| Product(s): | PondPack | ||
| Version(s): | CONNECT Edition, V8i | ||
| Area: | Modeling |
What options do I have to model a channel between two ponds? For example to ensure that the channel is properly sized (and does not impact pond outflow) including both the flow that enters directly into the channel from the road, plus pond runoff.
In PondPack if a conduit element is used between two ponds, ICPM will not occur. Meaning, the tailwater from the downstream pond will not "communicate" back to the channel and then act as a tailwater on the upstream pond. ICPM only works between two ponds that are directly connected via a pond outlet link. Here are some options to consider:
1) If the water surface in the channel does not have the possibility of backing up and affecting the pond discharge, then model the outlet structure of the upstream pond as a free outfall. The outlet link will connect to a junction, which would then connect to a conduit. The conduit should be configured with the geometry of your channel and will connect to an outfall. The outfall will connect to the downstream pond.
2) If the channel water surface could effect the upstream pond discharge, but not to the point of reverse flow, then model the tailwater condition of the upstream pond's composite outlet structure as "Downstream Channel". Then, select the channel geometry. This will cause the outlet structure rating curve to account for the tailwater of the channel, based on the Manning equation. Note that if you need to account for water that also enters the channel from other places such as a nearby road, this option will not work as the channel will only be passing the pond outflow.
3) If the channel water surface could potentially back up into the upstream channel, OR if you need to account for additional flow that enters the channel as well, then you must use the Interconnected Pond Modeling (ICPM) feature (pond outlet tailwater type). However, a channel link element cannot be used downstream of an ICPM pond route. So, you would need to model the channel as a third pond, adding a 'fake' pond on the upstream end of the channel (conduit) with a free outfall control structure that has a rating curve based on the channel's rating curve. Please see the "ICPM Channel.ppc" example model (within the "Samples" folder under your PondPack installation folder) to see how this would be set up. With this, you can also route catchment outflow to the "fake" pond (the upstream side of the "channel"). Note however that this option will not account for any effects from travel time in the channel. Another option would be to use CivilStorm or SewerGEMS (if available) as they include two fully dynamic solvers (Implicit and Expicit-SWMM) which can account for the channel travel time and tailwater effects automatically. You may need to consider if the travel time would significant impact the decision that you need to make based on the model results, or if a simplified approach would be considered more conservative.
PondPack User Notification "The X structure with the id 'Y' is out of range..."
| Original Author: | Jesse Dringoli |