When the principal mode of transportation is walking or boating, low flat land close to the river is chosen first and has the most value.
Although one would expect them to be in better shape due to all that walking, maybe modern, Western values will impart themselves on these folks and they will grow up and not just out.
It really seems densely populated. Is their entire life centered on the river?
My point was not to build landslide-prone hillside cities (a la Californica). Rather, to -- at least -- provide easily-accessible refuge routes. After all, you don't have to climb but few feet to escape a tsunami...
I see nothing of that sort on Sulawesi... And, I don't expect them to build them -- even after this disaster...
TXnMA