reservoir_outlet: Determine outlet coordinates of reservoirs
In tpilz/LUMP: Landscape Unit Mapping Program for R

reservoir_outlet

R Documentation

Determine outlet coordinates of reservoirs

Description

Takes a flow accumulation raster (or DEM for computation) and reservoir vector file from a GRASS location and estimates the outlet coordinates of each reservoir polygon. Can be run before reservoir_strategic to produce the required input. May also be used to provide outlet points for subbasin delineation.

Usage

reservoir_outlet(flowacc = NULL, dem = NULL, res_vct = NULL,
  outlets_vect = NULL, keep_temp = FALSE, overwrite = FALSE,
  silent = F)

Arguments

`flowacc`	Flow accumulation raster in GRASS location used for determination of reservoir outlets (= highest accumulation value). Set to `NULL` if it should be calculated based on a DEM. Default: `NULL`.
`dem`	Digital elevation model in GRASS location used for calculation of flow accumulation if no flow accumulation raster is given. Default: `NULL`.
`res_vct`	Reservoir vector file (polygon) in GRASS location. For each polygon coordinates of the outlet (cell with highest flow accumulation) are determined. Needs at least the column `res_id` (integer) as reservoir identifier. If there are no columns `elevation` (double) and `area` (double) [hectars], they will be added.
`outlets_vect`	Output: Name of vector file of outlet locations to be exported to GRASS location. Same fields as `res_vct`, fields `res_id`, `elevation` and `area` may have been added.
`keep_temp`	`logical`. Set to `TRUE` if temporary files shall be kept in the GRASS location, e.g. for debugging or further analyses. Default: `FALSE`.
`overwrite`	`logical`. Shall output of previous calls of this function be deleted? If `FALSE` the function returns an error if output already exists. Default: `FALSE`.
`silent`	`logical`. Shall the function be silent (also suppressing warnings of internally used GRASS functions)? Default: `FALSE`.

Value

Function returns nothing, but produces outlets_vect. WARNING: Up to version 2.5.0 this function returned a SpatialPoints object with the outlet coordinates.

Note

Prepare GRASS location and necessary files in advance and start GRASS session in R using initGRASS. Location should not contain any maps ending on *_t as these will be removed by calling the function to remove temporary maps.

Internal operations require a non-dbf datatabes driver (SQLite, PostgreSQL, MySQL, ODBC, ...). Automatic switiching to sqlite will be attempted.

res_vct must not contain a column cat_new as this will be the new identifier column for outlets_vect.

Check the results by investigating vector file with outlet points written to GRASS location. Due to small projection inaccuracies between the DEM / flow accumulation raster and the reservoir vector file, calculated outlet locations might more or less deviate from true locations!

Can be run before reservoir_strategic.