THE idea came from the mouth of the Progo River, Yogyakarta. Feriyonika, 22, discovered that the trees around this area of the river have been converted to residential districts, rice fields and neglected sites. The trees that serve to contain the water along the Progo River are diminishing, thus creating a flood-prone area at the river’s mouth in the event of heavy rain.

Even though the areas of the Progo River—that rises from Mount Merapi