Dams are obstructions placed in a river or stream to block its flow. In addition to water, sediment builds up behind the dam. How might a dam placed upriver affect the productivity of an estuary at the river's mouth?

Answer: Coastal Recession / Erosion

Explanation:

An Estuary is that part of the river that is semi closed and yet mixes with the sea or ocean.

Research has shown that rivers that have Dams built on them have led to rapid coastal erosion. This is because rivers usually carry sediments of SA and other particles with them but these sediments will instead be trapped by the dam instead of being deposited at the Estuary.

This Coastal erosion is a problem because it leads to serious Environmental problems such as the loss of habitat for some organisms, the loss of Coastal protection, loss of biodiversity as well as the reduction in livelihood of people living in Estuarine environments.