R/03_get_landscape_data.R

In pratikunterwegs/elemove: Mapping Elephant Movements in Kruger NP

#' ---
#' output: html_document
#' editor_options: 
#'   chunk_output_type: console
#' ---
#' 
#' # Getting Background Data
#' 
#' ## Load libraries
#' 
## -----------------------------------------------------------------------------
# load libs
library(sf)
library(rnaturalearth)
library(osmdata)

#' 
#' ## Get Africa landmass from _Natural Earth_
#' 
## -----------------------------------------------------------------------------
# only if local data does not exist
if (!file.exists("data/africa.gpkg")) {
  # get natural earth data
  land <- ne_countries(
    continent = "africa",
    scale = "small",
    returnclass = "sf"
  )
  # save
  st_write(land, "data/africa.gpkg", append = F)
}

#' 
#' ## Get Kruger boundary
#' 
#' The Kruger boundary was provided by SANParks.
#' 
#' ## Get rivers from OSM
#' 
## -----------------------------------------------------------------------------
# if data does not already exist
if (!file.exists("data/rivers_kruger.gpkg")) {
  # kruger bounding box
  kruger <- st_read("data/kruger_clip/kruger_clip.shp")
  q <- opq(bbox = st_bbox(kruger))

  # make query
  query_waterways <- add_osm_feature(q,
    key = "waterway",
    value = c("river", "stream")
  )

  # run query
  rivers_kruger <- osmdata_sf(query_waterways)

  # get only lines
  rivers_kruger <- rivers_kruger$osm_lines

  # assign crs
  st_crs(rivers_kruger) <- 4326

  st_write(
    rivers_kruger,
    "data/rivers_kruger.gpkg"
  )
}

#' 
#' ## Get Waterholes
#' 
#' Waterhole locations were provided by Abi Vanak and Maria Thaker, originally from SANParks.
#' 
#' ## Process LANDSAT data
#' 
## ----eval=FALSE---------------------------------------------------------------
## # do not evaluate because raster is large and not on GH
## # read data
## temp <- raster("data/kruger_landsat5_temp.tif")
## 
## # reproject
## temp_UTM <- projectRaster(
##   from = temp,
##   res = 200,
##   crs = st_crs(32736)$proj4string
## )
## 
## # save to file
## writeRaster(temp_UTM, filename = "data/kruger_temperature_UTM.tif")