Final answer:
Humans have several negative effects on the geosphere when building a dam, including loss of wildlife habitat, changes in water flow and characteristics, and obstruction of fish migration.
Step-by-step explanation:
When building a dam, humans can have several effects on the geosphere. These include:
- Loss of natural wildlife habitat: Building a dam often requires clearing land and flooding areas, resulting in the destruction of habitats for various plant and animal species.
- Changes in water flow and characteristics: The operation of a dam can alter the flow, temperature, chemistry, and silt loads of water, leading to significant changes in the ecology and physical characteristics of rivers both upstream and downstream of the dam.
- Obstruction of fish migration: Dams can block the natural migration paths of fish, affecting their ability to reach spawning areas. This can be mitigated by using fish ladders, but there is still a risk of fish getting injured or killed as they pass through the turbines in the dam.