Though the hulk of our planet is made of rock, around 70% of its surface is covered with water. The Earth’s seas and oceans account for most of this coverage — the Pacific Ocean (done covers more than a third of the Earth.
The Earth is a watery place. But just how much water exists on, in, and above our planet? The oceans hold about 96.5 percent of all Earth’s water. Water also exists in the air as water vapor, in rivers and lakes, in icecaps and glaciers in the ground as soil moisture and in aquifers, and even in you and your dog.
Water is never sitting still. Thanks to the water cycle, our planet’s water supply is constantly moving from one place to another and from one form to another. Things would get pretty stale without the water cycle!
The vast majority of water on the Earth’s surface, over 96 percent, is saline water in the oceans. The freshwater resources, such as water falling from the skies and moving into streams, rivers, lakes, and groundwater, provide people with the water they need every day to live. Water sitting on the surface of the Earth is easy to visualize, and your view of the water cycle might be that rainfall fills up the rivers and lakes. But, the unseen water below our feet is critically important to life, also. How do you account for the flow in rivers after weeks without rain? In fact, how do you account for the water flowing down a driveway on a day when it didn’t rain? The answer is that there is more to our water supply than just surface water, there is also plenty of water beneath our feet.
Even though you may only notice water on the Earth’s surface, there is much more freshwater stored in the ground than there is in liquid form on the surface. In fact, some of the water you see flowing in rivers comes from seepage of groundwater into river beds. Water from precipitation continually seeps into the ground to recharge aquifers, while at the same time water in the ground continually recharges rivers through seepage.
Humans are happy this happens because we make use of both kinds of water. In the United States in 2010, we used about 275 billion gallons (1,041 billion liters) of surface water per day, and about 79.3 billion gallons (300.2 billion liters) of groundwater per day. Although surface water is used more to supply drinking water and to irrigate crops, groundwater is vital in that it not only helps to keep rivers and lakes full, it also provides water for people in places where visible water is scarce, such as in desert towns of the western United States. Without groundwater, people would be sand-surfing in Palm Springs, California instead of playing golf.
Picture Credit : Google