Friday, April 22, 2011

How to redo the Arc GIS Extents in InfoSWMM

Problem:  The network looks very small when you zoom out to the maximum extents of the window
Step 1:  Zoom out a few times to a visible network

Step 2: ArcGIS View/Data Frame Properties/Other / Current Visible Extent will fix your network view.

Node Ground Elevation in InfoSWMM

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.
Figure 1.  Rim Elevation for Nodes instead of Maximum Depth

Figure 2. Maximum Depth instead of Rim Elevation for Nodes.

Thursday, April 21, 2011

InfoSWMM 11 (for ArcGIS 9, 10) and H20MAP SWMM v10 Updated for the new SWMM 5.0.022 Engine

EPA SWMM 5 Build 5.0.022 (04/21/11)
Engine Updates

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

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.

e. The calculation of infiltration in a Vegetative Swale was corrected so that a swale with vertical sides will produce the same results as a fully pervious subcatchment with the same dimensions, roughness, and slope.

f. The water initially stored in all LID units is now reported in the Status Report's Runoff Continuity table.

g. Error messages are now generated if the surface layer vegetation volume fraction is less than 1, if the area of all LIDs in a subcatchment is greater than the total area or if the total capture area of all LIDs is greater than the subcatchment's total impervious area.

2. Missing values for accumulation periods within an NWS rain file are now processed correctly. See rain.c.

3. A new error message (318) is now generated if a user-prepared rainfall file has its dates out of sequence.

4. Evaporation during wet time periods was including rainfall and run-on as moisture available for evaporation when it should only be the current ponded depth. See subcatch.c.

5. Curve Number infiltration was modified to use only direct precipitation, not including runon or internally routed flow, to compute an infiltration rate. See infil.h, infil.c, subcatch.c and lid.c.

6. A new error message (110) is now generated if the ground elevation of a subcatchment is less than the initial water table elevation of its groundwater aquifer. See gwater.c, err.h, and err.c.

7. A check was added to the tailwater term of the groundwater flow equation to insure that the term is zero when no tailwater depth exists. See gwater.c.

8. Checks were added to the solution of the governing groundwater mass balance equations to catch conditions where the lower zone depth is greater than the total depth or when the upper zone moisture content is greater than the porosity. See gwater.c.

9. A divide by zero error no longer occurs when computing the hydraulic radius of an empty Filled Circular pipe whose filled depth is zero. A similar error for the hydraulic radius of an empty trapezoidal channel whose bottom width was zero was also eliminated. See xsect.c.

10. The critical or normal depth adjustment made for a conduit is no longer allowed to set the depth to zero -- some small depth level is always maintained. See dynwave.c.

11. The 
Pump Summary Report was expanded to include number of start-ups, minimum flow, and time off both the low and high ends of the pump curve. See objects.h, link.c, stats.c, and statsrpt.c.

12. When the setting of an orifice or weir was changed to 0 (to completely block flow) the flow depth in the element wasn't being set to 0. This was only a reporting error and had no effect on the flow routing calculations. See link.c.

13. The Node Surcharge Summary in the Status Report did not report a ponded node as being surcharged. This was only a reporting error and had no effect on the flow routing calculations. See stats.c.

Monday, April 18, 2011

The Economics Of H2O

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.

Friday, April 15, 2011

Reverse Flow in SWMM 5 during one time step

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 Link UpPipe1

if ( q * qLast < 0.0 ) q = 0.001 * SGN(q); 

Two new parameters and a modified table in InfoSWMM 11 and H2OMAP SWMM

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. 

Sunday, April 10, 2011

Iterative Hot Start File in SWMM 5

Subject:  Iterative Hot Start File

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

Friday, April 8, 2011

InfoSWMM Map Display of Scenario Differences

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. 

The Goal of SWMM5 Input Files

 🌟 SWMM5 (Storm Water Management Model 5) is a widely used urban hydrology and hydraulic modeling software developed by the United States E...