envi sci aqa - hydrosphere

• What are some of the human uses of water?

  - 70% agriculture (irrigation)

  - 22% industry (cool/heating)

  - 8% domestic use (hygeine)
• What has increased global demand for water?

  - increased population

  - increased affluence leading to increase in per-capita use

  - increased farmland irrigation

  - industrialisation (different industries have different water requirements
• Why is water so important?

  - access to clean and abundant water is vital for economic development
• What are the top 3 stores of water?

  - oceans (97%)

  - land ice (2%)

  - ground water (0.7%)
• What is the hydrological cycle?

  - combination of natural processes which distribute water around the world

  - the cycle is in dynamic equilibrium
• What is dynamic equilibrium and what is an example of the hydrological cycle being in dynamic equilibrium?

  - a balance created by active processes whose impacts cancel each other out where there are constant changes but overall stays the same

  - e.g. reservoirs are constantly changing in depth but in long periods of time stay similar depths
• What are the sources of water?


  - all surface water stores e.g. lakes and ground water stores e.g. aquifers
• What are the key process of the hydrological cycle?

  - evaporation

  - precipitation

  - run off

  - infiltration

  - percolation

  - base flow

  - ground water flow

  - interception

  - transpiration
• What is the process of evaporation/evapotranspiration?

  - process of water going from a liquid to a gas and entering our atmosphere

  - water from surface stores to clouds

  - evapotranspiration is the same but with water vapour released from plants
• What is the process precipitation?


  - process of formation of rain when water goings from a gas to liquid

  - water from clouds to the ground
• What is the process of run off?

  - process of water moving over the top of the surface

  - moves from water on top of the ground to surface water stores e.g. rivers
• What is the process of infiltration?

  - process of water entering the top layer of the ground

  - moves from on top of the ground vertically down into the top layer of the soil
• What is the process percolation?

  - when waters moves downwards in the soil to due to gravity

  - water moves from top layer of soil to lower layers
• What is the process of base flow?

  - very slow horizontal movement of water through the ground into rivers
• What is the process of ground water flow?

  - very slow horizontal movement of water through the ground into large water masses
• What is process of interception?

  - when precipitation is prevented from reaching the ground by vegetation

  - water moves from atmosphere to vegetation store
• What is the process of transpiration?

  - process of water being released from plants in the form of water vapour
• What are the key stores of the hydrological cycle?

  - soil moisture

  - ground water

  - land ice

  - clouds

  surface water

  - lakes

  - rivers

  - oceans
• What are all the human impacts on the hydrological cycle?

  - deforestation

  - agriculture

  - urbanisation

  - climate change
• How can deforestation affect the hydrological cycle?

  - reduced interception from vegetation resulting in increased run off

  - less movement of water from soils into atmosphere as less up take and transpiration

  - in general reduced precipitation in the area as less evapotranspiration
• How can agriculture affect the hydrological cycle?

  - soil compaction as a result of farming can reduce infiltration and increase run off

  - crop irrigation increases evaporation rates
• How can urbanisation affect the hydrological cycle?

  - impermeable surfaces such as tarmac decrease infiltration and increase run off
• What can large amounts of run off result in?

  - rivers flooding
• How can climate change affect the hydrological cycle

  - climate change can have changes everywhere in the water cycle

  - increase global temperatures affect rates of melting, evaporation and condensation which all combine together to affect amount, timing and location of weather

  - less water stored in snow and ice
• How can climate change reduce extremes in river flows?

  - snow fall in cold weather and its later melting in warm weather reduces extremes in river flow
• What are the key sources for water extraction?

  - reservoirs (dams)

  - rivers

  - sea water

  - aquifers

  - rain water
• What are the factors affecting reservoir sites?

  topography

  - narrow exit from large deep basin

  geology

  - rock beneath reservoir must be impermeable so waster cant be lost

  water supply

  - area with regular and large volume of rainfall

  catchment area

  - reservoir must be in catchment area
• What factors make different rivers more favourable for exploitation?

  - total annual water flow

  - fluctuations in water flow

  - level of natural contaminants

  - amount of pollution
• What feature must an aquifer rocks have to be exploited?

  porosity (how much water can be held in the rock)

  - high porosity allows more water to be held in the rocks

  permeability (how easily water flows between rocks)

  - aquifer rocks must be permeable so water can easily flow in (recharge)

  - rocks surrounding aquifer apart from surface layer must be impermeable to prevent water loss
• What is an aquifer?

  - an aquifer is an under ground body of rock that holds water
• How are rivers/reservoirs exploited?

  - dams
• What is an example of a dam and its pros and cons?

  The 3 Georges Dam Project (largest)

  - HEP dam in China which spans across the Yangtze River

  pros

  - replaces coal power stations

  - produces great amounts of power

  cons

  - large area of houses was destroyed to make room for flooding forcing 1 million people to relocate

  - huge embodied energy

  - increased landslide risks

  - increased pollution as river runs slower
• What are the pros of reservoirs/dams?

  - can control flooding downstream

  - provide supply of water for e.g. irrigation

  - can be use for HEP

  - reservoirs created behind dams can be used for recreational activities

  - can create new valuable habitats
• What are the environmental impacts of reservoirs/dams up stream?

  - increased sediment build up behind dams forming silt and increasing turbidity and lowering the reservoirs capacity

  - increased temps and water is static which both decrease dissolved oxygen

  - can flood important habitats

  - migration barrier
• What are the environmental impacts of reservoirs/dams down stream?

  - less nutrients in flood plain soil as sediment builds up behind dam (sediment contains nutrients and is deposited onto soils when flood plain is flooded)

  - reduced river flow = less dissolved oxygen and less important flooded habitats

  - migration barrier
• How can reservoirs change microclimates?

  - large body of water has high specific heat capacity which reduces temp extremes

  - warmer winters and colder summers

  - wind speeds are also higher as water has less friction then land

  - increased humidity, cloud cover and precipitation due to greater evaporation from the reservoir
• What are some of the impacts of rivers being over exploited?

  - increased concentration of pollutants (less water, more pollutant)

  - shipping problems

  - aquatic ecosystems dry up such as wetlands
• Example of an over-exploited river?

  Rivers flowing into the Aral Sea

  - huge irrigation scheme to increase agricultural output in Kazahkstan

  - caused the Aral Sea, the 4th largest lake in the world to reduce in size by 90%

  impacts?

  - collapse of fishing industry

  - salinisation

  - change in micro climate (more extremes)

  - collapse of aquatic ecosystem

  - health problems caused by pesticide and fertiliser pollution increasing in concentration
• How do aquifers work?

  - aquifers are normally in a state of dynamic equilibrium whereby the recharge rate equals the rate that water flows out of the aquifer eg via groundwater/base flow
• What is aquifer recharge?

  - process of aquifers gaining water

  - most aquifer recharge is precipitation landing on the ground and infiltrating and percolating through soil and rock into the aquifer