If a dam is installed across a river, what effect will this have on the coastline? a. it will not allow any fish to swim down the river and into the ocean. b. it will stop the flow of water, which will lower sea level. c. it will change the chemistry of the water and pollute the estuary. d. it will starve the coast of sediment, and the beaches will disappear.

B. It will stop the flow of water, which will lower the sea level.

The dam that is installed across the river acts as a blockade that stops or applies restriction to the even flow of water or underground streams.

These dams not only serve as to protect from the flood but helps in storage of huge amount of water for irrigation and other purpose. Dams are also used to lower the large flow rate and make it use for the industrial purpose.  

answerformal;