GLM inflow values differ from lake.csv inflows— need help understanding why
CG
Hello everyone,
I am new to GLM and I’m trying to understand why there is a noticeable gap between the in situ inflow values and the flow values computed in the GLM output file lake.csv (see attached graph).
I am running GLM with an hourly time step, using daily inflow and outflow values and hourly meteorological data (UTC format).
Is it normal to observe such a discrepancy between the input and simulated flow values? Could it be related to my configuration?
Here is an extract of my glm3.nml file:
&time
timefmt = 2
start = '2020-01-01 00:00:00'
stop = '2024-12-31 00:00:00'
dt = 3600.0
!num_days = 2922
timezone = 0 !tous les capteurs sont en utc
/
&inflow
num_inflows = 3
names_of_strms = 'creuse','petite_creuse','sedelle'
strm_hf_angle = 60, 25, 52 !a changer ?
strmbd_slope = 0.259, 0.259, 0.259 !pente du lit du cours d'eau -> a calculer encore
strmbd_drag = 0.04, 0.04, 0.04 ! bottom roughness -> rate of entrainment as it enters the water body
inflow_factor = 1, 1, 1
inflow_fl = 'input_files/inflow_creuse_glm_v1.csv','input_files/inflow_petite_creuse_glm_v1.csv','input_files/inflow_sedelle_glm_v1.csv'
inflow_varnum = 3
inflow_vars = 'flow', 'temp', 'salt'
coef_inf_entrain = 0
time_fmt = 'YYYY-MM-DD'
/
&outflow
num_outlet = 2
outlet_type = 1, 1 ! outlet fixe 3= hauteur adaptee pour eviter faibles concentrations en o2
outl_elvs = 186.1, 150 !
bsn_len_outl = 5700, 760! verif pour le 30 pas des mesures exactes mesures dans mon espece d'ellipse
bsn_wid_outl = 175, 257 ! verif
outflow_fl = 'input_files/outflow_turbine_glm_v1.csv', 'input_files/outflow_reserve_glm_v1.csv'
outflow_factor = 1, 1
time_fmt = 'YYYY-MM-DD'
/
The time column in all inflow and outflow files is formatted as "YYYY-MM-DD".
If this mismatch is due to an error, do you have any idea where it might come from?
Thanks a lot for your help.
Best wishes,
Clara
