Baraj
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Un baraj este o barieră care separă apele. Barajele pot fi naturale, fiind create fără intervenţie umană, sau artificiale, adică realizate de oameni. Barajele artificiale servesc mai ales pentru reţinerea apei, în timp ce structuri similare, aşa cum sunt digurile sau ecluzele au rolul de a preveni apa să se reverse din cursul său, sau, respectiv, să asigure trecerea dintr-o parte sau alta a unui baraj, care separă volume diferite de apă aflate la diferite nivele.
Cel mai înalt baraj din lume are 300 de metri, Barajul Nurek din Tajikistan. [1]
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[modifică] Istorie
[modifică] Tipuri de baraje
Barajele pot fi formate de cauze naturale (aşa cum este cazul Lacului Roşu din Munţii Harghita, un lac format prin bararea naturală a cursului unui râu), prin intervenţia unor animale specializate în construirea de baraje, aşa cum sunt castorii şi prin intervenţia deliberată de barare realizată de om (aşa numitele barajele artificiale). Barajele realizate de om sunt clasificate după diverse criterii, aşa cum ar fi înălţimea, tipul de structură, scopul urmărit prin realizarea barajului, ş.a.m.d.
[modifică] Clasificare după mărime
International standards define large dams as higher than 15 meters and major dams as over 150 meters in height.[2]
[modifică] Clasificare după scop
[modifică] Clasificare după structură
Based on structure and material used, dams are classified as timber dams, arch-gravity dams, embankment dams or masonry dams, with several subtypes.
[modifică] Masonry dams
[modifică] Arch dams
[modifică] Gravity dams
[modifică] Arch-gravity dams
[modifică] Embankment dams
[modifică] Rock-fill dams
[modifică] Earth-fill dams
Earth-fill dams, also called earthen, rolled-earth or simply earth dams, are constructed as a simple embankment of well compacted earth. A homogeneous rolled-earth dam is
[modifică] Asphalt-Concrete Core
[modifică] Cofferdams
[modifică] Timber dams
[modifică] Steel dams
[modifică] Beaver dams
[modifică] Construction elements
[modifică] Power generation plant
[modifică] Spillways
[modifică] Dam creation
[modifică] Common purposes
[modifică] Siting (location)
One of the best places for building a dam is a narrow part of a deep river valley; the valley sides can then act as natural walls. The primary function of the dam's structure is to fill the gap in the natural reservoir line left by the stream channel. The sites are usually those where the gap becomes a minimum for the required storage capacity. The most economical arrangement is often a composite structure such as a masonry dam flanked by earth embankments. The current use of the land to be flooded should be dispensable.
Significant other engineering and engineering geology considerations when building a dam include:
- permeability of the surrounding rock or soil
- earthquake faults
- landslides and slope stability
- peak flood flows
- reservoir silting
- environmental impacts on river fisheries, forests and wildlife (see also fish ladder)
- impacts on human habitations
- compensation for land being flooded as well as population resettlement
- removal of toxic materials and buildings from the proposed reservoir area
[modifică] Impact assessment
[modifică] Environmental impact
ing up stream to their natural
[modifică] Human social impact
[modifică] Notes
- ^ Guinness Book of Records 1997 Pages 108-109 ISBN 0-85112-693-6
- ^ Methodology and Technical Notes (în English) (HTML). Watersheds of the World. Accesat la data de 2007-08-01. „A large dam is defined by the industry as one higher than 15 meters high and a major dam as higher than 150.5 meters.“

