SWMM-USERS Digest - 4 Jun 2008 to 5 Jun 2008 (#2008-100)

1 view

Skip to first unread message

Automatic digest processor

unread,

Jun 6, 2008, 12:00:32 AM6/6/08

to Recipients of SWMM-USERS digests

There are 2 messages totalling 234 lines in this issue.

Topics of the day:

1. System storage
2. Pipe Inlet Control

**********************************************************
* To sign off, email to: list...@listserv.uoguelph.ca *
* In the body of the message type: signoff swmm-users *
**********************************************************

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

Date: Thu, 5 Jun 2008 06:53:13 -0400
From: Robert E Dickinson <Robert.E....@US.MWHGLOBAL.COM>
Subject: Re: System storage

Hi,

I hope I can clarify this issue with a small example of the internal
workings of SWMM 5:

Step 1: Calculate the node surface area at the beginning of an iteration:

If the node is a storage node then the storage area for the
depth is used as newArea in the program;
If the node is a non storage area then the area is 0.0

before Xnode[i].newSurfArea 0.000000

Step 2: Compare newArea to the minimum user defined area of a node

If the value of newArea is less than the minimum nodal area (in
this case 10 feet square),
The value of newArea is set to the default node area

after Xnode[i].newSurfArea 10.000000

Step 3: Add in the node surface area contribution from the connecting
links

In this case the links are dry so the link contribution is only
0.09 square feet

area in node continuity 10.090000

The node area in this one iteration increased from 0 to 10 to 10.09 square
feet in on iteration. All nodes have a minimum surface area as defined by
the user.

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

On Wed, Jun 4, 2008 at 4:11 PM, Shyamprasad, Sangameswaran
<Shyamp...@cdm.com> wrote:
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

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

Date: Thu, 5 Jun 2008 13:52:08 -0700
From: Mark Boucher <mb...@PW.CCCOUNTY.US>
Subject: Re: Pipe Inlet Control

Lewis Rossman of EPA has checked out the pipe inlet control issue and
says that, because the criteria for Inlet v. Outlet control depends on a
supercritical flow condition at the inlet, and that SWMM has no way to
test this in the condition clause of a rule, that trying to use rules to
divert the inlet flow between the original conduit (for Outlet control)
and a parallel orifice (for Inlet control) can't be done with the
current version of SWMM.

Mark Boucher, PE
Senior Hydrologist
Contra Costa County Flood Control and Water Conservation District
Martinez, California

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

Environmental Scientist
Water Supply and Water Resources Division U.S Environmental Protection
Agency
Tel: 513-569-7603
Fax: 513-569-7185
email: rossma...@epa.gov

Mark Boucher

-----Original Message-----
From: SWMM-USERS [mailto:SWMM-...@listserv.uoguelph.ca] On Behalf Of
Mark Boucher
Sent: Tuesday, May 27, 2008 3:50 PM
To: SWMM-...@listserv.uoguelph.ca
Subject: Re: [SWMM-USERS] Pipe Inlet Control

The results I get from the orifice are close, but not as close as I'd
like them to be. I think that the orifice might be OK for a steady state
model, but I'm not so sure in an unsteady state model. I am struggling
to make the detention basins I'm working on meet a freeboard
requirement. I've got three detention basins that drain into the same
pipe. I trust the HEC-HMS results for the outlet performance, but HMS
does not do pipe systems. SWMM is great for pipes, but, so far, doesn't
do HEC-5.

I've passed my files on to Lewis Rossman of EPA off line. I'll report
his response.

Mark Boucher

-----Original Message-----
From: SWMM-USERS [mailto:SWMM-...@listserv.uoguelph.ca] On Behalf Of
Mike Kitchen
Sent: Tuesday, May 27, 2008 7:15 AM
To: SWMM-...@listserv.uoguelph.ca
Subject: Re: [SWMM-USERS] Pipe Inlet Control

I've tried modeling a culvert using HEC-5, though not with control
rules. What I did was to take the performance curve that was generated
by FHWA's Hy-8 program given what I knew about a specific culvert and
apply it as the rating curve for an outlet (representing a culvert
draining a field which acts as a detention pond in wet weather.

This did not account for any additional tailwater effects (e.g.
resulting from additional inflow from a downstream lateral ditch or
tributary area) - only the effects of the discharge from the culvert
into the downstream channel. The flow out of the culvert was completely
dependent on the upstream head (the assumed effect of tailwater due to
the flow in the downstream channel section is accounted for in
generating the Hy-8 performance curve).

If the culvert is just in inlet control (e.g. steep slope or tailwater
far enough below the downstream invert), wouldn't orifice or pipe-flow
equations be adequate to describe its performance? Otherwise, doesn't
SWMM5 allow control rules that alter which rating curve an outlet uses
based on head, flow rate, etc... in a node or link?

Michael A. Kitchen, P.Eng.
Martin Geomatic Consultants Ltd.
255 - 31 Street North
Lethbirdge, AB
T1H 3Z4
Tel: (403) 329-0050
Fax: (403) 329-6594

-----Original Message-----
From: SWMM-USERS [mailto:SWMM-...@listserv.uoguelph.ca] On Behalf Of
Mark Boucher
Sent: Thursday, May 22, 2008 12:54 PM
To: SWMM-...@listserv.uoguelph.ca
Subject: [SWMM-USERS] Pipe Inlet Control

Has anyone developed a method for bringing the pipe inlet control
aspects of culvert capacity into SWMM models?

I've done a side by side simple detention basin model comparison of EPA
SWMM 5 and HEC-HMS. I found quite a difference in the storage needed for
a specific hydrograph. HEC-HMS incorporates the FHWA Hydraulic
Engineering Circular 5 (HEC5) equations used for pipe inlet control. I
tried putting an orifice on the front end of the pipe in SWMM and I get
answers that are closer, but they still are not as close as I'd like to
be.

I have not used the Control Rules before. Could a set if these be
created to apply the pipe inlet control equations?

Mark Boucher, PE

Senior Hydrologist

Contra Costa County Flood Control and Water Conservation District

Martinez, California

PS - I'm resending this because I needed to change the subject title.

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

End of SWMM-USERS Digest - 4 Jun 2008 to 5 Jun 2008 (#2008-100)
***************************************************************

Reply all

Reply to author

Forward

0 new messages