Showing posts from 2009

15 GPM

From the South Florida Watershed Journal

Fifteen gallons per minute
Alternative measurement units:

0.03 cubic feet per second
508 barrels per day (using 42.5 gallon barrels)
24 acre feet per year
7.9 million gallons per year
12 Olympic swimming pools per year

Weather Underground Data and SWMM 5

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.

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.

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.

InfoSWMM and H2oMAP SWMM Release Notes

Node Convergence in SWMM 5

The solution is iterative but each iteration is dependent on the CFL or explicit time step. The time step we select is based on the CFL condition but instead of just using the explicit solution we iterate until the node depths are converged or a maximum of 4 iterations is reached.
The solution of node depths and link flows in SWMM 5 is an iterative process but the number of iterations for the flows and links depends on how fast the node depth converges. The node continuity equation is ALWAYS solved at each iteration for each node but depending on whether both the link upstream and downstream node depths have converged the the number of iterations for a link may be between 2 and 4. The minimum number of iterations for a link is 2.

Heavier Rainstorms Ahead in the Future

Heavier Rainstorms Ahead Due To Global Climate Change, Study Predicts
ScienceDaily (Sep. 27, 2009) — Heavier rainstorms lie in our future. That's the clear conclusion of a new MIT and Caltech study on the impact that global climate change will have on precipitation patterns.

But the increase in extreme downpours is not uniformly spread around the world, the analysis shows. While the pattern is clear and consistent outside of the tropics, climate models give conflicting results within the tropics and more research will be needed to determine the likely outcomes in tropical regions.
Overall, previous studies have shown that average annual precipitation will increase in both the deep tropics and in temperate zones, but will decrease in the subtropics. However, it's important to know how the frequency and magnitude of extreme precipitation events will be affected, as these heavy downpours can lead to increased flooding and soil erosion.
It is the frequency of these extreme events…

InfoSWMM and H2OMAP SWMM Version 8.5

MWH Soft Releases InfoSWMM and H2OMAP SWMM Version 8.5,
Leveraging the Latest EPA SWMM5 Functionality

Newest Iteration of Industry-Leading Geospatial Urban Drainage Modeling and Design Software
Delivers Expanded Engineering Simulation Value

Broomfield, Colorado USA, November 11, 2009 — MWH Soft, the leading global provider of environmental and water resources applications software, today announced the immediate release of Generation V8.5 of H2OMAP SWMM and InfoSWMM for ArcGIS (ESRI, Redlands, CA). The new version adds powerful features and leverages engine enhancements included in the latest release of EPA SWMM5 (5.0.017). It also improves the breadth and performance by extending MWH Soft tradition of including new enhancements specifically requested by customers. Version 8.5 marks a significant evolution of the company’s SWMM-based urban drainage modeling and design products, which continue to be top choices for the effective evaluation, design, management, rehabilitation and ope…

SWMM 5.0.018

Build 5.0.018 (11/18/09)
Engine Updates

1. Reporting of the total infiltration + evaporation loss for each
Storage Unit (as a percent of total inflow to the unit) was added
to the Storage Volume Summary table in the Status Report. See
objects.h, node.c, stats.c, and statsrpt.c.

2. Double counting the final stored volume when finding the nodes with
the highest mass balance errors has been eliminated. See stats.c.

3. A warning message was added for when a Rain Gage's recording
interval is less than the smallest time interval appearing in its
associated rainfall time series. (An error message is issued if
the recording interval is greater than the smallest time series
interval.) See gage.c and text.h.

4. Hot Start interface files now contain the final state of each
subcatchment's groundwater zone in addition to the node and
link information they have always had. See routing.c.

5. To avoid confusion, the …

Using the Link Geometry to Divide the Flow

You can use the geometry of the connecting pipes to divide the flow instead of flow divider in the dynamic wave solution of SWMM 5. You can try to do the same using an Outlet link but the method of using two outlets is sometimes very unstable and requires a small time step just to lower the continuity error. I used two flat rectangular links with the same maximum depth and but different width values (Figure 1). The flow was split based on the value of Q full for the link (which you can see in the text output file (Figure 2).

Figure 1. Link Geometry

Figure 2. Flow Division from a inflow of 10 mgd

Figure 3. SWMM 5.0.016 Cross section geometry for the two rectangular links.

Suggestion for Entering Population DWF Data at a Node

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 decreases in the catchment.

New Warning Messages in SWMM 5.0.014 to 5.0.016

These warning and error messages were added in SWMM to 5.0.016 to trap questionable raingage, link and node data. Correcting these errors does make a better model . The list shown below has the major new warnings and errors and help on interpreting the messages.
WARNING01: wet weather time step reduced to recording interval for RainGage Explanation: The user selected hydrology time step is automatically reduced by the engine to match the rain gage interval. The smallest rainfall interval among all of the gages will be used during the simulation. WARNING 02: maximum depth increased for Node Explanation: The rim elevation of a node has to be at least equal to the crown elevation of the highest connecting link to the node. The maximum depth of the node is increased to match the highest crown elevation. WARNING03: negative offset ignored forLink Explanation:Negative Offsets are set to offsets of 0.0 WARNING 04: minimum elevation drop used forConduit Explanation: If the elevation acro…

Peeling Back Pavement to Expose Watery Havens


Image via Wikipedia

Peeling Back Pavement to Expose Watery Havens
SEOUL, South Korea — For half a century, a dark tunnel of crumbling concrete encased more than three miles of a placid stream bisecting this bustling city.

The waterway had been a centerpiece of Seoul since a king of the Choson Dynasty selected the new capital 600 years ago, enticed by the graceful meandering of the stream and its 23 tributaries. But in the industrial era after the Korean War, the stream, by then a rank open sewer, was entombed by pavement and forgotten beneath a lacework of elevated expressways as the city’s population swelled toward 10 million.

Today, after a $384 million recovery project, the stream, called Cheonggyecheon, is liberated from its dank sheath and burbles between reedy banks. Picnickers cool their bare feet in its filtered water, and carp swim in its tranquil pools.

Surcharge Level in SWMM 5

How does the surcharge depth work in SWMM 5?

The surcharge depth from the node attribute table is added to the maximum full depth in the routine dynwave.c as an upper bound check for the new iteration depth of yNew.

    // --- determine max. non-flooded depth
    yMax = Node[i].fullDepth;
    if ( canPond == FALSE ) yMax += Node[i].surDepth;

If the new depth yNew is greater then yMax then the program will calculate either the amount of flooding from the node or the ponded depth and volume.  If the node cannot pond (canPond is False) then the amount of overflow is the excess flow in the node and the new depth yNew is set to yMax.

    if ( canPond == FALSE )
    {  Node[i].overflow = (Node[i].oldVolume + dV - Node[i].fullVolume) / dt;
        Node[i].newVolume = Node[i].fullVolume;
        yNew = yMax;    }
    else    {
        Node[i].newVolume = Node[i].fullVolume + (yNew-yMax)*Node[i].pondedArea;
        Node[i].overflow = (Node[i].newVolume - Node[i].fullVolume) / dt;    }

Q full vs Q dynamic vs Q normal in SWMM5

Introduction – the reason for these series of blogs are as an expanded view of the input, engine and output of #SWMM5 It is a companion to the EPA Documentation which I describe here:

I have noticed based on email questions and postings to the SWMM List Sever (a great resource hosted by CHI, Inc.) that many SWMM 5 users do not know about the really outstanding documentation on SWMM 5 posted on the EPA Website It consists of two now and in the near future three volumes on Hydrology, Water Quality, LID’s and SuDS and Hydraulics. The documentation is fantastically complete with detailed background on the theory, process parameters and completely worked out examples for all of the processes in SWMM5. It is truly an outstanding aid to modelers and modellers worldwide. It would benefit you to read them (if you have not already downloaded the PDF files)
1. It gets more flow than qFull because the water in the pipe has more th…

Future Rainfall

Published: April 2009 Outlook: Extreme As the planet warms, look for more floods where it’s already wet and deeper drought where water is scarce. By Elizabth Kolbert The world's first empire, known as Akkad, was founded some 4,300 years ago, between the Tigris and the Euphrates Rivers. The empire was ruled from a city—also known as Akkad—that is believed to have lain just south of modern-day Baghdad, and its influence extended north into what is now Syria, west into Anatolia, and east into Iran. The Akkadians were well organized and well armed and, as a result, also wealthy: Texts from the time testify to the riches, from rare woods to precious metals, that poured into the capital from faraway lands.Then, about a century after it was founded, the Akkad empire suddenly collapsed. During one three-year period four men in succession briefly claimed to be emperor. "Who was king? Who was not king?" a register known as the Sumerian King List asks.For many years, scholars blamed th…

Additional SWMM 3,4 Converter Information

Step 1: Open up or run the converter Step 2: Define your text editor if you want to use the Edit Button Step 3: Define the programs ini file if you want to use it multiple times Step 4: Click on Select to convert either a Runoff, Runoff and Transport or Runoff and Extran Step 5: Click on Convert to convert the two selected files Step 6: File Converted Message will tell you that the file9s) were converted correctly. Step 7: Please make sure to check the log file to confirm that everything was converted successfully.

SWMM5 Advanced Calibration File Formats

SWMM 5 Calibration Files

Steps for making calibration files from the SWMM 5.

Step 1.  Run the model and graph at least one Object class such as Nodes, Links or Subcatchments

Step 2:  Use the Command Copy To to bring up the Saving Selection Dialog

Step 3.  Select the type of Calibration File you want based on the Selection List

Step 4:  Go to the Calibration Data Selection Menu

Step 5:  Select the correct type of Calibration Data

Step 6:  Click on the Edit Button and paste the data you saved to the clipboard into the Text Box

Step 7: Graph with the Calibration Data

Step 8: Graph with the Calibration Data in Date/Time Format

Step 9: Graph with the Calibration Data in Date/Time Format

International Conference on Stormwater and Urban Water Systems Modeling

International Conference on Stormwater Urban Water Systems Modeling
Thursday and Friday February 19-20, 2009

SWMM 5 Complexity Index

SWMM 5 Complexity IndexThe complexity index for SWMM 5 compares a model to the first Extran example in Extran 3, which would be network #1 in this expanded SWMM 5 network. The baseline network has 22 objects and an 8 hour simulation duration. It took 5 minutes to run this network on a IBM AT in 1988.  The purpose of the complexity index is to supply a means of comparison for a present day model.   The complexity equation compares the number of objects in the new model to the number of objects in the baseline model and also factors in any increase in simulation duration.

The complexity index adds up the of raingages, subcatchments, junctions, outfalls, dividers, storages, conduits, pumps, orifices, weirs, outlets, control curves, diversion curves, pump curves, rating curves, shape curves, storage curves, tidal curves, time series, patterns, transects, hydrographs, aquifers, controls, climate objects and snowpacks objects. The complexity index is then multiplied by the number of pollutan…