import topotoolbox
import matplotlib.pyplot as plt
from matplotlib.colors import ListedColormap
dem = topotoolbox.load_dem("bigtujunga")
fd = topotoolbox.FlowObject(dem)
outlets = fd.getoutlets()
j, i = fd.unravel_index(outlets)
x, y = fd.transform * (i, j)
_ = dem.plot_hs(cmap=ListedColormap([0.9, 0.9, 0.9]), exaggerate=3)
_ = plt.scatter(x, y)
plt.show()