The Hydrosphere Flashcards
What are the main human uses of water?
Agriculture = 70%
Industry = 22%
Domestic uses = 8%
Why is the global demand for water increasing due to an increase in population?
Birth rate is higher then death rate, immigration = more water needed for more people
Why is the global demand for water increasing due to an increase in per-capita use with increased affluence?
As piped water becomes more available and people become increasingly affluent, use more for washing etc
Why is the global demand for water increasing due to an increase in irrigation if farmland?
Subsistence agriculture relies on naturally available water, as commercial farming expands increased income allows money to be invested in irrigation schemes
Why is the global demand for water increasing due to industrialisation?
Different industries have different water requirements, heavy industry such as chemical and steel industries or paper making, use much more water than lighter industries
What are the main processes of the natural hydrological cycle?
Precipitation, interception, infiltration, percolation, groundwater flow, runoff, evaporation, transpiration, river channel discharge
What is residence time and how can it be calculated?
Residence times, transfer rates and water volume are connected and one value can be calculated if the other two are known
Residence time = volume of water in the reservoir/mean transfer rate
How does deforestation impact the hydrological cycle?
- vegetation intercepts rainfall which may evaporate before it reaches the ground
- trees also return a lot of water from the soil to the atmosphere by transpiration
- loss of trees causes significant reduction in precipitation in downwind areas
How does agriculture impact the hydrological cycle?
- soil compaction due to heavy machinery or by livestock means water does not infiltrate easily into the ground so runoff increases
- crop irrigation increases evaporation rates
- loss of soil biota such as worms reduces infiltration, increases runoff and reduces water retention
How does urban development impact the hydrological cycle?
- urban areas often have impermeable surfaces
- reducing infiltration, increasing runoff
- flooding
How does global climate change impact the hydrological cycle?
- higher global temperatures affects melting, evaporation and condensation as well as wind patterns = change the timing, amount, type and location of precipitation
- more rapid snow melting may increase flooding after heavy rain and low river flow
How is habitat change an environmental effect of reservoirs?
Flooding the reservoir, destroys previous habitats, also creates new ones
- wetlands are uncommon habitats so it is valuable to create them
How are wildlife barriers an effect of reservoirs?
Dam and reservoir act as a barrier to wildlife that migrates along the river such as salmon and sturgeon
How is the downstream river regime affected by reservoirs/dams?
- holding back water during times of surplus to ensure adequate river flow in times of shortage, reducing risk of flooding
- it also reduces periods of lower flow which can be essential for turtles that lay their eggs in sandbanks
How is sedimentation an effect of reservoirs?
- sediments in the river are carried down and settle there
- sediment downstream may have been important for fertilising the floodplain
- built up riverbanks and coastlines and counteracted erosion
How are microclimates an effect of reservoirs?
- large bodies of water may change the local climate, high heat capacity of water helps to reduce temperature fluctuations
- warmer in the winter, cooler in the summer
- water provides less friction so wind speeds increase
- greater evaporation may increase humidity, cloud cover and precipitation
How are rivers flowing into the Aral Sea exploited?
Syr Darya and Amu Darya flow through Central Asia to the Aral Sea = used to be fourth largest lake
- huge irrigation schemes reduced the lake size by 90%
How is the River Nile exploited?
Longest river in the world
- as populations grow and countries develop economically the demand for water will increase and the risk of conflict may grow
How are the Rivers of Tibet exploited?
1500 million people rely on the water
- growing populations and increased demand for agriculture and industry may lead to water shortages and conflict
What is porosity?
Measure of the proportion of a rock’s volume that is space and could therefore hold water
- chalk, limestone, and sandstone are porous rocks that can form aquifers
What is permeability?
Measure of the ease with which fluids may flow through a rock because of the interconnections between the spaces and their size
What are the associated geological structures of aquifer?
Rock below the water-bearing rock must be impermeable to prevent water escaping
- granite and clay are impermeable rocks
- some of the rock above the water rock must be permeable to allow the aquifer to be recharged
How are aquifers recharged?
