Python--利用pysheds进行集水区提取

本文使用pysheds的包，记录一下参照官方步骤提取积水区域，最后结果生成shp:

from pysheds.grid import Grid
#导入数据
dem_path = r'D:\data\RASTER\Raster.tif'
grid = Grid.from_raster(dem_path)
dem = grid.read_raster(dem_path)

# Condition DEM
# ----------------------
# Fill pits in DEM
pit_filled_dem = grid.fill_pits(dem)

# Fill depressions in DEM
flooded_dem = grid.fill_depressions(pit_filled_dem)
    
# Resolve flats in DEM
inflated_dem = grid.resolve_flats(flooded_dem)
# Determine D8 flow directions from DEM
# ----------------------
# Specify directional mapping
dirmap = (64, 128, 1, 2, 4, 8, 16, 32)
    
# Compute flow directions
# -------------------------------------
fdir = grid.flowdir(inflated_dem, dirmap=dirmap)

# Calculate flow accumulation
# --------------------------
acc = grid.accumulation(fdir, dirmap=dirmap)

# Delineate a catchment
# ---------------------
# Specify pour point
x, y = 106.81, 27.02

# Snap pour point to high accumulation cell
x_snap, y_snap = grid.snap_to_mask(acc > 1000, (x, y))

# Delineate the catchment
catch = grid.catchment(x=x_snap, y=y_snap, fdir=fdir, dirmap=dirmap, 
                       xytype='coordinate')

# Crop and plot the catchment
# ---------------------------
# Clip the bounding box to the catchment
grid.clip_to(catch)
clipped_catch = grid.view(catch)

#Result to ShapeFile
import fiona

# Create view
catch_view = grid.view(catch, dtype=np.uint8)

# Create a vector representation of the catchment mask
shapes = grid.polygonize(catch_view)

# Specify schema
schema = {
        'geometry': 'Polygon',
        'properties': {'LABEL': 'float:16'}
}

# Write shapefile
with fiona.open(r'D:\data\vector\catchment.shp', 'w',
                driver='ESRI Shapefile',
                crs=grid.crs.srs,
                schema=schema) as c:
    i = 0
    for shape, value in shapes:
        rec = {}
        rec['geometry'] = shape
        rec['properties'] = {'LABEL' : str(value)}
        rec['id'] = str(i)
        c.write(rec)
        i += 1

结果的准确度并没有去做对比，本文只是记录了用开源方案快速提取集水区的一条路线，之前一直使用Arcgis来完成相关工作，但是在开源道路上，后端上一直没用到合适的路线，仅此作为记录。

最后附上原作相关地址：

@misc{bartos_2020,
    title  = {pysheds: simple and fast watershed delineation in python},
    author = {Bartos, Matt},
    url    = {https://github.com/mdbartos/pysheds},
    year   = {2020},
    doi    = {10.5281/zenodo.3822494}
}