Compare suspended material and deposition with erosion

[c.drinkorn]

Hi Sediment Modelers,

I happen to be very confused about the units of suspended material in the water column, and deposited or eroded sediments. I want to capture how much material I lose via the boundaries. In order to do so I integrate deposition (positive change in bed thickness) and erosion (negative change in bed_thickness) over the entire 2D domain which gives me volumina in square meters. The suspended material is integrated over the entire 3D domain and divided by the grain density which gives a volume of square meters, too. I did the calculations for a domain with closed borders which should give |erosion| = deposition + suspension. However, suspension happens to be roughly an order of magnitude too low. What am I missing?
Thank you!

[ckharris]

Are you accounting for porosity of the sediment bed? If you work in volumetric units, you need to account for porosity of the sediment bed.

If you keep everything in mass units (kg/m2) then you do not need to account for porosity of the sediment bed. For the sediment bed, you can use the "sandmass' or "mudmass" variables instead of bedthickness.