I’m having problems with NetStorm. I run the setup from the website and do the repair option and "Error 1316" pops up. Any suggestions on how to fix this?

Try uninstalling the old version from the Control Panel and then install the current version. Otherwise, install the Windows Installer CleanUp Utility, available from http://support.microsoft.com/kb/290301

Thanks, the uninstall and reinstall worked.

Can you confirm that interevent time in the NETSTORM IDF output is in hours?

Yes, interevent duration is hours. Here’s a description of this table from http://www.dynsystem.com/NetSTORM/netstormidfsample.htm/ :

The Year table lists annual statistics. The statistics shown are comparable with those in the previous tables with the addition of columns for Events, Non-Events, and Interevent. Events indicates the number of storms exceeding the specified threshold for the year. Non-events are periods of measureable precipitation falling below the threshold. Interevent is the average time (hours) between events. Means of the annual series are listed at the end of the table.

This value is very sensitive to definitions of minimum “storm” depth and distinct event definition (storm event separation time; termed ‘interevent time’ in the existing documentation). The program compiles ‘events’ and ‘non-events’ based on a minimum depth. For instance, if you specify a minimum depth of 0.15”, it discards any storm that fails to meet this criterion. Furthermore, it is very sensitive to how long you specify as an acceptable dry period within a single ‘event.’ For instance, if you specify a storm event separation time of 5 hours and it rains for 3 hours, is dry for 4 hours, and then rains for 6 hours more, the model will tabulate a single event lasting 13 hours. The dry period during the storm is then not considered in determining average interevent duration. (This discussion also demonstrates that I need to change the terminology to indicate the user specifies “storm event separation time” while the model computes “Interevent time ”)

Here’s the existing documentation describing specification of storm event separation time from http://www.dynsystem.com/NetSTORM/help/IDFAnalysis.html/

Interevent time has a major bearing on the listings of "continuous" storm events and plays a minor role in selection of interval events if sub-events are excluded. It is recommended that the interevent time be chosen to obtain a resulting coefficient of variation (standard deviation divided by mean) of 1. NetSTORM displays the coefficient of variation in its results. A trial and error approach should be used to identify the appropriate interevent time. As examples, it has been found to be 12 hours for Dallas, 8 hours in Indianapolis, and 5 hours in Boston. Dry periods longer than the minimum data gap to flag are excluded from the interevent time coefficient of variation calculation. This facilitates exclusion of seasonal dry periods from the computation of this parameter. Thus, with the minimum data gap to flag set to 30 days, an interevent time of 33 hours for Sacramento yields a coefficient of variation of 1.

I suggest that if you need to use the interevent time in an analysis you’re doing, you obtain NetSTORM and tinker with the interevent time and storm minimum total parameters. You may also want to tinker with the ‘minimum gap to flag’ parameter, although this generally has little effect in the eastern US where there is no dry season.

11/09 note - updating OWC also fixes problems we've encountered with the Plotter component of the program!!

I am installing NetSTORM at my computer at home and all the applications seem to be working properly except for STORM, which is the one I needed. When I go to Analyze > STORM, I get this message: Run-time error '339': Component "OWC11.DLL' or one of its dependencies not correctly registered: a file is missing or invalid.

OWC11 is Microsoft's Office Web Components. It has a spreadsheet control which several of the program dialogs use. Microsoft dropped it from Office 2007. NetSTORM depended on its presence on the host machine. Fortunately, it's a free download from Microsoft. You can download OWC11 from http://www.microsoft.com/downloads/details.aspx?familyid=C815DFFA-D5F3-4B71-BF46-13721BD44682

You might also try http://www.microsoft.com/downloads/details.aspx?familyid=644008e0-77c9-4a02-ac9b-e30d0930c4be

You can check which version of OWC you're running in NetSTORM by going to the Analyze | Gradually Varied Flow and clicking the colorful Microsoft icon on the left. I've got 12.0.0.6211

We're in the process of porting the program to C#. We expect this move to resolve issues such as this that relate to Microsoft's discontinued OWC software.

A user wrote I am in the process of migrating old NetSTORM files (i.e. version 2002) to the new NetSTORM platform. In the old NetSTORM, after I performed a simulation, I could perform a report generation which gave summary output of the overflow volume and frequency. I can't find that function in NetSTORM 2008. Are the report functions available in the new NetSTORM?

I coded the old NetSTORM interface in FoxPro in the mid-1990s. In 2002, I re-coded the interface in VB6. I did not create new detailed reports for the NetSTORM component of the program (i.e. the multi-structure STORM module). You can still generate the monthly summary and the structure summary, but the program only displays them in Access tables. It's up to you to format a report. The structure summary is saved to the Access table _CSOSummary. The monthly summary is in _MonthlySummary. Follow the links for details on their contents.

There are various places in NetSTORM where the program crashes with or without ceremony. The programming is a lot simpler when one doesn't have to 'trap' lots of errors. If you encounter a persistent problem, please report it to me, and I'll see about fixing it.

Recently, a user found that the program crashed whenever he opened the STORM dialog, giving a 'type mismatch' error before crashing. In a case like this, the only recourse is to wipe out the program's settings and start fresh. In most cases, you should be able to go to Edit | Options from the main menu, and click the Clear Settings button. If this fails to work, it may then be necessary to manually clear the Windows registry. Invoke REGEDIT.EXE from the Windows folder or from a Run prompt. Navigate to HKEY_CURRENT_USERSoftwareVB and VBA Program SettingsNetSTORM. Press the Delete key to remove all NetSTORM references. You'll need to re-register the program to use the IDF analysis again.

Mitch,

I've got a question about how you generate the sampling data used for an IDF analysis in NetStorm. As I understand it, the procedure goes something as follows:

1. Break up the historical rainfall file into discrete storm events, as in SWMM 5's Statistical analysis.
2. For a given storm duration of D hours, examine each event whose duration is >= D to determine the highest rain volume over a contiguous period of D hours.
3. Sort the D-hour volume values and use L-moments to estimate the parameters of the GEV distribution.
4. Identify the GEV D-hour rainfall volumes for selected return periods and save these.
5. Repeat steps 1-4 for other durations and then use the collection of GEV-generated volume/duration data to estimate the parameters of an IDF curve for each return period.

My question concerns step 3. Do you use all of the events with duration >= D to compute L-moments, or just the N highest volumes, where N is the number of years of record? The literature suggests that one uses just the N highest volumes. But is seems to me that this would lead to highly unreliable estimates when there are less than 10-15 years of data available. Which method do you use? Thanks.

Response:

NetSTORM uses the partial duration series (i.e. all storms), not the annual series. This is accepted practice for rainfall analysis, as events can generally be assumed to be fully independent beyond a minimum interevent threshold, as opposed to in streamflow analysis, where annual series are generally preferred, as event independence is otherwise harder to ensure.

Actual storm duration has minimal effect on the calculations. The program looks at all n-hour intervals in the dataset, identifying those with the largest totals. Thus, a 24-hour rainfall extremum could conceivably span two separate storms - e.g. with an interevent time of 6 hours, there might be one storm from 1 AM - 8 AM and another storm beginning 5 PM that day and running for two days. The peak 24-hour accumulation might be from 3 AM during the first storm to 2 AM the next morning. The only impact of the storm interevent definition is that the program will only list one extremum from a single meteorologic event. Thus, if a storm lasts 15 hours, it will only have one entry in the 6-hour interval listings based on the peak six hours within the storm, even though there may be a second 6-hour period within the same event with extreme rainfall.

A user asked how to identify the 85th percentile storm. Version 2007.9 reports the percentile for each storm in the IDF listings. Just make sure to make Number of events to list large enough to include the percentile you're interested in.

Here's another way:

1. Obtain an .ncd file for the gage of interest.
2. Run Read | Precipitation to convert the .ncd to NetSTORM's format.
3. Select Analyze | STORM
4. Enter the converted precip file as the data file. Choose an arbitrary filename for the output file.
5. Enter arbitrary parameters for the simulation. The only one that affects storm depth is Interevent time.
6. Run the analysis
7. Copy and paste the storm listings into Excel
8. If you don't need to set a threshold depth, you can compute percentiles on the column labeled RAIN, e.g. =PERCENTILE($D$2:$D$5070,0.85).
9. If you need compute depths above a threshold, sort the data by the rain column, and then perform the analysis on the censored dataset.

A user asked "How do I produce unit-depth Storage-Capture curves similar to those in the the California Stormwater BMP Handbooks"? An example is at http://www.dynsystem.com/netstorm/help/StormwaterBestManagementPracticeBMPFacilitySizing.html

Unit volumes are normalized to area. So storage volume as inches = Volume (MG) / Drainage area (Acres). 1 MG/Ac = 3.07 inches (1e6/(12^3/231)/43560)

Run Geometric Sequence to generate a table for contouring. That can be done with true contouring software such as 3DField (http://3dfmaps.com), or with more effort in Excel.

Version 2007.9 facilitates producing a table comparable with the CASQA example. Select Geometric sequence and constant Drawdown time. Specify a small initial Storage, enough iterations to yield a smooth curve (e.g. 20), the desired Maximum drawdown time, and a Storage multiplier such as 1.25. The treatment rate and Treatment multiplier parameter inputs are ignored for this analysis.

Maximum drawdown time for a detention basin is treatment rate / storage volume, where treatment rate is however the water gets out of the basin (orifice, infiltration, etc) other than overflow.

From: Heineman, Mitchell Sent: Wednesday, August 01, 2007 10:55 AM To: 'SWMM-USERS' Subject: RE: SWMM-USERS SWMM5

The SWMM Simplification dialog in NetSTORM allows one to import a SWMM5 text input file to an Access database, simplify a network, and export from Access back to SWMM format. Each function may be run independently, so you can import a spreadsheet to the Access tables on your own, and then use the program to export the tables to SWMM format.

Sometime soon, I'll upgrade it to a geodatabase format.

See http://www.dynsystem.com/netstorm/help/SWMM5Simplification.html for more info

Antecedent runoff is the depth of rain at the start of a storm that is treated before any overflow occurs. An error in the calculation was fixed where the reported depth was wrong for storms where overflow occurs at the start of a storm and antecedent runoff should be zero.