Question Paper-AECC-EVS 2018

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Unit 2 Lesson 5- Energy Flow in Ecosystem-Trophic Levels, Food Chain & Food Web

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Environmental Impacts of Dams The environmental consequences of large dams are numerous and varied, and includes direct impacts to the biological, chemical and physical properties of rivers and riparian (or "stream-side") environments. 1.      The dam wall itself blocks fish migrations, which in some cases and with some species completely separate spawning habitats from rearing habitats. 2.      The dam also traps sediments, which are critical for maintaining physical processes and habitats downstream of the dam (include the maintenance of productive deltas, barrier islands, fertile floodplains and coastal wetlands). 3.      Another significant and obvious impact is the transformation upstream of the dam from a free-flowing river ecosystem to an artificial slack-water reservoir habitat. Changes in temperature, chemical composition, dissolved oxygen levels and the physical properties of a reservoir are often not suit...
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