| Is HSPFToolkit™ accepted by the Washington State DOE?
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| The WS DOE manual states that HSPF is an accepted program. When you use our toolkit, you are using HSPF.
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| I keep getting a dialog message with a Non-Fatal Error title and
something about the help database. I also get a message about not being able to connect to the MySql Database.
Whats going on?
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The licensing and help database initialization is handled by and ISP website. Their server might be down.
Check the
Host Department ISP site and see if there is a problem with the Mysqlblade1 server. Currently, the help pages and the training videos are hosted on our
own site as well as all these pages. Consequently, there is the possibility
that this site is up and running but the program licensing site is experiencing
difficulties. |
| Why does my sheet flow calculation seem to change on me?
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| The sheet flow computation is based on the two year precipitation. If you change the two year precip, you
will need to go back to all your basins and update the TC calculation. The program will not do that for you! Also,
When you create a new project, there is a prototype record with a sheet flow travel time element in it. That
travel time is probably wrong because it was for a different two year precip value.
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| I just did a pond design where the max elevation that was set for all the
nodes and discharge structures was 1822 ft, but the pond design came back with a peak stage of 1823 ft or higher.
No warning or error message was given, what did the program do?
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Pond Design is based on the programs ability to create a stage-storage and stage-discharge relationship. If you are routing
through the pond and the pond depth is greater than the maximum elevation you specified for the pond, the program can do
one of two things, stop computation and tell you to increase the stage or try increase the stage for you based on
known geometrics. In the case of a trapezoidal shaped pond, the program knows what the side slope is, so there isn't
any ambiguity there. Ditto for most discharge structures.
The problem comes when either the storage or discharge structures
are stage-storage
or stage-discharge rating curves. In that case, the program doesn't really know what the "y" ordinate
of the next stage should be, but it can guess by doing a straight line interpolation of the last two point in your
rating curve.
The lesson learned from this story is that you should always check the peak stage in your pond design. If
it is higher than your maximum elevation, there might be a problem if either the storage or discharge control is a rating curve because the program "guessed" at the volume or
discharge that is above what you originally provided. The linear relationship that was assumed might be a wrong assumption.
We don't think a warning dialog is necessary because the whole point of doing a
pond routing is to see how the pond performs, so you have to look at the peak stage
and peak flow rates. |
| The program appears to have been installed on my machine, but when it starts up
I keep getting messages telling me that it has failed to connect to the MySQL server. |
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StormShed3G needs to authenticate against a server out on the internet. In order for the program
to reach the server, it must get through your firewall. Port 3306 needs to be open.
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While I was creating my conveyance system model, one of my reaches had a large slope (around 35%).
On the conduit constraint tab, the default minimum and maximum slopes were set at 0.5% and 2%.
I ran my model without increasing the maximum slope and got output values.
I went back and set the slope to 99% and the output values did not change.
It doesn’t seem to make any difference whether or not I change the conduit constraint slopes.
Why is that? What is the point of having slope conduit constraints
if they don’t affect the output values?
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The constraints tab only works in the design mode, that is, if you set the pipe slope to zero,
the program will then assume that you want it to attempt to find a slope for the pipe.
If the slope is set to anything else, then the program assumes that is the slope you want the
calculation based on. Ditto for the diameter. That is the reason why I provide a zero Slopes/Diam
dialog box, to make it easier to "reset" those params.
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Where do you get precipitation values to use with the model?
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The best place is your local jurisdiction, the ones telling you that you need to use an event model. However, there
are national locations, presumably where the local jurisdiction got their info. The most well known is
the National Weather Service. For those with
access to GIS (Arc-Info) try the
Precipitation Frequency Data Server.
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| What is the format of the .csv file for importing a stage-volume or area rating curve in StormShed2G? |
Yeah, that seems to be an undocumented secret. Basically, you need a .csv file with stage,volume on each line. The
undocumented part of the format is the first line:
STGSTOR,US,VOL or STGSTOR,US,AREA.
The US is for US units. If you are importing metric data, then it would be SI.
Incidentally, this isn't an issue with 3G because it supports cut and paste from
an Excel table. In Excel, highlight the stage-volume columns and rows, press
control-c to copy it. right mouse click on the 3G input table and select the paste
menu item. |
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Can we get more information on IDF Family and Rational Event Factors? |
Hmm, I didn't think there was too much to say about IDF family, but now that you ask, perhaps the reason I
didn't think there was much to say is because I am an old dog. Before the state came out with their coefficients
for use in the equations, all that was available were the idf charts. The IDF family is just the old chart with
intensities picked off every 5 minutes or whatever the engineer wants to enter. A family corresponds to a chart.
The charts typically contain all the design return frequencies. If you don't like the answers that the coefficients
give you, you could plot the curves for two sets of coefficients, them create design events that are inbetween those
two sets of coefficients, enter the new design events as an idf family.
I tried to expain the event factors right on the dialog. Generally they are all set to one (1). I have them
because in some parts of the country, the jurisdiction want a multiplier added. For example, they might want
the 100 year event to have a safety factor of 1.5 attached to it, but at the same time only want a safety factor
of 1.1 attached to the 25 yr event.
The TC Factor is more interesting. One of the weaknesses of using accumulated travel time from the most distant
upstream catchment to determine the intensity is that it assumes that since it is the most distant point, is
also represents the largest upstream contributing area. That assumption, in turn is based on the assumption
that when the engineer defines his drainage areas, they are all similar in area (thats what you get when you
have academics developing methology). In reality, engineers don't even think about the underlying assumptions,
so it is possible that you would end up with a situation where the most distant upstream runoff being a very small
area, and in fact as one proceeds downstream, all the contributing areas that it picks up are also very small.
Just to exagerate the point, suppose accumulate the travel times of all these small areas 1 mile downstream and
come up with a travel time of 2 hours, that translates to a small intensity. Thats Ok, if that is the point of
analysis, but what if one mile downstream you have a massive area entering your conveyance system with a tc of
only 30 minutes?
The rational procedure of using the longest time of concentration is clearly wrong, all the runoff is really
generated from the massive area with only 30 minutes TC! The TC factor sets the threshold for the decision.
What it is saying is that if the joining area is 90% of the total upstream cumulative area, use it instead of
the cummulative upstream travel time. Being the nice guy that I am, you can change the decision ratio to anything
that you want. The 0.9 ratio that is the default is an arbitrary one that I set and is not based
on any studies that I know of.
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The program seems to hang up when I start it. I have reinstalled, and it still does not start properly. What else can I do?
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3G will automatically load the last project that you worked on. So, if there was something wrong with that project
datafile, it could cause the program to hang before you could do something about it. To force the program to not
load the last project, you will need to clear out the following registry variable:
hkey_current_user/Software/ESI/StormShed3G/LastProjName
Just navigate to the location, double click on the LastProjName variable and clear the field.
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