unit one: the water cycle Flashcards
what is the percentage of global water in the stores: a) oceans b) the land c) the atmosphere?
a) 97.44%
b) 2.56%
c) 0.0009%
what are the inputs, outputs, flows and stores of the cryosphere?
- inputs = desublimation, precipitation in snow
- outputs = sublimation, meltwater, debris, evaporation, ablation
- flows = meltwater streams, glacial flows
- stores = glaciers, sea ice, permafrost
what are the inputs, outputs, flows and stores within a drainage basin?
- inputs = precipitation
- outputs = evaporation, transpiration
- flows = vapour transport, surface runoff, percolation, fluxes
- stores = ocean, soil, groundwater, atmosphere
what is the difference between an open and closed system and give an example for both?
- open system: the quantity of matter will vary over time e.g. drainage basin
- closed system: quantity of matter is fixed e.g. global water cycle
what are the main inputs and outputs of the groundwater store?
- inputs = precipitation, percolation
- outputs = groundwater flow
what are the main inputs and outputs of the rivers and lakes store?
- inputs = precipitation, surface run off
- outputs = evaporation, river flow, river discharge
what are the main inputs and outputs of the soil store?
- inputs = precipitation, infiltration
- outputs = root uptake, transpiration
what are the main inputs and outputs of the atmosphere store?
- inputs = evaporation, transpiration
- outputs = precipitation
what are the main inputs and outputs of the biosphere store?
- input = root uptake
- output = transpiration
how is fresh water stored in a way that humans can’t access?
- less than 1% of water is fresh water
- locked up in glaciers and permafrost
- may mix with saline water = undrinkable
how does the ice albedo feedback mechanism cause rapid changes to the cryospheric water stores?
- albedo is how much it reflects insulation
- increases the amount of ice melting
- causes an increase in the amount of areas with open water
- impact on temperature (positive feedback)
how has ablation on greenland’s ice sheets have affected sea levels?
- an additional 7cm of ocean rise could now be expected by the end of the century by green land
- has lost 3.8 trillion tonnes of ice since beginning of the study period
- losing ice due to surface melting and calving of icebergs
- 7 times faster than in 1990s
by how much has global mean sea level risen since 1880 and due to what?
- 25cm
1) run-off of melt water from glaciers and ice sheets
2) thermal expansion of sea water as it warms
what is the formula for water balance?
precipitation (p) = stream/river flow (q) + evapotranspiration (e)
- if p > q + e there will be a positive balance
- if p < q + e will be a negative balance
what is soil water surplus?
- excess water available to the system and the soil is saturated
- precipitation exceeded evapotranspiration for prolonged period
- excess is not used by plants
what is soil water utilisation?
- reduction of water available within the system
- evapotranspiration exceeds precipitation
- plant growth increases transpiration rates
- increasing temperatures increase evaporation
what is soil water recharge?
- after period of soil water deficiency
- precipitation exceeds evapotranspiration
- increase of water in soil
what is field capacity?
maximum amount of water that soil can hold before it becomes saturated
what are the different types of precipitation?
- rain
- snow
- sleet
- hail
- dew
- fog/mist
how would the drainage basin be affected by a prolonged period of intense rainfall?
- high levels of infiltration
- soil will become saturated
- less infiltration will begin to occur
- surface run-off will increase
- more water going to rivers and channels
how would the drainage basin be affected by a short period of light rain?
- low levels of infiltration
- more interception
- more evapotranspiration
what is throughflow?
horizontal movement of water down-slope, through the soil
what is infiltration?
movement of water from the ground surface into soil
what is throughfall?
water dripping off vegetation to the ground surface
what is transpiration?
water lost from vegetation through the stomata
what is the groundwater store?
water stored in soil and lone rock below the water table
what is interception?
water temporarily stored on the surface of vegetation
what is surface runoff (overland flow)?
the flow of water over the ground surface
what is baseflow?
water flowing into a river from the ground water store
what is the water table?
the upper level of the groundwater
what is the channel store?
water held within a river
what is percolation?
vertical, downward movement of water through the soil to ground water
what is surface storage?
water held in puddles, lakes and reservoirs
what is channel flow?
water flowing within a river
what is stem flow?
water flowing over leaves, stems and branches
how will interception loss vary between a deciduous woodland in winter and summer?
- winter: less interception because trees lose their leaves. colder temperatures = less evaporation
- summer: more interception because there is more area for interception. cooler = more evaporation
what is saturation-excess overland flow?
if soil is already saturated and there are no empty pore spaces between soil particles, then any further precipitation will runoff the surface
what is infiltration-excess overland flow?
on dry soil, when the rate of precipitation is greater than the rate of infiltration (infiltration capacity) = excess water will accumulate on the surface and begin to flow overland
how will soil texture affect the rate of infiltration?
- coarse gravel = many large macro pore spaces which means the water will infiltrate and percolate the soil faster
- sand = many macro pore spaces which are smaller which shows rate of infiltration will still percolate
- silt and clay = small micro pore spaces, which slows down the rate of infiltration
- clay rich soils = insufficient to become the high tension forces within tiny micro pores, meaning soil becomes impermeable
what factors affect infiltration and though-flow rates?
- gravity
- amount of soil
- moisture level (compaction of soil)
- seasons/weather conditions
- levels of vegetation
- amount of precipitation
- texture of soil
what affect will trees have on the flood risk in an area?
forests retain excess rainwater and help to moderate run-off pattern, which reduces the damage from flooding
what are aquifers and the 2 different types?
rocks that are capable of storing and transmitting water
- pervious rocks = water is stored or passes through cracks within the rock e.g. limestone
- porous rocks = water is stored or passes though the pores between rock particles e.g. sand stone and chalk
what factors may control the rate of transpiration?
- season (high in summer)
- density of vegetation (more = increase rate)
- time of day (increased during the day)
- typed of plant
what factors (natural and human) might affect the pattern of a river regime?
natural:
- seasonal changes
- amount of precipitation
- natural disasters
- temperature
- vegetation
- type of soil
- geology
- amount of evaporation
- relief of the land
human:
- building of roads
- man-made dams
- removal of vegetation
- impermeable surfaces
- reservoirs
- irrigation
- transfer schemes
what was the hoover dam and why was is constructed?
- 1936
- to be source of power generation (4 billion kw = 1.3 million people domestically)
- as flood control
- for water storage (lake meade - 28.9 million acres, 2 years of slow of the colorado river, largest reservoir in the usa)
- peak rainfall occurs in august due to intense storms from convectional rainfall
- storms could lead to flash flooding, due to infiltration-excess overland flow
what were the changes in discharge pattern of the colorado river before and after the construction of the hoover dam?
- before = mean monthly flow was reaching highs of 100 cfs and was fluctuating greatly
- after = mean monthly flow decreased by a lot. still fluctuating but more consistent
how do river catchment shapes affect discharge?
- elongated = lower peak discharge as the water at the head of the basin take longer to reach the river mouth than water closer to it
- circular = less time to reach river as all points are roughly equidistant from river so precipitation reaches river at the same time
what is drainage density?
- total length of streams/rivers per unit area of land
- high drainage density = shorter lag time and fairly steep falling limb
- water will drain out of them quickly
how will a slope gradient of basins affect discharge?
steep slopes = high peak discharge and a short lag time as water can travel faster downhill
