Drainage basins Flashcards
Define drainage basin
The area of land surrounding a river, from which the river receives water and subsequently drains this water
Is a drainage basin an open or closed system?
An open system
What is the edge of a drainage basin called?
Watershed
What inputs are there in a drainage basin
-Precipitation
What stores are there in a drainage basin
-Lakes
-River channels
-Vegetation
-Soil
-Groundwater
What flows are there in a drainage basin
-Infiltration
-Percolation
-Surface runoff (overland flow)
-Groundwater flow
-Stem flow
What outputs are there in a drainage basin?
-Evaporation
-Transpiration
-River discharge
What 2 factors affect drainage basin processes?
-Interception
-Infiltration
What 3 ways can interception affect drainage basin processes?
-Interception loss (keeps plants hydrated)
-Throughfall
-Stemflow
Give 3 examples of what can change the level at which trees/plants intercept?
-size of leaves
-intensity of precipitation
-layer of tree (e.g shrub or canopy)
Which type of vegetation intercepts the most?
Tropical rainforest (58%)
Which type of vegetation intercepts the least?
Arable crops, smaller surface area (10-15%)
What are 3 flows (fluxes)? I,P,CA
Infiltration- controlled by gravity/capillary action/ soil porosity
Porosity- controlled by texture , structure and organic content
Capillary action- water in small spaces/ channels being pulled up/down due to water being polar
Infiltration rates
Clay soil (least)- 0-4 mm/hr
Sandy soil- 3-12 mm/hr
Permanent pasture (land for animals-cattle)- 13-23 mm/hr
Moorland (Marshland, boggy areas)- 42 mm/hr
Forests (most)- 50 mm/hr
What are the 6 factors affecting infiltration rates?
- Vegetation cover
- Slope angle
- Soil texture/structure
- Amount of water
- Time
- Soil surface structure
