independentEvents function

Independent high- or low-flow events

Finds independent events greater than or less than a specified criterion. High (or low) -flow days occurring on consecutive days are considered part of one event. This function can be used to find events exceeding 2- or 10- year return levels (as calculated in lp3Events function, for example), or to find residual flows of a certain magnitude.

independentEvents(cutoff.val, data, data.column, below.cutoff=FALSE)

Arguments

• cutoff.val: Numeric specifying event criterion.
• data: Data matrix or data frame with one column of streamflow data.
• data.column: Numeric; specifies column in which to look for events.
• below.cutoff: Logical. TRUE to find events less than the cutoff.val and FALSE to find events greater than the cutoff.val.

Returns

A data.frame with columns - events.starts: Index of event start.

• events.ends: Index of event end.

• events.duration: Length (days) of event.

• extreme.this.events: Maximum or minimum flow for this event.

• ind.extreme: Index of maximum or minimum flow for this event. If extreme is not unique, the chronologically first index is given.

• ...: All columns of original data, corresponding to max or min flow. These columns will have the same column names as the original data.

• duplicates: 0 if the extreme is unique, 1 if it is not unique.

Examples

data(sycamore)
syc.sf<-asStreamflow(sycamore)
#find 10-year flood
q10<-lp3Events(syc.sf)$Q10

#find all events greater than 10-year flood
independentEvents(q10,syc.sf$data, data.col=8 , below.cutoff=FALSE)

See Also

lp3Events