Impact of physical and human factors on the drainage basin Flashcards
What are the five physical factors affecting drainage basin systems?
Climate Soils Geology Relief Vegetation
How does climate affect drainage basin systems?
Climate has a role in influencing the type and amount of precipitation overall and the amount of evaporation, i.e. the major inputs and outputs. Climate also has an impact on the vegetation type.
How do soils affect drainage basin systems?
Soils determine the amount of infiltration and thoughflow and, indirectly, the type of vegetation.
How does geology affect drainage basin systems?
Geology can impact on subsurface processes such as percolation and groundwater flow (and, therefore, on aquifers). Indirectly, geology affects soil formation.
How does relief affect drainage basin systems?
Relief can impact on the amount of precipitation. Slopes can affect the amount of runoff.
How does vegetation affect drainage basin systems?
The presence or absence of vegetation has a major impact on the amount of interception, infiltration and occurrence of overland flow, as well as on transpiration rates.
What are the four human factors affecting drainage basin systems?
River management
Deforestation
Changing land use - agriculture
Changing land use - urbanisation
How does river management affect drainage basin systems?
Construction of storage reservoirs holds back river flows
Abstraction of water for domestic and industrial use reduces river flows
Abstraction of groundwater for irrigation lowers water tables
How does deforestation affect drainage basin systems?
Clearance of trees reduces evapotranspiration, but increases infiltration and surface runoff.
How does changing land use (agriculture) affect drainage basin systems?
Arable to pastoral: compaction of soil by livestock increases overland flow.
Pastoral to arable: ploughing increases infiltration by loosening and aerating the soil.
How does changing land use (urbanisation) affect drainage basin systems?
Urban surfaces (tarmac, tiles, concrete) speed surface runoff by reducing percolation and infiltration. Drains deliver rainfall more quickly to streams and rivers, increasing chances of flooding.
Which components of the drainage basin system is most affected by humans?
Evaportation and evapotranspiration Interception Infiltration Groundwater Surface runoff
How has deforestation disrupted the drainage basin cycle in the Amazonia?
A lowering of humidities Less precipitation More surface runoff and infiltration More evaporation, less transpiration More soil erosion and silt being fed into the rivers.
