The Force of Water

The Force of Water

Introduction Water, Earth's most important resource, is a mighty force. It covers most of Earth and is always at work changing Earth's surface. Plants, animals, and humans need water to survive. So, we have to take care of the water for the good of the Earth.

Water is found above ground in lakes, ponds, rivers, streams, and oceans. It is also found below ground, between rocks and sand. This water is called groundwater. The air also holds water as clouds and an invisible gas called water vapor.

Water on the Move Much of Earth's water is on the move. Water falls from clouds as rain and snow and drains into streams and rivers. The land surrounding streams and rivers is called a watershed. Streams flow into small rivers, and small rivers flow into bigger rivers. The smaller streams and rivers that flow into bigger rivers are called tributaries. Over time, much of the water that flows into streams and rivers reaches the oceans.

Water as a Force As water flows in rivers and streams, it picks up dirt, sand, and rocks. The dirt and sand carried by water are called sediment. Sediment helps water carve away the land. The Grand Canyon is one of Earth's largest canyons. Over millions of years, it was carved by the fast-moving Colorado River. It shows how powerful water can be.

When water slows down, the sediment settles to the bottom of the stream or river. Deposits of sediment form new land, called sandbars and deltas. Large deltas form where big rivers meet oceans.