A-Level Geography: Fluvial Processes & Drainage Basins

Front

Define the Drainage Basin System

Back

An open system with inputs (precipitation), outputs (evaporation, transpiration, runoff), and flows/stores. It functions as a cascade system, transferring water from the atmosphere to the oceans via stores like soil moisture, groundwater, and channels.

Front

Distinguish between Interception and Stemflow

Back

**Interception:** Precipitation caught by vegetation canopy before reaching the ground. **Stemflow:** Water that runs down the trunks of trees or stems to reach the ground. Both reduce effective precipitation reaching the soil surface initially.

Front

Infiltration vs. Percolation

Back

**Infiltration:** The downward movement of water from the surface into the soil. **Percolation:** The continued downward movement of water from the soil into the underlying permeable rock (groundwater). Percolation replenishes aquifers.

Front

Soil Water Stores: Throughflow vs. Baseflow

Back

**Throughflow:** The lateral movement of water within the soil layer, typically slower than surface runoff. **Baseflow:** The sustained flow of water in a river channel derived from groundwater seepage; it maintains river flow during dry periods.

Front

Storm Hydrograph Components

Back

**Rising Limb:** The rapid increase in discharge due to surface runoff. **Peak Discharge:** The highest point of flow. **Recession (Falling) Limb:** The decrease in flow as stores deplete. **Lag Time:** The delay between peak rainfall and peak discharge.