Twain, Mark

Mark Twain, whose real name was Samuel Langhorne Clemens, was a great American author and humorist. His novels The Adventures of Tom Sawyer (1876) and The Adventures of Huckleberry Finn (1894) are considered by many as among the greatest American novels, and are still popular (and sometimes controversial) books to read.

Uses of Water

Water is one of the most vital natural resources for all life on Earth. The availability and quality of water always have played an important part in determining not only where people can live, but also their quality of life.

Utility Management

The management of water to provide a safe supply for domestic, industrial, commercial, and some agricultural use is supplied through facilities called waterworks, or water utilities. Although more than three-fourths of the U.S.

Volcanoes and Water

A volcano is a place on the Earth from which magma and gases associated with magma flow through the Earth's crust onto the surface, whether on land, in shallow waters along the shoreline, or under the sea. Scientists estimate that there are tens of thousands of active and dormant volcanoes on Earth, and thousands more extinct volcanoes.

Volcanoes, Submarine

One of the most exciting dimensions of the Earth-building process is volcanism. The power and destructive capability of volcanoes is well known, but there are many more volcanoes underwater, termed submarine volcanoes, than there are on land.

War and Water

With all of its life-giving properties, water is not often associated with acts of war. Yet many important interconnections are apparent in modern life.

Wastewater Treatment and Management

Waters that are used for drinking, manufacturing, farming, and other purposes are degraded in quality as a result of the introduction of contaminating constituents. Organic wastes, suspended solids, bacteria, nitrates, and phosphates are pollutants that commonly must be removed.


Waterfalls are places where a river plunges vertically for some distance, ranging from only a few meters to nearly 980 meters (more than 3,200 feet). A cascade occurs where the drop is not vertical and the stream pours steeply over the underlying rocks.

Watershed, Restoration of a

Restoration of a watershed returns the ecosystem to as close an approximation as possible of its state prior to a specific incident or period of deterioration. If a watershed has deteriorated abruptly due to a sewage spill, restoration may consist of only a few procedures.

Watershed, Water Quality in a

A watershed is the connected series of rivulets, streams, rivers, and lakes that collects and directs water from a given area of land into a single watercourse. Watersheds are important as habitats for animals and plants, as a source of drinking and recreational water for many communities, and as a source of irrigation water for farms and ranches.

Water works, Ancient

Knossos, approximately 5 kilometers (3 miles) from Iraklion, the modern capital of Crete, was one of the most ancient and most unique cities of the Aegean and of Europe. Knossos was first inhabited shortly after 6000 B.C.E., and within 3,000 years it had became the largest Neolithic-age (c.


The ocean surface is in continual motion. Waves are the result of disturbance of the water surface; waves themselves represent a restoring force to calm the surface.

Weather and the Ocean

Much of the weather experienced on land has its origins over the oceans. Weather is the state of the atmosphere at any given time and place.

Weathering of Rocks

Weathering is the alteration of rocks to more stable material from their exposure to the agents of air, water, and organic fluids. No rock is stable or immune to weathering.

Wells and Well Drilling

Approximately 97 percent of the fresh water available in the world is underground. Wells provide groundwater for individual domestic needs, communities, cities, industry, crop irrigation, and agriculture.


The very word "wetland" indicates that water is the first requirement for wetlands to exist. A wetland can be identified by three basic factors: soil, vegetation, and water regime (hydrology).

White, Gilbert

Gilbert F. White is an internationally renowned geographer who received the National Academy of Science's Public Welfare Medal in 2000 for his lifelong work to improve water supplies worldwide and to protect people from flood hazards.

Women in Water Sciences

Clad in hip waders, biologist Sallie Sheldon wades through the chilly waters of Brownington Pond near Middlebury, Vermont, in even the foulest of weather. There she studies Eurasian watermilfoil—the reedy aquatic plant Women scientists who also teach at universities play an important role in drawing more women into scientific endeavors.