Drainage Basin
- Created by: Ali Bland
- Created on: 18-03-15 13:29
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- Drainage Basin
- This is an area of land drained by a river and its tributaries
- Its an open system with inputs,outputs, stores, flows/transfers and outputs
- A drainage basin acts as a largely closed system because it has a very definite outer edge or boundary
- There is little, is any transfer of water between drainage bains
- The movement of water within the drainage basin is illustrated by the drainage basin hydrological cycle
- Drainage Basin Hydrological Cycle
- Precipitation
- All forms of moisture that reach the Earth’s surface e.g. rain, snow, sleet and hail
- Evapotranspiration
- the loss of water from a drainage basin into the atmosphere from the leaves of plants + loss from evaporation
- Interception
- This is when precipitation lands on buildings, vegetation and concrete before it reaches the soil
- Depression Storage
- When water is stored temporarily on the ground surface in the form of puddles
- Baseflow, or groundwater flow
- The very flow transfer of water through rocks
- River Channel
- The river forms the "exit" for water transferred through the drainage basin
- Percolation
- The deeper transfer of water into permeable rock - those with joints or are porous
- Throughflow
- The movement of water downslope within the soil layer
- Infiltration
- The downward movement of water into the soil surface
- Overland Flow
- A rapid form of water transfer over the surface of the ground
- Precipitation
- The Water Balance
- This is the balance between inputs and outputs in a drainage basin
- This is expressed as P=O+E+/-S
- P= Precipitation
- O=Total Runoff
- E=Evapotranspiration
- S=Storage
- When the inputs and outputs are balanced it is said to be a dynamic equilibrium
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