EVERYDAY SCIENCE

Detailed explanation-1: -Most rivers begin life as a tiny stream running down a mountain slope. They are fed by melting snow and ice, or by rainwater running off the land. The water follows cracks and folds in the land as it flows downhill. Small streams meet and join together, growing larger and larger until the flow can be called a river.

Detailed explanation-2: -Most rivers begin their life high up in the mountains and hills of the world. There are heavy downpours of rain here and perhaps melting snow. Some of the rain soaks into the ground and the rest runs over the surface, collects in pools, then trickles downhill with the force of gravity.

Detailed explanation-3: -All rivers and streams start at some high point. The high point can be a mountain, hill, or other elevated area. Water from some source like a spring, snow melt, or a lake starts at this high point and begins to flow down to lower points.

Detailed explanation-4: -A tributary is a freshwater stream that feeds into a larger stream or river. The larger, or parent, river is called the mainstem. The point where a tributary meets the mainstem is called the confluence. Tributaries, also called affluents, do not flow directly into the ocean.

Detailed explanation-5: -All rivers have a starting point where water begins its flow. This source is called a headwater. The headwater can come from rainfall or snowmelt in mountains, but it can also bubble up from groundwater or form at the edge of a lake or large pond.