SWMM-USERS Digest - 2 Jun 2008 to 4 Jun 2008 (#2008-99)

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Jun 5, 2008, 12:02:36 AM6/5/08

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There are 6 messages totalling 338 lines in this issue.

Topics of the day:

1. System storage (6)

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Date: Wed, 4 Jun 2008 15:12:35 -0400
From: Rishab Mahajan <maha...@EMAIL.UC.EDU>
Subject: System storage

I had a query regarding the system storage. It is sum of the total
nodal storage volume. But even if the network does not have any
stoarge node in it, it shows value, which is quite surprising.

Thanks
-Rishab

------------------------------

Date: Wed, 4 Jun 2008 16:11:17 -0400
From: "Shyamprasad, Sangameswaran" <Shyamp...@CDM.COM>
Subject: Re: System storage

Rishab,
Every node in the network by default has a storage area of 12.56 sq feet
and that is the reason you have a value for total storage volume in the
system.
-Shyam

CDM
Cambridge, MA 02139
phone/fax: (617) 452-6139

-----Original Message-----
From: SWMM-USERS [mailto:SWMM-...@listserv.uoguelph.ca] On Behalf Of
Rishab Mahajan
Sent: Wednesday, June 04, 2008 3:13 PM
To: SWMM-...@listserv.uoguelph.ca
Subject: [SWMM-USERS] System storage

I had a query regarding the system storage. It is sum of the total nodal
storage volume. But even if the network does not have any stoarge node
in it, it shows value, which is quite surprising.

Thanks
-Rishab

------------------------------

Date: Wed, 4 Jun 2008 16:19:16 -0400
From: Rob James <r...@COMPUTATIONALHYDRAULICS.COM>
Subject: Re: System storage

Rishab,

The output file's "System Storage" time series contains the total computed
volume of water in the hydraulic components of the model (links and nodes)
at each reported time step, including that in the storage nodes, ponded
volume in any nodes, and conduits. The "total nodal storage volume"
description in the EPA SWMM5 help file is (I presume) an artifact of the way
SWMM5 does its the mass balance - conduit storage volume is assigned to the
nodes. Roughly speaking, depending on the hydraulic condition in the
conduit, a conduit's volume of water may all be assigned to the upstream or
downstream node, or split between the nodes. For a more accurate discussion
of this mass balance - please refer to the Extran section of the SWMM4
user's manual.

In a similar fashion, the "Flow Routing Continuity" table's "Final Stored
Volume" includes the total volume of water remaining in the hydraulic
components.

Sincerely,

Rob James
Computational Hydraulics Int.
www.computationalhydraulics.com
Tel. 519-767-0197

I had a query regarding the system storage. It is sum of the total
nodal storage volume. But even if the network does not have any
stoarge node in it, it shows value, which is quite surprising.

Thanks
-Rishab

------------------------------

Date: Wed, 4 Jun 2008 16:38:31 -0400
From: Robert E Dickinson <robert.d...@GMAIL.COM>
Subject: Re: System storage

Hi Rashab,

In addition to what Shayam and Rob just mentioned, there is a minimum depth
or area in SWMM 5 (the same value was in SWMM 3 and SWMM 4):

//-----------------------------------------------------
// Minimum flow depth and area for dynamic wave routing
//-----------------------------------------------------
#define FUDGE 0.0001 // ft or ft2

this means that every node and every link has at least this minimum depth at
the start and end of the simulation or even during the simulation when no
inflow is occurring. This small depth value gets applied to the default
node storage area that Shayam mentioned and the allocation of the link
surface areas to the nodes that Rob mentioned respectively in their email
replies.

Best and Kind Regards,
Robert Edgar Dickinson
MWH Soft Inc.

On Wed, Jun 4, 2008 at 3:12 PM, Rishab Mahajan <maha...@email.uc.edu>
wrote:

------------------------------

Date: Wed, 4 Jun 2008 17:58:48 -0400
From: Rob James <r...@COMPUTATIONALHYDRAULICS.COM>
Subject: Re: System storage

Bob, Shayam, Rishab et al.

I think the concept of a default node storage area may be misleading, at
least as far as I understand its use.

There is a "minimum surface area" which is user-definable in the Dynamic
Wave tab of the Simulation Options editor. If this value is 0, then as
Shayam indicates, the program uses a default minimum surface area of 12.566
sq. ft (1.167 sq. m).

This minimum surface area is used in computing changes in water level at
nodes, and is applied (I believe) only when the allocated link surface area
for the node does not meet this minimum. I don't believe it represents
additional system storage added by junctions. For example, a non-ponding
junction between two 10 ft deep lengths of open channel does not add 125
cubic feet (12.566ft2 x 10ft) of storage capacity to the system.

Perhaps someone can shed some light on this for me.

Sincerely,

Rob James
Computational Hydraulics Int.
www.computationalhydraulics.com
Tel. 519-767-0197

-----Original Message-----
From: SWMM-USERS [mailto:SWMM-...@listserv.uoguelph.ca] On Behalf Of
Robert E Dickinson
Sent: Wednesday, June 04, 2008 4:39 PM
To: SWMM-...@listserv.uoguelph.ca
Subject: Re: [SWMM-USERS] System storage

Hi Rashab,

In addition to what Shayam and Rob just mentioned, there is a minimum depth
or area in SWMM 5 (the same value was in SWMM 3 and SWMM 4):

Best and Kind Regards,
Robert Edgar Dickinson
MWH Soft Inc.

On Wed, Jun 4, 2008 at 3:12 PM, Rishab Mahajan <maha...@email.uc.edu>
wrote:

------------------------------

Date: Wed, 4 Jun 2008 18:18:28 -0400
From: Robert E Dickinson <robert.d...@GMAIL.COM>
Subject: Re: System storage

Rob and Rishab,

If the network is totally dry and even if you have no storage nodes then the
starting system storage of the network will be:

Volume = Total Number of Nodes * ( FUDGE * MinSurfAreaFt2 +
approximately half the
surface area of the connecting links at a depth of FUDGE)

the default surface area gets applied in this case because of these lines of
code.

void initNodeState(int i)
//
// Input: i = node index
// Output: none
// Purpose: initializes node's surface area, inflow & outflow
//
{
// --- initialize nodal surface area
if ( AllowPonding )
{
Xnode[i].newSurfArea = node_getPondedArea(i, Node[i].newDepth);
}
else
{
Xnode[i].newSurfArea = node_getSurfArea(i, Node[i].newDepth);
}

if ( Xnode[i].newSurfArea < MinSurfAreaFt2 )
{
Xnode[i].newSurfArea = MinSurfAreaFt2;
}

Best and Kind Regards,
Robert Edgar Dickinson
MWH Soft Inc.

On Wed, Jun 4, 2008 at 3:12 PM, Rishab Mahajan <maha...@email.uc.edu>
wrote:

> Hi
>
> I had a query regarding the system storage. It is sum of the total
> nodal storage volume. But even if the network does not have any
> stoarge node in it, it shows value, which is quite surprising.
>
> Thanks
> -Rishab
>
> **********************************************************
> * To sign off, email to: list...@listserv.uoguelph.ca *
> * In the body of the message type: signoff swmm-users *
> **********************************************************
>

------------------------------

End of SWMM-USERS Digest - 2 Jun 2008 to 4 Jun 2008 (#2008-99)
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