Outlet Device Reporting
At the top of the pond summary report you will find basic information
on each of the pond outflows, showing the peak flow, time of peak, and total
volume. Since the peak flow is interpolated
from the three highest points on the hydrograph, the peak will generally be
somewhat higher than the closest discrete values, and can occur at a time that
is between the closest tabulated values.
At the bottom of the pond summary report you will find a separate
device analysis report. This report provides additional details on each
discharge point and the individual outlet devices.
1) Each discharge (primary, secondary, discarded) is labeled
with the following information:
Maximum flow rate
(non-interpolated)
Time of maximum flow
Headwater elevation at time of
maximum flow
Tailwater elevation at time of
maximum flow
Tailwater settings
The maximum flow is calculated directly from the discharge equations at the
listed HW and TW elevations. This value may be slightly less than the
interpolated peak flow that appears a the top of the summary.
This difference can often be reduced by using a smaller time step, but some
difference is expected due to the different calculation procedure. If
desired, the devices flows may be removed from the report by using the summary
report context menu. (Requires
HydroCAD-8.5 or later.)
2) Each device (culvert, weir, etc.) includes one of the following
messages describing its role in determining the maximum flow through its
designated discharge point:
Controls x.xx cfs @ x.x fps
- The device is acting as a control point, and is restricting the discharge to
the specified flow. This does not necessarily mean that the device is flowing
full, but that under the current conditions, its flow is more restrictive than
other devices to which it may be connected. The message also indicates the
approximate discharge velocity corresponding to this flow, and the governing
discharge equation.
Passes xx.xx cfs of xx.xx cfs
potential flow - The device is passing a specified flow that is less than
its potential flow for the headwater/tailwater conditions at that time. The
device is not a control point. The maximum flow is being controlled by other
device(s).
Passes < xx.xx cfs potential
flow - The device is passing a flow that is less than its potential flow,
but the flow could not be determined, since it is apportioned between two or
more devices. The device is not a control point. The maximum flow is being
controlled by another device to which this device contributes a portion of the
total flow.
Since the flows (and control points) are recalculated at each time step,
these values can be expected to vary throughout the routing. The flow
analysis shows only the conditions at the time of maximum discharge.
Furthermore, when using a dynamic tailwater procedure, the maximum flow may
occur at a different time for the primary and secondary discharge.
