Type II and Type III 24 hour rainfall distributions 1

[orshii]

My results from using either type II or type III rainfall distributions are coming out the same when I use the Hydrocad program. Is this right or what do I need to do to correct this?

 

[psmart]

Exactly what "results" are you comparing? Peak runoff? Runoff volume? Pond outflow? Please be specific.

A Type II storm will produce a higher peak runoff than the Type III, especially for small Tc values. Runoff volume will be the same, regardless of the rainfall distribution. (The volume is strictly a function of the curve number and total rainfall depth.)

 

[orshii]

Thanks for your excellent clarification.

Orshii