Geography – Hydrology, river processes and hazards | e-Consult

Answer: This question requires a detailed analysis of factors influencing river flood risk, considering both natural and anthropogenic influences, and the accelerating impact of climate change. A strong answer will select a specific location (e.g., the River Thames, the Ganges, or a local river) and then systematically evaluate the relative importance of various factors.

Physical Factors:

• Climate:** Increased frequency and intensity of rainfall events due to climate change are a primary driver. This leads to higher river discharge and increased flood potential.
• Topography:** Steep slopes can concentrate runoff, increasing flood risk. Low-lying areas are inherently more vulnerable.
• Geology:** Impermeable geology reduces infiltration, leading to increased surface runoff and faster river rises.
• River Morphology:** Channel shape (e.g., meandering vs. straights), gradient, and sediment load all influence flood behaviour. Meandering rivers are more prone to overbank flooding.

Human Factors:

• Land Use:** Deforestation increases runoff. Urbanisation creates impervious surfaces, leading to increased surface water flow and reduced infiltration.
• River Management:** Dam construction can alter natural flood regimes, potentially increasing flood risk downstream if not managed carefully. Channelisation can increase flow velocity and flood depth in some areas.
• Agriculture:** Intensive agriculture can lead to soil erosion and increased sediment load in rivers, exacerbating flooding.
• Population Density:** Higher population density in floodplains increases the potential for damage and loss of life.

Climate Change:**

• Increased Rainfall Intensity:** Climate change is projected to increase the intensity of rainfall events, leading to more frequent and severe floods.
• Sea Level Rise:** In coastal areas, sea level rise can exacerbate river flooding by increasing the likelihood of tidal flooding and saltwater intrusion.
• Changes in Snowmelt Patterns:** Altered snowmelt patterns can lead to earlier and more intense spring floods.

Relative Importance: The relative importance of these factors will vary depending on the specific location. For example, a densely populated urban area might be more vulnerable to human factors, while a region heavily impacted by climate change might be more vulnerable to physical factors. A strong answer will justify its assessment of relative importance with specific examples from the chosen location.