The river is a course of surface waters which has its source and mouth. River water flows in a curved riverbed and is fed with precipitation and smaller tributaries. The river ends its course, flowing into a larger river, sea or ocean. Due to the shape and size of the estuary, we can speak of a narrower, funnel-shaped estuary and a delta composed of a greater number of branches that form a wetland around the estuary. Estuary of a large river is an ideal location for ports that allow for the rapid development of the city.