Here is code for rain shadow

[SophieRothman]

for i in range(10):
D = (P0 + aP0z) 0.0005
fr3.run_one_step() # Flow Accumulator
sp3.run_one_step(dt) # StreamPower FastScape Eroder
ld.run_one_step(dt) # Linear Diffuser
z[mg3.core_nodes] += U * dt
mg3.at_node["water__unit_flux_in"][mg3.y_of_node>=2+mg3.y_of_node[z==max(z)]]=P0/2
D[mg3.y_of_node>=2+mg3.y_of_node[z==max(z)]] = (P0/2) 0.001np.ones(len( D[mg3.y_of_node>=10+mg3.y_of_node[z==max(z)]]))
mg3.at_node["water__unit_flux_in"][mg3.y_of_node<10+mg3.y_of_node[z==max(z)]]=P0 + aP0*z[mg3.y_of_node<10+mg3.y_of_node[z==max(z)]]

imshow_grid(mg3,"topographic__elevation")