Greetings, this four year old thread has been very helpful in my work, and also the paper by Dr. Kopecký. Thank you. Regarding calculation of total catchment area (step 3 above), I am trying to choose the appropriate flow accumulation module. I initially explored the recursive algorithm ta_hydrology 1, but found that the memory demands were prohibitive. I'm not sure if this is a property of the algorithm, but it demands >5x the memroy compared to the top-down implementation. Perhaps a memory leak?...