Function to compute flood extent or flood duration SpatRaster along the German federal waterways Elbe and Rhine using the 1d water level algorithms hyd1d::waterLevel() and hyd1d::waterLevelPegelonline()

Computes flood extent, if length(seq) equals 1, or flood duration for the active floodplains along the German federal waterways Elbe and Rhine based on 1d water levels computed by waterLevel or waterLevelPegelonline provided by package hyd1d.

Usage

flood3(x, seq, filename = "", ...)

Arguments

x

has to by type SpatRaster and has to include both input raster layers csa (cross section areas) and dem (digital elevation model). To compute water levels along the River Elbe x has to be in the coordinate reference system ETRS 1989 UTM 33N, for River Rhine in ETRS 1989 UTM 32N. Other coordinate reference systems are not permitted.

seq

has to be type c("POSIXct", "POSIXt") or Date and have a length larger than 0. If seq is type c("POSIXct", "POSIXt"), values must be in the temporal range between 31 days ago (Sys.time() - 2678400) and now (Sys.time()). Then waterLevelPegelonline is used internally for the water level computations. If seq is type Date, values must be in the temporal range between 1960-01-01 and yesterday (Sys.Date() - 1) and waterLevel is used internally.

filename

supplies an optional output filename and has to be type character.

...

additional arguments as for writeRaster.

Value

SpatRaster object with flood duration in the range of [0, length(seq)].

Details

For every time step provided in seq, flood3() computes a 1d water level along the requested river section. This 1d water level is transfered to a wl (water level) raster layer, which is in fact a copy of the csa (cross section areas) layer, and then compared to the dem (digital elevation model) layer. Where the wl layer is higher than the dem, layer flood duration is increased by 1.

References

Weber A (2022). “Flood durations and potential natural vegetation distribution on the floodplains of River Rhine and River Elbe, Germany.” doi:10.1594/PANGAEA.948042 .

Weber A (2023). “Flood durations of the year 2022 on the floodplains of River Rhine and River Elbe, Germany.” doi:10.1594/PANGAEA.961117 .

See also

waterLevel, waterLevelPegelonline, writeRaster, terraOptions

Examples

# \donttest{
  options("hydflood.datadir" = tempdir())
  options("timeout" = 200)
  library(hydflood)
  
  # import the raster data and create a raster stack
  c <- st_crs("EPSG:25833")
  e <- ext(309000, 310000, 5749000, 5750000)
  x <- hydSpatRaster(ext = e, crs = c)
  
  # create a temporal sequence
  seq <- seq(as.Date("2016-12-01"), as.Date("2016-12-31"), by = "day")
  
  # compute a flood duration
  fd <- flood3(x = x, seq = seq)
# }