Time of Concentration / Peak Runoff 1

[Rookie2]

I'm confused, please help. Why is it that as time of concentration for a watershed goes up, peak flow goes down?
And does it make sense to split a relatively small watershed(<100ac)into subwatersheds with different time of concentrations and combine hydrographs? Does this assume that a storm with different rainfall intensities is occurring at the same time? TIA

 

[RWF7437]

srtlaw,

Try this website:

http://www.cee.ucf.edu

 

[Rookie2]

Russ, You may be interested to know, or you may already be aware of it, but NRCS now has a windows based version of TR-55, which has expanded it's rainfall distributions. It now has a NM rainfall distribution and also allows you to enter historical storm events. Haven't used it yet, but it looks like a nice program. You can download it on their website.
Thought it might interest you.

 

[RWF7437]

Thanks Rookie2,

I'll check out the NRCS website. Wyoming has also developed their own rainfall distributions. I live and work in Oregon and have for 34 years. Still, we're backward here and have no such developments to report. Some of us only heard about rain last week!

Thanks again,

Russ

 

[Rookie2]

Sure thing, but I better clarify. I don't think the NM stands for New Mexico (I may be wrong). What it stands for I have no idea, I can't find it in the attached documentation. But it's worth a look.

 

[RWF7437]

Thanks Rookie2,

This thread has become way too long for me. I've learned a lot. But, at the end, I can only quote Henry David Thoreau ( which he pronouced like thourough )

&quot; The mass of men lead lives of quiet desperation.&quot;

Good luck in your career. Keep asking questions. They don't always lead to answers but to ask them is NOT wrong.

later and luck,

Russ