Robert Johnson, widely recognized as one of the greatest guitarists of all time, played the Delta blues. Listen to Robert Johnson here. Also called an alpha predator or top predator. Also called a birdfoot delta or bird's-foot delta. Usually rivers enter another body of water at their mouths. The audio, illustrations, photos, and videos are credited beneath the media asset, except for promotional images, which generally link to another page that contains the media credit. The Rights Holder for media is the person or group credited.
Jeannie Evers, Emdash Editing. Caryl-Sue, National Geographic Society. For information on user permissions, please read our Terms of Service. If you have questions about how to cite anything on our website in your project or classroom presentation, please contact your teacher. They will best know the preferred format. When you reach out to them, you will need the page title, URL, and the date you accessed the resource. If a media asset is downloadable, a download button appears in the corner of the media viewer.
If no button appears, you cannot download or save the media. Text on this page is printable and can be used according to our Terms of Service. Any interactives on this page can only be played while you are visiting our website. You cannot download interactives. Search through these resources to discover more about unique landforms and landscapes around the world. Landforms are natural and distinctive features. Explore how they show up in various landscapes.
These resources can be used to teach middle schoolers more about the natural world, its distinctive features, and landscapes. Of that, only about 1. Most of our drinking water comes from rivers and streams. This water is the lifeline of ecosystems around the world. Freshwater is a precious resource on the Earth's surface.
It is also home to many diverse fish, plant, and crustacean species. The habitats that freshwater ecosystems provide consist of lakes, rivers, ponds, wetlands, streams, and springs.
Use these classroom resources to help students explore and learn about these places. A biome is an area classified according to the species that live in that location. Temperature range, soil type, and the amount of light and water are unique to a particular place and form the niches for specific species allowing scientists to define the biome. However, scientists disagree on how many biomes exist. Some count six forest, grassland, freshwater, marine, desert, and tundra , others eight separating two types of forests and adding tropical savannah , and still others are more specific and count as many as 11 biomes.
Use these resources to teach middle school students about biomes around the world. A habitat is an environment where an organism lives throughout the year or for shorter periods of time to find a mate.
The habitat contains all an animal needs to survive such as food and shelter. A microhabitat is a small area which differs somehow from the surrounding habitat. Its unique conditions may be home to unique species that may not be found in the larger region. Unfortunately, some habitats are threatened by pollution, extreme weather, or deforestation. This puts many of the species that live there in danger and is causing many populations to decline.
Explore different types of habitats and microhabitats with this curated collection of classroom resources. Use this map to help students learn more about the Okavango Delta in Africa, including how it was formed and why it is important to the people and wildlife of southwestern Africa. Join our community of educators and receive the latest information on National Geographic's resources for you and your students.
Skip to content. Twitter Facebook Pinterest Google Classroom. Encyclopedic Entry Vocabulary. Types of Deltas There are two major ways of classifying deltas. Influence There are four main types of deltas classified by the processes that control the build-up of silt: wave -dominated, tide -dominated, Gilbert deltas, and estuarine deltas.
Deltas and People Deltas are incredibly important to the human geography of a region. Disappearing Deltas Extensive river management threatens deltas.
The triangle-shaped Nile Delta is a perfect example of an arcuate delta. Also called a food cycle. Gilbert delta. Hurricane Katrina. Media Credits The audio, illustrations, photos, and videos are credited beneath the media asset, except for promotional images, which generally link to another page that contains the media credit. Media If a media asset is downloadable, a download button appears in the corner of the media viewer. Text Text on this page is printable and can be used according to our Terms of Service.
Interactives Any interactives on this page can only be played while you are visiting our website. Deltas are formed by sediments deposited as rivers enter still or slow-moving water, such as oceans, estuaries and lakes, but their sediment supply is affected by waves, tides and rivers, as well as damming and deforestation. Nienhuis and colleagues developed a model to predict how delta shapes are affected as these factors influence sedimentation.
Developing mathematical theories, they used global models of waves and tides to apply the theories to nearly 11, deltas, including everything from small bayheads to mega-deltas, then validated them using satellite imagery. But river damming has severely reduced sediment flux, causing 23 square kilometres of delta land area to be lost. Despite the net land gain causing river deltas to grow, this is highly likely to change with sea level rise and continued dam construction, says Nienhuis.
Our findings can help tell people how much land loss would be expected for certain types of dams, for example. Deforestation outstripped damming in this region, leading to the largest amount of land gained. North America was the only continent with a net decrease of delta land area, which the authors attribute largely to the fast decline of the Mississippi Delta, partly because of damming, while arctic river deltas had virtually no change.
As Nick van de Giesen from Delft University of Technology notes in a related commentary in the journal, its comprehensive nature comes at a cost to fine-level precision, which will likely produce some inaccuracies in the predicted shapes of some deltas.
If you have found this site useful please support us keeping A Level Geography free by making a small, secure donation via Paypal towards to the running costs of the site. Hydrographs can be used to illustrate discharge. These can be used to show annual discharge patters of flow in relation to climate. The long profile of a river shows changes in the height altitude of the course of a river from its source to its mouth.
The balance between inputs and outputs is known as the water balance or budget. The water…. There are three main types of processes that occur in a river.
These are erosion, transportation and deposition. The characteristics of a river channel change along its long profile. Changes occur in the cross profile, wetted…. Deltas Deltas are landforms formed at the mouth of a river, where the river meets a body of water with a lower velocity than the river e.
The Nile Delta Deltas are formed in the following way: 1. As the river enters a body of water its velocity 2. This lateral movement of water reduces hydraulic radius and increases wetted perimeter; 3. This can create small islands that split the channel in the same was as braided streams; 5.
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