---
title: "Tutorial 4 - Advanced Surface Water Hydraulics"
canonical: "https://help.innovyze.com/space/xps/19661380/Tutorial%204%20-%20Advanced%20Surface%20Water%20Hydraulics"
format: markdown
---
The use of the program to model gravity flow in closed conduit networks is described in [Tutorial 3 - Surface Water Hydraulics](https://help-innovyze.atlassian.net/wiki/spaces/xps/pages/19661575). This lesson extends on the runoff collection system with additional features common to drainage systems. These include:

- Open topped channels and natural streams (in Part 1)
- Detention ponds and outlet control structures (in Part 2)
- Inlet capacity and street flow (in Part 3)

## Part 1 – Trapezoidal and Natural Channels

| **Level** | Novice |
| --- | --- |
| **Objectives** | Introduce the steps required to:<br>- Model open topped conduits
- Use shapes to define channel cross sections
- Add vertices to the layout of channels |
| **Time** | 1 hour |
| **Data files** | **Yarra31m.xp** (from Mod 2)<br>**Contours.xptin**<br>**Yarra_Area.dwg** |


1. Launch the program:
  1. Open *Yarra31.xp*. This is the model that was completed in [Tutorial 3 - Surface Water Hydraulics](https://help-innovyze.atlassian.net/wiki/spaces/xps/pages/19661575).
  2. Save As *Yarra40.xp*.
  3. Adjust the display of **Yarra_Area.dwg** by right-clicking the layer name and selecting **Properties** from the menu.> Macro (inline-media-image)
  4. On **CAD File Properties** dialog, clear the** Links**, **Nodes** and **Node ID** layers and then click **OK**.  
> Macro (inline-media-image)
2. Remove the outfall at node **3/375**:
  1. In the **Hydraulics** mode, double-click Node** 3/375** to open the **Node Data **dialog.
  2. Clear the **Outfall** button and then click **OK**.
3. Add downstream network objects:
  1. Select the link drawing icon.
  2. Click and hold on Node **3/375**. A vertical pipe will appear next to the cursor. Drag to draw a link. Click once to draw a node. Drag towards Alexandrina Drive and double-click to complete drawing.
  3. Add two links and two nodes as indicated in figure below.  
> Macro (inline-media-image)
4. Rename the objects:
  1. Select each of the new objects and right-click.
  2. Select** Properties** and edit the names to those indicated in the following figure.  
> Macro (inline-media-image)
5. The grass lined constructed channel will be modeled as a trapezoidal cross section. Double-click the link **Channel**. Select the **Trapezoidal **radio button. Enter the parameters according to the figure below. Click **OK**.  
> Macro (inline-media-image)
6. Enter pond data. The node labeled **Pond** will be converted to a storage node in the next section.
  1. Double-click the node **Pond**.
  2. In the **Node Data** dialog, enter **Spill Crest** = **1276.3 **and Invert = **1274.8**.   
Note: Do not select **Ponding** or **Storage**. > Macro (inline-media-image)
  3. Click **OK**.
7. Add vertices to stream:
  1. Select the link **Stream**. Right-click and choose **Edit Vertices** from the menu. The cursor will assume the pulsating crosses shape.
  2. Add vertices at locations ¼, ½, and ¾ the distance downstream from the pond.
  3. Move the cursor away from the link. The cursor will have a red dot next to it. Grab each vertex and drag until the stream assumes the 'zigzag' appearance as shown below.  
> Macro (inline-media-image)
8. Define natural channel shape:
  1. Double-click the **Stream** to open the **Conduit Data** dialog.
  2. Select the** Natural** cross section.
  3. Enter the** Upstream Elev** and **Downstream Elev** and the channel **len** values as shown in the figure below.
  4. Click the button next to **Shape** to open the** Select** dialog for natural section shapes.
9. Define the Natural Section Shape:
  1. In the **Select** dialog, type in **Stream shape** and click **Add**, then **Edit**.
  2. Enter the data as shown in the figure below.
  3. Click the **Insert** button to insert rows and **Delete** button to delete rows. Click **OK** to close the **Natural Section Shape** dialog.  
> Macro (inline-media-image)
  4. Click **OK** twice to return to the network view.
  5. Click **Select** to choose the **Stream Shape** record.
  6. Click **OK** twice.
10. Add Outfall data:
  1. Double-click the node **Outfall**.
  2. Enter the **Invert** and **Spillcrest** values as **1274.6** and **1276** respectively.
  3. Click the **Outfall **button.> Macro (inline-media-image)
  4. Select **Type 1, Free Outfall** and then **Use minimum of Y**<sub>**c**</sub>**-Y**<sub>**n**</sub>. > Macro (inline-media-image)
  5. Click **OK** three times.
11. Save your file as *Yarra41.xp*.
12. Solve the model. Specify *Yarra41.out* as the output file.
13. Select links **Channel** and **Stream** and click the **Review Results** tool. The maximum flows are **1.4295** and **1.4156** cms, respectively. To determine if either of these links flooded open the **Output** file.  
  
**Table E16** is used to determine maximum depths. For the Channel:
  > Macro (inline-media-image)

  
  
Review **Table E14** for information on flow in natural channel sections. Note that the flows are described here for the left over bank and the right over bank in addition to the center. The maximum depth is also shown by using the maximum in the upstream or downstream end.

![image](media://e47e8588-8262-4c2e-964d-3be018d3d2f2)

### Questions

Review the output file (*Yarr41.out*) to answer the following questions.

1. What is the total volume of flow at the outfall?_____ m<sup>3</sup>  
<sup> </sup>
2. What is the maximum depth in the channel?____ m.


## Part 2 – Detention Basins and Node Storage

A common practice is to use detention basins or ponds to temporarily store stormwater and release it downstream using passive control structures. The program has tools to model the depth to volume characteristics of any natural or man-made storage facility and a combination of weirs, orifices, or other devices that are used to control the discharge.

In this exercise, the flow in the network developed in Part 1 is reduced with a dry detention pond.

| **Level** | Novice |
| --- | --- |
| **Objectives** | Introduce the steps required to:<br>- Define a storage node
- Simulate an outlet structure consisting of weirs and orifices |
| **Time** | 1 hour |
| **Data files** | **Yarra41.xp **(from Part 1)<br>**Contours.xptin**<br>**Yarra_Area.dwg** |


1. Open *Yarra41.xp*. This is the model completed in Part 1.
2. Convert a node to pond:
  1. Double-click node **Pond** to open the **Node Data** dialog.
  2. Click the **Storage** button to open the **Storage Node Data** dialog.
  3. Set the **Measure Depth from** to **Node Invert**.
  4. Click **Stepwise Linea**r to open the next dialog.  
> Macro (inline-media-image)
  5. Click **Insert** six times to add blank data rows.
  6. Fill in the **Stepwise - Depth** and **Stepwise -** **Surface Area** table as shown in the following figure. The relationship is displayed graphically as the values are entered.   
> Macro (inline-media-image)
  7. Click **OK** three times to return to the network view.
3. Add a new upstream node:
  1. Select the node drawing tool and add a new node adjacent to the pond. Rename the node **StrmInlet** to indicate that it will represent the upstream node of the stream.
  2. Select the stream at a point near the pond. Holding left button down, drag the end to the **StrmInlet** node and release connecting the link **Stream** to the new node.  
> Macro (inline-media-image)
4. Enter node data:
  1. Double-click **StrmInlet **to open the **Node Data** dialog.
  2. Set the **Invert Elevation** to **1274.8 **and the **Spill Crest** to **1276.3**.> Macro (inline-media-image)
5. Add Outlet structure. The pond structure consists of three controls. An orifice drain, a primary sharp crested weir, and an emergency broad crested weir.
  1. Select the link drawing tool and add a link from **Pond** to **StrmInlet**. Rename the link **Outlet**.   
> Macro (inline-media-image)
  2. Right-click the link and select **Multi Link** from the menu.
  3. Double-click **Outlet** to open the **Multiple Link** dialog. Clear the conduit button in row 1. Click the **Orifice** button in row 1 to open the orifice dialog.  
> Macro (inline-media-image)
  4. The pond is drained with a 6-inch diameter (**0.2** ft<sup>2</sup>), **Side Outlet** located at the bottom (invert = **1269.5**). Set the orifice invert elevation to **1274.8**. Click **OK**.  
> Macro (inline-media-image)
  5. Click the **Weir 1** button in the **Multiple Link** dialog. Stormwater discharge is controlled with a 2-foot long sharp crested weir with a crest at **0.5** ft above the pond invert. Enter the data as shown in the figure below. Click **OK**.
  6. Click the **Weir 2** button in the **Multiple Link** dialog. Emergency overflow is provided with a gravel spillway at elevation **1273.5**. Enter the data as shown in the figure below. Click **OK** twice to return to the network view.
6. Save your file as *Yarra42.xp.* Solve the model.
7. Assess the performance of the detention pond. Open the hydrographs for link **Stream**. Note that the peak flow is **18.82** cfs. The peak flow entering the pond is **29.43** cfs. Thus the pond reduced peak flow by approximately 36 % for the design.  
  
> Macro (inline-media-image)

### Questions

Review the output file (*Yarr42.out*) to answer the following questions.

1. Did the pond eliminate flow in the left and right overbanks of the stream?
2. What was the maximum and volume of runoff stormed in the pond?

## Part 3 – Street Flooding and Dual Drainage

Up to this point, it has been assumed that the hydraulic capacity is controlled only by the conduits in the network. In some cases, the capacity of grated and curb inlets restrict the amount of flow entering the collection system. The program provides a variety of options for defining an Inlet Rating Curve (IRC). 

The Inlet Rating Curve works as follows:

- If Ponding None and no surface conduits - Divert flow according to the selected IRC method and lose excess.
- If Ponding None with surface conduits - Divert flow according to the selected IRC method and excess distributed according to hydraulic properties of surface conduits. Any excess that cannot be re-distributed is lost.
- If Ponding Allowed and no surface conduits - Divert flow according to the selected IRC method with excess ponding at the surface. Ponded surface water is added to the diverted flow at a flow rate equivalent to the volume of surface water divided by the time step. The maximum total diverted flow is capped at either the "Maximum Capacity" or at the maximum value entered in the rating curve so do not enter unrealistically high capture rates even if they have equally unrealistic approach flows because the approach flow is ignored when determining the absolute maximum allowed.
- If Ponding Allowed with surface conduits - Divert flow according to the selected IRC method and excess distributed according to hydraulic properties of surface conduits. Any excess that cannot be re-distributed is ponded as per three above with the total diverted flow increased accordingly.
- If the underground conduit has a constriction that causes reverse flow through the inlet then all the excess underground flow discharges back to the surface regardless of the inlet's maximum capacity (it blows its lid).

Whenever Inlet Capacity is turned on at a node, a second node is created, for computational purposes, with the text $I appended on the name. This new node is connected to the closed conduit and receives flow by an internal rating curve based on the inlet capacity. Results for this node are reported in the output file. In the Review Results graphical display, the new node is labeled as [Subsurface].

In Part 3, the inlet capacity feature will be used to control flow in conduits and excess flow will be routed in surface streets.

| **Level**** ** | Novice |
| --- | --- |
| **Objectives** | Introduce the steps required to:<br>- Define an inlet rating curve
- Route excess flow along a street modeled as a multilink |
| **Time** | 1 hour |
| **Data files** | **Yarra42.xp**<br>**Contours.xptin**<br>**Yarra_Area.dwg** |

1. Define shape for streets:
  1. Open the file *Yarra 42.xp*.
  2. In the **Configuration** menu, select **Global Data**, then **Natural Section Shapes** in the left panel.
  3. Type **Stream shape **for the record name. Click **Add Record** and then click **Edit**.  
> Macro (inline-media-image)
  4. The **Stream shape** section is defined as **20** ft wide with a **0.3** ft crown and **1** ft curbs. A value of **0.016** is used form Manning’s *n* in the center channel (from the **Left Overbank** at = 0 to the **Right Overbank** at = 20). Add data for the **Stream shape** as shown in the figure below.   
> Macro (inline-media-image)
  5. Click **OK** twice to exit **Global Database** dialog.
2. Convert links to multilinks:
  1. Select link **Pipe07**.
  2. Right-click and select **Multi Link** from the menu.
  3. Double-click **Pipe07** to open the **Multi Link** dialog. Add a second conduit, **Street 07** in the 2<sup>nd</sup> row of the conduit column and double-clicking the **2** box.  
> Macro (inline-media-image)
  4. **Street 07** is defined with the Stream shape record. Select **Natural** and then click the button next to **Shape** and select **Stream shape**. This section is **1** ft deep. Set the upstream and downstream elevations **1** ft below the ground elevations of the respective nodes as shown in the dialog below. Enter **110** in the length box. Click **OK **three times to return to the network view.  
> Macro (inline-media-image)
  5. Repeat the above steps for **Pipe06**. Select the same **Stream shape**. Set the upstream elevation to **1292.28**, downstream elevation to **1283.95** and the length to **178**.
  6. Click **OK** three times to return to the network view.
3. Double-click **Node 3/2** and then click the **Inlet Capacity** button to open the **Inlet Capacity** dialog. Set the **Maximum Capacity** to **2** cfs and select the **Maximum Capacity Only** radio button. Click **OK** twice to return to the network view.  
> Macro (inline-media-image)
4. Save the file as *Yarra43.xp*. Solve the model. Select **Pipe07** and open **Review Results**. Note that graphs are displayed for each conduit in the multi link. A new node 3/2 was created as the upstream end of the underground conduit. The flow in **Pipe07** reaches a maximum **2** cfs. The remaining is conveyed by the street.  
> Macro (inline-media-image)

  
The cross section of flow in the street may be obtained by selecting Node 3/2, holding the shift key down and selecting node Junction. Click the **Dynamic Section View** tool. The panel in the lower left shows the cross section of the **Street07**. Start the video to display. At the maximum flow the cross section will appear as shown in the figure below.  
> Macro (inline-media-image)

**Questions**

Review the output file (*Yarr43.out*) to answer the following questions.

1. What proportion of the total flow was conveyed in the street between nodes 3/2 to Junction?
2. Is this level in the street appropriate? Why?