Volumes and Areas

Volumes and Areas is an additional module to the ReefMaster PRO edition that provides calculation and export of the mapped area, and water and sediment volume information. For information on how to add additional ReefMaster modules see ReefMaster License Activation.

The volumes and areas module calculates the mapped area and the volumes of water and sediment within the mapped area of a Map Project. Water and sediment volumes can also be calculated for depth ranges, as defined by the current major contour interval settings within the project. Information such as the bounding area, maximum, minimum and average depths is also provided. Volume and area information can be easily copied to the clipboard, or exported in CSV file format for use in applications such as Microsoft Excel.

Technical Notes

·All distance and area calculations use the WGS84 Ellipsoid.

·Volume and area calculations are calculated using a data grid with a cell size of 1m. Area is calculated as the sum of filled grid cells, volume is calculated as the sum of the volume contained within each grid cell.

·Due to the nature of the source data, volume and area calculations are approximations only.

·The units used for area and volume depend on the current Global Settings.

The Volumes and Areas Edit Pane

The Volumes and Areas edit pane forms part of the Project Properties window and is displayed by clicking on the Volumes and Areas expander (1).

The Volumes and Areas edit area is split into a number of sections:

2. Calculate area and volumes

Volumes and areas are only calculated for a project when the Calculate area and volumes checkbox is selected. Checking this box will trigger the calculation of area and volumes for the current project, and the area and volume information will be re-calculated as the project changes, so long as this option remains selected. Calculating volumes and areas increases the project generate time, so this option should be de-selected when not required.

Export

The Export button exports all volume and depth information as a single CSV (comma separated value) file, suitable for use in Microsoft Excel or similar applications.

3. Area

Mapped area

The mapped area is the area within the project that has been filled with depth data. Areas within the project that are empty, due to a lack of data within the current interpolation range, are not considered when calculating areas or volumes. Note that this means that the mapped area may differ from the area contained within a shoreline, if empty areas are contained within that shoreline.

Bounding box

The dimensions of the bounding rectangle of the mapped area.

NW/SE

The geographic coordinates (WGS84) of the Northwest and Southeast corners of the bounding rectangle of the mapped area.

4. Depth

Minimum, maximum and average depth of the mapped area of the project. Average depth is calculated as the mean of the individual grid-cell depths.

5. Water Volumes

Water volume is calculated as the sum of the depth of each grid cell. Empty areas do not contribute to the volume calculation.

Total volume is shown, as well as the volume contained within depth-ranges defined by the Contour Spacing setting of the project. Area is also shown for each depth-range; area is calculated as the total area for which any volume exists in the specified depth-range.

The volume and area for each depth range is shown in a list view with columns for lower range, upper range, volume and area. The list can be sorted by any column value by clicking on the column header (1). Click again on the column header to reverse the sort order. Values can be copied from the list to the clipboard; all values can be copied using the Copy all button (2), whilst individual rows can by copied by right-clicking and selecting Copy to clipboard from the displayed menu (3). Multiple rows can be selected through the use of the left mouse button in conjunction with the SHIFT or CONTROL keys.

6. Sediment volumes

Sediment volume is calculated as the sum of (reference depth minus calculated depth) for each populated grid cell. Sediment volume is useful for calculating the volume of solids above a known reference depth in body of water.

Reference depth

A reference depth can be specified by checking the option Use reference depth and entering the required depth in the field provided. If this option is not checked, the maximum depth of the project is used as the reference depth. Depth-range bands are created between the reference depth and the minimum depth of the project.