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  1. psmart

    Error 81 in Hydrocad

    Please click the message for complete details and solutions: [81] Warning: {node} Exceeded Pond x by x.x' @ x.x hrs At some point during the routing, the node's water surface elevation has exceeded the water surface elevation of an inflowing pond, indicating a possible tailwater dependency...
  2. psmart

    Carlson Hydrology Module vs HydroCAD Results

    Pretty sure there is an input difference with Carlson. AMC 3 is unusual. I would stick with 2. To isolate the difference see www.hydrocad.net/scsresults.htm
  3. psmart

    Farm Tile Modeling

    Obviously, there will be a runoff component, but the presence of the tiles means that the soil will not exhibit standard runoff behavior as predicted by the SCS method, so standard CN values will not apply. You will also have some storage and time lag as the water penetrates the soil to the...
  4. psmart

    Oscillations and Equalizing in Hydrocad

    Assuming that the equalizer pipe is adequately sized, modeling as a single pond is recommended for simplicity and stability. Modeling as two ponds may become unstable (oscillate) as the ponds equalize, especially if you a modeling a reversing flow. I would start with DSI assuming one-way flow...
  5. psmart

    Modeling Exfiltration

    Just use an exfiltration outlet, possibly routed to a culvert outlet (if you want to check for possible culvert control.) All in the same pond.
  6. psmart

    Modeling Exfiltration

    Since the media layer is generally the outlet control (using exfiltration), the pond storage storage should include only the volume above the media. In other words, you should ignore the storage in the media and underlying stone. For details see www.hydrocad.net/raingarden.htm
  7. psmart

    Parallel Ponds & Simultaneous Routing

    OK, so the "outlet pipe" at the bottom of the control structure is the final discharge, and the bioretention area is basically "offline" storage. You could try: Pond 1 = "Dry Pond" Device#1=Culvert (connecting pipe), routing=Primary (routed to pond 2) Devcie#2=Rectangular orifice...
  8. psmart

    Parallel Ponds & Simultaneous Routing

    The connecting pipe is easy. That's just a culvert outlet from the first (dry) pond. But you seem to be also be feeding water through the perforated underdrain, into the media and presumably into the upper part of the pond as it fills up? So the same media is actually receiving water from...
  9. psmart

    Clogging potential: orifice vs. slot

    As swazimatt points out, you also need to consider the available storage. Assuming that you are trying to limit (regulate) the flow to a certain maximum, you will have to detain the excess volume and release it over time. You cannot do this with a flow-limiting device alone. You also need an...
  10. psmart

    Wet Pond Modeling

    I suspect that the pipe diameter will become the limiting factor before the perforations or flow rate through the gravel. Otherwise you could use an exfiltration outlet and/or orifice array in front of the culvert.
  11. psmart

    Wet Pond Modeling

    When configuring any outlet setup, start at the final device and work backwards towards the pond storage. For example: Device#1=Culvert outlet from riser structure, routing=Primary Device#2=Orifice at top of riser, Routing=Device#1 Device#3=Orifice in side of riser, Routing=Device#1...
  12. psmart

    Wet Pond Modeling

    Not sure exactly what "issues" you're trying to address. Normally you would set the starting elevation to the permanent pool. But your underdrain will cause the level to draw down, correct? So it's no longer a permanent pool. If you want to maintain the initial WSE you would need to...
  13. psmart

    Dekalb Method Model in HydroCAD

    There are lots of hidden complications with the Rational method, which is why we recommend the SCS/NRCS method instead. www.hydrocad.net/rational.htm
  14. psmart

    Flow splitter modeling

    You would probably need to model the space upstream of wall (A) as a separate pond. But then you'll have to deal tailwater issues. I would simplify the model rather than trying to include all the details of the WQ unit. Unless it provides a large storage (detention) volume, the WQ unit isn't...
  15. psmart

    HydroCAD-Pond Routing in Series

    The weir and orifice can both be primary, routed to the control structure. Just one culvert, leaving the control structure. Don't include anything twice.
  16. psmart

    HydroCAD-Pond Routing in Series

    If I understand correctly, you would need to model the inside of the outlet control structure as a separate zero-storage pond, so that you can route the inflows accordingly. For example, working from the bottom up: Pond 3 would be a zero-storage pond representing the inside of the control...
  17. psmart

    Dekalb Method Model in HydroCAD

    By way of background, here is some detail on using the Dekalb method in HydroCAD: https://www.hydrocad.net/dekalb.htm
  18. psmart

    Hydrocad Exfiltration Invert Elevation

    An exfiltration invert of zero with HydroCAD 8 is equivalent to "Allow exfiltration at all elevations" on later versions. Later versions will then report a zero invert. They do NOT set the pond bottom elevation.
  19. psmart

    Runoff through property line wall

    Remember that if you restrict the flow, you will have to detain the excess volume. You are essentially creating a detention pond. Do you have the space/volume to accommodate the excess? The required volume could be considerable. At some point it may also overflow (in undesirable directions)...
  20. psmart

    Tc always showing zero

    The minimum Tc is applied only if you enter a Tc value for the subcat. You can even enter zero, but there must be at least one Tc segment in order for the minimum Tc to be applied. The minimum Tc is normally used to avoid very small values (a few minutes). Since you have a significant Tc of...

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