Physical Jog - Part 19: Drainage Basin Hydrology

Key Concepts

Drainage Basin: An open system where water flows across land into streams or rivers.
- Inputs and outputs are defined beyond the drainage basin, primarily through precipitation.

Inputs
- Precipitation: Main input, includes rainfall in various forms such as snow, dew, or condensation.
- Influences the level of water flow and storage within the basin.
Outputs
- River Runoff: Water flowing from river channels to the sea.
- Evapotranspiration: Loss of water through evaporation and transpiration.
Pathways and Flows
- Interception Loss: Water held by vegetation; impacts amount reaching the ground.
- Infiltration: Water entering the ground's permeable surface; affected by soil permeability, rainfall intensity, and vegetation cover.
  - Infiltration Rate: Speed of infiltration.
  - Infiltration Capacity: Maximum water infiltrated over time.
- Percolation: Slower downward movement of water into deeper soil layers; affected by soil porosity and frequency of joints.
- True Flow and Base Flow: Horizontal flows within soil moisture storage and groundwater storage.
- Overland Flow: Fastest flow, occurs when water does not infiltrate.
  - Hortonian Overland Flow (HOF): When rainfall exceeds infiltration capacity.
  - Saturated Overland Flow (SOF): Occurs on saturated ground.

Understand the hydrological cycle within a drainage basin: Inputs, outputs, flows, and storages.
Explain the function and interaction of these components.

Factors like soil type, vegetation cover, and rainfall intensity affect infiltration and percolation.
Exam preparation should focus on understanding component interactions and factors affecting drainage basin hydrology.

Future content will cover factors affecting drainage basin hydrology and water balance in detail.