The Manning Flow Calculator provides an interactive dialog window for estimating various hydraulic parameters using Manning's Equation (Q = AR^(2/3)S^1/2)/n). To use the tool, a terrain surface must be active, as the surface is used to extract cross-sections and slopes.
1. Click the Cross-section button 
, then left click points across the desired cross-section on the surface, then right click to finish. The selected cross-section will then be displayed in the dialog.
2. Select the calculation method from the radio button list.
3. Enter the known data values. If slope is one of the known values, it can be measured from the surface. Click the Slope button 
, then left click a series of points to create a line up the slope, over which an average slope will be calculated. Right click to finish. Note that the slope is automatically calculated and updated in the edit box in the dialog as the cursor is moved and the final right click point is included.
4. Click the Run button 
to perform the calculation and display the results.
The procedure can be repeated as many times as desired with changes to the known variables and their values on a selected cross-section. Click the cross-section button again to start with a new cross-section. The Highlight button 
can be used to re-display the cross-section.