MIKE+ Rivers | 2D Overland | How to extract 1D/river and 2D/floodplain discharge through a section?

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Description

How can one extract 1D/river, 2D/floodplain or combined 1D/2D flows through a section in MIKE+?

The Flooding Toolbox ribbon (under the ‘Results’ menu) of MIKE+ includes the tool "Discharge through section tool" (Fig.1). This tool calculates the flow through sections represented as polylines in the map using 1D river and 2D result files producing a *.dfs0 file per each section. This file will store the discharge time series from the 1D river network, the 2D overland HD flow and the total discharge from both models. When one section only covers one of the two result types the dfs0 file will contain a single time series from the specified result.

Fig. 1 presents how to access to the Flooding Toolbox. When you access the tool, a dialog box will appear, guiding you through a wizard-style workflow.

Fig. 1 “Discharge through section” button in Flooding Toolbox ribbon ('Results' menu)

The tool is designed to work on a top to bottom approach, setting the input-output files, defining the location of the sections to extract and requesting reporting information of the process, as shown in Fig. 2.

Fig. 2 Discharge through section in configuration

Extracting the discharge from a section can be done either by using only 1D results, 2D results or combining both types of results.

#01 – Using 1D Results

The workflow to compute the discharge through a section using a 1D result file is described below. In the ‘General’ tab check in the "Use 1D results" option and select the hydrodynamic result file (.res1d). Fig. 3 presents the general configuration to compute the river discharge (Collection Systems pipes discharge cannot be computed with this tool) using only 1D results and defining the time series time span.

Fig. 3 Example of a configuration to extract river discharges based on a 1D result file.

Furthermore, it is required to define the specific section in the 1D river network where the discharge will be computed. This can be done by simply digitizing the crossing polyline(s) on the map or by importing them from a shapefile. In the Location tab clicking on "Add on Map" under Sections definitions will prompt the user to draw one or more polylines on the map (by left-clicking on the points along the section, while right-clicking will end the polyline creation). The tool also allows the option to export the digitized sections as a shapefile, which can then be edited in GIS software and reimported back into the tool's dialog as a shapefile (Fig. 4).

Fig. 4 Example of map digitalization of a section (blue line at the center crossing the river).

Once digitized, the section will be shown in the dialog together with the X|Y pair coordinates for the polyline(s). The ‘Section definitions will identify each section digitized on the map, while the user has the option to include or not in the computation, as presented in Fig. 5.

Fig. 5 Example of sections digitized on the map.

With the sections defined it is possible to run the configuration and expect the time series results. Once computed, the time series can then be displayed, as presented in Fig. 6.

Fig. 6 Reporting status of running the tool and pop-up dialog to display the time series file created.

Choosing the option "Yes" will display the time series of the 1D river discharge for the given section(s), as shown in Fig. 7.

Fig. 7 Time series discharge for a digitized section.

#02 – Using 2D Results

The workflow when one needs to include the 2D results it is the same as described above but with the inclusion of the 2D result files (.dfsu/.dfs2) in General | Input Files (Fig. 8).

Fig. 8 Discharge through section configuration using the 2D results file.

When having multiple sections defined on the map it may become cumbersome to follow through the different locations, thus the tool enables the option to rename the section names keeping track of the study locations, as shown below in Fig. 9.

Fig. 9 Definition of an alternative section and renaming the ID of the section.

Similarly to running the calculations based on 1D results once computed the Time Series for that section will be displayed right after computed.

#02 – Using Combined 1D and 2D Results

The workflow when one needs to include both 1D and 2D results is the same as described above but with the inclusion of the 1D and 2D result files in General | Input results.

In the following plot, time series are presented for both 1D and 2D result files for a given section (Fig. 10).