Compute Drain area using WhiteBox

This function will compute drain area of each segment using WhiteBox algorithms. Confluences nodes are mooved upstream with TNETshape_computeNdAreaDrain().

Usage

TNETshape_computeAreaDrain(path_DEM, path_segments, path_node, export_file,ID_special = NULL)

Arguments

path_DEM

Path to the raster DEM used for drain area calculation.

path_segments

Path to the shapefile with segments to merge.

path_node

Path to the shapefile with all segments nodes.

export_file

Path to the shapefile with results to create.

ID_special

paste to TNETshape_computeNdAreaDrain()

Value

None

Details

Whitebox algorithms use in this function are the following: (in that order)

1 - Prepare the DEM for computations

• wbt_fill_depressions(): To fill all depressions in the shapefile

• wbt_fill_burn(): To burn the river network in the shapefile

2- Compute flow accumulations for each DEM pixel

• wbt_d8_pointer(): To compute the flow direction of each pixel

• wbt_d8_flow_accumulation(): To count how many pixels are upstream

This is used to extract total drain area on each segments

3- Snap nodes on rivers

• TNETshape_computeNdAreaDrain(): To create one node for each segments.

• wbt_snap_pour_points(): Snap on the pixel with the most flow accumulation (to be on a river)

4- Compute sub Watershed drain area (area drain only by the studied segment)

• wbt_watershed(): Compute all sub watershed area

• wbt_raster_area(): convert ID into drain area

• wbt_extract_raster_values_at_points(): Extract D8_flow_accumulation and raster_area on every Nodes, to have total drain area and sub-watershed drain area

This is used to extract sub watershed drain area on each segments

Here is a figure on how sub-watershed area drain are calculated:

See also

TNETshape_computeNdAreaDrain()

Examples

## Read test files
shape_name <- system.file("extdata","TestNetwork_Ardiere.shp", package = "TnetRUI")
shapeND_name <- system.file("extdata","TestNetwork_ND_Ardiere.shp", package = "TnetRUI")
DEM_name <- system.file("extdata","DEM_Ardiere.tif", package = "TnetRUI")

#run computation
result_shape <- "test/TestNetwork_areaDrain.shp"
TNETshape_computeAreaDrain(path_DEM = DEM_name,
                           path_segments = shape_name,
                           path_node = shapeND_name,
                           export_file = result_shape)
#> Warning: cannot create dir 'test/tmp_wbt', reason 'No such file or directory'
#> Warning: `/builds/guillaume.hevin/tnet_rui/public/reference' not recognized as a supported file format. (GDAL error 4)
#> Error in h(simpleError(msg, call)): error in evaluating the argument 'x' in selecting a method for function 'res': Cannot create a RasterLayer object from this file.

data_result <- st_read(result_shape,quiet = TRUE)
#> Error: Cannot open "test/TestNetwork_areaDrain.shp"; The file doesn't seem to exist.
data_result[1:5,c('gid_new','areaTot','areaSbv')]
#> Error: object 'data_result' not found