From dd803b191062925eda830543236836e7822fd884 Mon Sep 17 00:00:00 2001 From: Johannes Ranke Date: Thu, 11 Jun 2015 16:57:43 +0200 Subject: Add UK tier 1 drainage PEC calculations --- pkg/R/PEC_sw_drainage_UK.R | 53 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 53 insertions(+) create mode 100644 pkg/R/PEC_sw_drainage_UK.R (limited to 'pkg/R/PEC_sw_drainage_UK.R') diff --git a/pkg/R/PEC_sw_drainage_UK.R b/pkg/R/PEC_sw_drainage_UK.R new file mode 100644 index 0000000..03c56c0 --- /dev/null +++ b/pkg/R/PEC_sw_drainage_UK.R @@ -0,0 +1,53 @@ +# Copyright (C) 2015 Johannes Ranke +# Contact: jranke@uni-bremen.de +# This file is part of the R package pfm + +# This program is free software: you can redistribute it and/or modify it under +# the terms of the GNU General Public License as published by the Free Software +# Foundation, either version 3 of the License, or (at your option) any later +# version. + +# This program is distributed in the hope that it will be useful, but WITHOUT +# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS +# FOR A PARTICULAR PURPOSE. See the GNU General Public License for more +# details. + +# You should have received a copy of the GNU General Public License along with +# this program. If not, see + +#' Calculate initial predicted environmental concentrations in surface water due to drainage using the UK method +#' +#' This implements the method specified in the UK data requirements handbook and was checked against the spreadsheet +#' published on the CRC website +#' +#' @param rate Application rate in g/ha +#' @param interception The fraction of the application rate that does not reach the soil +#' @param Koc The sorption coefficient normalised to organic carbon in L/kg +#' @return The predicted concentration in surface water in µg/L +#' @export +#' @author Johannes Ranke +#' @examples +#' PEC_sw_drainage_UK_ini(100) +PEC_sw_drainage_UK_ini <- function(rate, interception = 0, Koc, + latest_application = NULL, soil_DT50 = NULL) +{ + percentage_lost <- SSLRC_mobility_classification(Koc)[[2]] + amount_available <- rate * (1 - interception) # g/ha + + if (!missing(latest_application)) { + if (missing(soil_DT50)) stop("You need to supply a soil DT50 value") + k = log(2)/soil_DT50 + as.Date(paste(latest_application, "1999"), "%d %B %Y") + + lct <- Sys.getlocale("LC_TIME") + tmp <- Sys.setlocale("LC_TIME", "C") + latest <- as.Date(paste(latest_application, "1999"), "%d %b %Y") + tmp <- Sys.setlocale("LC_TIME", lct) + degradation_time <- as.numeric(difftime(as.Date("1999-10-01"), units = "days", latest)) + amount_available <- amount_available * exp(-k * degradation_time) + } + + volume = 130000 # L/ha + PEC = 1e6 * (percentage_lost/100) * amount_available / volume + return(PEC) +} -- cgit v1.2.1