Freshwater discharge problems - Salinity?

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rpsm@ua.pt
MOHID Beginner
Posts: 2
Joined: Thu Jan 01, 1970 00:00

Freshwater discharge problems - Salinity?

Postby rpsm@ua.pt » Fri Dec 21, 2012 10:53

Hi
I'm trying to implement the mohid to the Douro estuary. I already perform the model calibration and validation for the hydrodynamic processes (2D) and the results were excellent (<2% relative error) from the mouth to the Crestuma dam. But when I tried to run the model for the salinity and temperature something strange happens with the final results: It's impossible to reach the estuary equilibrium to the salinity transport.
I also tried to test with a discharge fraction (50%,25%,10%, 5% and 1% - you can see in the image bellow) and the results are the same: the mean salinity tends to 0 in a station (Avintes) at the middle point of the estuary.
And I assure that the tidal signal can reach all the estuary with a significant amplitude and the salinity in situ values for this station during this period were between 20 and 35.

http://imageshack.us/photo/my-images/191/graphki.jpg/


WaterProperties file:

REFERENCE_DENSITY : 1027.00

<beginproperty>
NAME : salinity
UNITS : psu
DESCRIPTION : salinity in the ocean
DEFAULTVALUE : 36
MAX_VALUE : 36.5
MIN_VALUE : 0

INITIALIZATION_METHOD : CONSTANT
!FILENAME : I:\Ria_de_Aveiro\Project_Ria_de_Aveiro_transport_validation\GeneralData\InitialConditions\salinity_teste2.dat
ADVECTION_DIFFUSION : 1
DISCHARGES : 1
ADVECTION_H_IMP_EXP : 0
DIFUSION_V_IMP_EXP : 0
BOUNDARY_INITIALIZATION : EXTERIOR
BOUNDARY_CONDITION : 2
DEFAULTBOUNDARY : 36.05
OUTPUT_HDF : 1
TIME_SERIE : 1
TIME_SERIE_LOCATION : E:\Renato\PhD\Rio_Douro\Pluma_V1\NM_Actual_TS\GeneralData\TimeSeries\TimeSerieLocation.dat
OUTPUT_TIME : 0 3600
DT_OUTPUT_TIME : 3600.
MAX_BUFFER_SIZE : 1000.
DATA_ASSIMILATION : 0
<endproperty>

Discharge file:

<begindischarge>
NAME : Douro River
DESCRIPTION : valor do rio douro para Setembro
I_CELL : 13
J_CELL : 526
DISCHARGE_UNIFORM : 1
K_CELL : 0
DATA_BASE_FILE : E:\Renato\PhD\Rio_Douro\Pluma_V1\NM_Actual_TS\GeneralData\Discharges\crestuma.dat
FLOW_COLUMN : 7
TIME_SERIE_COLUMN : 1

<<beginproperty>>
NAME : salinity
UNITS : psu
DESCRIPTION : Salinidade no rio
DEFAULTVALUE : .1
<<endproperty>>

<enddischarge>

txt file which contains the discharge:

TIME_UNITS : DAYS
SERIE_INITIAL_DATA : 2005 8 1 0 0 0
<BeginTimeSerie>
0 51.72 25.86 12.93 5.172 0.5172 2.586
1 139.5 69.75 34.875 13.95 1.395 6.975
2 134.67 67.335 33.6675 13.467 1.3467 6.7335
3 101.79 50.895 25.4475 10.179 1.0179 5.0895
4 135.41 67.705 33.8525 13.541 1.3541 6.7705
5 17.21 8.605 4.3025 1.721 0.1721 0.8605
...
time 100% 50% 25% 10% 1% 5% - m3/s

So... Is there something wrong with my input parameters?

thank you in advance :)

frank.maretec@ist.utl.pt
MOHID Guru
Posts: 151
Joined: Thu Jan 01, 1970 00:00
Location: Technical University of Lisbon
Contact:

Re: Freshwater discharge problems - Salinity?

Postby frank.maretec@ist.utl.pt » Wed Jan 09, 2013 12:34

Dear MOHIDer,

from your input data files, I can't see any problem.

If I understood right, you want to reach equilibrium conditions in the Estuary. Please be aware that you can only reach equilibrium conditions if the boundary conditions are also constant. So if you would run the model with constant discharge (flow and concentration) and cyclic tide (e.g. only M2), the model should tend to a equilibrium conditions (cyclic with the same frequency as the M2). Right?

Question: where did you got the salinity data from?

Hope this helps,
Frank
In order to understand recursivity you must first understand recursivity.


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