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external downstream head

Wed, 03/17/2010 - 4:58pm — Emily
I'm modeling a small reservoir and prefer to set my downstream boundary as an external water elevation instead of specifying outflow (Qout). So I supplied the model with EDH, TDH, and CDH files and changed BRANCH G so that DHS = -1 for an external head. Why are temperature and concentration profiles required at the downstream boundary? My calibration station is at the downstream end of the model. Is there a way to tell the model to ignore these profiles? From reading previous posts on the forum, is it better to set the downstream boundary as a spillway or structure so that temperature does not need to be specified? The drawback would be how to calculate the coefficients for the spillway, gate, etc. Thanks in advance for your help!
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Hydrodynamics
Thu, 03/18/2010 - 4:40pm — chris

Hi Emily, I wouldn't recommend using the external downstream head bc for a small reservoir. External downstream head bc's are generally used on estuary systems. The temperature (TDH) and constituent (CDH) files describe the water characteristics in case of reverse flow, which results in water flowing into the model and is common in tidal systems. It will probably be much easier for you to simulate the dam using a spillway or structure. Chris