Meaning of Hydrographic Basin
Since humans spend almost all of their time on land, it’s easy for us to forget that more than 70% of the 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 electrical power, we often take water for granted.
If we lived on another planet, that would not be the case! The other planets in our solar system are either too close or too far from the Sun for liquid water to exist. Why is that such a big deal? There is no life on those planets.
In fact, when scientists search for other planets in other solar systems that could support life, what do they look 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.
The Earth ‘s water cycle ensures that water changes from one state to another as it continuously moves above, above, and below the Earth’s surface. Ironically, there is one thing that is critically important to the water cycle: land.
Water falls and flows naturally through, over, through and under the ground. A particular area of land that collects and directs drainage of water downhill to a common outlet is known as a watershed . Basins are sometimes also known as watersheds or drainage basins .
The land you are standing or sitting on is now part of a watershed . Watersheds can be very large or very small. The upper limits of a basin are generally defined by high points, such as mountain tops or ridges.
Where does the water go in a basin?
Everything drains into a common body of water, such as a lake, stream, river, or even an ocean. A small watershed may be combined with or part of a larger watershed that feeds a network of larger water bodies.
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 earth’s surface within a basin will flow to its lowest point, which corresponds to a common outlet.
The topography, the natural features, and the shape of the land within a watershed determine how and where the water flows.
If the land within a basin is steep, the water will move quickly, forming streams and rivers. Flat land, on the other hand, allows water to move slowly, forming ponds, lakes, or swamps.
However, water just doesn’t flow through the land. It also sinks and percolates through the ground, accumulating in underground aquifers . This groundwater can be an important source of drinking water for many people.
Watersheds are important because they affect the quality of our water . If we are not careful, our various human activities such as agriculture, industry, and commerce can pollute the earth.
As water drains through a polluted watershed , it carries that pollution to other bodies of water, affecting water sources that can be hundreds of miles away from sources of pollution.