1. Introduction
This vignette is a short tutorial to the usage and functionalists of AquaBEHER R package. It is directed to first-time package users who are familiar with the basic concepts of R. The vignette presents the use of several key functions of the package, some useful hints and guidelines. AquaBEHER computes and integrates daily reference evapotranspiration (Eto) and a soil water balance model to estimate parameters of crop and soil water balances for agricultural crops. Using the computed daily soil water balance parameters, the package can estimates the rainy season calendar (Onset, Cessation and Duration) based on agroclimatic approach for a predefined window.
2. Installation and Loading
Installing the latest development version from the online repository using the devtools package. Note that to utilize the full functionality of devtools on Windows, Rtools must be installed.
# install.packages("devtools")
# devtools::install_github("RobelTakele/AquaBEHER", dependencies = TRUE, type = "source",
# build_manual = TRUE, build_vignettes = TRUE)
library(AquaBEHER)
library(ggplot2)3. Required Climate Data
The methods for calculating evapotranspiration from meteorological data require various physical parameters. Some of the data are measured directly in weather stations. Other parameters are related to commonly measured data and can be derived with the help of a direct or empirical relationship.
The meteorological factors determining evapotranspiration are weather parameters which provide energy for vaporization and remove water vapor from the evaporating surface. The principal weather parameters to consider are presented below.
- Maximum temperature
- Minimum temperature
- Solar radiation
- Dew point temperature or relative humidity
- Wind speed
In addition, georeferenced information on the location of the climate record is required:
- Latitude
- Longitude
- Elevation
data(AgroClimateData)
str(AgroClimateData)
#> 'data.frame': 14975 obs. of 14 variables:
#> $ GridID: chr "MOZ0007149" "MOZ0007149" "MOZ0007149" "MOZ0007149" ...
#> $ Lat : num -15.1 -15.1 -15.1 -15.1 -15.1 ...
#> $ Lon : num 39.3 39.3 39.3 39.3 39.3 ...
#> $ Elev : num 392 392 392 392 392 ...
#> $ WHC : num 97.8 97.8 97.8 97.8 97.8 ...
#> $ Year : num 1982 1982 1982 1982 1982 ...
#> $ Month : num 1 1 1 1 1 1 1 1 1 1 ...
#> $ Day : num 1 2 3 4 5 6 7 8 9 10 ...
#> $ Rain : num 0 0 0 1.91 0 ...
#> $ Tmax : num 32.2 33.1 33.5 32.8 32.7 ...
#> $ Tmin : num 23.1 23.1 23.1 23.6 22.8 ...
#> $ Rs : num 23.9 26.4 25 24.2 23.4 ...
#> $ Tdew : num 20.2 20.5 20.5 20.8 21.4 ...
#> $ Uz : num 4.72 4.28 3.62 2.54 1.48 ...
head(AgroClimateData)
#> GridID Lat Lon Elev WHC Year Month Day Rain
#> 1 MOZ0007149 -15.09238 39.2519 392.1337 97.84914 1982 1 1 0.000000
#> 2 MOZ0007149 -15.09238 39.2519 392.1337 97.84914 1982 1 2 0.000000
#> 3 MOZ0007149 -15.09238 39.2519 392.1337 97.84914 1982 1 3 0.000000
#> 4 MOZ0007149 -15.09238 39.2519 392.1337 97.84914 1982 1 4 1.907393
#> 5 MOZ0007149 -15.09238 39.2519 392.1337 97.84914 1982 1 5 0.000000
#> 6 MOZ0007149 -15.09238 39.2519 392.1337 97.84914 1982 1 6 0.000000
#> Tmax Tmin Rs Tdew Uz
#> 1 32.24396 23.11500 23.86698 20.21160 4.723783
#> 2 33.07202 23.12585 26.38375 20.48284 4.279407
#> 3 33.49679 23.12602 25.00704 20.45689 3.622179
#> 4 32.76818 23.60351 24.16475 20.83896 2.535047
#> 5 32.65872 22.79294 23.44483 21.36882 1.477617
#> 6 31.80630 22.43975 21.99277 21.29297 1.9534154. Potential Evapotranspiration
For many agricultural applications, it is relevant to get an estimate of the potential evapotranspiration (PET). Different methods are developed for estimating Eto. Most of them use empirical equations to determine the value of PET from weather variables. The AquaBEHER package provides options for estimating reference evapotranspiration (Eto) using the FAO Penman-Monteith, Priestley Taylor and Hargreaves-Samani formulations.