FVCOM sediment simulation hotstart error

[Razks]

Hi, all, the variable ‘bed_thick’ went wrong when I activate both the FVCOM sediment module and hot start at the same time.

At first, I ran the model with the sediment module enabled and cold start mode (with the initial bed thickness set to 10 m) from 2019-07-01 00:00:00, to 2019-07-02 00:00:00, and obtained a restart file. At this point, the bed thickness at 2019-07-02 00:00:00 in the restart file had already changed.

Then, I switched from cold start to hot start, used the restart file as input, and ran the model from 2019-07-02 00:00:00 to 2019-07-02 23:00:00. The final output file showed that at the first time step (2019-07-02 00:00:00), the variable 'bed_thick' remained consistent with its value in the restart file at 2019-07-02 00:00:00. However, at the second time step (2019-07-02 01:00:00), the 'bed_thick' value at every grid point reverted to 10 m, matching initial bed thickness('init_bed_thickness').

I don’t understand why this happened and would appreciate any explanations.
Thank you.
The paraments settings are as follow.

NCS = 2
NNS = 1
BEDLOAD = T
SUSLOAD = T
COHESIVE_BED = F
MIXED_BED = T
NONCOHESIVE_BED2 = F
SED_MORPH = F
SED_FLOCS = F
SED_BIOMASS = F
SED_BIODIFF = F
SED_DEFLOC = F
VERT_HINDERED = F

SED_ONED = F
SED_NUDGE = F
SED_ALPHA = 0.5
SED_RAMP = 0
SED_START = 0
N_REPORT = 10

SED_PTSOURCE = T
SED_HOT_START = T
NBED = 1
INF_BED = F
INIT_BED_THICKNESS = 10.0
INIT_BED_AGE = 1.0
INIT_BED_POROSITY = 0.5
INIT_BED_BIODIFF = 0.0
INIT_BED_TAU_CRIT = 0.12
INIT_BED_FRACTION = 0.4 0.4 0.2