Chapter 8 - The Hydrosphere Flashcards
Define: Hydrogen Bond
The weak electrostatic bond formed between water molecules, which gives water a high boiling point.
Define: Evaporation
The change of water from liquid to gas as hydrogen bonds are broken.
Define: Anomalous Expansion
Unusual expansion, usually applied to water, which expands as it is cooled below 4 degrees.
Define: Residence Time
The average length of time that a molecule remains in a reservoir.
Define: Aquifer
An underground rock structure from which water is abstracted.
Define: Reservoir
The general name for a storage location for any material. The term is also used for the stored water retained by a dam.
Define: Transfer Rate
The volume of material moved from one reservoir to another.
Define: Precipitation
Condensation of atmospheric water vapour that reaches the Earth’s surface in any liquid or solid form.
Define: Throughflow
The sideways movement of water in ground.
Define: Interception
Precipitation that does not reach the ground because it lands on vegetation.
Define: Infiltration
The process by which surface water enters the ground between the particles of soil or rock.
Define: Percolation
The movement of water between the particles of soil or rock.
Define: Groundwater Flow
The movement of water through the pore spaces and fissures in permeable rocks.
Define: River Channel Discharge
The volume of water flowing past a particular point on a river and is a product of cross sectional area and mean water velocity.
Define: Abstraction
The removal of water from the location where it was found.
Define: Irrigation
Artificial watering of plants, especially crops.
Define: Potable
Water that is stable for drinking.
Define: TSS
Total Suspended Solids. The total amount of organic and inorganic material suspended in a volume of water.
Define: Pathogen
An organism that causes disease.
Define: Coliform Count
A measure of sewage pollution based in the presence of the faecal bacterium.
Define: Catchment Area
The area of land that collects water, which will flow down to the lowest point.
Define: Anaerobic
A process or organism that does not require oxygen.
Define: Topography
The 3D shape of the landscape.
Define: Porosity
A measure of the percentage of the volume of a rock that is space.
Define: Permeability
A measure of the rate at which a fluid, such as water, can flow through rock.
Define: Subsidence
The collapse of the ground surface caused by undermining or a reduction in aquifer rock volume following the over-abstraction of water.
Define: Osmotic Dehydration
The loss of water, especially from crop roots, caused by low water potential of soils with a high salt content.
Define: Osmosis
The diffusion of water through a partially permeable membrane from an area of high water potential to an area of low water potential.
What are the unusual properties of water?
- Changes of state (narrow temperature range)
- Anomalous expansion (floating solid ice, unaffected deep water)
- Solvent properties (biological reactions occur with solutes dissolved in water)
- High heat capacity (maintain climatic stability)
What are the main stages of the hydrological cycle?
- Evaporation
- Condensation
- Precipitation
- Groundwater Flow
- Transpiration
- Evapotranspiration
- Interception
- Surface Runoff
- Percolation (Throughflow)
- Transport
What are the inputs of the hydrological cycle and how are they impacted by humans?
- Precipitation (rain, hail, sleet, snow)
> Temperature impacts e.g. global climate change
What are the throughflows of the hydrological cycle and how are they impacted by humans?
- Interception (precipitation landed on vegetation)
> Deforestation, afforestation, urbanisation - Infiltration (water flow through ground surface)
> Soil compaction, urbanisation, paved areas - Percolation (water flow through spaces in soil/rock)
> Soil compaction - Groundwater Flow (water movement through rock pore spaces)
> Groundwater abstraction, artificial aquifer recharge - Runoff (water flow over ground surface)
> Reduced infiltration/interception
What are the outputs of the hydrological cycle and how are they impacted by humans?
- Evaporation (liquid water to water vapour)
> Reservoirs, global climate change - Transpiration (water vapour loss from plants)
> Vegetation changes - River Channel Discharge (water carried by river)
> Abstraction of water, flood drainage
What are the abstractive uses of water?
- Domestic uses (washing, flushing toilets, drinking)
- Industrial uses (cooling, steam generation, heating)
- Agricultural uses (irrigation, livestock drinking)
- Water quality requirements
> Turbidity (removal of suspended solids)
> pH (pH 6.5 - 8.5)
> Calcium content (reduce tooth decay, osteoporosis)
> Pesticide concentration (remove pesticides)
> Heavy metal concentrations (could damage nervous system)
> Dissolved O2 (affects smell of water)
> Chlorine retention (sterility)
> E. Coli abundance (cholera and typhoid)
What are the non-abstractive uses of water?
- Energy (HEP schemes, nuclear power stations)
- Transport (ships)
- Recreation (sailing, canoeing, swimming)
- Wildlife Conservation (wetlands)
What factors affect the location of a reservoir?
- Topography (narrow exit, large deep basin)
- Geology (strong impermeable rock, percolation)
- Catchment Area (flowing fallen rain)
- Water Supply (Large regularly rainfall)
- Existing Land Use (unimportant land)
- Pollution Risk (no pollution risk to water)
- Sedimentation (less soil erosion in catchment area)
- Infrastructure (building dam, treating and transporting water)
- Estuarine Barrages (dam creates freshwater lake)
What are the environmental effects of a reservoir?
- Habitat Change (flooding destroys old habitat, creates new one)
- River Flow Changes (flow fluctuations change erosion/sedimentation)
- Sedimentation (sediments settle in reservoir, riverbanks prevented)
- Reservoir Microclimate (local climate changed, temperature fluctuations)
What are the main features of an aquifer?
- Porosity (proportion of rock’s volume that can hold water)
> e.g. chalk, limestone and sandstone - Permeability (rate of water flowing through rock)
- Suitable Geological Structures
> Impermeable rock below water-bearing rock
> e.g. clay and granite
> Permeable rock above to allow recharge
> Abstracted through well, borehole or naturally
What are the consequences of aquifer overuse?
- Reduced Supplies (extraction rate exceeds recharge rate)
- Subsidence (collapse of ground surface, building damage)
- Changes in Surface Hydrology (lowered water table, dry wetlands)
- Ecological Impacts (food webs affected, plants dying)
- Saltwater Incursion (seawater replacing aquifer freshwater)
What are the stages of freshwater treatment and their purpose?
1) Screens (remove floating vegetation/plastic that could clog processes)
2) Sedimentation (static water to allow suspended solids to settle)
3) Aeration (ensure high dissolved oxygen content, smell good water)
4) Flocculation/Coagulation (particles combine then settle)
5) Filtration (remove remaining solids and bacteria)
6) Activated Carbon Filters (remove organic chemicals)
7) Sterilisation (sterilise water and kill pathogens with chlorine/ozone/UV)
8) Fluoridation (fluorides improve dental health)
What are the two types of seawater treatment processes?
1) Reverse Osmosis (saline water filtered through semi permeable membrane at high pressure)
2) Distillation (water boiled, steam condensed and collected)
What are the factors that cause the demand for water to change?
- Change in Population Size (birth rate higher than death rate or high immigration rate)
- Change in Living Standards (high domestic appliance usage, link between affluence and water consumption)
- Industrialisation
> Subsistence farming uses water naturally available
> Heavy industries use large volumes of water - Changes in Attitude to Water Use (personally collecting water, carefully consuming it)
How can water be conserved and managed more effectively?
- Increasing Water Availability
> Increased Abstraction (building storage reservoirs)
> Catchment Management
> Reservoirs maintain river water levels and store water
> Pollution prevention upstream of water abstraction points
> Aquifer Recharge (recharge during periods of surplus surface water) - Better Water Distribution
> Reducing Distribution Losses (prevent pipe leaks)
> Inter-basin Transfer (water transferred by rivers and pipes) - More Efficient Water Use
> Metering (charged for amount of water used with meter)
> Low Water-use Appliances (dual flush designed toilets)
> Grey Water Use (recycling previously used water)
