I would do modeling for storm system and would use CivilStorm or SewerGEMS, is anybody able to explain me how to generate the Rainfall Intensity (mm/hour) to use it in the model (or generate hyetograph)? the method suggested is "Chicago 100 Yr storm Method" so how can I generate the rainfall intensity for 24 hours and use it in the model??
as I know the formula is
where
i = average rainfall intensity (mm/hr or inch/hr) td = storm duration (minutes) a,b,c = constants dependent on the units employed and the return frequency of the storm.
is that what I should use? if yes how can I obtain those parameter? is there any xls file developed to help? any example??
Note: The Rainfall data is attached
Mohamad,
Juan Carlos gives some good info about converting recorded rainfall data into IDF curves, but I think that has already been done and is given in table 2b in the file you attached.
Do you want to use the attached data to create a design storm hyetograph (rainfall versus time)?
In general here are your options to do that in SewerGEMS:
- Add a new 'Time-Depth' or 'Time-Intensity' storm event group, then add a new storm event from a 'Dimensionless Curve'. The dimensionless curve you select should be relevant to your local area, and the total storm depth for, say, a 100 Yr, 24 Hr storm can come from the attached data
- Add the IDF data you attached (from table 2b) to a new user defined IDF Table. Then create a new Time-Depth event 'From IDF'. This will build up a hyetograph using the IDF data as input.
I don't know what the "Chicago 100 Yr Storm Method" is, but it is possible that they are referring to a dimensionless curve from the Chicago area. We have some built in curves from 'Bulletin 71' (www.isws.illinois.edu/.../ISWSB-71.pdf) which may be appropriate.
Regards,
Mal
Mal,
you are at the point, I have already the IDF in table 2b, and I would go for the second option you suggested, would you please explain and drive me after I Add the IDF data you attached (from table 2b) to a new user defined IDF Table; how to create a new Time-Depth event 'From IDF' and how hyetograph will be built???
for Chicago Method; here is what I mean
http://www.miduss.com/theory-Derivation-Chicago-Storm.htm
Any suggestion how to do that??? is there any excel sheet could help?