wflow_lib Module

wflow_lib - terrain analysis and hydrological library

The goal of this module is to make a series functions to upscale maps (DEM) and to maintain as much of the information in a detailled dem when upscaling to a coarser DEM. These include:

  • river length (per cell)
  • river network location
  • elevation distribution
  • other terrain analysis

the wflow_prepare scripts use this library extensively.

$Author: schelle $ $Id: wflow_lib.py 808 2013-10-04 19:42:43Z schelle $ $Rev: 808 $

wflow_lib.area_percentile(inmap, area, n, order, percentile)

calculates percentile of inmap per area n is the number of points in each area, order, the sorter order of inmap per area (output of areaorder(inmap,area)) n is the output of areatotal(spatial(scalar(1.0)),area)

Input:
  • inmap
  • area map
  • n
  • order (riverorder)
  • percentile
Output:
  • percentile map
wflow_lib.area_river_burnin(ldd, dem, order, Area)

Calculates the lowest values in as DEM for each erea in an area map for river of order order

Input:
  • ldd
  • dem
  • order
  • Area map
Output:
  • dem
wflow_lib.area_riverlength_factor(ldd, Area, Clength)

ceates correction factors for riverlength for the largest streamorder in each area

Input:
  • ldd
  • Area
  • Clength (1d length of a cell (sqrt(Area))
Output:
  • distance per area
wflow_lib.areastat(Var, Area)

Calculate several statistics of Var for each unique id in Area

Input:
  • Var
  • Area
Output:
  • Standard_Deviation,Average,Max,Min
wflow_lib.checkerboard(mapin, fcc)

checkerboard create a checkerboard map with unique id’s in a fcc*fcc cells area. The resulting map can be used to derive statistics for (later) upscaling of maps (using the fcc factor)

Input:
  • map (used to determine coordinates)
  • fcc (size of the areas in cells)
Output:
  • checkerboard type map
wflow_lib.configget(config, section, var, default)

Gets a string from a config file (.ini) and returns a default value if the key is not found. If the key is not found it also sets the value with the default in the config-file

Input:
  • config - python ConfigParser object
  • section - section in the file
  • var - variable (key) to get
  • default - default string
Returns:
  • string - either the value from the config file or the default value
wflow_lib.configsection(config, section)

gets the list of lesy in a section

Input:
  • config
  • section
Output:
  • list of keys in the section
wflow_lib.configset(config, section, var, value, overwrite=False)

Sets a string in the in memory representation of the config object Deos NOT overwrite existing values if overwrite is set to False (default)

Input:
  • config - python ConfigParser object
  • section - section in the file
  • var - variable (key) to set
  • value - the value to set
  • overwrite (optional, default is False)
Returns:
  • nothing
wflow_lib.detdrainlength(ldd, xl, yl)

Determines the drainaige length (DCL) for a non square grid

Input:
  • ldd - drainage network
  • xl - length of cells in x direction
  • yl - length of cells in y direction
Output:
  • DCL
wflow_lib.detdrainwidth(ldd, xl, yl)

Determines width of drainage over DEM for a non square grid

Input:
  • ldd - drainage network
  • xl - length of cells in x direction
  • yl - length of cells in y direction
Output:
  • DCL
wflow_lib.find_outlet(ldd)

Tries to find the outlet of the largest catchment in the Ldd

Input:
  • Ldd
Output:
  • outlet map (single point in the map)
wflow_lib.getRowColPoint(in_map, xcor, ycor)

returns the row and col in a map at the point given. Works but is rather slow.

Input:
  • in_map - map to determine coordinates from
  • xcor - x coordinate
  • ycor - y coordinate
Output:
  • row, column
wflow_lib.getValAtPoint(in_map, xcor, ycor)

returns the value in a map at the point given. works but is rather slow.

Input:
  • in_map - map to determine coordinates from
  • xcor - x coordinate
  • ycor - y coordinate
Output:
  • value
wflow_lib.getcols()

returns the number of columns in the current map

Input:
Output:
  • nr of columns in the current clonemap as a scalar
wflow_lib.getgridparams()

return grid parameters in a python friendly way

Output:

[ Xul, Yul, xsize, ysize, rows, cols]

  • xul - x upper left centre
  • yul - y upper left centre
  • xsize - size of a cell in x direction
  • ysize - size of a cell in y direction
  • cols - number of columns
  • rows - number of rows
wflow_lib.getrows()

returns the number of rows in the current map

Input:
Output:
  • nr of rows in the current clonemap as a scalar
wflow_lib.lddcreate_save(lddname, dem, force, corevolume=1e+35, catchmentprecipitation=1e+35, corearea=1e+35, outflowdepth=1e+35)

Creates an ldd if a file does not exists or if the force flag is used

input:
  • lddname (name of the ldd to create)
  • dem (actual dem)
  • force (boolean to force recreation of the ldd)
  • outflowdepth (set to 10.0E35 normally but smaller if needed)
Output:
  • the LDD
wflow_lib.points_to_map(in_map, xcor, ycor, tolerance)

Returns a map with non zero values at the points defined in X, Y pairs. It’s goal is to replace the pcraster col2map program.

tolerance should be 0.5 to select single points Performance is not very good and scales liniear with the number of points

Input:
  • in_map - map to determine coordinates from
  • xcor - x coordinate (array or single value)
  • ycor - y coordinate (array or single value)
  • tolerance - tolerance in cell units. 0.5 selects a single cell 10 would select a 10x10 block of cells
Output:
  • Map with values burned in. 1 for first point, 2 for second and so on
wflow_lib.riverlength(ldd, order)

Determines the length of a river using the ldd. only determined for order and higher.

Input:
  • ldd, order (streamorder)
Returns:
  • totallength,lengthpercell, streamorder
wflow_lib.sCurve(X, a=0.0, b=1.0, c=1.0)

sCurve function:

Input:
  • X input map
  • C determines the steepness or “stepwiseness” of the curve. The higher C the sharper the function. A negative C reverses the function.
  • b determines the amplitude of the curve
  • a determines the centre level (default = 0)
Output:
  • result
wflow_lib.sCurveSlope(X, a=0.0, b=1.0, c=1.0)

First derivitive of the sCurve defined by a,b,c at point X

Input:
  • X - value to calculate for
  • a
  • b
  • c
Output:
  • first derivitive (slope) of the curve at point X
wflow_lib.snaptomap(points, mmap)

Snap the points in _points_ to nearest non missing values in _mmap_. Can be used to move gauge locations to the nearest rivers.

Input:
  • points - map with points to move
  • mmap - map with points to move to
Return:
  • map with shifted points
wflow_lib.subcatch(ldd, outlet)

Determines a subcatchment map using LDD and outlet(s). In the resulting subcatchment map the i’s of the catchment are determiend by the id’s of the outlets.

Input:
  • ldd
  • Outlet - maps with points for each outlet.
Output:
  • map of subcatchments
wflow_lib.subcatch_order_a(ldd, oorder)

Determines subcatchments using the catchment order

This version uses the last cell BELOW order to derive the catchments. In general you want the _b version

Input:
  • ldd
  • order - order to use
Output:
  • map with catchment for the given streamorder
wflow_lib.subcatch_order_b(ldd, oorder, Largest=False)

Determines subcatchments using the catchment order

This version uses the bottommost cell of order If Largest is true the analysis is only done for the largest basin found in the ldd

Input:
  • ldd
  • oorder - order to use
  • largest - toggle, default = False
Output:
  • map with catchment for the given streamorsder
wflow_lib.upscale_riverlength(ldd, order, factor)

Upscales the riverlength using ‘factor’ The resulting maps can be resampled (e.g. using resample.exe) by factor and should include the accurate length as determined with the original higher resolution maps. This function is depricated, use are_riverlength instead as this version is very slow for large maps

Input:
  • ldd
  • minimum streamorder to include
Output:
  • distance per factor cells