I am assuming you mean the rivers and rivulets that flow int a bigger river and contribute to its flow. In that case they are called tributaries. If you mean what are the rivers called when they flow into the sea, then they are called delta's or river mouths.
smaller streams or rivers that flow into larger ones are called tributaries
yes. lakes are a source for rivers because they help the water flow most of the time
No, rivers flow into oceans, and "source" implies "from." Sources of rivers are found in the mountains.
Rivers and streams that flow in to a larger river are called tributaries. They all form in the same spot.
In mainland France, there are 119 rivers that flow directly to the Atlantic Ocean, the English Channel, and the Mediterranean Sea. These direct rivers are called fleuve, from the word flow. There are also hundreds of tributaries, which are rivers that do not flow directly, no matter their widths or flow rates. These tributaries are called rivières.Rhone Soane Loire Dordogne Seine Aisne Garronne & many more.
The Estuary.
lava rivers -Your welcome
A dam
The Missouri river's source are at the Gallatin, Madison, and Jefferson Rivers in Montana, and they flow to the Mississippi River, at St. Louis.
The source is the confluence of the Sengge and Gar rivers.
runoff
Small creeks, streams and rivers that flow into larger rivers are called tributaries