Geography – Hydrology, river processes and hazards | e-Consult
Hydrology, river processes and hazards (1 questions)
Human activities have a profound and often detrimental impact on drainage basin systems, significantly altering the natural hydrological processes and resulting in changes to discharge relationships and hydrograph characteristics. These alterations often exacerbate flood risks and negatively affect water resources.
Examples of Human Impacts:
- Deforestation: Removing forests reduces interception, increases surface runoff, and decreases infiltration. This leads to higher peak discharges, increased flood risk, and reduced baseflow. The hydrograph will show a steeper rise and fall.
- Urbanization: Urban areas are characterized by impermeable surfaces (roads, buildings) that prevent infiltration. This dramatically increases surface runoff and peak discharges. Urban areas often experience flash floods. The hydrograph will show a very rapid rise to a high peak.
- Agriculture: Intensive agriculture can lead to soil degradation and reduced infiltration. Overgrazing can also reduce vegetation cover, increasing runoff. Irrigation can alter groundwater flow patterns and potentially lead to waterlogging.
- Dam Construction: Dams regulate river flow, reducing peak discharges and creating a more sustained baseflow. However, dams can also alter sediment transport patterns and have ecological impacts. The hydrograph will show a flattened peak and a more consistent discharge.
- Drainage of Wetlands: Wetlands act as natural sponges, absorbing excess rainfall and reducing flood risk. Draining wetlands removes this natural flood control mechanism, increasing flood risk and altering groundwater flow.
The cumulative effect of these human activities can be substantial, leading to significant alterations in drainage basin hydrology. Changes in discharge relationships can make water resources less reliable and increase the frequency and severity of floods. The hydrograph becomes a powerful indicator of the impacts of human intervention, highlighting the need for sustainable land management practices to protect drainage basin systems.