Factors affecting water in river landscapes
Precipitation Patterns: The intensity and duration of rainfall are primary drivers of discharge. Intense 'cloudbursts' often exceed the soil's infiltration capacity, while steady, light rain is more likely to be absorbed.
Temperature and Evapotranspiration: Higher temperatures increase the rate of evaporation from water bodies and transpiration from plants. This effectively removes water from the drainage basin system, leading to lower river levels during summer months.
Annual Regime: This refers to the seasonal pattern of a river's discharge over a year. For example, rivers fed by snowmelt will experience a 'spring peak' as temperatures rise and ice melts into the system.
Urbanization: The construction of towns and cities replaces natural surfaces with impermeable concrete and tarmac. This, combined with artificial drainage systems (gutters and pipes), speeds up the delivery of water to the river, increasing flood risk.
Land Use Changes: Deforestation removes the 'biological umbrella' of the canopy, leading to higher surface run-off. In contrast, afforestation (planting trees) increases interception and slows the movement of water through the basin.
River Management: The construction of dams and reservoirs allows humans to regulate discharge. By storing water during high-flow periods and releasing it slowly, the river regime becomes more consistent and predictable.
| Feature | Flashy Hydrograph | Subdued Hydrograph |
|---|---|---|
| Lag Time | Short (water reaches river quickly) | Long (water is delayed) |
| Peak Discharge | High (sharp increase) | Low (gentle increase) |
| Surface Type | Impermeable (Urban/Rock) | Permeable (Forest/Soil) |
| Relief | Steep slopes | Gentle/Flat slopes |
Link the Process: When explaining a factor, always use a 'chain of reasoning'. For example: 'Urbanization leads to more impermeable surfaces, which increases surface run-off, resulting in a shorter lag time.'
Identify the Command Word: If asked to 'Compare', ensure you use connective words like 'whereas' or 'in contrast' to highlight differences between physical and human factors.
Check the Units: Discharge is typically measured in cumecs (cubic meters per second). Ensure you understand that this is a measure of volume over time.
Common Error: Do not confuse infiltration (water entering the soil) with interception (water caught by leaves). They occur at different stages of the water cycle.