The drainage basin Flashcards
In what way is the drainage basin an open system?
It is an open system with external inputs and outputs. Since those inputs vary over time, so does the amount of water in the drainage basin.
What are the characteristics of precipitation that can have a significant impact on the drainage cycle?
Form Amount Intensity Seasonality Distribution
How will the form of precipitation affect the drainage cycle?
Rain, snow or hail. Clearly, with snow, entry of water into the drainage system will be delayed.
How will the amount of precipitation affect the drainage cycle?
This will affect the amount of water in the drainage basin and fluxes within it.
How will the intensity of precipitation affect the drainage cycle?
The greater the intensity, the greater the likelihood of flooding.
How will the seasonality of precipitation affect the drainage cycle?
This is likely to result in the drainage basin system operating at different flow levels at different times of the year.
How will the distribution of precipitation affect the drainage cycle?
This is significant in very large basins, such as the Nile and the Ganges, where tributaries start in different climate zones.
What is a drainage basin?
A drainage basin is an area of land drained by a river and its tributaries, sometimes referred to as a river catchment. The boundary of a drainage basin is defined by the watershed.
What are the seven flows that are important in transferring the precipitation that has fallen on the land into the drainage network?
Interception Infiltration Percolation Throughflow Groundwater flow Surface runoff River or channel flow
What is interception?
The retention of water by plants and soils which is subsequently evaporated or absorbed by the vegetation.
What is infiltration?
The process by which water soaks into, or is absorbed by the soil.
What is percolation?
Similar to infiltration, but a deeper transfer of water into permeable rocks.
What is throughflow?
The lateral transfer of water downslope through the soil.
What is groundwater flow?
The very slow transfer or percolated water through pervious or porous rocks. Also known as base flow.
What is surface runoff?
The movement of water that is unconfined by a channel across the surface of the ground. Also known as overland flow.
