mass balance error when using EQUILIBRIUM NEAR BED CONCENTRATION
When using suspended sediment transport in GAIA, in combination with the keyword EQUILIBRIUM NEAR BED CONCENTRATION, a mass balance error occurs (see for example gai_yen-expRestart.cas in the yen test case). In case we impose a concentration value on the boundary, the mass balance is OK.
The reason for the mass balance error is that the change in the bed (EVCL_MS) due to erosion (in the variable variable FLUER) are calculated during the first call of gaia_step. However, when using the equilibrium near bed concentration, FLUER is later overwritten (in eqcae_bc_gaia, called by prep_adv_gaia) . This overwritten value value is used in the mass balance calculation (in the second call of gaia_step).
This issue was observed in v8p4.