100 yr 24 hour vs 100 yr 2 hour
100 yr 24 hour vs 100 yr 2 hour
(OP)
What design storm would have higher peak flow rate in general, Is it 100 yr 24 hour or 100 yr 2 hour event??
thanks
thanks
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS Come Join Us!Are you an
Engineering professional? Join Eng-Tips Forums!
*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail. Posting GuidelinesJobs |
100 yr 24 hour vs 100 yr 2 hour
|
100 yr 24 hour vs 100 yr 2 hour100 yr 24 hour vs 100 yr 2 hour(OP)
What design storm would have higher peak flow rate in general, Is it 100 yr 24 hour or 100 yr 2 hour event??
thanks Red Flag SubmittedThank you for helping keep Eng-Tips Forums free from inappropriate posts. Reply To This ThreadPosting in the Eng-Tips forums is a member-only feature.Click Here to join Eng-Tips and talk with other members! |
ResourcesWhat is rapid injection molding? For engineers working with tight product design timelines, rapid injection molding can be a critical tool for prototyping and testing functional models. Download Now
The world has changed considerably since the 1980s, when CAD first started displacing drafting tables. Download Now
Prototyping has always been a critical part of product development. Download Now
As the cloud is increasingly adopted for product development, questions remain as to just how cloud software tools compare to on-premise solutions. Download Now
|
RE: 100 yr 24 hour vs 100 yr 2 hour
There is no simple answer, except that generally for a smaller area, a shorter duration storm is more critical and for a larger area, a longer duration is worse.
RE: 100 yr 24 hour vs 100 yr 2 hour
I was going to post after I read the original post, but you sais it quicker and more clearly than I could. I guess ir depends on how much land the "general" owns or is downstream of.
Dick
RE: 100 yr 24 hour vs 100 yr 2 hour
A peak rainfall event does not necessarily equate to the same flood magnitude. For example, if the storm occurs when the drainage area is dry, the flood magnitude may be considerably less than if the drainage area is saturated from previous storms.
RE: 100 yr 24 hour vs 100 yr 2 hour
bimr's reply is appropriate for the Rational method.
For the SCS/NRCS method, the peak RAINFALL intensity should be the same for the 2-hr and 24-hr events. This is because the 24-hr rainfall contains all shorter storms, including the 2-hr storm. And since the 24-hr storm will have a greater rainfall depth, the runoff volume and peak will be greater. This happens because the initial abstraction is satisfied earlier in the storm, resulting in more runoff when the peak hits.
Peter Smart
HydroCAD Software
www.hydrocad.net
RE: 100 yr 24 hour vs 100 yr 2 hour
Every basin is different, and another thing not considered is the orientation of the basin compared with the probable direction of travel of the storm. Thunderstorms traveling up-basin will not produce the flow of one traveling down-basin.
RE: 100 yr 24 hour vs 100 yr 2 hour
RE: 100 yr 24 hour vs 100 yr 2 hour
RE: 100 yr 24 hour vs 100 yr 2 hour
Peter Smart
HydroCAD Software
www.hydrocad.net
RE: 100 yr 24 hour vs 100 yr 2 hour
Psmart - thanks for your response - The uniform hyetograph of the rational method and the SCS extreme peak hyetograph represent the two extremes of possible, but improbable storm profiles. The actual being somewhere in-between. I now understand and agree comment that using the SCS curve the 24 hour event will always give a higher runoff than a 2 hour event regardless of area. (But because the SCS hyetograph represents a much rarer event than 1 in 100 - not true in reality ?)
RE: 100 yr 24 hour vs 100 yr 2 hour
Peter Smart
HydroCAD Software
www.hydrocad.net