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Environmental Impact Of Reservoirs
The environmental impact of reservoirs comes under ever-increasing scrutiny as the global demand for water and energy increases and the number and size of reservoirs increases. Dams and reservoirs can be used to supply drinking water, generate hydroelectric power, increase the water supply for irrigation, provide recreational opportunities, and flood control. In 1960 the construction of Llyn Celyn and the flooding of Capel Celyn provoked political uproar which continues to this day. More recently, the construction of Three Gorges Dam and other similar projects throughout Asia, Africa and Latin America have generated considerable environmental and political debate. Currently, 48 percent of rivers and their Ecohydrology, hydro-ecological systems are affected by reservoirs and dams. Upstream impacts Fragmentation of river ecosystems A dam acts as a barrier between the upstream and downstream movement of migratory river animals, such as salmon and trout. Some communities ha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alluvial Fan
An alluvial fan is an accumulation of sediments that fans outwards from a concentrated source of sediments, such as a narrow canyon emerging from an escarpment. They are characteristic of mountainous terrain in arid to Semi-arid climate, semiarid climates, but are also found in more humid environments subject to intense rainfall and in areas of modern glaciation. They range in area from less than to almost . Alluvial fans typically form where a flow of sediment or rocks emerge from a confined channel and are suddenly free to spread out in many directions. For example, many alluvial fans form when steep mountain valleys meet a flat plain. The transition from a narrow channel to a wide open area reduces the carrying capacity of flow and results in Deposition (geology), deposition of sediments. The flow can take the form of infrequent debris flows like in a landslide, or can be carried by an intermittent stream or creek. The reduction of flow is key to the formation of alluvial ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Land Loss
Land loss is the term typically used to refer to the conversion of coastal land to open water by natural processes and human activities. The term ''land loss'' includes coastal erosion. It is a much broader term than coastal erosion because land loss also includes land converted to open water around the edges of estuaries and interior bays and lakes and by subsidence of coastal plain wetlands. The most important causes of land loss in coastal plains are erosion, inadequate sediment supply to beaches and wetlands, subsidence, and global sea level rise. The mixture of processes responsible for most of the land loss will vary according to the specific part of a coastal plain being examined.Morton, R.A., 2003''An overview of coastal land loss: with emphasis on the Southeastern United States.''''Open-File report 03-337. US Geological Survey'', Center for Coastal and Watershed Studies, St. Petersburg, Florida. 28 pp.Britsch, L.D. and Kemp III, E.B., 1990. ''Land loss rates: Mississippi Ri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ebro River
The Ebro (Spanish and Basque ; , , ) is a river of the north and northeast of the Iberian Peninsula, in Spain. It rises in Cantabria and flows , almost entirely in an east-southeast direction. It flows into the Mediterranean Sea, forming a delta in the Terres de l'Ebre region, in southern Catalonia. In the Iberian peninsula, it ranks second in length after the Tagus and second in discharge volume, and drainage basin, after the Douro. It is the longest river entirely within Spain; the other two mentioned flow into Portugal. The Ebro flows through many cities (): Reinosa in Cantabria; Frías and Miranda de Ebro in Castile and León; Haro, Logroño, Calahorra, and Alfaro in La Rioja; Tudela in Navarre; Alagón, Utebo, and Zaragoza in Aragon; and Flix, Móra d'Ebre, Benifallet, Tivenys, Xerta, Aldover, Tortosa, and Amposta in the province of Tarragona (Catalonia). Geography Upper part and tributaries The source of the river Ebro is in the Cantabrian Mountains, in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sediment Transport
Sediment transport is the movement of solid particles (sediment), typically due to a combination of gravity acting on the sediment, and the movement of the fluid in which the sediment is entrained. Sediment transport occurs in natural systems where the particles are clastic rocks (sand, gravel, boulders, etc.), mud, or clay; the fluid is air, water, or ice; and the force of gravity acts to move the particles along the sloping surface on which they are resting. Sediment transport due to fluid motion occurs in rivers, oceans, lakes, seas, and other bodies of water due to current (fluid), currents and tides. Transport is also caused by glaciers as they flow, and on terrestrial surfaces under the influence of wind. Sediment transport due only to gravity can occur on sloping surfaces in general, including hillslopes, escarpment, scarps, cliffs, and the continental shelf—continental slope boundary. Sediment transport is important in the fields of sedimentary geology, geomorphology, c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Erosion
Erosion is the action of surface processes (such as Surface runoff, water flow or wind) that removes soil, Rock (geology), rock, or dissolved material from one location on the Earth's crust#Crust, Earth's crust and then sediment transport, transports it to another location where it is deposit (geology), deposited. Erosion is distinct from weathering which involves no movement. Removal of rock or soil as clastic sediment is referred to as ''physical'' or ''mechanical'' erosion; this contrasts with ''chemical'' erosion, where soil or rock material is removed from an area by Solvation, dissolution. Eroded sediment or solutes may be transported just a few millimetres, or for thousands of kilometres. Agents of erosion include rainfall; bedrock wear in rivers; coastal erosion by the sea and Wind wave, waves; glacier, glacial Plucking (glaciation), plucking, Abrasion (geology), abrasion, and scour; areal flooding; Aeolian processes, wind abrasion; groundwater processes; and Mass wastin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dam Removal
Dam removal is the process of demolishing a dam, returning water flow to the river. Arguments for dam removal consider whether their negative effects outweigh their benefits. The benefits of dams include hydropower production, flood control, irrigation, and navigation. Negative effects of dams include environmental degradation, such as reduced primary productivity, loss of biodiversity, and declines in native species; some negative effects worsen as dams age, like structural weakness, reduced safety, sediment accumulation, and high maintenance expense. The rate of dam removals in the United States has increased over time, in part driven by dam age. As of 1996, 5,000 large dams around the world were more than 50 years old. In 2020, 85% percent of dams in the United States are more than 50 years old. In the United States roughly 900 dams were removed between 1990 and 2015, and by 2015, the rate was 50 to 60 per year. France and Canada have also completed significant removal proje ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
River Delta
A river delta is a landform, archetypically triangular, created by the deposition of the sediments that are carried by the waters of a river, where the river merges with a body of slow-moving water or with a body of stagnant water. The creation of a river delta occurs at the '' river mouth'', where the river merges into an ocean, a sea, or an estuary, into a lake, a reservoir, or (more rarely) into another river that cannot carry away the sediment supplied by the feeding river. Etymologically, the term ''river delta'' derives from the triangular shape (Δ) of the uppercase Greek letter delta. In hydrology, the dimensions of a river delta are determined by the balance between the watershed processes that supply sediment and the watershed processes that redistribute, sequester, and export the supplied sediment into the receiving basin. River deltas are important in human civilization, as they are major agricultural production centers and population centers. They can provide ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elevation
The elevation of a geographic location (geography), ''location'' is its height above or below a fixed reference point, most commonly a reference geoid, a mathematical model of the Earth's sea level as an equipotential gravitational equipotential surface, surface (see Geodetic datum#Vertical datum, Geodetic datum § Vertical datum). The term ''elevation'' is mainly used when referring to points on the Earth's surface, while ''altitude'' or ''geopotential height'' is used for points above the surface, such as an aircraft in flight or a spacecraft in orbit, and ''three-dimensional space, depth'' is used for points below the surface. Elevation is not to be confused with the distance from the center of the Earth. Due to the equatorial bulge, the summits of Mount Everest and Chimborazo (volcano), Chimborazo have, respectively, the largest elevation and the largest ECEF, geocentric distance. Aviation In aviation, the term ''elevation'' or ''aerodrome elevation'' is defined by the IC ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aquatic Ecosystem
An aquatic ecosystem is an ecosystem found in and around a body of water, in contrast to land-based terrestrial ecosystems. Aquatic ecosystems contain communities of organisms—aquatic life—that are dependent on each other and on their environment. The two main types of aquatic ecosystems are marine ecosystems and freshwater ecosystems. Freshwater ecosystems may be lentic (slow moving water, including pools, ponds, and lakes); lotic (faster moving water, for example streams and rivers); and wetlands (areas where the soil is saturated or inundated for at least part of the time). Types Marine ecosystems Marine coastal ecosystem Marine surface ecosystem Freshwater ecosystems Lentic ecosystem (lakes) Lotic ecosystem (rivers) Wetlands Functions Aquatic ecosystems perform many important environmental functions. For example, they recycle nutrients, purify water, attenuate floods, recharge ground water and provide habitats for wildlife. The biota of an aqu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sediment
Sediment is a solid material that is transported to a new location where it is deposited. It occurs naturally and, through the processes of weathering and erosion, is broken down and subsequently sediment transport, transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand and silt can be carried in suspension (chemistry), suspension in river water and on reaching the sea bed deposited by sedimentation; if buried, they may eventually become sandstone and siltstone (sedimentary rocks) through lithification. Sediments are most often transported by water (fluvial, fluvial processes), but also wind (aeolian processes) and glaciers. Beach sands and stream channel, river channel deposits are examples of fluvial transport and deposition (geology), deposition, though sediment also often settles out of slow-moving or standing water in lakes and oceans. Desert sand dunes and loess are examples of aeolian transport and deposition. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shore
A coast (coastline, shoreline, seashore) is the land next to the sea or the line that forms the boundary between the land and the ocean or a lake. Coasts are influenced by the topography of the surrounding landscape and by aquatic erosion, such as that caused by waves. The geological composition of rock and soil dictates the type of shore that is created. Earth has about of coastline. Coasts are important zones in natural ecosystems, often home to a wide range of biodiversity. On land, they harbor ecosystems, such as freshwater or estuarine wetlands, that are important for birds and other terrestrial animals. In wave-protected areas, coasts harbor salt marshes, mangroves, and seagrasses, all of which can provide nursery habitat for finfish, shellfish, and other aquatic animals. Rocky shores are usually found along exposed coasts and provide habitat for a wide range of sessile animals (e.g. mussels, starfish, barnacles) and various kinds of seaweeds. In physical ocean ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
