Answer:
providing a flow of water through the canals
Explanation:
Nan Mandol consists of a series of artificial islands connected by a network of channels, located in the southeast of the island of Pohnpei. Each artificial island was built between the channels and this created the need to create eawalls and breakwaters around those islands to allow access to the ocean via canoes and to allow the ocean water to pass through the channels, cleaning them, that is, eawalls and breakwaters were created so that there would be a flow of water within the channels that connect the islands, preventing them from getting dirty.