Volume Calculation using cross-sections
This volume calculation tool uses cross sections to calculate the total volume of a river section. Please note that this method is only suitable in scenarios where the cross sections are almost the same length.
To calculate the volume, the difference between the depths or elevations is converted to an area and multiplied with the distance between the cross sections.
To calculate volumes for frac pits, reservoirs or ponds, we recommend the use of the "Stages" method. In order to use this tool, you should already have generated soundings and cross sections.
This tool can be used to:
- Calculate the total volume of a river section;
- Calculate the amount of sediment by comparing the same soundings at low and high frequency;
- Calculate the volume difference between two soundings, for instance, post- and pre dredging;
- Calculate the amount of volume to be removed compared to a channel design;
- Print graphical views of cross sections;
- Generate dredging volume reports.
Volume calculation conventions
In Hydromagic, the following conventions are used when calculating volumes:
Sounding data above the fixed reference or channel design is used to calculate the "above volume". This is normally the amount of material that has to be dredged in order to get the channel design.
Sounding data below the fixed reference or channel design is used to calculate the "below volume". This is normally the amount of material that has to be dumped in order to get the channel design.
In 'depth mode,' a value higher than the reference value is considered below. Please note that in "elevation mode", when a vertical reference (datum) is used, it is the other way around. In this case, values less than the reference value are used to calculate the below values.
The following image shows an example of a volume calculation (in "depth mode") with above and below values:
Volume calculation tool
To start the matrix volume calculation tool, select the "Volumes (Sections)" option from the "Tools" menu. The following dialog will be shown:
Data selection
The data to be selected depends on how you use the tool. Use the pre- and post soundings to select the soundings to use in the calculation.
When you want to calculate the amount of sediment, you select the same sounding in both input boxes, and select different frequencies. If you end up with negative values, swap the selected frequencies or the values in the 'Pre-Sounding(s)' and 'Post-Sounding(s)' fields.
For dredging volumes, select the soundings created before the dredging operations in the "Pre-Sounding(s)" field, and the soundings created after the dredging operations in the "Post-Sounding(s)" field.
The use of shorelines is optional. The same shorelines will be used for the pre- and post-soundings.
View cross sections
When the data has been loaded, you can check the result in the graph by using the "Prev" and "Next" buttons. When "NO DATA" is displayed in the graph, it means that there are no soundings or shorelines near the cross section.
The pre-sounding will be displayed in red, the post-sounding in green, and the channel design in blue.
You can click the "Depth Mode" button to switch between depth and elevation.
Reporting
To generate a volumes report, click the "Report..." button. Please note that this function does not work in the demo version of the software.
By default PDF reports are generated under the "Reports" folder in your project folder.
To view reports, you should have a PDF viewer installed, such as 'Acrobat Reader' or 'FoxIt PDF Viewer'. Windows 8, 8.1, and 10 users can use the built-in 'Reader' application as well.
When clicking the print button, graphs for all sections will be sent to the printer. Together with the generated PDF report, you have a full report on, for instance, the performed dredging operations.
Save Images
To save all the graphs as image files, use the "Save Images..." option. This will generate image files containing 4 graph views each in the specified folder. These images can be used to include in other documents.
Video Tutorial
The following YouTube video tutorial shows how to calculate volumes using cross sections, and generate a volume report in Hydromagic. Click below to play the video. When you like the video, please click the like button and subscribe so you will receive an update when new video tutorials on Hydromagic are uploaded.
Hydromagic allows you to generate a cross sections volumes report.