How the USGS Measures Surface Water

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.

Find out more about how the USGS measures groundwater levels.

Learn how river "stage" relates to streamflow and discharge, and how the USGS calculates them.

Water Questions & Answers - Floods This page offers some questions and answers about the hydrology of floods. This information is from the U.S. Geological Survey's MD-DE-DC Water Science Center website of frequently-asked questions about water.

The USGS collects data about the country's water resources including the quantity and quality of water in our streams, rivers, groundwater, and more.

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...

If you have to spend time in other people's shoes before judging them, you'd have to do a lot more than walk a mile to understand a USGS water scientist. For example, if you were Hydrologic Technician, or "Hydrotech," John Jastram, you would be perched 40 feet above a river as you made water-quality measurements from a swaying cable car. And if you were Hydrotech Karl Dydak, you would actually be...

How can one tell how much water is flowing in a river? Can we simply measure how high the water has risen/fallen? The height of the surface of the water is called the stream stage or gage height. However, the USGS has more accurate ways of determining how much water is flowing in a river. Read on to learn more.

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.

It is important to understand how hurricanes and major storms affect coastal areas that are also subject to tidal flows. The only way to do this is to deploy many monitoring sites in the path of these storms, and collect data before, during, and after the storm passes. USGS often deploys this storm-tide monitoring equipment.

The U.S. Geological Survey (USGS) has been measuring the amount of water flowing in rivers since the 19th century. Having reliable past and present streamflow information is vital for many reasons, both at the personal and national level.

A 100-year flood happened last year so it won't happen for another 99 years, right? Not exactly. Misinterpretation of terminology often leads to confusion about flood recurrence intervals. Read on to learn more.