Чем stream отличается от итератора
Перейти к содержимому

Чем stream отличается от итератора

  • автор:

Stream

Streams are flowing bodies of water that provide benefits to humans and are important habitats to plants and animals.

Grades

Stream in Colorado

This stream in Crested Butte, Colorado, United States is an important water source for many humans and animals.

Photograph by Adam Springer

This stream in Crested Butte, Colorado, United States is an important water source for many humans and animals.

Article Vocabulary

A stream is a body of water that flows on Earth’s surface. The word stream is often used interchangeably with river , though rivers usually describe larger streams.

Streams provide many benefits to humans. Besides providing drinking water and irrigation for crops, streams wash away waste and can provide electricity through hydropower . People often use streams recreationally for activities such as swimming, fishing, and boating. Streams also provide important habitat for wildlife.

Streams need two things to exist: gravity and water. When precipitation falls onto the ground, some water trickles into groundwater , but much of it flows downhill across the surface as runoff and collects into streams . A watershed , or drainage basin , is the area that collects water for a stream . As smaller streams flow downhill, they often merge together to form larger streams . These smaller streams are called tributaries.

Streams create channels by wearing down rock and carrying it and other sediment down stream . This process is called erosion . The forces that make backyard gullies are the same as those that carved out the Grand Canyon.

Depending on the landscape they flow through, streams have different shapes. Meandering streams have one channel that snakes across the landscape. Over time, these curves can become so wide that they meet and cut off the bend from the rest of the stream , creating oxbow lakes . Braided rivers have many channels that separate and merge like a braid of hair. Planetary scientists have found formations that look like stream channels on the surface of Mars, suggesting water flowed there in streams at one point in the planet’s history.

Streams provide an important ecosystem for many plants and animals, including fish, birds, salamanders, snails, and mammals. Different plants and animals have evolved to thrive in streams . Plants often have strong root systems that act as anchors, and long, flexible stems that can move with the current. Fly larvae nibble on leaves that have fallen into the water, and the flies themselves later become fish food. Mussels bury into sediment on the stream ’s floor, to stay in place as they filter the water for food. Many fish have streamlined shapes that help them stay in position and keep them from being washed away by strong currents.

Many factors can harm a stream ’s health. Dams stop the natural flow of sediment and water, and prevent wildlife, nutrients, and water from flowing freely through the stream system. Urban areas sometimes flush untreated sewage into streams , causing algal blooms that suffocate wildlife. Pollutants can wash into streams from farms and factories, and harm wildlife and humans who depend on the water.

In response to these threats, scientists and conservationists are taking action. Hydrologists study streams and how water quality and flow change over time. Conservationists can work with communities to revive stream basins. Osvel Hinojosa Huerta is a National Geographic Explorer who worked to improve the Colorado River ecosystem in the United States and Mexico. Sandra Postel, a past National Geographic Freshwater Fellow, created a program that restored billions of gallons of water to river systems in North America.

Streams

A stream is any body of flowing fluid. The most familiar type of stream is made of water, although streams can also be made of air, lava, electricity, or any other fluid.

Grades

Subjects

Geography, Physical Geography, Physics

Loading .

Powered by

Background Info Vocabulary

A stream is any body of flowing fluid . The most familiar type of stream is made of water, although streams can also be made of air , lava , electricity , or any other fluid .

Jet streams , for instance, are cold, fast-moving winds that circulate high in the atmosphere . Lightning is a stream of electricity that circulates from cloud to cloud , from the cloud to the ground, or even from the ground to a cloud . Hydrothermal vents eject a stream of vent fluid into the ocean that surrounds them. Although vent fluid contains water, it is much, much hotter than the water surrounding it, and filled with materials from the Earth ‘s crust , such as sulfur , zinc , and copper . Vent fluid is sometimes visible as white or black streams pouring from the vent .

Still, the most familiar type of stream is made of free-flowing water. These streams are fed by rain , melting snow and ice , and groundwater —the water that penetrates deeper into the Earth after the surface soil is completely soaked. Streams vary in size from tiny rills or streamlets , to larger brooks , creeks , and rivers . The term “ stream ” is often used interchangeably with “ river ,” though “ stream ” usually refers to a smaller body of water.

Streams take on different shapes depending on the landscape through which they flow. Cascades , or waterfalls , are formed when shallow water flows over and around large rocks. Normally, waterfalls are found in mountainous areas.

A stream containing large amounts of sediment lining its bottom and sides can change its shape and develop large curves called meanders . Sometimes, meanders are so wide that they e ventually are cut off from the main stream . The U-shaped body of water left behind is called an oxbow lake .

Large amounts of sediment in a stream may cause it to split into many intertwined channels , called braided channels . Braided rivers are different from meandering streams . While meandering streams find a single new channel , braided streams flow over a series of wide, shallow channels .

Human engineering efforts can change the flow of a stream . For example, a meander might be straightened to improve a shipping channel .

Multiple streams can flow together so that one stream e ventually carries water that originated from different parts of a large area. This area is known as the stream ’s drainage basin , or watershed . The Amazon River in South America is the world’s largest stream and also has the world’s largest d rainage basin . At more than 6.9 million square kilometers (2.3 million square miles), it is nearly as large as the entire country of Australia.

Nile v. Amazon
The Nile and Amazon rivers have shared a long rivalry to determine which is the world’s longest stream. Stretching 6,695 kilometers (4,160 miles) from its source in Burundi to its mouth in the Mediterranean Sea, the Nile is generally considered the longest. However, in 2007, a team of Brazilian scientists claimed to have found a new starting point for the Amazon River, 6,800 kilometers (4,225 miles) from its mouth.

Добавить комментарий

Ваш адрес email не будет опубликован. Обязательные поля помечены *