Raifall events
Raifall events
(OP)
I want to test my slope model sensitivity to a hypothetical extreme rainfall event.
Is an extreme precipitation event represented by a daily rain amount of 50 mm over 3 consecutive days realistic in Canada and /or the US regions.
Please refer me to a refernce (if possible). Environment Canada website is not explicit enough about this matter.
Also, I could not get what I want from reading several articles in the Climte journals . I have spent the whole day trying to officially find a source justifying my above extreme event assumption which I made just for academic purpose. Thanks for your help
Is an extreme precipitation event represented by a daily rain amount of 50 mm over 3 consecutive days realistic in Canada and /or the US regions.
Please refer me to a refernce (if possible). Environment Canada website is not explicit enough about this matter.
Also, I could not get what I want from reading several articles in the Climte journals . I have spent the whole day trying to officially find a source justifying my above extreme event assumption which I made just for academic purpose. Thanks for your help





RE: Raifall events
In the U.S. one source for extreme rainfall events may be found at the USGS website, using the National Flood Frequency program (NFF). There you will find extreme rainfall amounts based on work by Crippen & Bue.
Also, for the U.S. try googling it.
good luck
RE: Raifall events
RE: Raifall events
RE: Raifall events
Hope this helps.
Jeff
RE: Raifall events
RE: Raifall events
Dear DMcGrath
I need the infilitration as I want to examine how far the phreatic surface level will be influenced by the rainfull event so if the extreme rainfall event is 100 mm/day I am applying it fully as a flow on the surface of the slop neglecting the evaboration oth the influence of the other near surface conditions. Please guide
RE: Raifall events
In a nutshell, heavy, clay soils will have more runoff (less infiltration) and sandy soils will have less runoff and more infiltration. Ground cover (vegetation or bare soil) and slope also influence infiltration. For some background reference, start with the TR-55 method, read Chapter 2.
http://www.info.usda.gov/CED/ftp/CED/tr55.pdf
The TR-55 method calculates what is called the "initial abstraction" which is the first bit of a rain event that does not run off (your infiltration). The Ia is based on the characteristics of the soil (modeled as the curve number (CN)).
This is a bit simplistic, but you can decide how much detail for the infiltration you need.