Sunday, September 26, 2010

SWMM 5 Related Websites


Conduit Lengthening in SWMM 5

Conduit Lengthening in SWMM 5
If you use the conduit lengthening option in SWMM 5 then your short conduits will be lengthened based on the CFL or explicit time step criterion. Any conduits in which the Length Factor or the courant time step link length over the original length is greater than 1 will be lengthened and will have its roughness lowered so that the conduit is hydraulically the same at full conduit depth. The full area, full width and full hydraulic radius stay the same in the modified link – only the length, slope and roughness are altered.
Length Factor = (Wave Celerity + Full Depth Velocity) * Time Step / Conduit Length, and for those links in which the Length Factor is greater than 1
New Roughness = Old Roughness / (Length Factor) ^1/2
New Slope = Old Slope / Length Factor
A few metric's for showing how this option has altered the network are shown in the figure below:
1. The most important is the increase in Network full volume as you never want to drastically alter the volume of your network,
2. The number of conduits modified along with the new mean slope (lower) and the new total conduit length are important indicators,
3. The mean wave celerity, full flow velocity and courant time step mean give the user some idea of the optimal time step for the simulation.

SWMM 5 Flooding Volumes for Ponding and Without Ponding

SWMM 5 Flooding Volumes for Ponding and Without Ponding

No Ponded Area for a Flooded Node

Ponded Area for a Flooded Node

Mud Flow in SWMM 5

Comment: A method to model Mud flow and other Non Newtonian Fluids in a modified SWMM 5.  You will have to modify the code as described in the link to actually model mud flow. Link Here

Tuesday, September 21, 2010

LPS Output Units when the Inflow is CMS

LPS Output Units when the Inflow is CMS
1. The inflow time series is in units of CMS,
2. If you set the internal units to LPS in Run Manager,
3. Set the output units to LPS in Output Unit Manager,
4. Add a Scale multiplier of 1000 in the Inflows DB Table then
The inflows do not have to be altered, the internal model flows will LPS, the velocity will be m/s with 6 decimal places in the RPT file and the flows will be LPS with 3 decimal places in the RPT file.

Sunday, September 19, 2010

The Three Flows in SWMM 5 for a Link

The Three Flows in SWMM 5 for a Link
There are actually three flows computed or used for a link in SWMM 5:
1. The St. Venant Flow equation flow
2. The Upstream Normal Flow Manning’s equation based on the link roughness, slope, upstream cross sectional area and upstream hydraulic Radius,
3. The flow actually used in the model which is either the flow computed from St. Venant or Manning’s equation
The following three links shows how this works in a real model:
· Link 8040 almost always uses the St. Venant Equation because it is dominated by backwater and surcharge
· Link 8100 almost always uses Manning’s equation except at the beginning and end of the simulation,
· Link 1600 is an adverse slope link and it mainly uses the St. Venant equation.
· Flow = the flow actually used during the simulation
· Qdynamic = the flow computed from the St. Venant Equation
· QNormUp = Flow based on Manning's equation at the upstream end of the link.
· QNormDown = Flow based on Manning's equation at the downstream end of the link.

Link 8100 almost always uses Manning’s equation except at the beginning and end of the simulation. The beginning and end of the simulation is when the non linear terms dominant.

Orifice Open and Close Speed and the Target Setting in SWMM 5

Orifice Open and Close Speed and the Target Setting
In SWMM 5 there is an orifice parameter called setting which opens or closes the orifice opening by modifying the depth of the orifice. The setting is based either on a RTC rule of the orifice or the Flap Gate condition of the orifice and can be between 0 and 1. Closed is 0; Open is 1. The difference is that the target setting is what the setting should be based on the condition of the Flap Gate or the RTC Rules and the setting is the value actually used in the model.
The open and close speed of the orifice modifies the orifice setting by changing the orifice setting based on the open and closing speed using the equation:
New Orifice Setting = Old Orifice Setting + (Target Setting – Orifice Setting) * Time Step / Orifice Open and Close Speed
If your target setting and the current orifice setting are both 1 or 0 then the orifice Open and Close option does not change the orifice setting. New Setting equals Old Setting in that case. If the target and setting are out of phase then the Open and Close Option will function correctly. For example, if the Open and Close Speed is 1 hour then the orifice setting will open and close in a one hour period. The table shown below shows how the orifice setting changes as a function of the speed and the difference between the target and orifice settings. The setting starts out open but the target says closed – the orifice then closes over a 1 hour period. At one hour the target setting is 1 and the orifice will then open over a one hour period.
Table - Link OR1@82309b-15009b
Setting Target
Days Hours
0 00:00:00 1.00 0.00
0 00:15:00 0.74 0.00
0 00:30:00 0.50 0.00
0 00:45:00 0.25 0.00
0 01:00:00 0.00 0.00
0 01:15:00 0.25 1.00
0 01:30:00 0.50 1.00
0 01:45:00 0.75 1.00
0 02:00:00 1.00 1.00
0 02:15:00 0.75 0.00
0 02:30:00 0.50 0.00
0 02:45:00 0.25 0.00
0 03:00:00 0.00 0.00
0 03:15:00 0.00 0.00
0 03:30:00 0.00 0.00
0 03:45:00 0.00 0.00

Example rule for the opening and closing of the orifice

Here is an example Real Time Control (RTC) rule for the opening and closing of an orifice.
RULE Orifice1
THEN ORIFICE OR1@82309b-15009b SETTING = 1
ELSE ORIFICE OR1@82309b-15009b SETTING = 0
; Opens up the orifice at hour 1 of the simulation

Saturday, September 18, 2010

SWMM 5 Link Time Step Calculations

SWMM 5 Link Time Step Calculations
It you select the variable time step option in SWMM 5 then the program will compute the CFL time step for each link based on the ending system variables in the last time step based on the following steps. The smallest value of t is used for each time step but often the same small set of links will be the controlling time for the whole simulation. In the example shown below link 1570c is controlling the time step 83 percent of the time. The link time step is usually the controlling time step.

Tuesday, September 14, 2010

Graphical Representation of Results in InfoSWWM

If you are graphing from the attribute browser you are restricted to 24 hours.
If you are using the report manager then you select the graphing by changing the From and To dates.

Saturday, September 11, 2010

SWMM 5 Interface Guide Tips for C Compilers

SWMM 5 Interface Guide Tips
SWMM 5 has a Interfacing guide on for creating a VB, Delphi or command line C program to both run and printout some of the output file results from SWMM 5. The readme file is self explanatory in the file but here are a few tips for those of you who want to compile the InterFaceGuide C code in a Executable file for Windows.
1. The first step is to make a new console program in Visual Studio

2. The second step is to add the files swmm5.h, swmm5_iface.h, swmm5_iface.c, test.c to the project header and source files.
3. Next add the file swmm5.lib as an additional dependency along with the directory name.
4. If you want to save the .out and .rpt files then you must comment out the remove statements at the end of test.c

5. You need to make a batch file to both run and save the input and output files from SWMM 5,
6. The file swmm5.dll must be in the same directory as the created interface executable file,
7. It will help you see the intermediate output if you add a pause statement in the batch file to hold the fprintf statements on the screen for you to view.

Weather Underground to SWMM 5 Rainfall Time Series

Weather Underground is a site that provides excellent local weather information in the form of graphs, tables and csv files. You can use the data very easily in SWMM 5 by copying from Excel to a time series in SWMM 5. Here is the rainfall for a storm event in Tampa, Florida in September, 2010
Export from WeatherUnderground using the CSV File Export Option
The data imported from the csv file to Excel and after the text to columns tool is used looks like this in Excel. The data is now ready to be imported into SWMM 5 after the time column is adjusted to fall on even 5 minute intervals. In Excel you can use the formula @ROUND((B2)/"0:05:00",0)*"0:05:00" to round all of the time values to 5 minutes. If you do not do this step then you will have problems in SWMM 5 due to the rainfall interval not being equal to the defined raingage interval.

You will need to format the new rounded time as a time format for import into SWMM 5
Open up and make a new time series in SWMM 5 and then copy and paste the date, rounded time column and rainfall column into the SWMM 5 time series columns.

DWF Scale Factor in SWMM 5 for entering Population Data

I (and a few others) think a welcome change to the DWF dialog in SWMM 5 would be the addition of another scale factor to modify the average flow field.  The purpose of the scale factor would be to allow the users to enter the DWF contributing population * the various DWF patterns * the scale factor (in units of cfs/person or l/s/person) in the Inflows dialog.  Some users of SWMM 5 prefer to use population directly in the GUI rather than doing this calculation externally and entering either the flow in cfs or l/s.  An example of why this would be useful is a future conditions model in which the population either increases or decreased in the catchment.

InfoSwmm import / export capabilities

InfoSWMM can both import and export to shapefiles and other databases using the Import and Export Manager, GIS Gateway and CSV file import and export generator.

AI Rivers of Wisdom about ICM SWMM

Here's the text "Rivers of Wisdom" formatted with one sentence per line: [Verse 1] 🌊 Beneath the ancient oak, where shadows p...