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104-549: The Millennium Cities Initiative (MCI) is a project of the Earth Institute at Columbia University . Founded by Earth Institute director Professor Jeffrey Sachs in 2006, MCI aims to assist through research and policy analysis selected mid-sized cities across sub-Saharan Africa , located near Millennium Villages , to achieve the Millennium Development Goals (MDGs). The project's initial focus

208-582: A lake , an ocean , or another river. A stream refers to water that flows in a natural channel , a geographic feature that can contain flowing water. A stream may also be referred to as a watercourse. The study of the movement of water as it occurs on Earth is called hydrology , and their effect on the landscape is covered by geomorphology . Rivers are part of the water cycle , the continuous processes by which water moves about Earth. This means that all water that flows in rivers must ultimately come from precipitation . The sides of rivers have land that

312-639: A paleoclimatologist and Columbia University Dean of Science in the Faculty of Arts and Sciences. Established in 1994, the Center for Climate Systems Research is a key Earth Institute center that has 25+ scientists and staff researching the Earth's climate. As Columbia's Gateway to NASA and Beyond , the center has a special relationship with the NASA Goddard Institute for Space Studies , as it

416-547: A trip hammer , and grind grains with a millstone . In the Middle Ages , water mills began to automate many aspects of manual labor , and spread rapidly. By 1300, there were at least 10,000 mills in England alone. A medieval watermill could do the work of 30–60 human workers. Water mills were often used in conjunction with dams to focus and increase the speed of the water. Water wheels continued to be used up to and through

520-740: A boat along certain stretches. In these religions, such as that of the Altai in Russia , the river is considered a living being that must be afforded respect. Rivers are some of the most sacred places in Hinduism. There is archeological evidence that mass ritual bathing in rivers at least 5,000 years ago in the Indus river valley . While most rivers in India are revered, the Ganges is most sacred. The river has

624-671: A broad range of disciplines including, public health , medicine , engineering , nursing , and The Earth Institute. The center is led by Irwin Redlener . The aim of the program Climate Science, Awareness and Solutions is to help people understand global climate change — and how the factors that drive climate are changing. The research areas that the team intends to focus on are as follows: The Program on Child Well-Being and Resilience will serve as an academic center for Columbia University faculty and researchers, across various academic departments and schools, to support greater understanding of

728-461: A broad study of global climate change . Goals include basic research in space sciences in support of Goddard programs. Its director is Gavin Schmidt . 40°48′27″N 73°57′43″W  /  40.80750°N 73.96194°W  / 40.80750; -73.96194 River A river is a natural freshwater stream that flows on land or inside caves towards another body of water at

832-515: A central role in various Hindu myths, and its water is said to have properties of healing as well as absolution from sins. Hindus believe that when the cremated remains of a person is released into the Ganges, their soul is released from the mortal world. Freshwater fish make up 40% of the world's fish species, but 20% of these species are known to have gone extinct in recent years. Human uses of rivers make these species especially vulnerable. Dams and other engineered changes to rivers can block

936-408: A continuous flow of water throughout the year. This may be because an arid climate is too dry depending on the season to support a stream, or because a river is seasonally frozen in the winter (such as in an area with substantial permafrost ), or in the headwaters of rivers in mountains, where snowmelt is required to fuel the river. These rivers can appear in a variety of climates, and still provide

1040-564: A habitat for aquatic life and perform other ecological functions. Subterranean rivers may flow underground through flooded caves. This can happen in karst systems, where rock dissolves to form caves. These rivers provide a habitat for diverse microorganisms and have become an important target of study by microbiologists . Other rivers and streams have been covered over or converted to run in tunnels due to human development. These rivers do not typically host any life, and are often used only for stormwater or flood control. One such example

1144-495: A large scale. This has been attributed to unusually large floods destroying infrastructure; however, there is evidence that permanent changes to climate causing higher aridity and lower river flow may have been the determining factor in what river civilizations succeeded or dissolved. Water wheels began to be used at least 2,000 years ago to harness the energy of rivers. Water wheels turn an axle that can supply rotational energy to move water into aqueducts , work metal using

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1248-466: A lower elevation , such as an ocean , lake , or another river. A river may run dry before reaching the end of its course if it runs out of water, or only flow during certain seasons. Rivers are regulated by the water cycle , the processes by which water moves around the Earth. Water first enters rivers through precipitation , whether from rainfall, the runoff of water down a slope, the melting of glaciers or snow , or seepage from aquifers beneath

1352-556: A peak in the 1970s, when between two or three dams were completed every day, and has since begun to decline. New dam projects are primarily focused in China , India , and other areas in Asia . The first civilizations of Earth were born on floodplains between 5,500 and 3,500 years ago. The freshwater, fertile soil, and transportation provided by rivers helped create the conditions for complex societies to emerge. Three such civilizations were

1456-891: A ritualistic sense has been compared to the Christian ritual of baptism , famously the Baptism of Jesus in the Jordan River . Floods also appear in Norse mythology , where the world is said to emerge from a void that eleven rivers flowed into. Aboriginal Australian religion and Mesoamerican mythology also have stories of floods, some of which contain no survivors, unlike the Abrahamic flood. Along with mythological rivers, religions have also cared for specific rivers as sacred rivers. The Ancient Celtic religion saw rivers as goddesses. The Nile had many gods attached to it. The tears of

1560-425: A river can take several forms. Tidal rivers (often part of an estuary ) have their levels rise and fall with the tide . Since the levels of these rivers are often already at or near sea level, the flow of alluvium and the brackish water that flows in these rivers may be either upriver or downriver depending on the time of day. Rivers that are not tidal may form deltas that continuously deposit alluvium into

1664-756: A river such as fish , aquatic plants , and insects have different roles, including processing organic matter and predation . Rivers have produced abundant resources for humans, including food , transportation , drinking water , and recreation. Humans have engineered rivers to prevent flooding, irrigate crops, perform work with water wheels , and produce hydroelectricity from dams. People associate rivers with life and fertility and have strong religious, political, social, and mythological attachments to them. Rivers and river ecosystems are threatened by water pollution , climate change , and human activity. The construction of dams, canals , levees , and other engineered structures has eliminated habitats, has caused

1768-460: A section of the river behind them into a lake or reservoir. This can provide nearby cities with a predictable supply of drinking water. Hydroelectricity is desirable as a form of renewable energy that does not require any inputs beyond the river itself. Dams are very common worldwide, with at least 75,000 higher than 6 feet (1.8 m) in the U.S. Globally, reservoirs created by dams cover 193,500 square miles (501,000 km ). Dam-building reached

1872-438: A water body is that body's riparian zone . Plants in the riparian zone of a river help stabilize its banks to prevent erosion and filter alluvium deposited by the river on the shore, including processing the nitrogen and other nutrients it contains. Forests in a riparian zone also provide important animal habitats . River ecosystems have also been categorized based on the variety of aquatic life they can sustain, also known as

1976-563: A world where value is measured according to the sustained well-being of all people and our planet. The center works to cultivate the public consciousness needed to make changes in policy and culture that will establish a new value system that is based on this vision of the world. This mission is advanced through four core programs that complement and connect to each other in all our public programs, academics and movement-building: Eco-ministry; Environmental Justice and Civic Engagement; Original Caretakers; Sustainability and Global Affairs. Its director

2080-549: Is Karenna Gore . The Center for the Study of Social Difference at Columbia Graduate School of Arts and Sciences (GSAS) is an interdisciplinary research center supporting collaborative projects that address gender, race, sexuality, and other forms of inequality to foster ethical and progressive social change. Bringing Arts and Sciences faculty into conversation with faculty from Columbia’s professional schools and Global Centers, along with scholars, artists, writers, and policymakers in

2184-430: Is Upmanu Lall . The Center for River and Estuaries is focused on the better understanding of rivers and estuaries worldwide. This includes the distribution, transport, and flux of contaminants , sediments , nutrients , organic material , carbon , and aerosols . The center also studies the evolution and linkage of marshes and wetlands . The center is divided into three main areas of research: maintenance of

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2288-572: Is Dr. Michael J. Puma. The Columbia Water Center was founded in 2008 and is looking into the assessment, understanding and resolution of the global crisis of water scarcity . The center aims to design reliable, sustainable models of water management and development that can be implemented on local, regional and global levels. The Columbia Water Center conducts projects both domestically and internationally, with projects currently underway in India , Mali , Brazil , and China . The current director of CWC

2392-558: Is a research institution specializing in the Earth science and climate change . Though part of Columbia University , it is located on a separate closed campus in Palisades, New York . AC 's current director is Joshua Fisher who joined in 2014. The center is organized around four focus areas, named Complexity, Peace and Sustainability; Environment, Peace, and Sustainability; Youth, Peace and Security; and Women, Peace and Security which

2496-445: Is a tributary , and the place they meet is a confluence . Rivers must flow to lower altitudes due to gravity . The bed of a river is typically within a river valley between hills or mountains . Rivers flowing through an impermeable section of land such as rocks will erode the slopes on the sides of the river. When a river carves a plateau or a similar high-elevation area, a canyon can form, with cliffs on either side of

2600-518: Is a joint venture between Rockefeller University and Columbia that researches populations and their changes, including the spread of disease and social structures. Sciences used to that effort include demography , epidemiology , and statistical modeling to best measure the various changes in populations that are always in flux. Its director is Joel Cohen. The Sabin Center for Climate Change Law develops legal techniques to fight climate change, trains law students and lawyers in their use, and provides

2704-578: Is a part of the Henry Krumb School of Mines and linked to the earth and environmental engineering department. Its current director is Professor Nickolas Themelis . Lenfest research areas include advanced fuel concepts, carbon sequestration , and small scale energy conversion systems (e.g., Fischer–Tropsch process ). The Center for Sustainable Development is a research unit of The Earth Institute of Columbia University charged with managing social science activities. The mission of CGSD

2808-504: Is also important for the lumber industry , as logs can be shipped via river. Countries with dense forests and networks of rivers like Sweden have historically benefited the most from this method of trade. The rise of highways and the automobile has made this practice less common. One of the first large canals was the Canal du Midi , connecting rivers within France to create a path from

2912-564: Is an ancient dam built on the Nile 4,500 years ago. The Ancient Roman civilization used aqueducts to transport water to urban areas . Spanish Muslims used mills and water wheels beginning in the seventh century. Between 130 and 1492, larger dams were built in Japan, Afghanistan, and India, including 20 dams higher than 15 metres (49 ft). Canals began to be cut in Egypt as early as 3000 BC, and

3016-448: Is at a higher elevation than the river itself, and in these areas, water flows downhill into the river. The headwaters of a river are the smaller streams that feed a river, and make up the river's source. These streams may be small and flow rapidly down the sides of mountains . All of the land uphill of a river that feeds it with water in this way is in that river's drainage basin or watershed. A ridge of higher elevation land

3120-516: Is based upon a theory of capitalism where entrepreneurs and financiers are the key actors and the discovery of viable ideas is the essential activity. The director is Professor of Economics and Nobel-Laureate Edmund Phelps . The Center for Sustainable Urban Development was established in 2004 by the Volvo Research and Education Foundations and seeks the creation of sustainable cities, both physically and socially. The center's first project

3224-405: Is because any natural impediment to the flow of the river may cause the current to deflect in a different direction. When this happens, the alluvium carried by the river can build up against this impediment, redirecting the course of the river. The flow is then directed against the opposite bank of the river, which will erode into a more concave shape to accommodate the flow. The bank will still block

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3328-550: Is co-located with GISS in Columbia University's Armstrong Hall above Tom's Restaurant in New York City. Here, Columbia and NASA scientists jointly work together to gain a greater understanding of climate sensitivity and variability including the forcing and feedback mechanisms that influence climate, particularly with regard to how this can impact humanity and environmental stability. The director of CCSR

3432-453: Is correlated with and thus can be used to predict certain data points related to rivers, such as the size of the drainage basin (drainage area), and the length of the channel. The ecosystem of a river includes the life that lives in its water, on its banks, and in the surrounding land. The width of the channel of a river, its velocity, and how shaded it is by nearby trees. Creatures in a river ecosystem may be divided into many roles based on

3536-422: Is focused on hazard assessment and risk management by advancing predictive capability and integrating core sciences to that effort. Physical and social scientists work to reduce impacts on society from hazards, both natural and man-made. Its director is Art Lerner-Lam. The center is an academic center which focuses on the areas of research, policy, and practice. The center's 20 affiliated faculty represent

3640-497: Is in part because of a projected loss of snowpack in mountains, meaning that melting snow can't replenish rivers during warm summer months, leading to lower water levels. Lower-level rivers also have warmer temperatures, threatening species like salmon that prefer colder upstream temperatures. Attempts have been made to regulate the exploitation of rivers to preserve their ecological functions. Many wetland areas have become protected from development. Water restrictions can prevent

3744-399: Is led by Nobel Laureate Leymah Gbowee as executive director. The Center for Climate and Life is a multidisciplinary climate science research initiative based at Lamont–Doherty Earth Observatory . The center advances research focused on how climate change affects access to basic resources such as food, water, shelter and energy. The center's founder and director is Peter B. de Menocal ,

3848-686: Is on policy analysis impacting foreign direct investment (FDI), with a view to creating employment, stimulating domestic enterprise development and fostering economic growth. In addition to foreign investment, the MCI is working to promote an integrated City Development Strategy. The MCI draws upon, and strengthens, the MDGs work already underway by adding a focused urban-based component. MCI aims to demonstrate through its research and policy analysis that more FDI can be attracted to regional urban centers in Africa, with

3952-402: Is part of permafrost ice caps, or trace amounts of water vapor in the atmosphere. However, there is evidence that rivers flowed on Mars for at least 100,000 years. The Hellas Planitia is a crater left behind by an impact from an asteroid. It has sedimentary rock that was formed 3.7 billion years ago, and lava fields that are 3.3 billion years old. High resolution images of the surface of

4056-633: Is rarely static, the exact location of a river border may be called into question by countries. The Rio Grande between the United States and Mexico is regulated by the International Boundary and Water Commission to manage the right to fresh water from the river, as well as mark the exact location of the border. Up to 60% of fresh water used by countries comes from rivers that cross international borders. This can cause disputes between countries that live upstream and downstream of

4160-701: Is that of the Mississippi River , whose drainage basin covers 40% of the contiguous United States . The river was then used for shipping crops from the American Midwest and cotton from the American South to other states as well as the Atlantic Ocean. The role of urban rivers has evolved from when they were a center of trade, food, and transportation to modern times when these uses are less necessary. Rivers remain central to

4264-490: Is the Sunswick Creek in New York City, which was covered in the 1800s and now exists only as a sewer-like pipe. While rivers may flow into lakes or man-made features such as reservoirs , the water they contain will always tend to flow down toward the ocean . However, if human activity siphons too much water away from a river for other uses, the riverbed may run dry before reaching the sea. The outlets mouth of

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4368-434: Is to apply social science approaches to international development problems. The center collaborates with the faculty of the social science departments of Columbia University and is primarily focused on interdisciplinary research and policy application. The Center for the Study of Science and Religion is a collaborative forum designed to examine the issues "lying at the boundary of scientific and religious ways of comprehending

4472-842: Is what typically separates drainage basins; water on one side of a ridge will flow into one set of rivers, and water on the other side will flow into another. One example of this is the Continental Divide of the Americas in the Rocky Mountains . Water on the western side of the divide flows into the Pacific Ocean , whereas water on the other side flows into the Atlantic Ocean . Not all precipitation flows directly into rivers; some water seeps into underground aquifers . These, in turn, can still feed rivers via

4576-599: The 2024 Summer Olympics . Another example is the restoration of the Isar in Munich from being a fully canalized channel with hard embankments to being wider with naturally sloped banks and vegetation. This has improved wildlife habitat in the Isar, and provided more opportunities for recreation in the river. As a natural barrier , rivers are often used as a border between countries , cities, and other territories . For example,

4680-487: The Atlantic Ocean to the Mediterranean Sea . The nineteenth century saw canal-building become more common, with the U.S. building 4,400 miles (7,100 km) of canals by 1830. Rivers began to be used by cargo ships at a larger scale, and these canals were used in conjunction with river engineering projects like dredging and straightening to ensure the efficient flow of goods. One of the largest such projects

4784-532: The Hudson River and New York Harbor , finding solutions to use the water system without harming the ecosystems of the watershed , and maintaining the diverse estuary fisheries for commercial and recreational use. The Earth Institute Center for Environmental Sustainability (EICES), formerly known as the Center for Environmental Research and Conservation (CERC), has been actively involved in protecting biodiversity and ecosystems. The Earth Engineering Center

4888-501: The Industrial Revolution as a source of power for textile mills and other factories, but were eventually supplanted by steam power . Rivers became more industrialized with the growth of technology and the human population . As fish and water could be brought from elsewhere, and goods and people could be transported via railways , pre-industrial river uses diminished in favor of more complex uses. This meant that

4992-791: The Lamari River in New Guinea separates the Angu and the Fore people in New Guinea. The two cultures speak different languages and rarely mix. 23% of international borders are large rivers (defined as those over 30 meters wide). The traditional northern border of the Roman Empire was the Danube , a river that today forms the border of Hungary and Slovakia . Since the flow of a river

5096-600: The Lamont–Doherty Earth Observatory in Palisades, New York. CIESIN provides a large amount of data and information about the Earth to meet the needs of both scientists and decision makers by means of education, consultation, and training. The center is focused on applying modern information technology towards many research problems to meet this goal. Specifically CIESIN was one of the first groups that developed and provided interactive Informatics tools using

5200-525: The Nile and the Ganges . The Quran describes these four rivers as flowing with water, milk, wine, and honey, respectively. The book of Genesis also contains a story of a great flood . Similar myths are present in the Epic of Gilgamesh , Sumerian mythology, and in other cultures. In Genesis, the flood's role was to cleanse Earth of the wrongdoing of humanity. The act of water working to cleanse humans in

5304-568: The River Continuum Concept . "Shredders" are organisms that consume this organic material. The role of a "grazer" or "scraper" organism is to feed on the algae that collects on rocks and plants. "Collectors" consume the detritus of dead organisms. Lastly, predators feed on living things to survive. The river can then be modeled by the availability of resources for each creature's role. A shady area with deciduous trees might experience frequent deposits of organic matter in

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5408-627: The River Lethe to forget their previous life. Rivers also appear in descriptions of paradise in Abrahamic religions , beginning with the story of Genesis . A river beginning in the Garden of Eden waters the garden and then splits into four rivers that flow to provide water to the world. These rivers include the Tigris and Euphrates , and two rivers that are possibly apocryphal but may refer to

5512-787: The Sumerians in the Tigris–Euphrates river system , the Ancient Egyptian civilization in the Nile, and the Indus Valley Civilization on the Indus River . The desert climates of the surrounding areas made these societies especially reliant on rivers for survival, leading to people clustering in these areas to form the first cities . It is also thought that these civilizations were the first to organize

5616-485: The climate . The alluvium carried by rivers, laden with minerals, is deposited into the floodplain when the banks spill over, providing new nutrients to the soil, allowing them to support human activity like farming as well as a host of plant and animal life. Deposited sediment from rivers can form temporary or long-lasting fluvial islands . These islands exist in almost every river. About half of all waterways on Earth are intermittent rivers , which do not always have

5720-625: The cultural identity of cities and nations. Famous examples include the River Thames 's relationship to London , the Seine to Paris , and the Hudson River to New York City . The restoration of water quality and recreation to urban rivers has been a goal of modern administrations. For example, swimming was banned in the Seine for over 100 years due to concerns about pollution and the spread of E. coli , until cleanup efforts to allow its use in

5824-484: The discharge of a river, the amount of water passing through it at a particular time. The flow of a river can act as a means of transportation for plant and animal species, as well as a barrier. For example, the Amazon River is so wide in parts that the variety of species on either side of its basin are distinct. Some fish may swim upstream to spawn as part of a seasonal migration . Species that travel from

5928-465: The extinction of some species, and lowered the amount of alluvium flowing through rivers. Decreased snowfall from climate change has resulted in less water available for rivers during the summer. Regulation of pollution, dam removal , and sewage treatment have helped to improve water quality and restore river habitats. A river is a natural flow of freshwater that flows on or through land towards another body of water downhill. This flow can be into

6032-436: The sea . The sediment yield of a river is the quantity of sand per unit area within a watershed that is removed over a period of time. The monitoring of the sediment yield of a river is important for ecologists to understand the health of its ecosystems, the rate of erosion of the river's environment, and the effects of human activity. Rivers rarely run in a straight direction, instead preferring to bend or meander . This

6136-461: The sustainability of investments in extractive industries , land and agriculture , their relationship with investment policy and law, and cross-cutting topics such as the relationship between sustainable investment and climate change. CCSI is led by Lisa Sachs . The Earth Institute is a member of or closely affiliated with the below entities. The Black Rock Forest Consortium is a collection of universities, schools, and institutions that operate

6240-521: The water table , the groundwater beneath the surface of the land stored in the soil . Water flows into rivers in places where the river's elevation is lower than that of the water table. This phenomenon is why rivers can still flow even during times of drought . Rivers are also fed by the melting of snow glaciers present in higher elevation regions. In summer months, higher temperatures melt snow and ice, causing additional water to flow into rivers. Glacier melt can supplement snow melt in times like

6344-465: The 3,750-acre (15.2 km ) Black Rock Forest in the Hudson Highlands . The forest acts as a field station for research, education, and conservation. Its director is William Schuster. The Columbia Electrochemical Energy Center (CEEC) at SEAS is using a multiscale approach to discover groundbreaking technology and accelerate commercialization. CEEC joins faculty and researchers from across

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6448-807: The Sabin Center. The Urban Design Lab is an interdisciplinary research unit of Columbia University’s Earth Institute in New York City. Established in 2005, it advances design-based solutions to issues in sustainable development and global urbanization. Richard Plunz, founder of the UDL, currently directs the program. The Columbia Centre on Sustainable Investment is a joint center of the Earth Institute and Columbia Law School . CCSI conducts research, performs policy and advisory work, facilitates multi-stakeholder dialogues and teaches about issues related to sustainable investment. In particular, these issues include

6552-495: The School of Engineering and Applied Sciences who study electrochemical energy with interests ranging from electrons to devices to systems. Industry partnerships enable the realization of breakthroughs in electrochemical energy storage and conversion. Its co-directors are Alan West and Daniel Steingart. CEEP at SIPA undertakes original research into the causes of environmental change, the consequences of this change for humanity, and

6656-596: The United States and abroad, CSSD deepens Columbia’s partnerships at home and abroad. The center's work has two overarching research themes: Women Creating Change and Imagining Justice. Its co-directors are Paige West and Catherine LaSota. The NASA Goddard Institute for Space Studies was established in 1961 as the Goddard Space Flight Center Institute for Space Studies. It is a component laboratory of NASA's Goddard Space Flight Center Earth Sciences Division. Research at GISS emphasizes

6760-695: The bodies of humans and animals worldwide, as well as in the soil, with potentially negative health effects. Research into how to remove it from the environment, and how harmful exposure is, is ongoing. Fertilizer from farms can lead to a proliferation of algae on the surface of rivers and oceans, which prevents oxygen and light from dissolving into water, making it impossible for underwater life to survive in these so-called dead zones . Urban rivers are typically surrounded by impermeable surfaces like stone, asphalt , and concrete. Cities often have storm drains that direct this water to rivers. This can cause flooding risk as large amounts of water are directed into

6864-405: The complete draining of rivers. Limits on the construction of dams, as well as dam removal , can restore the natural habitats of river species. Regulators can also ensure regular releases of water from dams to keep animal habitats supplied with water. Limits on pollutants like pesticides can help improve water quality. Today, the surface of Mars does not have liquid water. All water on Mars

6968-436: The effect of normalizing the effects of rivers; the greatest floods are smaller and more predictable, and larger sections are open for navigation by boats and other watercraft. A major effect of river engineering has been a reduced sediment output of large rivers. For example, the Mississippi River produced 400 million tons of sediment per year. Due to the construction of reservoirs , sediment buildup in man-made levees , and

7072-442: The environment, especially in developing countries. (see Effects of global warming ) The IRI conducts this mission through strategic and applied research, education, capacity building, and by providing forecasts and information products, with an emphasis on practical and verifiable utility and partnership. The institute was directed by Lisa Goddard who led efforts to forecast climate change. The Center for Hazards and Risk Research

7176-451: The fish zonation concept. Smaller rivers can only sustain smaller fish that can comfortably fit in its waters, whereas larger rivers can contain both small fish and large fish. This means that larger rivers can host a larger variety of species. This is analogous to the species-area relationship , the concept of larger habitats being host to more species. In this case, it is known as the species-discharge relationship, referring specifically to

7280-673: The floating of wood on rivers to transport it, was especially important. Rivers also were an important source of drinking water . For civilizations built around rivers, fish were an important part of the diet of humans. Some rivers supported fishing activities, but were ill-suited to farming, such as those in the Pacific Northwest . Other animals that live in or near rivers like frogs , mussels , and beavers could provide food and valuable goods such as fur . Humans have been building infrastructure to use rivers for thousands of years. The Sadd el-Kafara dam near Cairo , Egypt,

7384-412: The flow of the river beneath its surface. These help rivers flow straighter by increasing the speed of the water at the middle of the channel, helping to control floods. Levees are also used for this purpose. They can be thought of as dams constructed on the sides of rivers, meant to hold back water from flooding the surrounding area during periods of high rainfall. They are often constructed by building up

7488-399: The flow, causing it to reflect in the other direction. Thus, a bend in the river is created. Rivers may run through low, flat regions on their way to the sea. These places may have floodplains that are periodically flooded when there is a high level of water running through the river. These events may be referred to as "wet seasons' and "dry seasons" when the flooding is predictable due to

7592-650: The form of leaves. In this type of ecosystem, collectors and shredders will be most active. As the river becomes deeper and wider, it may move slower and receive more sunlight . This supports invertebrates and a variety of fish , as well as scrapers feeding on algae. Further downstream, the river may get most of its energy from organic matter that was already processed upstream by collectors and shredders. Predators may be more active here, including fish that feed on plants, plankton , and other fish. The flood pulse concept focuses on habitats that flood seasonally, including lakes and marshes . The land that interfaces with

7696-508: The goddess Isis were said to be the cause of the river's yearly flooding, itself personified by the goddess Hapi . Many African religions regard certain rivers as the originator of life. In Yoruba religion , Yemọja rules over the Ogun River in modern-day Nigeria and is responsible for creating all children and fish. Some sacred rivers have religious prohibitions attached to them, such as not being allowed to drink from them or ride in

7800-446: The internet. The current Office of Directors include director Robert S. Chen , Deputy Directory Marc Levy , and Communications Coordinator Elisabeth Sydor. The International Research Institute for Climate and Society was established in 1996 and became part of the Earth Institute in 2005. The IRI's mission is to enhance society's capability to understand, anticipate and manage the impacts of climate in order to improve human welfare and

7904-428: The irrigation of desert environments for growing food. Growing food at scale allowed people to specialize in other roles, form hierarchies, and organize themselves in new ways, leading to the birth of civilization. In pre-industrial society , rivers were a source of transportation and abundant resources. Many civilizations depended on what resources were local to them to survive. Shipping of commodities, especially

8008-466: The issues, challenges, and opportunities involving children and youth. The Research Program on Sustainability Policy and Management researches public policy, management and financial tools that can enable organizations to incorporate the physical dimensions of sustainability into routine organizational decision making. The following unites were established jointly by the Earth Institute and another entity The Center for Research on Environmental Decisions

8112-440: The landscape around it, forming deltas and islands where the flow slows down. Rivers rarely run in a straight line, instead, they bend or meander ; the locations of a river's banks can change frequently. Rivers get their alluvium from erosion , which carves rock into canyons and valleys . Rivers have sustained human and animal life for millennia, including the first human civilizations . The organisms that live around or in

8216-434: The late summer, when there may be less snow left to melt, helping to ensure that the rivers downstream of the glaciers have a continuous supply of water. Rivers flow downhill, with their direction determined by gravity . A common misconception holds that all or most rivers flow from North to South, but this is not true. As rivers flow downstream, they eventually merge to form larger rivers. A river that feeds into another

8320-474: The level of river branching in a drainage basin. Several systems of stream order exist, one of which is the Strahler number . In this system, the first tributaries of a river are 1st order rivers. When two 1st order rivers merge, the resulting river is 2nd order. If a river of a higher order and a lower order merge, the order is incremented from whichever of the previous rivers had the higher order. Stream order

8424-561: The local ecosystems of rivers needed less protection as humans became less reliant on them for their continued flourishing. River engineering began to develop projects that enabled industrial hydropower , canals for the more efficient movement of goods, as well as projects for flood prevention . River transportation has historically been significantly cheaper and faster than transportation by land. Rivers helped fuel urbanization as goods such as grain and fuel could be floated downriver to supply cities with resources. River transportation

8528-407: The mechanical shadoof began to be used to raise the elevation of water. Drought years harmed crop yields, and leaders of society were incentivized to ensure regular water and food availability to remain in power. Engineering projects like the shadoof and canals could help prevent these crises. Despite this, there is evidence that floodplain-based civilizations may have been abandoned occasionally at

8632-400: The migration routes of fish and destroy habitats. Rivers that flow freely from headwaters to the sea have better water quality, and also retain their ability to transport nutrient-rich alluvium and other organic material downstream, keeping the ecosystem healthy. The creation of a lake changes the habitat of that portion of water, and blocks the transportation of sediment, as well as preventing

8736-399: The natural meandering of the river. Dams block the migration of fish such as salmon for which fish ladder and other bypass systems have been attempted, but these are not always effective. Pollution from factories and urban areas can also damage water quality. " Per- and polyfluoroalkyl substances (PFAS) is a widely used chemical that breaks down at a slow rate. It has been found in

8840-429: The natural terrain with soil or clay. Some levees are supplemented with floodways, channels used to redirect floodwater away from farms and populated areas. Dams restrict the flow of water through a river. They can be built for navigational purposes, providing a higher level of water upstream for boats to travel in. They may also be used for hydroelectricity , or power generation from rivers. Dams typically transform

8944-425: The plain show evidence of a river network, and even river deltas. These images reveal channels formed in the rock, recognized by geologists who study rivers on Earth as being formed by rivers, as well as "bench and slope" landforms, outcroppings of rock that show evidence of river erosion. Not only do these formations suggest that rivers once existed, but that they flowed for extensive time periods, and were part of

9048-527: The policies that can prevent and – where possible – reverse harmful environmental change to ensure sustainable development. CEEP’s goal is to share this knowledge with policymakers, fellow researchers, students, and concerned citizens worldwide. A defining feature of the center's research is the integration of analytic approaches from economics with the natural sciences and engineering. Its co-directors are Douglas Almond and Wolfram Schlenker. The Center for Earth Ethics at Union Theological Seminary (UTS) envisions

9152-487: The public with up-to-date resources on key topics in climate law and regulation. It works closely with the scientists at Columbia University 's Earth Institute and with governmental, nongovernmental and academic organizations. Its activities are spearheaded by Michael Gerrard , director of the Sabin Center and Andrew Sabin Professor of Professional Practice at Columbia Law School , and Michael Burger, Executive Director of

9256-448: The removal of natural banks replaced with revetments , this sediment output has been reduced by 60%. The most basic river projects involve the clearing of obstructions like fallen trees. This can scale up to dredging , the excavation of sediment buildup in a channel, to provide a deeper area for navigation. These activities require regular maintenance as the location of the river banks changes over time, floods bring foreign objects into

9360-533: The resulting employment and economic growth effects. The Initiative will also produce urban development strategies issuing from the Initiative’s own MDG-based needs assessments that will inform municipal and national governments and their donors of the accurate, actual costs of achieving the MDGs. Earth Institute The Earth Institute supports projects in the biological, engineering, social, and health sciences. The Lamont-Doherty Earth Observatory (LDEO)

9464-536: The reverse, death and destruction, especially through floods . This power has caused rivers to have a central role in religion , ritual , and mythology . In Greek mythology , the underworld is bordered by several rivers. Ancient Greeks believed that the souls of those who perished had to be borne across the River Styx on a boat by Charon in exchange for money. Souls that were judged to be good were admitted to Elysium and permitted to drink water from

9568-468: The river, and natural sediment buildup continues. Artificial channels are often constructed to "cut off" winding sections of a river with a shorter path, or to direct the flow of a river in a straighter direction. This effect, known as channelization, has made the distance required to traverse the Missouri River in 116 kilometres (72 mi) shorter. Dikes are channels built perpendicular to

9672-552: The river. Areas of a river with softer rock weather faster than areas with harder rock, causing a difference in elevation between two points of a river. This can cause the formation of a waterfall as the river's flow falls down a vertical drop. A river in a permeable area does not exhibit this behavior and may even have raised banks due to sediment. Rivers also change their landscape through their transportation of sediment , often known as alluvium when applied specifically to rivers. This debris comes from erosion performed by

9776-625: The river. A country that is downstream of another may object to the upstream country diverting too much water for agricultural uses, pollution, as well as the creation of dams that change the river's flow characteristics. For example, Egypt has an agreement with Sudan requiring a specific minimum volume of water to pass into the Nile yearly over the Aswan Dam , to maintain both countries access to water. The importance of rivers throughout human history has given them an association with life and fertility . They have also become associated with

9880-457: The rivers themselves, debris swept into rivers by rainfall, as well as erosion caused by the slow movement of glaciers. The sand in deserts and the sediment that forms bar islands is from rivers. The particle size of the debris is gradually sorted by the river, with heavier particles like rocks sinking to the bottom, and finer particles like sand or silt carried further downriver . This sediment may be deposited in river valleys or carried to

9984-412: The rivers. Due to these impermeable surfaces, these rivers often have very little alluvium carried in them, causing more erosion once the river exits the impermeable area. It has historically been common for sewage to be directed directly to rivers via sewer systems without being treated, along with pollution from industry. This has resulted in a loss of animal and plant life in urban rivers, as well as

10088-409: The sea from their mouths. Depending on the activity of waves, the strength of the river, and the strength of the tidal current, the sediment can accumulate to form new land. When viewed from above, a delta can appear to take the form of several triangular shapes as the river mouth appears to fan out from the original coastline . In hydrology , a stream order is a positive integer used to describe

10192-414: The sea to breed in freshwater rivers are anadromous. Salmon are an anadromous fish that may die in the river after spawning, contributing nutrients back to the river ecosystem. Modern river engineering involves a large-scale collection of independent river engineering structures that have the goal of flood control , improved navigation, recreation, and ecosystem management. Many of these projects have

10296-519: The spread of waterborne diseases such as cholera . In modern times, sewage treatment and controls on pollution from factories have improved the water quality of urban rivers. Climate change can change the flooding cycles and water supply available to rivers. Floods can be larger and more destructive than expected, causing damage to the surrounding areas. Floods can also wash unhealthy chemicals and sediment into rivers. Droughts can be deeper and longer, causing rivers to run dangerously low. This

10400-410: The surface of the Earth. Rivers flow in channeled watercourses and merge in confluences to form drainage basins , areas where surface water eventually flows to a common outlet. Rivers have a great effect on the landscape around them. They may regularly overflow their banks and flood the surrounding area, spreading nutrients to the surrounding area. Sediment or alluvium carried by rivers shapes

10504-498: The world." CSSR works across disciplines and schools in an effort to have social scientists incorporate religion and rituals in the modeling and prediction of human behavior , particularly in the areas of social planning, research and policy. The director is Robert Pollack . The Center on Capitalism and Society seeks to determine the means by which a country can successfully achieve economic success through its ability to generate and develop sound commercial ideas. The center's work

10608-526: Was established in 1996 and serves as the principal engineering unit of the Earth Institute. The EEC aims to find solutions to achieve sustainable development of Earth's resources including water , energy , minerals , materials , and the environment at large. It includes over 20 members of the Engineering School faculty at Columbia and specialists from other Columbia schools as well as environmental organizations and other universities. The EEC

10712-743: Was established under the National Science Foundation 's Decision Making Under Uncertainty (DMUU) program. CRED serves to research decision making under climate uncertainty and environmental risk. The center's objectives include promoting scientific information and communication for a collective response to climate change and variability. CRED is also affiliated with the Institute for Social and Economic Research and Policy (ISERP). Its directors are David Krantz, Elke Weber, Benjamin Orlove, and Kenneth Broad. The Laboratory of Populations

10816-502: Was to develop land use and transport planning in developing countries that promote sustainable growth . The director is Jacqueline Klopp . The Center for International Earth Science Information Network was established in 1989 as an independent NGO to research the interaction between man and the environment. In 1998, CIESIN became part of the Columbia University Earth Institute. Offices are located at

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