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Rainfall Intensity

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

idf_v2-00_2010_04_13_301_AB_3016761_VEGREVILLE_CDA.rar
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  • 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

          

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  • 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

          

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