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31 Cards in this Set
- Front
- Back
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Blue Water |
Water stored in rivers, streams, lakes and groundwater in liquid form |
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Green Water |
Water stored in soil and vegetation |
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Transpiration |
Diffusion of water from vegetation into atmosphere |
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Residence Time |
•Average time a water molecule will spend in reservoir or store •Impacts turnover within water cycle |
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Drainage Basin |
•Open system •Area of land drained by a river and its tributaries •Boundary defined by watershed |
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Watershed |
The highland which divides and separates waters flowing to different rivers |
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Drainage Basin System Inputs |
•Precipitation •Six key factors influence basin: ▪Amount of precipitation (Impacts drainage discharge) ▪Type e.g. snow can acts as temp store ▪Seasonality affects patterns of rainfall ▪Intensity as infiltration difficult as soil capacity exceedes ▪Variability ▪Distribution within a basin noticeable in larger basins such as the Nile |
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Flows in Drainage Basin (Interception) |
•Interception (water stored in vegetation) ▪Interception loss: water retained by plant surfaces, evaporated/transpired later ▪Throughfall: Intense/persistent rainfall, water drops from leaves etc ▪Stem flow |
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Flows in Drainage Basin (Infiltration) |
•Rate influenced by: ▪Duration of rainfall (capacity decreases with longer rainfall) ▪Soil capacity (if soil saturated, surface run-off takes place) ▪Soil porosity ▪Vegetation cover (infiltration greater in forests) ▪Raindrop size ▪Slopes (steeper more surface run-off) |
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Drainage Basin Outputs |
•Evaporation •Transpiration |
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Physical factors that influence drainage basin |
•Climate (Impacts vegetation too) •Soils •Geology •Relief •Vegetation |
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Human impact on precipitation |
•Cloud seeding •Aims to increase rainfall in drought-stricken areas |
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Amazonia Case Study (Humans impact on processes) |
•20% forest been destroyed in last 50 years due to commercial agriculture for biofuels, soya and development of infrastructure •Less interception, more surface run-off increase flood risk in Amazon drainage basin •Surface run-off increases soil erosion and degradation |
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Water Budget |
•Balance between inputs, flows and outputs •Tropical climate higher risk of flooding due to more precipitation (South America) |
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River Regimes |
•Annual variation in discharge of river at particular point •River flow supplied by groundwater rather than precipitation |
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Factors that influence regime |
•Size of river and where measurements are taken •Amount, pattern, intensity of precipitation •Temperatures (more evaporation in summer) •Geology and permeability/porosity of soils: (water stored as GW in permeable rocks, released into river as base flow which regulates flow during dry period) •Amount/type of vegetation cover: wetlands hold water, release very slowly into system •Human activities e.g. dam building can regulate flow •Climate has biggest impact on flow |
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Storm Hydrograph |
•Shows variation of discharge within a short period of time •Records changing discharge of river/stream in response to specific precipitation |
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Features of storm hydrograph |
•Rainfall begins, discharge rises (rising limb) •Peak discharge: river reaches its highest flow •Lag time: interval between peak rainfall and peak discharge •Once input stops, amount of water in river decreases (falling limb) •Discharge eventually returns to normal level (base flow) |
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Factors the effect shape of hydrograph |
Physical: •Rock type (permeability/percolation) •Soils (clay: low infiltration rate, sand: high rates) •Relief •Basin size (small basins-shorter lag time) Human: •Urbanisation •Deforestation/Reforestation |
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Meteorological Drought |
•Precipitation deficiency •Can be caused by natural variations in atmosphere, desiccation caused by deforestation and El Nino •Low precipitation, high temps, strong wind, more solar radiation |
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Hydrological Droughts |
•Reduced stream flow/groundwater levels due to reduced precipitation and more evaporation •Results in reduced storage in lakes/reservoirs and poor water quality •Linked to decreased water supplies in urban areas |
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El Nino |
1) Trade winds in western Pacific die 2) May be reverse direction flow 3) Water in west moves back east, leads to sea level rise in Peru 4) Eastern Pacific becomes warmer. El Nino overrides cold Humboldt Current, breaks food chain |
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Human Influences on Drought (Sahel Case Study) |
Drought impacts increased by: •Overgrazing: by nomadic tribes led to environmental degradation •Deforestation for fuelwood •High levels of rural poverty •Overpopulation: population growth outstripped food production •War between Ethiopia and Eritrea blocked access to food |
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Wetlands |
Perform number of key roles: •Act as temp water stores (mitigates downstream floods, protects land from destructive erosion and recharges aquifers) •Giant water filters, trap and recycle nutrients/pollutants, maintains water quality •Provides resources e.g. fish, fuelwood |
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Impact of drought on wetland |
•Less interception as vegetation dies •Less infiltration/percolation to groundwater stores, causes water table levels to fall •Desiccation accelerates destruction through wild fires |
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Areas more at risk of flooding |
•Low-lying flood plains/river estuaries: prone to groundwater flooding after saturation •Low-lying urbanised lands, impermeable surfaces, surface water flooding •Small basins subject to flash flooding |
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Causes of Flooding |
•Either meteorological or climatic •Prolonged/heavy rain associated with low-pressure systems or depressions (UK) •Intense seasonal monsoonal rainfall (Common in south and east Asia, low-lying plains of India, China, Pakistan at risk) •Melting snow, quick transition from winter to spring cause rapid snow melting |
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Human Impact on Flooding |
•Deforestation •Urbanisation: ▪Impermeable surfaces ▪Straightening channels results in flooding downstream |
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UK flood events 2007 (Impacts of flooding) |
•Dozen people killed •Cost of £6 million •Homes flooded •Power supplies damaged •Water supplies cut off |
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Water Poverty Index |
Resources: quantity of surface and groundwater per person and its quality Access: time/distance in obtaining sufficuent safe water Capacity: how well community manages its water Use: how water is used at home, agriculture and industry Environment: ecological sustainability |
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Nile Case Study (Conflicts over water sources) |
•Nile basin crosses large number of national borders •Sudan and Egypt have increasing needs for more Nile water |
