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)
#> 
 Décalage des noeuds           [                    ]   0%
 Décalage des noeuds           [>                   ]   2%
 Décalage des noeuds           [>                   ]   5%
 Décalage des noeuds           [>                   ]   8%
 Décalage des noeuds           [=>                  ]  10%
 Décalage des noeuds           [=>                  ]  12%
 Décalage des noeuds           [==>                 ]  15%
 Décalage des noeuds           [==>                 ]  18%
 Décalage des noeuds           [===>                ]  20%
 Décalage des noeuds           [===>                ]  22%
 Décalage des noeuds           [====>               ]  25%
 Décalage des noeuds           [====>               ]  28%
 Décalage des noeuds           [=====>              ]  30%
 Décalage des noeuds           [=====>              ]  32%
 Décalage des noeuds           [======>             ]  35%
 Décalage des noeuds           [======>             ]  38%
 Décalage des noeuds           [=======>            ]  40%
 Décalage des noeuds           [=======>            ]  42%
 Décalage des noeuds           [========>           ]  45%
 Décalage des noeuds           [========>           ]  48%
 Décalage des noeuds           [=========>          ]  50%
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 Décalage des noeuds           [==========>         ]  55%
 Décalage des noeuds           [==========>         ]  57%
 Décalage des noeuds           [===========>        ]  60%
 Décalage des noeuds           [===========>        ]  62%
 Décalage des noeuds           [============>       ]  65%
 Décalage des noeuds           [============>       ]  68%
 Décalage des noeuds           [=============>      ]  70%
 Décalage des noeuds           [=============>      ]  72%
 Décalage des noeuds           [==============>     ]  75%
 Décalage des noeuds           [==============>     ]  78%
 Décalage des noeuds           [===============>    ]  80%
 Décalage des noeuds           [===============>    ]  82%
 Décalage des noeuds           [================>   ]  85%
 Décalage des noeuds           [================>   ]  88%
 Décalage des noeuds           [=================>  ]  90%
 Décalage des noeuds           [=================>  ]  92%
 Décalage des noeuds           [==================> ]  95%
 Décalage des noeuds           [==================> ]  98%
 Décalage des noeuds           [====================] 100%
#> Problems on drain area calculations was found on 2 segments:
#> 	2 segments have a drainage area exceeding 40% of their upstream segment. (Threshold_limit)
#> All affected segments are saved in Area_problem.shp shapefile.

data_result <- st_read(result_shape,quiet = TRUE)
data_result[1:5,c('gid_new','areaTot','areaSbv')]
#> Simple feature collection with 5 features and 3 fields
#> Geometry type: LINESTRING
#> Dimension:     XY
#> Bounding box:  xmin: 815250.2 ymin: 6562288 xmax: 823552 ymax: 6566542
#> Projected CRS: RGF93 v1 / Lambert-93
#>   gid_new  areaTot areaSbv                       geometry
#> 1  226527   813000  813000 LINESTRING (815339.3 656457...
#> 2  484239  1564300  934300 LINESTRING (819583.5 656236...
#> 3  506993  1151400  409400 LINESTRING (815250.2 656652...
#> 4  521815   824400  317800 LINESTRING (823552 6565477,...
#> 5  719833 55986500  527000 LINESTRING (822789.3 656266...