changes within the water cycle

Question 1

seasonal variations within water cycle - winter

Answer 1

winter:
- more precipitation
- more water locked up in snow and ice (2-6 months)
- increase in discharge

Question 2

seasonal variations within water cycle - summer

Answer 2

summer:
- increase in vegetation, increases interception
- decrease in precipitation in mid-latitude areas
- increase in storm events at lower latitudes as sea surface temperatures rise
- soil potentially dried out by warm temperatures causing no infiltration

Question 3

natural causes: extreme weather events

Answer 3

tropical storms = increase in river discharge from heavy rainfall and storm surges, strong winds damage vegetation which reduces interception, saturated soils reduce permeability increases overland flow
droughts = decrease in river discharge, soil dries out and becomes impermeable reducing overland flow, vegetation may die out which reduces interceptions
= possibility of wildfires (positive feedback effect)

Question 4

human causes: deforestation (short term)

Answer 4

less interception from vegetation and trees causes increased overland flow and increased river discharge
less evapotranspiration as no trees to return water to atmosphere
same amount of precipitation increases river discharge, increases risk of flooding

Question 5

human causes: deforestation (long term)

Answer 5

water flows out to sea, less evapotranspiration from trees reduces water vapour in atmosphere, less precipitation
as more water flows out to sea and less water being returned to river discharge through precipitation = river discharge decreases

Question 6

human causes: urbanisation

Answer 6

population growth = predicted increase to 9.7 bill by 2050
needs more housing and transport routes causes impermeable surfaces, increased runoff
human drainage systems direct water from surface into river at very fast rate = short lag time, increased peak discharge causes flashy hydrograph

Question 7

human causes: agricultural processes

Answer 7

pastoral farming (cows) and machinery compacts soil making infiltration and percolation difficult, increases overland flow of water
farmers drain farmland to reduce over saturation, use of soil pipes increases throughflow into rivers, increases river discharge at fast pace