GEOLOGY

Detailed explanation-1: -The point where a tributary meets the mainstem is called the confluence. Tributaries, also called affluents, do not flow directly into the ocean. Most large rivers are formed from many tributaries. Each tributary drains a different watershed, carrying runoff and snowmelt from that area.

Detailed explanation-2: -Flowing water finds its way downhill initially as small creeks. As small creeks flow downhill they merge to form larger streams and rivers. Rivers eventually end up flowing into the oceans.

Detailed explanation-3: -Together, a river and its tributaries make up a river system. A river system is also called a drainage basin or watershed. A river’s watershed includes the river, all its tributaries, and any groundwater resources in the area. The end of a river is its mouth.

Detailed explanation-4: -One method of classifying streams is through physical, hydrological, and biological characteristics. Using these features, streams can fall into one of three types: perennial, intermittent, and ephemeral.

Detailed explanation-5: -The lower course is the final part of a river, where the gradient and the water velocity decrease. The river no longer has erosion capacity, and the processes that predominate are sedimentation and transport of very fine material.