pressurize. Any of the closed cross-section shapes can potentially pressurize and thus function as force mains that use the Manning equation to compute friction losses.

A constant rate of exfiltration of water along the length of the conduit can be modeled by supplying a Seepage Rate value (in/hr or mm/hr). This only accounts for seepage losses, not infiltration of rainfall dependent groundwater. The latter can be modeled using SWMM’s RDII feature .

The principal input parameters for conduits are:

  • names of the inlet and outlet nodes
  • offset height or elevation above the inlet and outlet node inverts
  • conduit length
  • Manning’s roughness
  • cross-sectional geometry
  • entrance/exit losses (optional)
  • seepage rate (optional)
  • presence of a flap gate to prevent reverse flow (optional)
  • inlet geometry code number if the conduit acts as a culvert (optional).

 

 

7 Pumps

Pumps are links used to lift water to higher elevations. A pump curve describes the relation between a pump’s flow rate and conditions at its inlet and outlet nodes. Five different types of pump curves are supported:

Type1 An off-line pump with a wet well where flow increases incrementally with available wet well volume

Type2 An in-line pump where flow increases incrementally with inlet node depth.

Type3 An in-line pump where flow varies continuously with head difference between the inlet and outlet nodes.

Type4 A variable speed in-line pump where flow varies continuously with inlet node depth.

 

Ideal

An “ideal” transfer pump whose flow rate equals the inflow rate at its inlet node. No curve is required. The pump must be the only outflow link from its inlet node. Used mainly for preliminary design.

The on/off status of pumps can be controlled dynamically by specifying startup and shutoff water depths at the inlet node or through user-defined Control Rules. Rules can also be used to simulate variable speed drives that modulate pump flow.

The principal input parameters for a pump include:

  • names of its inlet and outlet nodes
  • name of its pump curve (or * for an Ideal pump)
  • initial on/off status
  • startup and shutoff depths.

 

Flow Regulators

Flow Regulators are structures or devices used to control and divert flows within a conveyance system. They are typically used to:

  • control releases from storage facilities
  • prevent unacceptable surcharging
  • divert flow to treatment facilities and interceptors

SWMM can model the following types of flow regulators: Orifices, Weirs, and Outlets.

 

 

8 Orifices

Orifices are used to model outlet and diversion structures in drainage systems, which are typically openings in the wall of a manhole, storage facility, or control gate. They are internally represented in SWMM as a link connecting two nodes. An orifice can have either a circular or rectangular shape, be located either at the bottom or along the side of the upstream node, and have a flap gate to prevent backflow.

 

Orifices can be used as storage unit outlets under all types of flow routing. If not attached to a storage unit node, they can only be used in drainage networks that are analyzed with Dynamic Wave flow routing.

 

The flow through a fully submerged orifice is computed as

where Q = flow rate, C = discharge coefficient, A = area of orifice opening, g = acceleration of gravity, and h = head difference across the orifice. The height of an orifice’s opening can be controlled dynamically through user-defined Control Rules. This feature can be used to model gate openings and closings. Flow through a partially full orifice is computed using an equivalent weir equation.

The principal input parameters for an orifice include:

  • names of its inlet and outlet nodes
  • configuration (bottom or side)
  • shape (circular or rectangular)
  • height or elevation above the inlet node invert
  • discharge coefficient
  • time to open or close.

 

9 Weirs

Weirs, like orifices, are used to model outlet and diversion structures in a drainage system. Weirs are typically located in a manhole, along the side of a channel, or within a storage unit. They are internally represented in SWMM as a link connecting two nodes, where the weir itself is placed at the upstream node. A flap gate can be included to prevent backflow.

 

Five varieties of weirs are available, each incorporating a different formula for computing flow across the weir as listed in Table.

Weir Type Cross Section Shape Flow Formula
Transverse Rectangular
Side flow Rectangular
V-notch Triangular
Trapezoidal Trapezoidal
Roadway Rectangular
Cw = Weir discharge coefficient, L = Weir length, S = side slope of V-notch or trapezoidal weir, h = head difference across the weir, Cws = discharge coefficient through sides of trapezoidal weir

The Roadway weir is a broad crested rectangular weir used model roadway crossings usually in conjunction with culvert-type conduits. It uses curves from the Federal Highway Administration publication Hydraulic Design of Highway Culverts Third Edition (Publication No. FHWA-HIF-12-026, April 2012) to determine CW as a function of h and roadway width.

Weirs can be used as storage unit outlets under all types of flow routing. If not attached to a storage unit, they can only be used in drainage networks that are analyzed with Dynamic Wave flow routing.

The height of the weir crest above the inlet node invert can be controlled dynamically through user-defined Control Rules. This feature can be used to model inflatable dams.

Weirs can either be allowed to surcharge or not. A surcharged weir will use an equivalent orifice equation to compute the flow through it. Weirs placed in open channels would normally not be allowed to surcharge while those placed in closed diversion structures or those used to represent storm drain inlet openings would be allowed to.

The principal input parameters for a weir include:

  • names of its inlet and outlet nodes
  • shape and geometry
  • crest height or elevation above the inlet node invert
  • discharge coefficient.

 

10 Outlets

Outlets are flow control devices that are typically used to control outflows from storage units. They are used to model special head-discharge relationships that cannot be characterized by pumps, orifices, or weirs. Outlets are internally represented in SWMM as a link connecting two nodes. An outlet can also have a flap gate that restricts flow to only one direction.

Outlets attached to storage units are active under all types of flow routing. If not attached to a storage unit, they can only be used in drainage networks analyzed with Dynamic Wave flow routing.

A user-defined rating curve determines an outlet’s discharge flow as a function of either the freeboard depth above the outlet’s opening or the head difference across it. Control Rules can be used to dynamically adjust this flow when certain conditions exist.

The principal input parameters for an outlet include:

  • names of its inlet and outlet nodes
  • height or elevation above the inlet node invert
  • function or table containing its head (or depth) – discharge relationship

 

11 Map Labels

Map Labels are optional text labels added to SWMM’s Study Area Map to help identify particular objects or regions of the map. The labels can be drawn in any Windows font, freely edited and be dragged to any position on the map.