Today’s Wonder of the Day was inspired by Victoria. Victoria Wonders, “What is a water shed” Thanks for WONDERing with us, Victoria!
Since human beings spend nearly all their time on land, it's easy for us to forget that over 70% of Earth's surface is covered in water. Although we drink water every day and rely on it for cleaning our bodies, recreation, and even to generate electric power, we frequently take water for granted.
If we lived on another planet, that wouldn't be the case! The other planets in our solar system are either too close or too far away from the Sun for liquid water to exist. Why is that a big deal? There's no life on those planets.
In fact, when scientists look for other planets in other solar systems that could possibly support life, what do they search for? You guessed it: water! We Earthlings are very lucky to have so much fresh water in the form of precipitation, rivers, streams, lakes, ponds, and even underground aquifers.
Earth's water cycle ensures that water changes from one state to another as it moves continuously on, above, and below Earth's surface. Ironically, there's one thing that's critically important to the water cycle: land.
Water falls upon and flows naturally across, over, through, and under land. A particular area of land that collects and directs draining water downhill into a common outlet is known as a watershed. Sometimes watersheds are also known as catchments or drainage basins.
The land you're standing or sitting upon right now is part of a watershed. Watersheds can be very large or really small. The upper boundaries of a watershed are usually defined by high points, such as mountaintops or ridges.
Where does the water within a watershed go? It all drains to a common body of water, such as a lake, a stream, a river, or even an ocean. A small watershed may combine with or be part of a larger watershed that feeds a network of larger bodies of water.
Think of a watershed as an upside-down umbrella. Any water that hits the surface of the umbrella will flow to the bottom of the umbrella. Likewise, any water that hits the surface of the land within a watershed will flow to its low point, which corresponds to a common outlet.
Topography — the natural features and shape of the land within a watershed — determines how and where water flows. If the land within a watershed is steep, water will move quickly, forming streams and rivers. Flat land, on the other hand, allows water to move slowly, forming ponds, lakes, or swamps.
Water just doesn't run across and over land, though. It also sinks in and filters through the soil, collecting in underground aquifers. This underground water can be an important source of drinking water for many people.
Watersheds are important because they affect the quality of our water. If we're not careful, our various human activities, such as agriculture, industry, and commerce, can pollute the land. As water drains through a polluted watershed, it carries that pollution to other bodies of water, thereby affecting water sources that can be hundreds of miles away from pollution sources.