Distance to river network

[MauKruisheer]

My apologies for opening this issue as I don't know how else to do this, but I was wondering if the pyfldir toolkit can be used to calculate the distance to a river network? I've been desperately looking for an open-source tool to do this. So a method that uses a flow direction raster to calculate the flow distance to the nearest stream.

[DirkEilander]

I think pyflwdir can help you here. It has the stream_distance method for that, see example below based on the "rhine_d8.tif" arcgis D8 raster in the notebooks folder of this repository:

import rasterio
import pyflwdir

# read and parse D8 flow direction data
with rasterio.open("rhine_d8.tif", "r") as src:
    flw = pyflwdir.from_array(
        src.read(1),
        ftype="d8",
        transform=src.transform,
        latlon=src.crs.is_geographic,
    )

# stream defined based on upstream area threshold
stream = flw.upstream_area(unit="km2") > 100  
# calculate distance to the nearest stream following the D8 flow direction
distance_to_stream = flw.stream_distance(unit="m", mask=stream)

[DirkEilander]

I have not seen this error before. In which function do you get the error? If you can share your code and data with me I'll try to investigate it further.

from @MauKruisheer: Thanks for your help! I got it to work for a small DEM, but ran into the following error when using the same code on a larger, 3 arc-second DEM when trying to create a FlowDir raster:

TypingError: No implementation of function Function(<built-in function heappush>) found for signature:

heappush(list(Tuple(int16, uint32, uint32))<iv=None>, Tuple(int64, uint32, uint32))

There are 2 candidate implementations:

  - Of which 2 did not match due to:

  Overload in function 'heappush': File: numba\cpython\heapq.py: Line 150.

    With argument(s): '(list(Tuple(int16, uint32, uint32))<iv=None>, Tuple(int64, uint32, uint32))':

   Rejected as the implementation raised a specific error:

     TypingError: heap type must be the same as item type

  raised from C:\Users\maukr\anaconda3\envs\52waste\lib\site-packages\numba\cpython\heapq.py:119

During: resolving callee type: Function(<built-in function heappush>)
During: typing of call at C:\Users\maukr\anaconda3\envs\52waste\lib\site-packages\pyflwdir\dem.py (106)

[DirkEilander]

Closing this issue as the original request has been answered. If the numba error with your large dataset is not solved please open a new issue and if possible provide a minimal reproducible example (with data) in order to debug the error.

EDIT: your error could be related to the used numba version, see also #6. Could you try updating your numba library to see if that solves the error?