Sugarcane cultivation requires efficient irrigation, but the area where it can be planted in Madeira is the dry part of the island, where water is scarce. On the opposite side of the island however, water sources are abundant. To bring water from the wet northwest region of Madeira, the Portuguese began building irrigation canals in the 16th century. The canals, called levadas, were created out of necessity and function to this day. New levadas are built to ensure an uninterrupted water supply for residents and agriculture.