Surface-Water Basics

Our planet is covered in water. We see it in our oceans and on land we see it in our lakes and rivers. The vast amount of water on the Earth's surface is in the oceans, and only a relatively small amount exists as fresh surface water on land. Yet, it is vitally important to all life on Earth. Here at the Water Science School we have the answers to your questions about surface water.

The Earth is covered in water. We find it in the air, under the ground, in our bodies, and most noticeably on Earth's surface. With so much water around us we might begin to ask all the where, when, and why's about water.

Rain and snow are key elements in the Earth's water cycle, which is vital to all life on Earth. Rainfall is the main way that the water in the skies comes down to Earth, where it fills our lakes and rivers, recharges the underground aquifers, and provides drinks to plants and animals.

When looking at the location of rivers and the amount of streamflow in rivers, the key concept is the river's "watershed". What is a watershed? Easy, if you are standing on ground right now, just look down. You're standing, and everyone is standing, in a watershed.

Water is everywhere, from huge oceans to invisible water molecules making up water vapor in the air. But how much water is there on, in, above, and below the Earth, and where is it located? Use the topics below to explore the basic concepts and facts about water.

Learn about water science using pictures.

Learn about surface water using pictures.

When a drought hits and little or no rain has fallen in a long time, you might expect small streams and even larger rivers to just dry up, right? In many cases, they don't. Streamflow might lessen to a trickle or so, but water continues to flow. How is that possible? Read on to find out how "base flow", which is water seeping into the stream from groundwater, helps keep water in streams during...

Surface water is the most recognizable part of the water cycle that we can see. Lakes and rivers may be the first types of surface water that come to mind but don't forget those snowbanks in your front yard! We think of oceans when we think of surface water but did you remember to add glaciers to your list? The Water Science School has plenty to teach you about the different types of surface water...

A major storm or hurricane hits your area and on the radio you hear reference to a "100-year flood". But what exactly is a "100-year flood"? The term "100-year flood" is often used to describe a flood of great magnitude, but there is a lot more to it.

In your everyday life you are not involved much with saline water. You are concerned with freshwater to serve your life's every need. But, most of Earth's water, and almost all of the water that people can access, is saline, or salty water. Just look at the oceans and remember that oceans comprise about 97% of all water on, in, and above the Earth.

The U.S. Geological Survey (USGS) has been measuring streamflow at thousands of streams for over a century. When extensive records of past streamflows exist, it is possible to see a pattern of streamflow variation by month and season.