rdwplus (version 0.1.0)

compute_metrics: 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).

Usage

compute_metrics(
  metrics = c("iFLO", "iFLS", "HAiFLO", "HAiFLS"),
  landuse,
  sites,
  elevation,
  flow_dir,
  flow_acc,
  streams,
  idwp = -1,
  max_memory = 300,
  lessmem = FALSE
)

Value

A data.frame object, which is a table with rows corresponding to those from the sites argument plus columns for each combination of land use and metric type.

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 all except for lumped, iEDO and iEDS.

landuse

Names of binary landuse or landcover rasters in the current GRASS mapset for which spatially explicit watershed metrics should be computed. Binary means land use cells are coded 1 and all other cells are given a value of 0.

sites

A shapefile of sites; either a file path to the shapefile or a SpatialPoints* object.

elevation

File name of a filled (hydrologically-conditioned) digital elevation model in the current GRASS mapset.

flow_dir

A 'Deterministic 8' (D8) flow direction grid derived from derive_flow.

flow_acc

File name of a flow accumulation grid derived from derive_flow in the current GRASS mapset.

streams

File name of a streams raster in the current GRASS mapset. Optional if you are not asking for the iFLS, iEDS, and/or HAiFLS metrics.

idwp

The inverse distance weighting parameter. Default is -1.

max_memory

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

lessmem

A logical indicating whether to use the less memory modified watershed module. Defaults to FALSE.

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
if(check_running()){
# Load data set
dem <- system.file("extdata", "dem.tif", package = "rdwplus")
landuse <- system.file("extdata", "landuse.tif", package = "rdwplus")
sites <- system.file("extdata", "site.shp", package = "rdwplus")
stream_shp <- system.file("extdata", "streams.shp", package = "rdwplus")

# Set environment parameters and import data into GRASS
set_envir(dem)
raster_to_mapset(rasters = c(dem, landuse), as_integer = c(FALSE, TRUE),
overwrite = TRUE)
vector_to_mapset(vectors = c(sites, stream_shp), overwrite = TRUE)

# Create binary stream
out_name <- paste0(tempdir(), "/streams_rast.tif")
rasterise_stream("streams", out_name, overwrite = TRUE)
reclassify_streams("streams_rast.tif", "streams_binary.tif", 
out_type = "binary", overwrite = TRUE)

# Burn dem 
burn_in(dem = "dem.tif", stream = "streams_binary.tif", 
out = "dem_burn.tif", burn = 10, overwrite = TRUE)

# Fill sinks
fill_sinks(dem = "dem_burn.tif", out = "dem_fill.tif", size = 1, overwrite = TRUE)

# Derive flow accumulation and direction grids
derive_flow(dem = "dem_fill.tif", flow_dir = "fdir.tif", 
flow_acc = "facc.tif", overwrite = TRUE)

# Snap sites to pour points (based on flow accumulation)
out_snap <- paste0(tempdir(), "/snapsite.shp")
snap_sites(sites = "site", flow_acc = "facc.tif", max_move = 2, 
out = out_snap, overwrite = TRUE)

# Compute metrics
lu_metrics <- compute_metrics(metrics = c("iFLO", "iFLS", "HAiFLO", "HAiFLS"), 
                              landuse = "landuse.tif",
                              sites =  out_snap, 
                              elevation = "dem_fill.tif", 
                              flow_dir = "fdir.tif", 
                              flow_acc = "facc.tif", 
                              streams = "streams_rast.tif")
print(lu_metrics)
}