Some rain water soaks through the ground while some evaporates into gas. The rain water that doesn’t do wither one of these, runs over the ground and ends up in lakes, streams and oceans and is called run off.
The amount of rain and how long it rains for are two factors that affects run off.
Light rain over a long period will have time to soak into the ground, where as heavy rain over a short period of time will not.
Streams are part of river systems. The water comes from rills, gullies and smaller streams that are upstream.
Run off enters streams, and these streams flow into rivers.
A drainage basin is the area of land from which a stream or river collects run off ( like a bathtub). Like water in a bathtub goes towards the drain, water in a river system flows to the main river. The largest one being the Miss. River drainage basin.
Young streams flow swiftly through steep valleys. They may have white water rapids and waterfalls.
Mature streams is the next stage, and it flows more smoothly through its valley. A mature stream erodes along its sides and causes curves to form. Water in a shallow area will move slower, and water in a wider part of the channel will flow faster.
As the curve of a mature stream becomes a broad arc, it is known as a meander
Water that soaks into the ground and collects in the pores of the soil is called ground water
Scientists estimate that 14% of fresh water on Earth exists as ground water.
Soil and rock are permeable because the pore spaces are connected and water can pass through them. Rock and soil that do not have large connected pores are considered impermeable and water cannot pass through them.