compute_metrics_precomputed {rdwplus}

Compute spatially explicit watershed attributes for survey sites on streams

Description

Workhorse function for rdwplus. This function computes the spatially explicit landuse metrics in IDW-Plus (Peterson and Pearse, 2017). In contrast to compute_metrics(), this version of the function assumes most of the intermediate data layers (i.e., flow path distance and inverse-distance weight rasters) have been precomputed.

Usage

compute_metrics_precomputed(
  metrics = c("lumped", "iFLO", "iFLS", "HAiFLO", "HAiFLS"),
  landuse,
  sites,
  out_fields,
  watersheds,
  flow_dir,
  flow_acc,
  iEDO_weights,
  iFLO_weights,
  HAiFLO_weights,
  iEDS_weights,
  iFLS_weights,
  HAiFLS_weights,
  percentage = TRUE,
  max_memory = 300
)

Arguments

metrics

A character vector. This vector specifies which metric(s) should be calculated. Your options are lumped, iFLO, iFLS, iEDO, iEDS, HAiFLO and HAiFLS. The default is to calculate the lumped, iFLO, iFLS, HAiFLO, and HAiFLS metrics.

landuse

Names of landuse or landcover rasters in the current GRASS mapset. These can be continuous (e.g., percentage cover or NDVI) or binary, with a value of 1 for cells with a particular land use category and a value of 0 otherwise.

sites

A set of survey sites in the current GRASS mapset.

out_fields

A character vector of output field names to store the metrics. Note that length(out_fields) must be the same as length(landuse) * length(metrics).

watersheds

A vector of watershed raster names in the current GRASS mapset.

flow_dir

Name of a flow direction raster produced by derive_flow in the current GRASS mapset.

flow_acc

Name of a flow accumulation raster produced by derive_flow in the current GRASS mapset.

iEDO_weights

A vector of names of iEDO weight rasters in the GRASS mapset.

iFLO_weights

A vector of names of iFLO weight rasters in the GRASS mapset.

HAiFLO_weights

A vector of names of HAiFLO weight rasters in the GRASS mapset.

iEDS_weights

A vector of names of iEDS weight rasters in the GRASS mapset.

iFLS_weights

A vector of names of iFLS weight rasters in the GRASS mapset.

HAiFLS_weights

A vector of names of HAiFLS weight rasters in the GRASS mapset.

percentage

A logical indicating whether the result should be expressed as a percentage. Defaults to TRUE. Set to FALSE if the landuse/landcover raster is continuous.

max_memory

Max memory used in memory swap mode (MB). Defaults to 300.

Value

A sf object of the snapped survey sites that also contains the computed landscape metrics.

References

Peterson, E.E. & Pearse, A.R. (2017). IDW-Plus: An ArcGIS toolset for calculating spatially explicit watershed attributes for survey sites. JAWRA, 53(5), 1241-1249.

Examples

# Will only run if GRASS is running
# You should load rdwplus and initialise GRASS via the initGRASS function
if(check_running()){
# Retrieve paths to data sets
dem <- system.file("extdata", "dem.tif", package = "rdwplus")
lus <- system.file("extdata", "landuse.tif", package = "rdwplus")
sts <- system.file("extdata", "site.shp", package = "rdwplus")
stm <- system.file("extdata", "streams.shp", package = "rdwplus")

# Set environment
set_envir(dem)

# Get other data sets (stream layer, sites, land use, etc.)
raster_to_mapset(lus)
vector_to_mapset(c(stm, sts))

# Reclassify streams
out_stream <- paste0(tempdir(), "/streams.tif")
rasterise_stream("streams", out_stream, TRUE)
reclassify_streams("streams.tif", "streams01.tif", overwrite = TRUE)

# Burn in the streams to the DEM
burn_in("dem.tif", "streams01.tif", "burndem.tif", overwrite = TRUE)

# Fill dem
fill_sinks("burndem.tif", "filldem.tif", "fd1.tif", "sinks.tif", overwrite = TRUE)

# Derive flow direction and accumulation grids
derive_flow("dem.tif", "fd.tif", "fa.tif", overwrite = T)

# Derive a new stream raster from the FA grid
derive_streams("dem.tif", "fa.tif", "new_stm.tif", "new_stm", min_acc = 200, overwrite = T)

# Recode streams
reclassify_streams("new_stm.tif", "null_stm.tif", "none")

# Snap sites to streams and flow accumulation
snap_sites("site", "new_stm.tif", "fa.tif", 2, "snapsite", T)

# Get watersheds
get_watersheds("snapsite", "fd.tif", "wshed.tif", T)

#  Get pour points
coord_to_raster("snapsite", which = 1, out = "pour_point")

# Get iFLO weights
compute_iFLO_weights(
"pour_point", 
"wshed.tif", 
"null_stm.tif", 
"fd.tif", 
"fl_outlet.tif", 
"iFLO_weights.tif", 
idwp = -1, 
remove_streams = FALSE
)

# Get iFLS weights
compute_iFLS_weights(
"new_stm.tif", 
"null_stm.tif", 
"fd.tif", 
"fl_streams.tif", 
"iFLS_weights.tif", 
idwp = -1, 
watershed = "wshed.tif", 
remove_streams = FALSE, 
overwrite = T
)

# Compute metrics for this site
compute_metrics_precomputed(
  metrics = c("iFLO", "iFLS"),
  landuse = "landuse.tif",
  sites = "snapsite",
  out_fields = c("iFLO", "iFLS"),
  watersheds = "wshed.tif",
  iFLO_weights = "iFLO_weights.tif",
  iFLS_weights = "iFLS_weights.tif",
  flow_dir = "fd.tif",
  flow_acc = "fa.tif"
)
}