UKFE (version 0.4.0)

DDFExtract: Derive and plot rainfall Depth Duration Frequency curves.

Description

Derive and plot rainfall Depth Duration Frequency curves from an input of rainfall data.

Usage

DDFExtract(x, Plot = TRUE, main = NULL, Truncate = TRUE)

Value

A dataframe with hours (1 to 96) in the first column then depths associated with a range of return periods (2 to 1000) in the remaining nine columns. If Plot = TRUE, a plot of the DDF curves is also returned.

Arguments

x

A data.frame with POSIXct in the first column and rainfall in the second. The data must have an hourly or sub-hourly sampling rate.

Plot

Logical argument with a default of TRUE. If TRUE, the DDF curves are plotted.

main

Title for the plot (character string). The default is no title.

Truncate

Logical argument with a default of TRUE. If TRUE the extraction of annual maximum process truncates the data to incorporate only full hydrological years. If there is significant rainfall within a partial year it will not be included unless Truncate = FALSE. If Truncate = FALSE, ensure that there are at least 92 hours of data available in the partial years or the function will fail.

Author

Anthony Hammond

Details

The function works by extracting the annual maximum sample (by hydrological year - starting Oct 1st) of rainfall for a range of sliding durations (1 hour to 96 hours). It then calculates the median annual maximum rainfall depth (RMED) and a GEV growth curve for each duration. To ensure RMED increases with duration a power curve is fit as a function of duration to provide the final RMED estimates. Then the average growth factor for each return period (across the durations) is assumed.

Examples

# We'll extract all available 15 minute rainfall from the St Ives (Cambridgeshire)
#rain gauge (WISKI ID = 179365).
if (FALSE) StIves <- GetDataEA_Rain(WISKI_ID = "179365", Period = "15Mins")
#Then apply the DDF function.
if (FALSE) DDFExtract(StIves)