With reference to an example which you have studied, describe and explain ONE way that humans can have an effect on river processes or marine (sea) processes or mass movement. - Leaving Cert Geography - Question 1 - 2007

Dams are built to regulate water flow, provide hydroelectric power, and facilitate irrigation.

1. Regulation of Water Flow: Dams control the seasonal flow of rivers, which can prevent flooding during heavy rain seasons and create a steady water supply in dry seasons.

2. Hydroelectric Power: By harnessing the flow of water, dams generate electricity, contributing to energy needs while altering the natural flow regime of rivers.

3. Sediment Trapping: Dams trap sediments that would typically flow downstream, which can impact river ecology and sediment transport processes, leading to erosion downstream and alteration of habitats.

4. Alteration of Ecosystems: The creation of reservoirs changes the local environment, affecting fish populations and other wildlife that depend on specific river conditions.

5. Microclimate Changes: The presence of large water bodies can influence local climates, potentially affecting agriculture and other land uses in nearby areas.

6. Flood Control: Dams reduce the risk of flood damage in downstream areas, but this can lead to the unintended consequence of encouraging development in previously flood-prone regions.

7. Recreational Opportunities: Dams create lakes that provide recreational opportunities, which increases human activity in previously untouched areas, possibly leading to pollution and habitat disruption.

8. Water Quality Changes: The stagnation of water in reservoirs behind dams can lead to reduced oxygen levels and increased temperatures, impacting aquatic life.

In summary, while dams offer various benefits such as flood control and energy generation, they also have profound impacts on river processes, ecosystems, and human interactions with these water bodies.