Preissmann Slot and Baseflow Correction
InfoWorks ICM allows you to compensate for the effects of the Preissmann Slot and Baseflow on storage in an InfoWorks network.
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- the Preissmann Slot increases storage in pipes by a small amount
- baseflow reduces storage in pipes by a small amount
In the past, these slight variations in storage were assumed to cancel out. This is a good approximation, and is still perfectly valid in many cases. However, you may want to compensate more accurately for these storage variations.
Numerical Correction
InfoWorks ICM compensates for these slight numeric variations in the following way:
- Preissmann Slot - InfoWorks ICM reduces the cross section area of the manhole to provide a reduction in volume equivalent to the volume of the slot.
- Baseflow - InfoWorks ICM increases the cross section area of the manhole node to provide an increase in volume equivalent to the volume occupied by baseflow in the pipe.
Because the Preissmann Slot correction involves reducing the plan area of the manhole, it is possible for the sum of all storage compensation parameters to be negative. The Minimum Plan Area at Nodes values in the Simulation Parameters ensure that the effective plan area of a node can never fall to zero.
Instructions
The process has two parts. You must first set up the parameters used for numerical correction, and then carry out the correction itself on the network.
