Drainage basins are open systems, with inputs, stores and outputs. The main input is precipitation which is regulated by various means of storage. Outputs include channel runoff, evapotranspiration and groundwater flow.
The Drainage basin system
- Complete the system diagram using information from the flow chart
- Identify and annotate a feedback loop on your system diagram
- Make notes on pp 104-106 Core Book
water balance in a drainage basin
The water balance is the relationship between inputs (precipitation) and outputs (evapotranspiration). It is influenced by a number of factors:
- Soil moisture deficit - the degree to which soil moisture falls below its capacity
- Soil moisture recharge - precipitation > potential EVT
- Soil moisture surplus - soil is saturated leading to overland flow
- Soil moisture utilisation - water is drawn to the surface by the capillary action of plants, which is then used or evaporated
These factors may change over time (seasons, long term changes in ice/water balance) or space (precipitation, EVT and runoff vary between countries).
Match the words with the definitions to create a circle