Object Edits – Stormwater Networks

In this section we describe how the point and path subsurface objects can be combined to form entire stormwater networks. 

Getting started video: You can also consult our getting started video on stormwater networks for an easy to understand walk-through of how the networks work and how they are created and modified.

To see how stormwater networks are treated in the various analyses, please see the corresponding manual page.

• Flash Flood Map
• Sea-level rise
• Depression-free flow
• The depression map treats subsurface structures identical to the Flash Flood Map, so we refer to the documentation there.

Stormwater pipes have a lot of interesting use cases, one of them is to easily create subcatchments for all the inlets in the network. For more information about how this works, please see the watershed tool documentation.

Creating networks

The basic premise is quite simple. When you have the path subsurface tool enabled, we will automatically snap to existing segments, allowing you to create larger networks.

A subsurface network can be in two different modes, depending on whether a particular sink point is present in the network or not. These modes are called "surface to surface" and "surface to sink" and are briefly described below. We refer to the analysis-specific documentation for more information about how these modes are handled in a particular analysis. We will automatically create subsurface points where two paths connect, but you can also create additional points along the network using the subsurface tool.

The surface-to-surface mode is the standard mode. Here the elevation at the subsurface points determine the direction of the water flow. The elevation of the subsurface point is extracted from the elevation model.

The network shown in the figure at the top of this section is an example of a surface-to-surface network, as indicated by the absence of a red sink point, and of arrows on the edges.

In surface-to-sink mode, you can identify a particular subsurface point as the sink of the network. Water is directed towards this point regardless of what the elevation model says. Thus, the sink elevation can be at a higher elevation than some of the inlets. This can for example be used to model stormwater systems where there are pumps or other active measures that can move the water upwards, or situations where the pipes are buried deep enough for their slopes not to follow the elevation model in the way suggested by the surface-to-surface mode.

To turn a network into a surface-to-sink network, right click any of the subsurface points (using the Select tool) in the network and select the option to place a network sink. The point will be highlighted in red, and the path in the network will now be rendered with arrows pointing in the direction towards this sink. There can only be one sink in a network.

To remove a sink, right-click on the point (using the Select tool) and choose the option to remove the sink or to delete the feature. You can also relocate a sink using the right-click menu on any of the non-sink modes.

There are many ways to modify existing networks. Here we cover some of them

Multi-selection

You can use the Select tool to easily modify the properties of individual features, both for points, paths and areas. Note that multi-select is also supported. For instance, if you want to add an inlet radius to multiple inlets, you can simply hold down the Ctrl key and drag a box around the desired points. You can then change inlet radius (and the volume) of all the selected points at the same time.

Context menu

If you want more advanced features, try right-clicking on points and paths in the network using the Select Tool. Through the right-click context menu you can for example perform the following operations:

• Place/replace/remove network sinks
• Delete features
• Retrieve surface elevation profiles to the outlet (if the network is in surface-to-sink mode)