SCALGO Live Documentation

Exploring the river network

To explore the river network (model information), open the "River Network Tools" dialog and click "Network Tools". Then click to active the Select or Length profile tool.

Select tool

This tool lets you select any node or edge (or group) in the river network by clicking on them on the map. An example use is shown in the video below. Once selected, the node or edge is highligted on the map and a dialog with further options appears in the bottom right corner. Depending on the selection, different options are available:

Edge: If the selected item is an edge, the dialog shows the Manning number for that edge, as well as a button that allows you to view (and edit) the cross section representing the geometry of the river along the edge. The cross section is displayed in a separate profile window similar to the regular profile window. If the cross section is measured (rather than sampled), the extent of the measured part of cross section is marked with orange nodes. The cross section outside the orange nodes has been sampled from the terrain model. The bottom of the river, as used for water height computations, is marked with a green node.

Node: When a node is selected, the dialog shows the upstream area of the node.

The video below shows an example of the usage of the select tool and the cross section profile window.

Demonstration of querying elementary aspects of the river network.

Length profile tool

The length profile tool allows you to sample a stretch of the river from upstream to downstream. When the tool is activated, click on two points on the river such that the second point is downstream of the first point. After clicking on the second point, the length profile window will show up. The length profile shows the elevation of the bottom of the river from the first point to second. You can also enable any elevation model in the layer selection menu and see how the river network differs from the terrain model. The terrain model is usually above (at higher elevation than) the river network since the bottom of the river is usually not represented in the terrain model. The length profile view can also be used to study computations.

The video below demonstrates the use of the length profile tool.

Demonstration of querying the river network along a downstream path to get a length profile.

Groups

Pipes, underpasses and similar structures are represented in groups. In a group the water can take two (or more) different paths downstream, depending on the particular event. For instance, a bridge with a piped underpass will allow water to pass through the pipe, but in extreme events the pipe may not be able to handle the flow in the river and the excess flow will take a path above the bridge instead, flooding it. Grouped sections of the river network are marked in pink, see the screenshot below.

Screenshot showing the river network crossing a bridge with a road in the center of the image, the group is marked with a pink line. When selected (using the Select tool), a graphical representation of the group is shown in the top left corner.

When groups are selected using the select tool, a window showing the structure of the group is shown. The group itself is also marked in the map. Typically this involves one closed cross section (e.g. a pipe or a measured underpass) and an open cross section representing the terrain above the closed cross section. By selecting the edges in the river network group view, you can investigate the nodes and cross sections contained in the group in the same way as with nodes and edges on the map.

Binding Reports

The binding reports layer is available in the river network box along with the river network layer itself. The binding report layer highlights issues with the river network data that were found during the initial import and during the fusion of the terrain model with the river network data.

A key property of river networks in SCALGO Live is the fusion of the terrain model with the external river network data. This allows for automatic extraction of upstream area sizes and flow rates, for extending cross sections onto the terrain model, as well as for computing realistic flooding extends at high water levels by "pushing" water from the river out on the terrain. In order to effectively fuse the river network data with the terrain model, the terrain model and the river cross section data should agree on the location of the river. For the terrain model, this means it needs to be of sufficient quality such that the real-world location of rivers can be accurately extracted from flow accumulation computations.

If some cross sections are too far from a river as found from the terrain model, those cross sections are ignored and their locations are marked with a light-blue icon with a white cross. For these and other types of issues, the query tool can be used to get more information by clicking on the corresponding symbol on the map. Most issues are benign, but some issues (especially those marked with crosses) could indicate more serious local issues.

Screenshot showing the binding reports for a section of the river where the external river network data is out of date with the more recent terrain model. The river has undergone stream channelization which was later reversed. The external data is from before this reversal and shows a straight channel (the blue markers) whereas the river, according to the terrain model, has a meandering path. By clicking the binding report using the query tool we see that the cross section in the external data was unable to be matched ("snapped") to the terrain model and it has been ignored.

In the next section of the documentation we describe how to create and manage computations.