Modification of drainage cycle Flashcards
Due to dams, there is an increase…
of evaporation. E.g. Lake Nasser loses 1/3 of its water by evaporation.
Increased urbanisation leads to…
reduction in evapotranspiration due to lack of vegetation but increase in evaporation due to higher temperatures.
Deforestation leads to…
a decline of surface storage, reduction in evapotranspiration.
Afforestation may have a negative…
impact, as in river Severn catchments sediment loads increased 4x.
Increased erosion due to afforestation decreased…
as the trees grew up.
Infiltration is up to…
5x higher under forest compared to grasslands.
Grazing leads to decline in…
infiltration due to compaction and pounding of the soil.
Ploughing increases…
the infiltration as it loosens the soil.
When the water table is close to the surface…
evaporation of water leaves salts behind and it may form an impermeable crust.
Increase surface storage in urban areas due to…
large-scale dams.
Problems with dams:
- salinisation
- increased erosion
- local changes in the climate
Over-abstraction may lead to…
the drying of rivers, falling water tables and saltwater intrusion in coastal areas.
In Malta, most underground can no longer be…
used because it is contaminated by the saline intrusion.
The saline intrusion is…
the movement of saline water into freshwater aquifers.
Irrigation is the main…
cause of groundwater overexploitation.
