To enable more precise analysis of dam reservoirs and surface depressions using topographic maps, the Stage-Volume Relation tool has been developed. With this tool, you can use a topographic map and define the area of interest (such as a reservoir or a depression) to extract the water surface area and volume at various elevation levels and determine the Stage-Area-Volume Relation for your selected area.
To get started, go to the Terrain menu, then the Terrain Analysis section, and select the Stage-Volume Relation tool.
In the DEM section, select the topographic map. In the AOI section, choose a polygon that defines the area of interest (e.g., the dam reservoir or depression), or draw it manually using the Draw on Map button.
The Pace option specifies the step size for incrementing from the base elevation up to the maximum elevation under study.
In the Max Elevation Mode section, you can choose whether to enter a specific elevation manually or let the software automatically detect the maximum elevation within the selected area.
- If you select Multiplier of maximum AOI Elevation, then in the Max Elevation Value field, enter a multiplier. The software will multiply this value by the maximum elevation found in the selected AOI, and the calculations will proceed from the lowest elevation in your area of interest up to the computed maximum elevation.
- If you select User-Defined Elevation, you can manually enter the desired maximum elevation in the Max Elevation Value field. In this case, the calculations will run from the lowest elevation within your AOI up to the value you entered.
Click Compute to start the calculations.
After the calculations are complete, the Stage-Area-Volume Relation window will appear. On the right side of this window, the computed values will be displayed in a table. You can right-click on this table to either copy the values or export them as a CSV file.
- On the top left, a chart showing the elevation-volume relation will be displayed.
- On the bottom left, a chart showing the elevation-area relation will be shown.
By clicking on the Fill With Water button, you can generate raster maps showing the filling of the reservoir at different elevation levels and create animations from them.
When you click this option, the Fill Storage with Water window will open.
- By enabling the Water Surface Elevation option, the software will generate water surface elevation maps at each stage of reservoir filling. These maps can be used as initial condition maps for 2D dam breach modeling.
- By enabling the Flow Depth option, maps showing water depth at each fill stage will be created.
Use the Add to Layers option to select which of the activated maps should be added to the time series layer for sequential display and animation.
Select the output raster file format using the Output Format option, and choose the destination Output Folder to save the results.
After clicking the Compute button, the maps will be generated in order, starting from the lowest elevation, and added to the time series layers for visualization.
