answers: A tributary or affluent
context: Inflow (hydrology) In hydrology, the inflow of a body of water is the source of the water in the body of water. It can also refer to the average volume of incoming water in unit time. It is contrasted with outflow. All bodies of water have multiple inflows, but often, one inflow may predominate and be the largest source of water. However, in many cases, no single inflow will predominate and there will be multiple primary inflows. For a lake, the inflow may be a river or stream that literally flows into the lake. Inflow may also be, strictly speaking, </s> Headwater areas are the upstream areas of a watershed, as opposed to the outflow or discharge of a watershed. The river source is often but not always on or quite near the edge of the watershed, or watershed divide. For example, the source of the Colorado River is at the Continental Divide separating the Atlantic Ocean and Pacific Ocean watersheds of North America. A "river" is considered a "linear" geographic feature, with only one mouth and one source. For an example, note how the Mississippi River and Missouri River sources are officially defined: The verb "rise" can be used to </s> Tributary A tributary or affluent is a stream or river that flows into a larger stream or main stem (or parent) river or a lake. A tributary does not flow directly into a sea or ocean. Tributaries and the main stem river drain the surrounding drainage basin of its surface water and groundwater, leading the water out into an ocean. A confluence, where two or more bodies of water meet together, usually refers to the joining of tributaries. The opposite to a tributary is a distributary, a river or stream that branches off from and flows away from the main
question: a small river or stream flowing into a large river