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Vertical profile file

Tue, 07/31/2007 - 5:33pm — kent
I have a few questions regarding setting up the vertical concentration file for initial conditions within a lake (vpr_br1.npt). I have specified the following active constituents as on in the control file: TDS, generic constituent, phosphate, ammonium, nitrates-nitrites,6 algal groups, DO and alkalinity. I have data at 1m vertical increments for temperature, pH and DO. I have grab sample data forTDS, phosphate, ammonium, nitrates-nitrites,6 algal groups, and alkalinity collected within the photic zone (layers 2 -15). My model bathymetry has 59 active layers each 0.5 m (total of 61 layers including boundary layers. The lake I am modeling is not stratified at the start of the modeling period. for the vertical profile file, it is my understanding that I must provide information for each constituent that I have on in the control file for initial conditions including temperature. Here are my questions. 1) Do I need to specify a value for every layer? If yes, is it appropriate to list the measured value for 1m off teh bottom (active layer 58 as the algal concentration for all layers below the photic zone? 2) In the example files for version 3.5 the number of entries in the vpr.npt file do not match up with the number of layers in the bathymetry bth file. why is this? 3) Do you have a recomendation for a concentration for a generic constituent if I am using it as a tracer to see that my model is properly routing water quality constituents? thanks
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Water Quality
Thu, 08/02/2007 - 9:09am — Rob

Hi Kent, 1) You need to provide water quality constuents for each "wet" layer in them odel for the first time step (based on Initial Water SUrface Elevation) in the vpr file for each constituent you have turned on in the control file (in the order you turned them on) and that you have specified in the control that you want a vertical profile (under WQ and Temp initial conditions the value should be set to negative 1). If the the lake is isothermal then temperature is easy to implement. If you do not have a vertical gradient in water quality then this is easy as well. You could use the measurements from 1 m off the bottom from the area below the photic zone. This is a godo starting point. Once the model is up and running and you are able to calibrate it you can test the "assumption" with a sensitivity run. Conversely if you have problems with the claibration then this might be an indicator to change. Since youmay not have more data to characterize the area below the photic zone this is good start. 2) In the Version 3.5 example problem there are 16 water quality constitutents plus temperature turned on, but only 3 have negative values in the control file so one 3 are listed in the vpr file. The number of wet layers in the model at the first time step is based on the initial water surface elevation and is 28 which matches the vpr file. This measne that of 34 active layer in the model grid the top 6 are not wet becuase the water surface is lower. 3) If you are trying to model the routing from that location in the water column then you can pick a number like 10 or 100 to ensure you can track a range of concentrations. If you are trying to track the water quality from an incoming source, trib, point source, then set the initial condition to zero. I hope this helps. Cheers, Rob