Stormwater Management Model (SWMM) Information for watershed water quality, hydrology and hydraulics modelers (Note this Blog is not associated with the EPA). You will find Blog Posts and Twitter Embeds on the Subjects of SWMM5, InfoSWMM, InfoSewer, SWMMLive, InfoSWMM SUSTAIN, SWMM4 and SWMM in general.
Note: Why isn’t the “Ground Elevation” of the Junctions listed in the “Junction Information” table of the DB Editor?
The ground elevation is listed in the Junction Hydraulic Data DB Table under:
1.Max Depth if Store Absolute Junction Rim is off in Tools/Preferences/Operation or 2.Junction Rim Elevation in the same column of the DB Table if Store Absolute Junction Rim is on in Tools/Preferences/Operation 3.It is not listed in Junction Information which is designed for user extra input data.
1. The following fixes and updates were made to the LID module of the code (lid.c):
a. The Drain Delay time for a Rain Barrel LID is now correctly converted internally from hours to seconds.
b. The meaning of the Conductivity property of an LID's Storage layer has been changed. It is now defined as the saturated hydraulic conductivity of the native soil below the layer instead of the conductivity of the layer itself.
c. Storage layers are now optional for Bio-Retention Cells and Permeable Pavement LIDs by allowing the layer height to be zero. One should still enter a non-zero conductivity for the layer if infiltration into native soil is allowed.
d. If the top width of the overland flow surface for an LID is zero then any excess water above the surface storage depth simply spills out instantaneously.
The Economics Of H2O
Charles Fishman explains why “free” is the wrong price for water:
[R]esources that are free are wasted; there’s no incentive to learn to use them smartly; there’s no money to maintain and modernize the existing water system; there’s no incentive to reach back and protect the source of something that’s free. If it’s free, the message is that it’s unlimited.
In the U.S., we spend $21 billion a year on bottled water. We spend $29 billion maintaining our entire water system: the pipes, treatment plants, and pumps. We spend almost as much on crushable plastic bottles as we do on our most fundamental infrastructure system.
Source Daily Dish http://andrewsullivan.thedailybeast.com/2011/04/the-economics-of-h2o.html
Subject: Reverse Flow in SWMM 5 during one time step Reverse flow in a link of SWMM 5 occurs if the downstream head is greater than the upstream head. The flow calculations for the link are based on the time step head, cross sectional area(s), hydraulic radius and old time step flow of the link. The only extra criterion for the link flow is the requirement that the flow cannot reverse during one iteration but must first become zero before being allowed to be negative if the old flow was positive or positive if the old iteration flow (qLast) was negative. This calculation is done in dynwave.c using the current iteration flow, q, the last iteration flow, qLast and the sign of the current iteration flow q. The requirement prevents the flow from oscillating sign during the iterative process in a time step.
In this example, a large flow from Upnode_2 causes a high head at node Middle which causes a reverse flow up link UpPipe1 to node UpNode_1. The image show here shows the flow in…
Subject: Two new parameters and a modified table in InfoSWMM 11 and H2OMAP SWMM v10 that does the following:
1.Allows you to control the maximum number of iterations in the solution, 2.Controls the Stopping tolerance (internal units of feet) for node iterations, and 3.Shows not only the percent continuity error at a node but the error in million gallons (Mgal)
If you have a high continuity error or want to reduce your existing continuity error then you can increase the number of iterations or lower the stopping tolerance so that at each time step there is less continuity error.
1. If the continuity error is due to the lack of a hot start file, 2.You should make the hot start file iteratively, or successively Save and Use two hot start files until the initial and final stored volume is about the same in the flow routing continuity table, 3.1st Step: Save Hot Start File 1, 4.2nd Step: Use Hot Start File 1 and Save Hot Start File 2 5.3rd Step: Use Hot Start File 2 and Save Hot Start File 1 and
6. Repeat until the initial and final storage volume is about the same
Subject: InfoSWMM Map Display of Scenario Differences
You can also make a table and map of the differences between the existing and future scenario. The red in the image shows the pipes in which the flows have increased and the blue shows the pipes in which the flows have decreased between the existing and future scenarios. You make the table by
1.Making a conduit report for both scenarios at the same date/time, 2.Copy the flow in the link for all links to Excel and make a new column with the difference between the future and existing conditions, 3.Make a new column in the Conduit Information Table of InfoSWMM for real data and paste the new column from Excel into the Conduit Information Table, 4.You then can use Map Display for links and show a Map Display of the flow differences at that particular date/time for all the links.