Surface-Water Hazards

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.

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.

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.

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.

Sea level and climate. If you wondering how they relate to one another all you need to think of is water storage. How does the earth store water during cold periods and how is water stored when the earth warms? If you're curious about the delicate connection the earth has between climate and sea level, don't stop here. Read on!

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.

You don't hear about tsunamis very often, but when they do strike, they can be huge newsmakers and can have drastic and devastating effects. The occurrence and potential for tsunamis on the coasts of the United States is not out of the question. Read on to learn about tsunamis.

Wastewater and sewage treatment are important topics in any society, all throughout history and into today. Improperly disposed of or treated sewage can cause disease and harm the ecosystem. That is why when a sewage overflow occurs it garners negative news attention.

Mine drainage is metal-rich water formed from a chemical reaction between water and rocks containing sulfur-bearing minerals. Problems that can be associated with mine drainage include contaminated drinking water, disrupted growth and reproduction of aquatic plants and animals, and the corroding effects of the acid on parts of infrastructures such as bridges.

The following topics provide background on some of the scientific issues regarding floods.

If a low-lying area near a river near you usually gets about 50 inches of rain a year, you might think "Well, that is about 1 inch per week, so that won't cause any flooding". But, nature doesn't think the same way, and often a large percentage of a year's precipitation can fall in a major storm, in a single day. Your river might not react much to a 1 inch rain, but things might be much different...

At places where the U.S. Geological Survey (USGS) does not have real-time monitoring equipment, we use high-water marks to measure the maximum height (stream stage) of a flood or high-water event.