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Fluvio-thermal Erosion
In geomorphology fluvio-thermal erosion is the combined mechanical and thermal erosion of an unfrozen river or stream against ice-rich soils and sediments. The erosional process includes the thawing of ice sediments by a strong water flow and once the surface is unfrozen, mechanical erosion occurs only if hydraulic forces are powerful enough to incise the riverbank material. This kind of erosion sometimes causes the banks to collapse into the river, and when this occurs collapses are commonly controlled by ice wedges. Rivers where this process has been observed include the Lena, the Colville River delta, and the Yukon River. The Yakutia region in Central Siberia, where the Lena River is located, is an exceptional point of interest to study this type of erosion based on its record low temperatures and extreme thickness of permafrost. During the winter when water level is low, a thick sheet of ice forms on top of the Lena River, that is sometimes as much as 2 m thick. Sea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geomorphology
Geomorphology (from Ancient Greek: , ', "earth"; , ', "form"; and , ', "study") is the scientific study of the origin and evolution of topographic and bathymetric features created by physical, chemical or biological processes operating at or near Earth's surface. Geomorphologists seek to understand why landscapes look the way they do, to understand landform and terrain history and dynamics and to predict changes through a combination of field observations, physical experiments and numerical modeling. Geomorphologists work within disciplines such as physical geography, geology, geodesy, engineering geology, archaeology, climatology, and geotechnical engineering. This broad base of interests contributes to many research styles and interests within the field. Overview Earth's surface is modified by a combination of surface processes that shape landscapes, and geologic processes that cause tectonic uplift and subsidence, and shape the coastal geography. Surface processes co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yakutia
Sakha, officially the Republic of Sakha (Yakutia),, is the largest republic of Russia, located in the Russian Far East, along the Arctic Ocean, with a population of roughly 1 million. Sakha comprises half of the area of its governing Far Eastern Federal District, and is the world's largest country subdivision, covering over 3,083,523 square kilometers (1,190,555 sq mi). ''Sakha'' following regular sound changes in the course of development of the Yakut language) as the Evenk and Yukaghir exonyms for the Yakuts. It is pronounced as ''Haka'' by the Dolgans, whose language is either a dialect or a close relative of the Yakut language.Victor P. Krivonogov, "The Dolgans’Ethnic Identity and Language Processes." ''Journal of Siberian Federal University'', Humanities & Social Sciences 6 (2013 6) 870–888. Geography * ''Borders'': ** ''internal'': Chukotka Autonomous Okrug (660 km)(E), Magadan Oblast (1520 km)(E/SE), Khabarovsk Krai (2130 km)(SE), Amur Oblast (S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrology
Hydrology () is the scientific study of the movement, distribution, and management of water on Earth and other planets, including the water cycle, water resources, and environmental watershed sustainability. A practitioner of hydrology is called a hydrologist. Hydrologists are scientists studying earth or environmental science, civil or environmental engineering, and physical geography. Using various analytical methods and scientific techniques, they collect and analyze data to help solve water related problems such as environmental preservation, natural disasters, and water management. Hydrology subdivides into surface water hydrology, groundwater hydrology (hydrogeology), and marine hydrology. Domains of hydrology include hydrometeorology, surface hydrology, hydrogeology, drainage-basin management, and water quality, where water plays the central role. Oceanography and meteorology are not included because water is only one of many important aspects within those fields. H ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Soil Erosion
Soil erosion is the denudation or wearing away of the upper layer of soil. It is a form of soil degradation. This natural process is caused by the dynamic activity of erosive agents, that is, water, ice (glaciers), snow, air (wind), plants, and animals (including humans). In accordance with these agents, erosion is sometimes divided into water erosion, glacial erosion, snow erosion, wind (aeolean) erosion, zoogenic erosion and anthropogenic erosion such as tillage erosion. Soil erosion may be a slow process that continues relatively unnoticed, or it may occur at an alarming rate causing a serious loss of topsoil. The loss of soil from farmland may be reflected in reduced crop production potential, lower surface water quality and damaged drainage networks. Soil erosion could also cause sinkholes. Human activities have increased by 10–50 times the rate at which erosion is occurring world-wide. Excessive (or accelerated) erosion causes both "on-site" and "off-site" problems. On- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Weathering
Weathering is the deterioration of rocks, soils and minerals as well as wood and artificial materials through contact with water, atmospheric gases, and biological organisms. Weathering occurs ''in situ'' (on site, with little or no movement), and so is distinct from erosion, which involves the transport of rocks and minerals by agents such as water, ice, snow, wind, waves and gravity. Weathering processes are divided into ''physical'' and ''chemical weathering''. Physical weathering involves the breakdown of rocks and soils through the mechanical effects of heat, water, ice, or other agents. Chemical weathering involves the chemical reaction of water, atmospheric gases, and biologically produced chemicals with rocks and soils. Water is the principal agent behind both physical and chemical weathering, though atmospheric oxygen and carbon dioxide and the activities of biological organisms are also important. Chemical weathering by biological action is also known as biological wea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Porous Medium
A porous medium or a porous material is a material containing pores (voids). The skeletal portion of the material is often called the "matrix" or "frame". The pores are typically filled with a fluid (liquid or gas). The skeletal material is usually a solid, but structures like foams are often also usefully analyzed using concept of porous media. A porous medium is most often characterised by its porosity. Other properties of the medium (e.g. permeability, tensile strength, electrical conductivity, tortuosity) can sometimes be derived from the respective properties of its constituents (solid matrix and fluid) and the media porosity and pores structure, but such a derivation is usually complex. Even the concept of porosity is only straightforward for a poroelastic medium. Often both the solid matrix and the pore network (also known as the pore space) are continuous, so as to form two interpenetrating continua such as in a sponge. However, there is also a concept of closed porosit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flood
A flood is an overflow of water ( or rarely other fluids) that submerges land that is usually dry. In the sense of "flowing water", the word may also be applied to the inflow of the tide. Floods are an area of study of the discipline hydrology and are of significant concern in agriculture, civil engineering and public health. Human changes to the environment often increase the intensity and frequency of flooding, for example land use changes such as deforestation and removal of wetlands, changes in waterway course or flood controls such as with levees, and larger environmental issues such as climate change and sea level rise. In particular climate change's increased rainfall and extreme weather events increases the severity of other causes for flooding, resulting in more intense floods and increased flood risk. Flooding may occur as an overflow of water from water bodies, such as a river, lake, or ocean, in which the water overtops or breaks levees, resulting ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Permafrost
Permafrost is ground that continuously remains below 0 °C (32 °F) for two or more years, located on land or under the ocean. Most common in the Northern Hemisphere, around 15% of the Northern Hemisphere or 11% of the global surface is underlain by permafrost, with the total area of around 18 million km2. This includes substantial areas of Alaska, Greenland, Canada and Siberia. It can also be located on mountaintops in the Southern Hemisphere and beneath ice-free areas in the Antarctic. Permafrost does not have to be the first layer that is on the ground. It can be from an inch to several miles deep under the Earth's surface. It frequently occurs in ground ice, but it can also be present in non-porous bedrock. Permafrost is formed from ice holding various types of soil, sand, and rock in combination. Permafrost contains large amounts of biomass and decomposed biomass that has been stored as methane and carbon dioxide, making tundra soil a carbon sink. As global war ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Siberia
Siberia ( ; rus, Сибирь, r=Sibir', p=sʲɪˈbʲirʲ, a=Ru-Сибирь.ogg) is an extensive geographical region, constituting all of North Asia, from the Ural Mountains in the west to the Pacific Ocean in the east. It has been a part of Russia since the latter half of the 16th century, after the Russians conquered lands east of the Ural Mountains. Siberia is vast and sparsely populated, covering an area of over , but home to merely one-fifth of Russia's population. Novosibirsk, Krasnoyarsk and Omsk are the largest cities in the region. Because Siberia is a geographic and historic region and not a political entity, there is no single precise definition of its territorial borders. Traditionally, Siberia extends eastwards from the Ural Mountains to the Pacific Ocean, and includes most of the drainage basin of the Arctic Ocean. The river Yenisey divides Siberia into two parts, Western and Eastern. Siberia stretches southwards from the Arctic Ocean to the hills of north-ce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yukon River
The Yukon River (Gwichʼin language, Gwich'in: ''Ųųg Han'' or ''Yuk Han'', Central Alaskan Yup'ik language, Yup'ik: ''Kuigpak'', Inupiaq language, Inupiaq: ''Kuukpak'', Deg Xinag language, Deg Xinag: ''Yeqin'', Hän language, Hän: ''Tth'echù'' or ''Chuu k'onn'', Southern Tutchone: Chu Nìikwän, russian: Юкон, Yukon) is a major watercourse of northwestern North America. From its source in British Columbia, Canada, it flows through Canada's territory of Yukon (itself named after the river). The lower half of the river continues westwards through the U.S. state of Alaska. The river is long and empties into the Bering Sea at the Yukon–Kuskokwim Delta. The average flow is . The total drainage area is , of which lies in Canada. The total area is more than 25% larger than Texas or Alberta. The longest river in Alaska and Yukon, it was one of the principal means of transportation during the 1896–1903 Klondike Gold Rush. A portion of the river in Yukon—"The Thirty Mile" se ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermal Erosion
A thermal column (or thermal) is a rising mass of buoyant air, a convective current in the atmosphere, that transfers heat energy vertically. Thermals are created by the uneven heating of Earth's surface from solar radiation, and are an example of convection, specifically atmospheric convection. Thermals on Earth The Sun warms the ground, which in turn warms the air directly above. The warm air near the surface expands, becoming less dense than the surrounding air. The lighter air rises and cools due to its expansion in the lower pressure at higher altitudes. It stops rising when it has cooled to the same temperature, thus density, as the surrounding air. Associated with a thermal is a downward flow surrounding the thermal column. The downward-moving exterior is caused by colder air being displaced at the top of the thermal. The size and strength of thermals are influenced by the properties of the lower atmosphere (the ''troposphere''). When the air is cold, bubbles of warm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Colville River (Alaska)
The Colville River (; Inupiat: ''Kuukpik'') is a major river of the Arctic Ocean coast of Alaska in the United States, approximately long. One of the northernmost major rivers in North America, it drains a remote area of tundra on the north side of the Brooks Range entirely above the Arctic Circle. The river is frozen for more than half the year and floods each spring. It rises on the north slope of the De Long Mountains, at the western end of the Brooks Range, north of the continental divide in the southwestern corner of the National Petroleum Reserve. It flows initially north, then generally east through the foothills on the north side of the range, broadening as it receives the inflow of many tributaries that descend from the middle Brooks Range. Along its middle course it forms the southeastern border of the National Petroleum Reserve. At the Iñupiat village of Umiat it turns north to flow across the Arctic plain, entering the western Beaufort Sea in a broad delta near Nuiq ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
