Water Held and Water Falling: Great Reservoirs and Waterfalls

Lake Volta lies entirely within Ghana, formed by the Akosombo Dam, and is the largest reservoir in the world by surface area at about 8,502 square kilometers. Its filling in 1964 flooded roughly 15,000 homes across 740 villages and required relocating about 78,000 people.

Lake Nasser, created by the Aswan High Dam completed in 1970, spans southern Egypt and northern Sudan and runs up to 550 kilometers long. Its creation displaced tens of thousands of Nubian residents and prompted an international effort to relocate threatened monuments, including the temples of Abu Simbel.

Lake Kariba on the Zambezi River is the world's largest artificial lake by volume, holding about 180 cubic kilometers behind the Kariba Dam. It filled between 1958 and 1963, submerged the Kariba Gorge, and towns such as Siavonga and Sinazongwe grew up for the people displaced.

The Three Gorges Reservoir on the Yangtze River began filling in 2003 and reached its designed level of 175 meters above sea level by 2010. It stretches as much as 600 kilometers and serves flood control, water storage and the dam's hydroelectric generation.

Lake Mead, formed by the Hoover Dam on the Colorado River, is the largest reservoir in the United States by water capacity and first filled on September 30, 1935. It supplies water to nearly 20 million people but has stayed below full capacity since 1983 because of drought and rising demand.

Angel Falls in Venezuela's Canaima National Park is the world's tallest uninterrupted waterfall, with a total height of 979 meters and a main plunge of 807 meters. It is named for the American aviator Jimmie Angel, who first flew over it in 1933, and is known locally as Kerepakupai Vena.

Yosemite Falls falls into Yosemite Valley in six drops totaling 739 meters, with the Upper Fall alone plunging 436 meters. Its flow depends on Sierra Nevada snowmelt, peaking in late spring and often slowing to a trickle or stopping by late summer in drier years.

Kaieteur Falls on the Potaro River in Guyana combines great height with large volume: a main plunge of 226 meters and an average flow of about 663 cubic meters per second. That makes it about four and a half times as tall as Niagara Falls.

Niagara Falls is three waterfalls on the border of Ontario and New York State, led by Horseshoe Falls at about 57 meters high and 790 meters wide. Together they carry the highest flow of any waterfall in North America, averaging about 2,400 cubic meters per second.

Iguazu Falls on the Argentina and Brazil border is considered the largest waterfall system in the world, made up of about 275 individual drops across some 2,700 meters. Alvar Nunez Cabeza de Vaca was the first European to document it, in 1541.