Construction of the terraces is carried out with great care and precision. An underground conduit is placed within the fill for drainage purposes. The groups of terraces blanket the mountainsides, following their contours. Above them, rising to the mountain-tops, is the ring of private woods (muyong ), intensively managed in conformity with traditional practices, which recognize a total ecosystem which assures an adequate water supply to keep the terraces flooded. Water is equitably shared, and no single terrace obstructs the flow on its way down to the next terrace below. There is a complex system, of dams, sluices, channels and bamboo pipes, communally maintained, which drain into a stream at the bottom of the valley.