Compute volumes defined by a upper and lower values in polygons for all frames. Upper values corresponds to a scalar variable, whereas lower values can be zero, a constant (initial frame) or another variable.

Positive and negative volumes for each polygon can be computed in addition to the net volume.

Upper values	Lower values	Interpretation
WATER DEPTH	0	Liquid volume
FREE SURFACE	BOTTOM
BOTTOM	RIGID BED	Solid volume
BOTTOM	initial values	Solid volume from beginning
BED SHEAR STRESS	0	Bottom friction force (approx.)

⚠️ The computed solid volumes are apparent and include the void (Depending what you want, do not forget to take into account the porosity).