Water cycle Flashcards
System
An assemblage of interrelated parts that work together by way of a driving process
Open system
Matter and energy transferred in/out of system boundary
Closed system
Energy transferred in/out of system boundary e.g. water cycle
Isolated system
No energy/matter transferred in/out of system boundary
Stores
Parts of the system where energy/mass is stored/transferred
Components/elements
Things that make up the system of interest
Attributes
Perceived characteristics of elements
Relationships
How elements and attributes interact to carry out a process
Dynamic equilibrium
Balance between inputs and outputs with unchanging store magnitude, preserved by negative feedback, disrupted by positive feedback
Earth system
Closed system with four major open subsystems (atmosphere, lithosphere, hydrosphere, biosphere) to form a cascading system
Water stores
Oceanic, cryospheric, terrestrial, atmospheric. Not evenly distributed worldwide (Antarctic ice caps, NW Saharan aquifers). Transfers over time
Water remains in shallow groundwater stores for how long
100-200 years
Water remains in deep groundwater stores for how long
10,000 years
Water remains in seasonal snow cover for how long
2-6 months
Water remains in glaciers for how long
20-100 years
What % of the Earth’s water is saline
97.5%
Of the % freshwater, what % is snow and ice
68.7%. 95% in 2 ice sheets covering Antarctica and Greenland. Long and short term storage
Of the % freshwater, what % is aquifers
30.1%. Can be fossil (NW Sahara), saline, etc.
Of the % freshwater, what % is surface and other
1.2%
Relief rainfall
Warm moist ocean air hits highland, rises, cools, and condenses, causing rainfall and a rain shadow on the other side
Convectional rainfall
Evaporation saturates air to be energetic and unstable, it then rises with particles bumping into each other making charge, at dew point temp this forms storms
Frontal rainfall
Warm and cold air from equators and poles meet, different densities don’t mix so warmer rises, cools, and condenses to rain. Temperature inversion forms fog
Global atmospheric circulation model
Explains cloud formation and precipitation varying with time and space. Inter-tropical convergence zone, local variance with storms, mid-latitude cloud formation from air convergence and jet streams
Glacial cycle significance
Currently in interglacial period where ablation>accumulation so functional hydrological cycle, in past interglacial 50m higher water levels
P=
Q+E+-change in storage
Water budget graph
Months on x-axis, mean precipitation on y-axis, mean evapotranspiration on z-axis
Flashy hydrograph
Flood, short lag time
Subdued hydrograph
No flood, long lag time
Physical factors affecting lag time
Gradient, antecedent rainfall, geology, vegetation, rainfall amount and intensity, basin size, drainage density
Human factors affecting lag time
De/afforestation, agriculture, urbanisation, flood alleviation schemes, water abstraction
Physical factors affecting water cycle
Rock permeability, evaporation rate, precipitation, drought, soil, topography, desertification, extreme weather events
Human factors affecting water cycle
Climate change, de/afforestation, agriculture, land use, urbanisation, abstraction, desertification, irrigation
Effect of drought on the water cycle example
2012-16 Californian drought
Effect of land use changes on the water cycle
Mainly from urbanisation and deforestation
Effect of seasonal changes on the water cycle
Affect soil water, river channel flow, evaporation, vegetation and precipitation
Effect of farming practice on the water cycle - UK
East Anglian Fens and Somerset levels drained to farm, 584m tonnes C in English peatlands, lowered water table so friable peat and Fen Blows, still floods e.g. 2014 Somerset
Effect of farming practice on the water cycle - global
Perforated plastic tube network below soil surface for drainage, aerates soil, Ohio State University shows for $1 spent on corn/soy $1.20-1.90 back. However, nitrate loss, expensive, more throughflow, eutrophication, dry topsoil
Effect of abstraction on the water cycle - Middle East
Aquifers in danger of depletion so use nets to stop evaporation
Effect of abstraction on the water cycle - Malta
Must desalinise as saline intrusion
Effect of abstraction on the water cycle - Greek Argolid Plains
400m deep seawater contaminated boreholes
Effect of abstraction on the water cycle - London
Chalk-basal sands aquifer overabstracted in 19th and 20th century so in 1960s 88m below sea level. Deindustrialised, rise at 3m/yr, threatened London Basin, 2000-14 GARDIT, E,C+S fell
