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Spillways Upstream and Downstream ?

Thu, 05/15/2008 - 5:25pm — Thomas
I have a reservoir with a spillway at a dam located at the downstream end of the model. I understand the data required for the SPILLWAYS card, but I am not clear on what the SPILL UP and SPILL DOWN cards do. Are these different types of spillways, or are they cards to modify or further describe the hydraulics of the SPILLWAY card. The termonology in the Users manual is not clear. It's possible that the SPILL UP card may be describing how the water enters the spillway from the segment upstream of the spillway described on the SPILLWAYS card, and in that same line of thought the SPILL DOWN card may be describing where the water that leaves the spillway goes to, in the segment downstream of the spillway described in the SPILLWYS card. But, the card description for the spill Up card talks about how "inflows enter the upstream spillway segment", not how water leaves the upstream segment and enters the spillway, so I am not sure what these cards are actually doing. I am new with Qual-W2 so any clarification would be really helpfull.
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Hydrodynamics
Fri, 05/16/2008 - 2:49pm — chris

Thomas, Although it may not apply to your model, the spillway feature allows flow from the "upstream" segment to the "downstream" segment or vice versa depending on the water levels in the segments. Thus, if the downstream segment has a higher water level than the upstream segment, reverse flow can occur over the spillway and the SPILL UP card describes how this flow is distributed into the upstream segment. If the flow is from the upstream segment to the downstream segement, the SPILL DOWN card describes how flow is distributed into the downstream segment. Hope this helps, chris
Mon, 05/19/2008 - 1:50pm — Thomas

Thanks for the response. Ok, that makes sense. Then, if I understand this correctly, for the SPILL DOWN Card, ETDSP and EBDSP designate the downstream segment elevations that the spillway discharge will be distributed into? And, the KTDSP and KBDSP designate the upper and lower upstream segment layers that water will be withdrawn from? Lastly, if my spillway is the outlet from the model and the discharge is lost, do I need a SPILL DOWN card?
Mon, 05/26/2008 - 1:22pm — chris

Thomas, Yes, you got it. Remember that for the SPILL DOWN card the KTDSP and KBDSP define the upper and lower layers of how water is withdrawn from the downstream segment if direction of flow is from "downstream" to "upstream". Also, the model won't use the parameters in the SPILL DOWN card if spillway outlet discharges to the domain outside of the model. I wouldn't be surprised though if the pre-processor generates an 'error' if you don't have numbers in the SPILLDOWN card... chris