Category Rivers

What is the role of the Ministry of Jal Shakti?

If you have been following the news, you will be aware that the Union Jal Shakti Ministry will be conducting field surveys ahead of the monsoon season as part of the ‘Catch the Rain’ programme. But do you know what the role of the Ministry of Jal Shakti is and when it was set up? Come, let’s find out.

When was it formed?

The Ministry of Jal Shakti (water power) was established in May 2019 by the Indian Government to focus on the management and development of water resources in the country. The Ministry of Water Resources, River Development and Ganga Rejuvenation, and the Ministry of Drinking Water and Sanitation were merged to form the Ministry of Jal Shakti to address water-related issues. The Ministry was formed in the face of mounting water crisis witnessed by the country over the past few decades. Its main objective is to create an integrated approach to water management and provide clean drinking water to all citizens. It also encompasses issues such as inter-State water disputes, cleaning of the Ganga and its tributaries, interlinking of rivers and assessing the impact of climate change on water resources.

Major initiatives

Some of the major initiatives of the Jal Shakti Ministry are the Jal Jeevan Mission, Jal Shakti Abhiyan, Namami Gange Programme, and the National Aquifer Mapping Programme. The Jal Jeevan Mission, launched in August 2019, aims to provide adequate potable water through tap water connections to all rural households by 2024. Under implementation in partnership with the States, it focusses on promoting water conservation efficient use of water resources tensure sustainability of water supply systems, rainwater harvesting, renovation of water bodies, and use of recycled water. Through its Namami Gange Programme, the Ministry has taken steps to rejuvenate and conserve River Ganga and its tributaries. This includes setting up of sewage treatment infrastructure to reduce pollution, river front development. ban on disposal of waste, and promotion of eco-friendly methods of cremation of the dead. The National Aquifer Mapping Programme is aimed at developing plans for sustainable management of groundwater resources. The ‘Catch the Rain’ programme focusses on strengthening water sources in 150 water-stressed districts identified by the Jal Jeevan Mission. According to a statement, a central team will conduct two field visits to the identified districts before and after monsoon, first to assess the preparation for the campaign and then to assess its impact.

Besides these initiatives, the Ministry works with the States, UTS, and other stakeholders to implement water management programmes and conducts awareness campaigns to promote water conservation. All these efforts are expected to have a major impact on the country’s water governance and management in the future.

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What type of lake is Crawford Lake?

Sediment deposited at Crawford Lake in Ontario, Canada, provides solid evidence that Earth entered a new human-driven geological chapter-the Anthropocene epoch- some seven decades ago, a team of scientists said recently. The members of the Anthropocene Working Group plan to submit the evidence to the international scientific body responsible for naming geological chapters in Earth’s history. The scientists conducted research at a dozen sites worldwide and cited Crawford Lake as the location that provided particularly persuasive geological markers that the Anthropocene epoch- essentially the age of humans – had arrived in the 1950s.

ANTHROPOCENE – – ETYMOLOGY

The word Anthropocene is derived from the Greek words “anthropo” for “man” and “cene” for “new”.

The idea of the Anthropocene was proposed at a science conference more than 20 years ago by the late Nobel Prize-winning chemist Paul Crutzen.

Teams of scientists have debated the issue since then and finally set up the working group to study whether it was needed and, if so, when the epoch would start and where it would be commemorated.

THE LAKE IN CANADA AND THE FINDINGS

From climate change to species loss and pollution, humans have etched their impact on Earth with such strength and permanence since the middle of the 20th century that a special team of scientists says a new geologic epoch began then. Called the Anthropocene, this epoch started sometime between 1950 and 1954, according to the scientists.

While there is evidence worldwide that captures the impact of burning fossil fuels, detonating nuclear weapons and dumping fertilizers and plastics on land and in waterways, the scientists are proposing a small but deep lake outside of Toronto, Canada – Crawford Lake to place a historic marker. “It’s quite clear that the scale of change has intensified unbelievably and that has to be human impact,” said University of Leicester geologist Colin Waters, who chaired the Anthropocene Working Group.

The  scientists aims to determine a specific start date of the Anthropocene by measuring plutonium levels at the bottom of Crawford Lake. The lake which is 79 ft deep and 258,333 sq ft in area was chosen over 11 other sites because the annual effects of human activity on the earth’s soil, atmosphere and biology are so clearly preserved in its layers of sediment. That includes everything from nuclear fallout to species-threatening pollution to steadily rising temperatures. There are distinct and multiple signals starting around 1950 in Crawford Lake – showing that “the effects of humans overwhelm the Earth system,” said Francine McCarthy, a committee member who specialises in that site as an Earth sciences professor at Brock University in Canada.

‘The remarkably preserved annual record of deposition in Crawford Lake is truly amazing,” said U.S. National Academies of Sciences President Marcia McNutt, who wasn’t part of the – committee. “If you know your Greek tragedies you know power, hubris, and tragedy go hand in hand,” said Harvard science historian Naomi Oreskes, a working group member. “If we don’t address the harmful aspects of human activities, most obviously disruptive climate change, we are headed for tragedy.”

DID YOU KNOW?

Geologists measure time in eons, eras, periods, epochs and ages.

The scientific working group is proposing that Anthropocene epoch followed the Holocene Epoch, which started about 11,700 years ago at the end of the Ice Age.

They are also proposing that it starts a new age, called Crawfordian after the lake chosen as its starting point.

* The reason geologists didn’t declare the Anthropocene the start of a bigger and more important time measurement, such as a period, is because the current Quaternary Period, which began nearly 2.6 million years ago, is based on permanent ice on Earth’s poles, which still exist. But in a few hundred years, if climate change continues and those disappear, it may be time to change that. AGENCIES

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What are the terms which start from Yellow?

Yellow journalism

Yellow journalism refers to sensational and dramatic news stories, often manufactured to attract readership. The trend was started by media barons Joseph Pulitzer (New York World) and William Randolph Hearst (New York Journal) in the 1890s. The term derives from the comic character the Yellow Kid featured in the New York World comic called Hogan’s Alley. These yellow journals had a major role to play in the Spanish-American war fuelling public passion with sensational headlines and reports.

Yellow card

In football a yellow card raised by a referee indicates that the player in question has committed a foul and is being cautioned.

Yellow flag

In motor racing, when a solid yellow flag is waved it indicates that there is danger ahead and that the vehicles may have to stop.

Yellow fever

It is a viral disease spread by certain mosquitoes. When the mosquito bites a human being the virus enters the body. It damages the liver and kidneys and many body tissues. As a result, the liver cannot function properly, urine output is reduced and yellow bile pigments collect in the skin. These pigments turn the skin yellow and hence the name yellow fever.

It was Carlos Finlay, a Cuban doctor, who discovered that a certain mosquito transmitted the disease, and Max Theiler, a South African doctor, developed a vaccine in 1937.

Yellow jersey

In a cycling race involving stages, a yellow jersey is worn each day by the rider who is ahead on time over the whole race to that point, and presented to the one with the shortest overall time at the finish of the race. The most prized jersey was first awarded in 1919. The colour yellow was chosen because the pages of the magazine. L’Auto, the sponsor, were yellow.

Yellowhammer

It is a sparrow-sized bright yellow bird that is found in Europe and Asia. It has a strong pointed beak and sings a characteristic song. It feeds on seeds and insects. It builds its nest on the ground or in a low bush. Its white or pale-lavender eggs have bold scribble-like markings on them.

Yellow poplar

Also known as the tulip tree, it grows tall-up to 32m-towering over oaks and maples. It has a long straight trunk and large flowers which resemble tulips, hence the name. It bears cone-shaped fruits which release winged seeds. It is home to squirrels and woodpeckers and provides good cover for deer, hints and small mammals.

Yellowlegs

These are large North American birds which live on wetlands- along shores and marshes. They have long yellow legs which have white and black markings. They eat insects and fish They are known for their flute-like whistle.

Yellow Sea

A part of the Pacific Ocean extending inland between the east coast of China and Korea, it gets its name from the deposits brought in by the Yellow River. Fishing and navigation are major activities on the Yellow Sea. The Yellow Sea is considered among the most degraded marine ecosystems facing severe challenges, including land reclamation, widespread pollution leading to harmful algae blooms.

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Why is the Ganga said to be the longest river in India?

As per the overall distance covered by a river within the country, the Ganga is the longest river in India. Even though Brahmaputra and Indus are longer than the Ganga in total length, distances these two major rivers of the Indian subcontinent cover within the country is shorter than that of the Ganga.

Originating from the Gangotri and Yamunotri glaciers in Uttarakhand, the Bhagirathi and Alaknanda rivers meet at Devprayag to form the Ganga. Ganga covers the states of Uttarakhand, Uttar Pradesh, Bihar, West Bengal and then enters Bangladesh. Rishikesh, Varanasi, Kanpur, Prayagraj, Haridwar, Patna, and Bhagalpur are some of the major cities along the banks of this river. Son, Yamuna, Gomti, Koshi, Ghaghara, and Gandak are some of its major tributaries. It covers 2,525 kilometres before merging with the Bay of Bengal.

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Why is the title of the longest river a matter of controversy?

There is a centuries old dispute about which river is the longest. The contestants for this title are the Amazon River and the Nile River, and they both have strong claims on their sides. According to the Guinness Book of World Records, Nile is officially the longest river. Its main source is Lake Victoria in east central Africa and it flows over 6600 kilometres to merge into the Mediterranean Sea. The Nile River is a source of water for the following eleven countries: Burundi, the Democratic Republic of the Congo, Kenya, Tanzania, Uganda, Rwanda, Ethiopia, Eritrea, South Sudan, Sudan and Egypt.

Until 1971, the true source of the Amazon River was not discovered. In the same year, Loren McIntyre, an American photojournalist who worked extensively in South America, claimed that this river originated in the snow-covered Andes of southern Peru. This makes the Amazon River’s length 6700 kilometres when it flows into the South Atlantic Ocean through the Par estuary (which is its most distant mouth). But here again, the calculations are not that simple as the Amazon has several mouths, making it extremely difficult to ascertain the exact point where the river ends.

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Which is the longest constructed waterway?

The longest waterway that has ever been constructed is located in China, and connects Hang-zhou in Zhejiang province with Beijing. The Grand Canal, also called Jing-Hang Yunhe, is not a single waterway but a series of waterways with length of around 1776 km. Successive Chinese regimes used this waterway to transport surplus grains from the agriculturally rich Yangtze (Chang) and Huai river valleys to feed the capital cities and the large armies in northern China. This structure is now considered as a UNESCO World Heritage site.

The part of the canal that was originally on the Huang He (Yellow River) is the oldest part of this waterway. It was traditionally known as the Shanyang Canal but it is now called the Southern Grand Canal (Nan Yunhe) and is located between the Yangtze and the city of Huaiyin (formerly called Qingjiang) in Jiangsu province. It reaches its maximum height of 42 metres in the mountains of Shan-dong.

This system of canals has led to faster trading between different provinces and has supported China’s economy. The part of the canal in the south of the Yellow River continues to be extensively used by barges carrying bulk materials and containers.

Picture Credit : Google 

Why is the Ganges delta unique?

Known as the Sundarbans Delta or the Bengal Delta, the delta of the river Ganges is the world’s largest river delta. By definition, deltas are wetlands that are formed by the rivers as they empty their water and sediments into oceans, lakes, or other water bodies. The Sundarbans Delta encompasses more than 105,000 square kilometres and covers West Bengal and Bangladesh. This delta is formed when the combined waters of several river systems that include the Brahmaputra and the Ganges rivers, empty into the Bay of Bengal. Because of its rich soil, it is also one of the most fertile regions in the world, and is called the Green Delta. It begins at the Meghna River and stretches till the Hooghly River.

The biodiversity of the Ganges delta is also very vast. It is covered with deciduous forests and mangroves and is home to the famous Bengal Tiger. Sundarbans, which forms a major part of this delta, is the world’s largest mangrove forest and has a wide variety of wildlife such as the Indian python, elephants, and crocodiles. One can also find exotic birds like kingfishers, eagles, and woodpeckers here. It is also one of the world’s most populated regions, with approximately 130 million inhabitants.

Picture Credit : Google

The river as a dumpyard

The Mekong is one of the longest rivers in the world, cutting across several Asian regions from Tibet and China to Thailand and Cambodia. But spanning a large area means the threats it faces are just as huge. What are they? Come, let’s find out.

Waste generated in any region is disposed of in many ways, including being dumped at landfills. (Only a minuscule fragment of waste is recycled globally.) Some countries export their waste. Several Asian countries have been taking in plastic waste from such countries, without really being equipped to handle waste disposal safely. In addition, these Asian countries have their own waste to deal with. The waste in landfills reach rivers and oceans through winds, rains, and drains. One such river is the Mekong. Painfully, three “of the worst six plastic polluting countries China, – Thailand, and Vietnam – have a presence in Mekong”, meaning the quantum of waste this river takes in is huge and increasing. The pandemic, with its masks, plastic sanitiser containers, take-away plastic boxes, etc., has exacerbated the situation. And, this is of grave concern.

The Mekong is a treasure trove of biodiversity – several species of plants, birds, reptiles, and fishes call the river and its surrounding regions home. But in the current scenario, rubbish is finding its way into the water, endangering wildlife. Animals and birds are in danger of being affected by plastic debris through entanglement or ingestion. There have been instances of dead whales “turning up in Thailand and Indonesia with many kilograms of plastics in their stomachs”. It is not just wildlife that’s affected. When humans consume creatures such as fish, we end up consuming plastic, which has the potential to cause serious health problems such as cancer. Since rivers drain into larger waterbodies such as seas (the Mekong mixes with the South China Sea) and oceans, the pollution they carry is transferred too.

An increase in the pollution of waterbodies is an indication of increasing pollution on land. And a grim reminder that unless we change our lifestyles to make this planet greener, we are likely to face the negative consequences of our own actions.

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What is harmful algal bloom?

Recently, Lake Merrit in Oakland, California, the U.S… turned reddish brown, causing fear among the residents. They were advised to not use the water and to keep their pets away from the water body. Scientists suspected a possible case of Harmful Algal Bloom (HAB), and the samples have been sent for investigation. This is not the first time that HAB has been experienced in the lakes in the US. In the last few months, there has been a sporadic rise in the detection of algal bloom in the lakes. Lakes such as Hopatcong, Anna, Erie, and so on have been witnessing the highest concentration of HAB, triggering concerns.

Algal bloom is an overgrowth of algae or algae-like bacteria in fresh, salt, or brackish waters. They can occur in a variety of colours, namely red, blue-green, brown, and pink. Depending on the algae, they can lead to the formation of scum, foam, froth, or a slick. Not all algal blooms are toxic. A HAB, though, is, and can endanger humans and many organisms.

What causes HAB?

Most are caused by cyanobacteria. Though they are bacteria, they perform photosynthesis just like algae, and are often called blue-green algae. Some produce dangerous cyanotoxins. The most reported cyanobacteria is microcystis. HAB Occurs naturally as well as due to human activities. In fact, human activities such as the burning of fossil fuels, land development, and deforestation have all led to an increase in the amount of carbon dioxide. The cyanobacteria feed on the carbon dioxide, which fuels their growth.

Most harmful algal blooms are caused by cyanobacteria. Though they are bacteria, they perform photosynthesis just like algae, and are often called blue-green algae.

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WHAT IS PELAGIC ZONE?

The pelagic zone is the open region of any lake, sea, or ocean that is away from any part of land, be it the coast or the sea floor. Marine life-from microscopic plankton and tuna to sharks – dominates this area. Due to the abundance of marine creatures, it is a critical space for producing oxygen, regulating climate, and economic activity.

Pelagic Zone Facts

The pelagic zone plays many critical roles that make it essential to life on Earth. Factors that make the pelagic zone unique include:

It covers more than 50% of the Earth in water, more than 3.2 kilometers (2 miles) deep.
It makes up more than 99% of the inhabitable space on our planet.
The deepest part of the ocean, the Mariana Trench, is about 11,000 meters (7 miles) deep.
The open ocean produces more than 50% of the world’s oxygen.
It is a critical carbon sink, storing 50 times more carbon dioxide than the atmosphere.
Many of its inhabitants never experience sunlight.

The open ocean provides food, medicine, and economic opportunities for people worldwide. In addition to seafood, ocean harvests provide ingredients for foods like peanut butter and soy milk. Medications for Alzheimer’s disease, cancer, heart disease, and arthritis use materials extracted from the ocean, and the United States alone produces $282 billion in ocean-dependent goods and services.

Layers of the Pelagic Zone

The pelagic realm is divided into five distinct regions based on average depth and sunlight availability. Moving from the surface to the ocean floor, the zones are labeled:

Epipelagic
Mesopelagic
Bathypelagic
Abyssopelagic
Hadopelagic

Sunlight, oxygen, and temperature decrease with depth while pressure increases. The organisms in each zone have adapted to live in these conditions.

Credit : Study.com

Pucture Credit : Google 

WHAT IS MR. TRASH WHEEL DEVICE?

Mr. Trash Wheel, officially called the Inner Harbor Water Wheel, is a trash interceptor, a vessel that removes trash from the Jones Falls river as it empties into the Inner Harbor in Baltimore, Maryland. It is powered by water wheels and solar cells, and places trash from the harbor onto an onboard conveyor belt which routes it into dumpsters on the vessel. Mr. Trash Wheel was invented by John Kellett in 2008, who launched a pilot vessel at that time. A larger vessel was later developed; it replaced the pilot vessel and was launched in May 2014. The Mr. Trash Wheel vessel is part of the Waterfront Partnership of the City of Baltimore’s “Healthy Harbor Plan.”

Mr. Trash Wheel is a moored vessel that removes trash from the mouth of the Jones Falls river at Baltimore’s Inner Harbor. Rubbish from the streets of Baltimore is flushed into storm drains that empty into the Jones Falls river. The floating rubbish is then carried by the river to its outlet into the Inner Harbor, where it is captured by Mr. Trash Wheel. Mr. Trash Wheel is powered by the current from the river, and backup power is provided by solar panels when the current is sluggish. These power a conveyor belt. Mr. Trash Wheel removes flo

ating debris using rotating forks that dip into and out of the water, and which then place the trash onto a conveyor belt which moves it into a dumpster. The water wheel can be controlled remotely on the Internet. Mr. Trash Wheel was constructed using $720,000 of public and private funding.

Credit : Wikipedia

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HOW DID THE AMAZON RIVER GET ITS NAME?

The Spanish soldiers who explored the region for the first time in 1541 battled native female warriors who fought bravely. The name the invaders gave to the river came from the Persian hamazan, meaning ‘those who fight together’ – also used in Greek mythology for outstanding women warriors.

Before the conquest of South America, the Rio Amazonas had no general name; instead, indigenous peoples had names for the sections of the river they occupied, such as Paranaguazu, Guyerma, Solimões, and others.

In the year 1500, Vicente Yañez Pinzon, in command of a Spanish expedition, became the first European to explore the river, exploring its mouth when he discovered that the ocean off the shore was freshwater. Pinzon called the river the Rio Santa Maria de la Mar Dulce, which soon became abbreviated to Mar Dulce, and for some years, after 1502, it was known as the Rio Grande.

Pinzon’s companions called the river El Río Marañón. The word Marañón is thought by some to be of indigenous origin. This idea was first stated in a letter from Peter Martyr to Lope Hurtado de Mendoza in 1513. However, the word may also be derived from the Spanish word maraña; meaning a tangle, a snarl, which well represents the bewildering difficulties that the earlier explorers met in navigating not only the entrance to the Amazon, but the whole island-bordered, river-cut, and indented coast of what is now the Brazilian state of Maranhão.

The name Amazon arises from a battle that Francisco de Orellana had with a tribe of Tapuyas where the women of the tribe fought alongside the men, as was the custom among the entire tribe. Orellana derived the name Amazonas from the ancient Amazons of Asia and Africa described by Herodotus and Diodorus.

Credit: New World Encyclopedia

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HOW OLD IS THE COLORADO RIVER?

Colorado River, major river of North America, rising in the Rocky Mountains of Colorado, U.S., and flowing generally west and south for 1,450 miles (2,330 kilometres) into the Gulf of California in northwestern Mexico. Its drainage basin covers 246,000 square miles (637,000 square kilometres) and includes parts of seven states—Wyoming, Colorado, Utah, New Mexico, Nevada, Arizona, and California. For 17 miles the river forms the international boundary between the U.S. state of Arizona and Mexico. The river drains a vast arid and semiarid sector of the North American continent, and because of its intensive development it is often referred to as the “Lifeline of the Southwest.”

For more than a thousand miles of its course, the Colorado has cut a deep gorge. Where the river system is joined by lateral streams—the Virgin, Kanab, Paria, Escalante, Dirty Devil, and Green rivers from the west, and the Little Colorado, San Juan, Dolores, and Gunnison from the east—a transverse system of narrow, winding deep canyons has been cut. Each entering river and each lateral creek has cut another canyon, and thus the upper and middle parts of the Colorado basin are traversed by a labyrinth of deep gorges. The longest of these unbroken trunk canyons through which the Colorado flows is the spectacular Grand Canyon, extending from the mouth of the Paria to the Grand Wash Stream. Other canyons cut by the river include Marble Canyon, Glen Canyon, and Cataract Canyon. Canyonlands National Park encompasses another of these regions at the juncture of the Green and Colorado rivers in southeastern Utah.

Credit: Britannica

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HOW OLD IS THE NILE RIVER?

The Nile River flowing through Egypt could be six times as old as previously thought, according to a study which estimated it to have originated at least 30 million years ago. The study, published in the journal Nature Geoscience, assessed the links between the geographical and physical features — or topography — of the Nile River to the flow of molten rocks in the Earth’s mantle.

The researchers, including those from the University of Texas (UT) at Austin in the US, connected the tilted nature of the Nile’s topography to a conveyor belt of mantle rock pushing up against the Ethiopian Highlands in the south, and pulling the surface down in the north. This gentle gradient, they said, keeps the Nile on a consistent northward course from its beginning to the end. The study said the Nile would have turned west long ago — probably changing the course of history along with it — if it weren’t for the mantle movement keeping the river on course.

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HOW DO RIVER CURRENTS IMPACT THE LANDSCAPE?

Current refers to the speed of the movement of water. This can be very fast, especially in the mountains, close to the source of the river. River currents have tremendous power – they can tear out boulders and carry huge rocks and smash them deep into the riverbed. As the river reaches the plains, the current slows it down; causing it to deposit a lot of the debris it carried, creating a wider valley with fertile soil.

Rivers and streams begin their lives as smaller creeks, often called “the headwaters”. These small tributaries flow downhill until they merge to form bigger tributaries, which continue merging to form larger rivers. Rivers keep flowing to lower altitudes, towards the oceans. River systems are similar to the blood vessels in your body. Tiny capillaries that carry blood keep merging together until all of the blood empties into large veins, which deliver the blood to your heart.

All rivers are surrounded by a certain amount of land that is higher in altitude (upgradient) than the actual river. Precipitation that falls in this area eventually flows downhill towards the river. At any particular point on a river, the land upgradient of the point is the river’s watershed, or drainage basin. This example of a watershed gives a rough idea of how precipitation flows downhill into rivers (and lakes) movement of a fluid within a larger body of that fluid. Fluids are materials capable of flowing and easily changing shape. The most familiar natural fluid is water. But air is considered a fluid as well. Electricity can also flow as a current.

Air currents flow in the atmosphere, the layer of air surrounding the Earth. Water currents flow in rivers, lakes, and, oceans. Electric currents flow through power lines or as lightning.

Credit: usgs.gov

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HOW MANY TRIBUTARIES DOES THE NILE RIVER HAVE?

The Nile in Africa is the longest river in the world. The river has three tributaries; the two main ones are the White Nile that begins in Burundi and the Blue Nile that has its source in Ethiopia. Both rivers merge in Sudan. The third tributary, Atbara River, is dry most of the year and flows only if it rains in Ethiopia.

The Nile River, considered the longest river in the world, is approximately 4,258 miles (6,853 kilometers) long, but its exact length is a matter of debate. Flowing northward through the tropical climate of eastern Africa and into the Mediterranean Sea, the river passes through 11 countries: Tanzania, Uganda, Rwanda, Burundi, the Democratic Republic of the Congo, Kenya, Ethiopia, Eritrea, South Sudan, Sudan and Egypt.

The Nile has two major tributaries: the longer White Nile, considered the prime stream and headwaters; and the Blue Nile, which carries about two-thirds of the river’s water volume and most of the silt.

The White Nile begins at Lake Victoria, Africa’s largest lake, which touches the countries of Uganda, Kenya and Tanzania. But Lake Victoria isn’t necessarily the most distant and “true” source of the Nile River because the lake itself has many feeder rivers coming in from the surrounding mountains. In 2006, a British explorer named Neil McGrigor said he’d traveled to the Nile’s most distant source at the beginning of the Kagera River, Lake Victoria’s longest feeder river.

Credit: Live Science

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WHAT IS AN OXBOW LAKE?

When a river flows through low-lying plains, it slows down, carving out a meandering path with many U-shaped curves. Over time, some of these curves become cut off from the main flow of the river by the build-up of silt deposits, and form oxbow lakes. These distinctive, curved water bodies are close to a river but separate from it.

An oxbow lake starts out as a curve, or meander, in a river. A lake forms as the river finds a different, shorter, course. The meander becomes an oxbow lake along the side of the river.

Oxbow lakes usually form in flat, low-lying plains close to where the river empties into another body of water. On these plains, rivers often have wide meanders.

Meanders that form oxbow lakes have two sets of curves: one curving away from the straight path of the river and one curving back. The corners of the curves closest to each other are called concave banks. The concave banks erode over time. The force of the rivers flowing water wears away the land on the meanders concave banks.

The banks opposite the concave banks are called convex banks. The opposite of erosion happens here. Silt and sediment build up on convex banks. This build-up is called deposition.

Erosion and deposition eventually cause a new channel to be cut through the small piece of land at the narrow end of the meander. The river makes a shortcut. Oxbow lakes are the remains of the bend in the river.

Oxbow lakes are stillwater lakes. This means that water does not flow into or out of them. There is no stream or spring feeding the lake, and it doesnt have a natural outlet. Oxbow lakes often become swamps or bogs, and they often dry up as their water evaporates.

Credit: National Geographic Society

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Which are the major rivers and lakes in Ukraine?

Ukraine is blessed with several rivers and waterbodies. The most prominent among the rivers are the Dnieper River, the Southern Buh and the Danube. The longest river in Ukraine, Dnieper dominates the central region of the country with many tributaries and has several hydroelectric dams and huge reservoirs along its course to the Black Sea. The Southern Buh also flows into the Black Sea along with the Inhul, its major tributary. The Danube flows along Ukraine’s southwestern frontier.

Almost 3 per cent of Ukraine is marshland, which is mostly found in the northern river valleys and in the lower reaches of rivers like the Dnieper and Danube.

The rivers are a major source of water, and to enable its proper supply a series of canals have been built in Ukraine. There are dams and hydroelectric plants built on all the larger rivers.

Ukraine has a few natural lakes, too, but they are small in size. Lake Svitiaz in the northwest is one of the largest; with an area of 28 square km. Along the coast there are some saline lakes which are larger. There are also some artificial lakes, like the reservoir on the Dnieper near the city of Kremenchuk.

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HOW DO WATERFALLS FORM?

A waterfall develops when the bed of the river changes from hard to soft rock. As the force of the water wears away soft rock faster, the level of the softer riverbed drops, and the river plunges over a ledge of hard rock. The depth of the fall increases over time as more and more of the soft rock is washed away.

A waterfall is a river or a body of water that steeply falls over a rocky edge into a plunge pool. These are also called cascades.

Erosion is the process of wearing away the earth. It plays an important part in the formation of waterfalls. Waterfalls also contribute to erosion.

The process of formation of waterfalls happens when a stream flows from soft rock to hard rock. This happens both laterally and vertically. In every case the soft rock erodes and leaves the hard rock as it is. Over this a stream falls.

The fall line is an imaginary line along which parallel rivers plunge while flowing from uplands to low lands. Many waterfalls in this way help the geologists determine a region’s fall line and underlying rock structure.

As the stream flows it carries various amounts of sediments- be it microscopic silt, pebbles or boulders. Sediments erode the beds of soft rocks like sandstone or limestone. The stream then cuts the beds so deep that only hard rocks like granite are left.

Credit: jagranjosh.com

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HOW DO RIVERS KEEP FLOWING?

Rivers are kept running by the addition of water from rainfall or melting snow. Even when it does not rain, underground reservoirs (water stores) keep rivers supplied with water and flowing. When it rains, a lot of water seeps and sinks into the ground to surface somewhere else as a spring. Over thousands of years, rivers can carve huge valleys out of solid rock with a wide floodplain, which is a flat area that catches the overflow when the river is full.

Rivers keep flowing because gravity is constantly pulling the water down the path of least resistance (downhill). A river flows because there is a water table to support it. A river is nothing more than an outward manifestation of the water table.

A river that does not run dry at any time of year is carrying surplus water from precipitation that collects in the permeable rocks of hills and mountains that surround the watershed. Most rivers get their water from the mountains, where there is far more precipitation than over the lowlands.

Credit: SidmartinBio

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WHICH IS THE HIGHEST WATERFALL?

Angel Falls or Salto Ángel (indigenous name: Kerepakupay Vená) is the world’s highest free-falling waterfall at 3,212 feet with an uninterrupted drop of 2,648 feet lying in the Canaima National Park, Venezuela. It is situated on the Churún River, an affluent of the Carrao. Curún in indigenous Pemón language means “thunder.”

Angel Falls is located in the Guayana highlands, one of the five topographical regions of Venezuela. It plunges off the edge of a tepui, or table-top mountain, called Auyan Tepui (“Devils Mountain”). It is 500 feet wide at its base and in total is 15 times higher than America’s Niagara Falls Angel Falls in Venezuela, which plunge 979 m vertically.

Angel Falls is one of Venezuela’s top tourist attractions, despite its remoteness and the absence of roads leading to nearby villages. One of the world’s great natural wonders, Angel Falls inspires feelings of awe in the hearts of those who make the journey.

Although sighted in the early twentieth century by the explorer Ernesto Sanchez La Cruz, the waterfall was not known to the Western world until it was visited in 1935 by the American aviator, James Crawford Angel, on a flight while searching for a valuable ore bed. In 1936, he returned and landed his plane at the top of the waterfall. The falls are currently named “Angel Falls” after him; interestingly, the indigenous name for the falls means “Devil’s Mouth.”

Credit: NEW WORLD ENCYCLOPEDIA.

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WHICH IS THE WORLD’S LONGEST RIVER?

Flowing northward through the tropical climate of eastern Africa and into the Mediterranean Sea, the Nile river is the longest river in the world at 4,135 miles (6,650 kilometers), according to the U.S. National Park Service.

The Nile runs through Egypt, as well as nine other African nations Sudan, Eritrea, Ethiopia, Uganda, Kenya, Tanzania, Rwanda, Burundi and the Democratic Republic of Congo. More than 300 million people depend on the Nile for their water supply and the irrigation of seasonal crops, according to the Council of Ministers of Water Affairs of the Nile Basin.

The Nile’s energy is harnessed by the Aswan High Dam, which was completed in 1970 and provides hydroelectricity and controls summer flooding. During the 1980s, the dam provided half of Egypt’s electricity, although that amount has decreased over the years and it currently contributes 20 percent of total energy generated in Egypt, according to NASA’s Earth Observatory.

Credit: LIVESCIENCE

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WHAT IS A DELTA?

As a river reaches the sea or a lake and slows down, sediment- sand, silt and mud – builds up at its mouth, blocking its flow. The river then breaks up into several individual strands of water that make their way to the larger water body. The Nile forms a classic delta formation as the river enters into the Mediterranean Sea.

One of the first texts to describe deltas was History, written during the 5th century BCE by Greek historian Herodotus. In that work, Herodotus mentioned that the Ionian people used the term delta to describe the low-lying region of the Nile River in Egypt. During a visit to the region, Herodotus also recognized that the land bounded by the seaward-diverging distributary branches of the Nile and the sea was deltoid in shape; he is often given credit for first using the Greek letter ? (delta) to describe it. Although many of the world’s deltas are deltoid, or triangular, in shape, notable exceptions exist. In most cases, the delta shape is controlled by the outline of the water body being filled by sediments. For this reason, the term delta is now normally applied, without reference to shape, to the exposed and submerged plain formed by a river at its mouth.

Deltas have been important to humankind since prehistoric times. Sands, silts, and clays deposited by floodwaters were extremely productive agriculturally; and major civilizations flourished in the deltaic plains of the Nile and Tigris-Euphrates rivers. In recent years geologists have discovered that much of the world’s petroleum resources are found in ancient deltaic rocks.

Deltas display much variation in size, structure, composition, and origin. These differences result from sediment deposition taking place in a wide range of settings. Numerous factors influence the character of a delta, the most important of which are: climatic conditions, geologic setting and sediment sources in the drainage basin, tectonic stability, river slope and flooding characteristics, intensities of depositional and erosional processes, and tidal range and offshore energy conditions. Combinations of these factors and time give rise to the wide variety of modern deltas. The presence of a delta represents the continuing ability of rivers to deposit stream-borne sediments more rapidly than they can be removed by waves and ocean currents. Deltas typically consist of three components. The most landward section is called the upper delta plain, the middle one the lower delta plain, and the third the subaqueous delta, which lies seaward of the shoreline and forms below sea level.

Credit: Britannica

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WHERE DO RIVERS START AND END?

Rivers start off as small springs and streams high in the mountains. As they tumble downhill, they are joined by other streams, called tributaries, and become broader as they flow further. Upon reaching flat plains, they flow smoothly and deeply until they empty their waters into the sea or a lake.

Most rivers begin their life high up in the mountains and hills of the world. There are heavy downpours of rain here and perhaps melting snow. Some of the rain soaks into the ground and the rest runs over the surface, collects in pools, then trickles downhill with the force of gravity. Small streams are formed, which get bigger as they collect more water and join up with other streams. The ever-increasing stream wears away the ground as it goes, carving out valleys and shaping the landscape. The speed of the flowing water and the hardness of the ground have an effect on the shape created. The ‘wearing away’ is called erosion.

A mountain stream is sometimes called a youthful river and it is fast flowing, making deep valleys with steep sides. Once it begins to cut a valley it is trapped in it and will continue to carve out the same valley for perhaps thousands of years. As it tumbles downhill, the stream collects and carries rocks, stones and pebbles along with it. Progressing on its journey towards the sea, it collects more and more water until it is big enough to be called a river. Eventually, the land becomes flatter and the water flow slows down, causing the river to drop its stones and pebbles onto the river bed. This is called deposition. As an ‘old river’ meanders slowly through flat land (a bend in a river is called a meander), it is carrying only mud.

Eventually a river meets the sea and the place where it does is called the mouth. The last of the mud is deposited at the river’s mouth. A wide mouth is called an estuary. Some estuaries are enormous – the estuary of the Amazon is 333 kilometres wide!

Sometimes a lowland river winds so much that the looping meanders almost touch. The river may eventually erode away the narrow area of land between two loops so that its course runs straight and a horseshoe-shaped area of water is stranded – an ox-bow lake.

Credit: Young People’s Trust for the Environment (YPTE) 

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