Dear all,

Have any one worked with autodesk storm and sanitary system 2012?

I have a question about ponded area in that.

Does ponded area have a significant effect on calculation process?

How can I estimate ponded area accurately?

What will happen if the ponded area would be equal to zero?

Thanks in advance.

Yasert

## Replies

Yes, that is what I am suggesting, a preliminary estimate of the ponded area, followed by a global calibration based on the results of the preliminary simulation run, I mention this as I do not totally trust the answer with a zero ponded area.

I am extremely grateful to you.

So I have to initially run model without ponded area to determine primary flooded volume for flooded node. Then, I will assume a logical ponded depth above the node and use your equation to calculate ponded area for each node. Is it right?

Yes, that is right but I would start off with a small area of 50 square meters and use the peak volume from that, it will be a better estimate of the volume.

I am sorry. but I am a little confused about your answer.

You start off with a 50 square meters ponded area?

it means, at first, you assign that ponded area is equal to 50 square meters to all nodes. So you find initial flooded volume for each node.

So you calculate a initial ponded depth. Then you take another ponded depth which you think it is more accurate and calculate ponded area again. Could I correctly get what you mean?

before that,I am sorry to bother you.

OK. Thanks for your attention.

But there is a ponded area option in SWMM which is often left zero.

What will happen if the ponded area would be equal to zero?

I have founded in SWMM manual when we want to use hydrodynamic routing, there is a need to take a non-zero value for ponded area. However, in examples of SWMM application manual conducted by Gironas et al., ponded area have been left "zero".

How does you justify this?

Thanks in advence.

It will work with a ponded area of zero but I do not recommend it, the water will flow into and out of the no volume flooded zone every time step and never build up a flooded depth. I do not like the answer with a ponded area of zero, it leads to continuity error and the need for a small time step,

I hope this answers your question.Thank you so much Bob. Your answer really is useful for me. As you expressed, ponded area can tangibly affect flood depth in nodes. Now, how can I estimate ponded area accurately? can you suggest me a way for this?

I would do it using this method,

estimate before how deep the ponded area can be and make the ponded area = total flooded volume / your estimated deepest ponded area

The ponded area should not be zero and yes, the depth is affected by the ponded area.