What Is A Delta
A delta is a special geographic feature of a river. Typically, rivers run into larger bodies of water. Sometimes, the larger body of water is an ocean or a sea. The larger body of water can even be a bigger river. Deltas are often marshy areas or wetlands. Some people refer to a delta as the mouth of a river.
Water is a powerful force of nature. As water runs through a river, the water erodes the riverbed, stirring up rocks, silt, grains of sand, soil and other natural debris called sediment. The river picks up and carries much of this material along its path, and all of that sediment washes into a delta.
When a river reaches the point of a delta, the speed of its water starts to slow down as it nears the larger body of water. A delta is the slowest part of a river, in part because it holds the most buildup of sediment.
Due to the ratios of water and sediment they contain, deltas are often very muddy. These wetlands can support different types of plant and animal life than the free-flowing parts of the river upstream can. As the intersection of a small body of water and a large one, a delta is often one of the widest parts of a river.
Know Your Body : The Differences Between A Bay A Sound And A Delta
Bays, sounds and deltas are all geographical formations of land and water. Each formation involves water flowing from a large body of water to a much smaller one which can make telling the difference between the three quite the task. Just what is the difference between a sound, a bay and a delta, and why are deltas especially important? Learn the answers to these questions along with some other un-bay-lievable facts below.
Coastal Development And Sedimentation Near Coral Reefs
Watershed development near coral reefs is a primary cause of sediment-related coral stress. The stripping of natural vegetation in the watershed for development exposes soil to increased wind and rainfall, and as a result, can cause exposed sediment to become more susceptible to erosion and delivery to the marine environment during rainfall events. Sediment can negatively affect corals in many ways, such as by physically smothering them, abrading their surfaces, causing corals to expend energy during sediment removal, and causing algal blooms that can ultimately lead to less space on the seafloor where juvenile corals can settle.
When sediments are introduced into the coastal regions of the ocean, the proportion of land, marine and organic-derived sediment that characterizes the seafloor near sources of sediment output is altered. In addition, because the source of sediment is often correlated with how coarse or fine sediment grain sizes that characterize an area are on average, grain size distribution of sediment will shift according to relative input of land , marine , and organically-derived sediment. These alterations in marine sediment characterize the amount of sediment that is suspended in the water column at any given time and sediment-related coral stress.
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Formation Of The Mississippi River Delta
The river delta is a river-dominant delta, with a prominent birds foot delta and was formed approximately 4,500 years. The path of the river slowly deposited and dropped sand, clay, and silt along the river banks and in the existing basin, which created blockages within the river, which over time made the plain more shallow. These buildups are known as delta lobes. The larger, or more common these lobes became, the more difficult it was for the river to flow in its original path. Eventually, the resistance to the former path became so great that the river was forced to find new routes, and the river changed course. This process continued repeatedly, which is why the river delta has such a forked, meandering appearance to it when seen from above. The lobes, and silt-heavy areas became prominent marshlands, and important ecosystems for wetland plants and animals.
What Is A Bluff Geography
A bluff is a small, rounded cliff that usually overlooks a body of water, or where a body of water once stood. A bluff is a type of broad, rounded cliff. Most bluffs border a river, beach, or other coastal area. Bluffs may form along a river where it meanders, or curves from side to side.Feb 9, 2016
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How Do River Deltas Form
River Delta Formation of Delta. River deltas form when a river carrying sediment reaches either a body of standing water, such as a lake, ocean, or reservoir, another river that Types of Deltas. Sedimentary structure. Deltas and alluvial fans. Examples of notable deltas. Ecological threats to deltas.
Importance Of Deltas For Humankind
Deltas are abundant sources of ground water, which can be extensively used for agriculture. Common crops grown in deltas are rice, asparagus and other irrigating crops.
These wetlands are diverse ecosystems with immense ecological importance. They absorb runoff waters from storms and floods. They create friendly environment for the survival of a number of animals as well, including fish, oysters, insects, birds and others. Bears and tigers can also be part of a delta in Geography.
They filter water that is slowly entering the larger water body through a network of river distributaries. Due to this, the pollution elements flowing into the water body is minimized from the upstream. Deltas are significant wetland habitats as well, and are home to a number of plants and herbs, including worts, hibiscus and lilies.
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Deltas In The Economy
Ancient deltas are a benefit to the economy due to their well sorted sand and gravel. Sand and gravel is often quarried from these old deltas and used in concrete for highways, buildings, sidewalks, and even landscaping. More than 1 billion tons of sand and gravel are produced in the United States alone. Not all sand and gravel quarries are former deltas, but for ones that are, much of the sorting is already done by the power of water.
Urban areas and human habitation tends to locate in lowlands near water access for transportation and sanitation. This makes deltas a common location for civilizations to flourish due to access to flat land for farming, freshwater for sanitation and irrigation, and sea access for trade. Deltas often host extensive industrial and commercial activities as well as agricultural land which are often in conflict. Some of the world’s largest regional economies are located on deltas such as the Pearl River Delta, Yangtze River Delta, European Low Countries and the Greater Tokyo Area.
Formation Of A River Delta
A river delta is formed when sediment in that river flows into another body of water, and begins to deposit that sediment there. As the river hits the width of a lake or ocean, the water flow quickly slows down, allowing for large amounts of sediment to drop from the water onto the river bottom. Over time, this sediment builds up, decreasing the gradient of the river bed and the floor of the river channel becomes closer to the floodplain. This can make the river channel unstable and prone to flooding.
When a river breaches its banks and floods, the water flow finds the fastest and easiest route downstream. Similarly, mouth bars – a bar of sand, gravel or heavy sediment in the mouth of a river can cause the flow of that river to divert around it, causing a forking. At the fork, sediment from the river builds up, which over time can also form delta conditions.
Over time, as the river continues to breach various distributaries form. This gives many deltas their distinctive shape, although different types of deltas exist, based in part on how they were formed.
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What Is Mouth Of River Class 9
A delta is formed where a river empties into a larger body of water and deposits large amounts of alluvium. So many smaller rivers empty into the Ganges Delta, the area is sometimes called the Mouths of the Ganges. The place where a river enters a lake, larger river, or the ocean is called its mouth.
The Formation And Importance Of River Deltas
- M.A., Geography, California State University – East Bay
- B.A., English and Geography, California State University – Sacramento
A river delta is a low-lying plain or landform that occurs at the mouth of a river near where it flows into an ocean or another larger body of water. Deltas’ greatest importance to human activities, fish and wildlife lay in their characteristic highly fertile soil and dense, diverse vegetation.
In order to fully appreciate the role deltas play in our larger ecosystem, it is first important to understand rivers. Rivers are defined as bodies of fresh water generally flowing from high elevations toward an ocean, a lake or another river sometimes, even back into the ground.
Most rivers begin at high elevations where snow, rain, and other precipitation run downhill into creeks and small streams. These small waterways flow ever farther downhill, eventually meeting to form rivers.
Rivers flow toward oceans or other larger bodies of water, oftentimes combining with other rivers. Deltas exist as the lowest part of these rivers. It is in these deltas where a river’s flow slows and spreads out to create sediment-rich dry areas and biodiverse wetlands.
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Settlements In The Mississippi River Delta
Some 2 million or so people live in the Mississippi River Delta area. Due to its location at the mouth of the river, and the Gulf, the region was a gateway for goods and culture. People from a variety of nationalities settled here, including a large population of French settlers and traders, and Creole and Cajun culture are still prominent in the area today.
River Delta Facts For Kids
A river delta is a landform created by deposition of sediment that is carried by a river as the flow leaves its mouth and enters slower-moving or stagnant water. This occurs where a river enters an ocean, sea, estuary, lake, reservoir, or another river that cannot carry away the supplied sediment. The size and shape of a delta is controlled by the balance between watershed processes that supply sediment, and receiving basin processes that redistribute, sequester, and export that sediment. The size, geometry, and location of the receiving basin also plays an important role in delta evolution. River deltas are important in human civilization, as they are major agricultural production centers and population centers. They can provide coastline defense and can impact drinking water supply. They are also ecologically important, with different species’ assemblages depending on their landscape position.
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The Countries Of Nile River Delta Found
The Nile Delta is located in northern Egypt, where the Nile reaches the Mediterranean Sea. The Nile is the longest river in the world. It starts near the equator and flows north for about 7000 km. The delta starts about 20 km north of Cairo and extends about 150 km north. The delta on the coast is about 250 km wide, stretching from Alexandria in the west to Port Side in the east. The area of the Nile Delta is about 20,000 km. The Nile Valley and the Nile Delta are some of the most fertile agricultural regions in the world and are surrounded by a very dry climate.
As a result, the delta population is dense. About 50% of the population of Egypt lives in the Nile Delta.The Nile flows over 6,600 kilometers until it disappears into the Mediterranean Sea. For thousands of years, the river has provided irrigation resources to convert the dry area around it into lush agricultural land. Today, the river remains a source of irrigation and an important transport and trade route.
Women and children on the banks of the NileThe Nile has been a central feature of life in Northeast Africa for thousands of years. Even today, families draw water from the banks of the river, which is surrounded by the remains of ancient civilizations.
Humans And River Deltas
River deltas have been important to humans for thousands of years because of their extremely fertile soils. Major ancient civilizations grew along deltas such as those of the Nile and the Tigris-Euphrates rivers, with the inhabitants of these civilizations learning how to live with their natural flooding cycles.
Many people believe that the ancient Greek historian Herodotus first coined the term delta nearly 2,500 years ago as many deltas are shaped like the Greek delta symbol.
Deltas remain important to humans even today as, among many other things, a source of sand and gravel. Used in highway, building and infrastructure construction, these highly valuable materials quite literally build our world.
Delta land is also important in agricultural use. Witness the Sacramento-San Joaquin Delta in California. One of the most agriculturally diverse and productive areas in the state, the region successfully supports numerous crops from kiwi to alfalfa to tangerines.
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What Is A Delta In Geography
When you study Geography, you will come to know that our Earth is huge, and the massive land on which we live is just ¼ of its total size. Three quarters of the Earths size is water, and the land on which we live is divided into a number of landforms that come into contact with it. Typical landforms are islands, sounds, rivers, shorelines and deltas. When we talk about a delta, it is a wetland that forms as a river empties its contents into another water body. If you are fascinated about the Geography of this Earth, then this oneHOWTO article will give you a deeper understanding of what is a delta in Geography.
Biodiversity And Importance Of River Deltas
In addition to these human uses, river deltas boast some of the most biodiverse systems on the planet. As such, it is essential that these unique and beautiful havens of biodiversity remain as healthy habitat for the many species of plants, animals, insects, and fish — some rare, threatened or endangered — which call them home.
In addition to their biodiversity, deltas and wetlands provide a buffer for hurricanes, as open land often stands to weaken the impact of storms as they travel toward larger, more populated areas. The Mississippi River Delta, for example, buffers the impact of potentially strong hurricanes in the Gulf of Mexico.
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Existential Threats To Deltas
Human activities in both deltas and the river basins upstream of deltas can radically alter delta environments. Upstream land use change such as anti-erosion agricultural practices and hydrological engineering such as dam construction in the basins feeding deltas have reduced river sediment delivery to many deltas in recent decades. This change means that there is less sediment available to maintain delta landforms, and compensate for erosion and sea level rise, causing some deltas to start losing land. Declines in river sediment delivery are projected to continue in the coming decades.
The extensive anthropogenic activities in deltas also interfere with geomorphological and ecological delta processes. People living on deltas often construct flood defences which prevent sedimentation from floods on deltas, and therefore means that sediment deposition can’t compensate for subsidence and erosion. In addition to interference with delta aggradation, pumping of groundwater,oil, and gas, and constructing infrastructure all accelerate subsidence, increasing relative sea level rise. Anthropogenic activities can also destabilise river channels through sand mining, and cause saltwater intrusion. There are small-scale efforts to correct these issues, improve delta environments and increase environmental sustainability through sedimentation enhancing strategies.
How Is A Delta Formed
A delta is a land form comprised of sediments found at the mouth of the river. A delta can only form when river channels carry sediments into another body of water. Herodotus, a Greek historian, first used the term “delta” for the Nile River in Egypt. This is because the sediment land mass developed at mouth of this river formed a triangular shape that looks like the upper case Greek letter delta.
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Deltas And Human Activity
Deltas have been important centers of human activity throughout history, in part because of the fertility of the land and easy access to transportation. Many early human civilizations developed on deltas. For instance, the Nile River delta has hosted Egyptian cultures for over seven thousand years.
Deltas contain large expanses of wetlands where organic matter rapidly accumulates. Consequently,
Edited By Franz Krause And Mark Harris
Franz Krause and Mark Harris are the editors of Delta Life: Exploring Dynamic Environments where Rivers Meet the Sea .
What is a river delta? There is a popular answer to this question among people who have had geography lessons and seen satellite images of deltas: usually, a delta is the area formed by the sediments of a river as it spills into another waterbody. It often features a fascinating network of meandering channels and distributaries, and its human land uses must adapt to the vagaries of a dynamic terrain characterized by land subsistence, flood risk, rampant erosion and high sediment loads.
This is the view from the geography textbook. But what about the view from the delta itself, from the perspectives of the people whose home the delta is? The recently published book Delta Life explores this perspective. Based on ethnographic research in eight river deltas around the world, and on critical readings of existing literature in anthropology, geography and beyond, this book treats river deltas as lifeworlds rather than as objects. The focus is squarely on delta life, by which we mean delta inhabitants everyday practices, worries, challenges and hopes. But why is this perspective useful, or even necessary?
Captions:
A geography-textbook version of a river delta: satellite image of the north-eastern section of the Mackenzie Delta in the Inuvialuit Settlement Area, Canada, from July 2017. Courtesy of the U.S. Geological Survey.
About The Editors:
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