Ponding at a Extran Node

Hello Panel,

I would like to request some clarification regarding the "ponding
allowed" flag in EXTRAN of SWMM. I am using Visual SWMM.

When a node goes into surchage with the ponding flag on, is head being
calculated on the system based upon the ponding depth at the node?

And my second question is under Junction Defaults in the Extran Job
Control the ponding area equation is defined as:

ponding area = (constant) e ^ (ponding depth)

where the ponding depth is entered as a constant. Please clarify this
for me, as the equation would seem to make more sense if the exponent
was a variable (variable depth).

Thanks!
Kenneth G. Schrock
kgschrock@civiltecheng.com

Question: When a node goes into surchage with the ponding flag on, is
head being calculated on the system based upon the ponding depth at the
node? Answer: When the HGL rises above the Spillcrest of a hydraulics
(Extran) node with ponding on in XP-SWMM the head on the system does
include the ponded depth.

Question: Junction Defaults in the Extran Job Control the ponding area
equation is defined as:

ponding area = (constant) e ^ (ponding depth)

where the ponding depth is entered as a constant. Please clarify this
for me, as the equation would seem to make more sense if the exponent
was a variable (variable depth).

Answer: The equation is actually: ponding area = coefficient times e ^
(exponent times ponded depth)

Therefore it is variable since the user can enter a value for exponent.
Only a value of zero would make the area constant for a given depth.
Basically the area increases as the depth on the surface increases.

Anthony Kuch