Question

what is one potential drawback of building large dams on shared rivers?
dams give more economic power to downstream communities who can control the water flow.
dams can limit water flow downstream, impacting countries or communities that rely on that water.
dams often dry up the river completely, making it unusable for all communities who rely on it.
dams increase the likelihood of downstream flooding and water pollution

Explanation:

When a dam is built on a shared river, the upstream country or community controls the water flow. This can limit the water available downstream, affecting the countries or communities that depend on that river for various purposes like drinking water, agriculture, etc.

• The first option is incorrect because dams give economic power to upstream (not downstream) communities who control the water flow.
• The third option is an over - statement. Dams do not "often dry up the river completely". They regulate the flow, not eliminate it.
• The fourth option is incorrect. Dams are often built to control flooding (by regulating water flow) and there is no inherent increase in water pollution due to dam construction on this basis.

Answer:

Dams can limit water flow downstream, impacting countries or communities that rely on that water.