priority_flow.river_slope

Apply minimum slope and secondary scaling to river cells.

Line-by-line translation of River_Slope.R (RivSlope) from the R PriorityFlow package. R uses 1-based indexing; we use 0-based.

Functions

riv_slope(→ Dict[str, numpy.ndarray])

Apply minimum slope and secondary scaling to river cells.

Module Contents

priority_flow.river_slope.riv_slope(direction: numpy.ndarray, slopex: numpy.ndarray, slopey: numpy.ndarray, minslope: float, river_mask: numpy.ndarray | None = None, remove_sec: bool = False) → Dict[str, numpy.ndarray][source]

Apply minimum slope and secondary scaling to river cells.

A funtion that will apply a minimum slope threshold for the primary flow direciton along river cells. This function can also limit secondary slopes out of river cells to zero.

Parameters:

  • direction (np.ndarray) – 2D array of D4 flow directions for each cell, using the convention 1 = down, 2 = left, 3 = up, 4 = right.

  • slopex (np.ndarray) – 2D array of face-centered slopes in the x-direction. These should be the same slopes produced by slope_calc_standard.

  • slopey (np.ndarray) – 2D array of face-centered slopes in the y-direction, compatible with slope_calc_standard.

  • minslope (float) – Threshold for slope adjustment. For each river cell, the absolute value of the primary-direction slope is adjusted so that abs(slope) >= minslope.

  • river_mask (np.ndarray, optional) – 2D mask indicating which cells are treated as river cells (typically 1 for river, 0 for non-river). Only these cells are subject to minimum-slope and secondary-slope adjustments.

  • remove_sec (bool, optional) – If True, any secondary outflows from river cells (i.e. positive slopes in non-primary directions) are set to zero. Defaults to False.

Returns:

Dictionary containing:

  • "slopex": adjusted x-direction slope field.

  • "slopey": adjusted y-direction slope field.

  • "adj_mask": mask of cells that were adjusted (non-zero where primary or secondary slopes were modified).

  • "SlopeOutlet": original primary outlet slope at each river cell before adjustment.

  • "SlopeOutletNew": primary outlet slope at each river cell after adjustment.

Return type:

Dict[str, np.ndarray]