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oceans and hydrosphere
The oceans hold about 97.5% of earth’s water, making them the largest reservoir. This water is mainly saline.
hydrosphere and freshwater
Only about 2.5% of earth’s water is freshwater. Of this, approximately 68.7% is stored in glaciers and ice caps, primarily in Antarctica and Greenland.
hydrosphere and groundwater
Groundwater accounts for about 30.1% of the freshwater, with lakes containing about 87% of surface freshwater.
drainage basin characteristics
-source of the river
-main river channel
-tributaries
-confluence
-mouth of river
-watershed
drainage basin
area of land drained by a river system
watershed
the boundary of a drainage basin, following the highest land between adjacent drainage basins
main components of hydrological cycle
-infiltration
-throughflow
-groundwater store
-percolation
-evapotranspiration
-groundwater flow
-precipitation
-channel flow
-interception
-overland or surface flow
-condensation
-depression storage
-evaporation
infiltration
water soaking into the soil from the surface
throughflow
water moving downhill through the soil layers, generally slowly, but flow may concentrate along the line of roots or soil weaknesses, which form natural pipe, in which the flow will be much faster.
groundwater store
water held below the water table in aquifers.
percolation
water moving from the surface layers of soil into deeper layers of soil and rock.
evapotranspiration
the combined processes of evaporation and transpiration that result in the loss of water from the leaf. Transpiration is the loss of water through the tiny boles called stomata in the leaf surface. In reality, it is very different to calculate the two amounts separately, soo they are often grouped together.
interception
plants trap some of the precipitation, so it may not immediately pass to the ground: some water may drip to the ground as through fall: some may flow down the stem as stem flow. Alternatively, the precipitation may evaporate directly off the leaf surface and never reach the round.
evaporation
water changing from its liquid form to a gas (water vapour) and returning to the atmosphere.
groundwater flow
water moving within rocks below the ground
precipitation
water deposited on the ground as a liquid or as a solid, for example, rain, hail, snow, fog.
overland or surface flow
water moving across the surface of the ground, which occurs when rain cannot soak quickly enough into the ground, due to tarmac surfaces, or hard-baked soil, very heavy rainfall, or when the soil is saturated and infiltration cannot take place (saturated overland flow).
condensation
the process by which water vapour is converted into water
depression storage
storage of water in hollows and holes in the ground surface to form puddles.
subsurface return flow (hill slope hydrological pathways)
after water infiltrates the soil on an up-slope portion of a hill, the water may flow laterally through the soil, and exfiltrate (flow out of the soil) closer to a channel.
global water budget
oceans lose more water through evaporation than they gain through precipitation, whereas it’s the opposite for landmasses.
surface runoff makes the difference -> known as balance _> known as global water budget
water does not stay in the atmosphere for long -> residence time is short, because the yearly flux of 460,000km is almost 35 times greater than the amount of water the atmosphere can hold at any time.
why does the water reside in oceans for longer periods?
the oceans are 300 times bigger than either the annual flux to or from the atmosphere, or from the land.
where is about two-thirds of the earths freshwater locked up in?
cryosphere
cryosphere
places where the temperature remains below freezing for much of the year, such as ice sheets and glaciers.
what’s happening to cryosphere water, as the global climate continues to warm?
some of the frozen cryosphere water is released by melting to flow into the sea- adding to the closed hydrological cycle
importance of the polar regions
the polar regions contribute to the circulation of water, and the transfer of heat around the world, which drive the global hydrological cycle.
an ocean circulation occurs, known as the thermocline circulation- sometimes called the global conveyor belt
fossil water
untapped ancient stores of freshwater exist in the polar regions and beneath many deserts.
new technologies now make it possible to access the water stores, known as aquifers, beneath Greenland’s ice sheets and under the Kenyan desert
aquifer in Kenya
Kenya’s Lotikipi aquifer contains an estimated 200 billion cubic metres of freshwater- that’s 70 years supply at Kenya’s current rates of use, even without the natural replenishment that it receives from mountain streams.
global stores and flows
life depends on freshwater. (most of it is locked up in the cryosphere, or below the surface, as groundwater.
less than 0.4% of freshwater is contained within surface lakes, rivers, the biosphere and atmosphere at any one time, and much of that is transferred globally by flows, known as fluxes.
these fluxes vary with the season and the temperature, and the variation is known as annual fluxes.
earth’s four major subsystems
-atmosphere (water vapour)
-lithosphere (water stored in the crust and upper mantle)
-biosphere
-hydrosphere (any liquid water)
how much of earth’s total water does the atmosphere contain?
the atmosphere contains about 0.001% of earth’s total waters primarily as water vapour.
what is the water vapour crucial for (atmosphere),and how does this work?
weather and climate patterns.
Clouds and precipitation: water vapour condenses to form clouds, which can lead to precipitation (rain, sleet, snow, hail).
how much of the earth’s freshwater does the biosphere hold and where is it found?
The biosphere holds less than 1% of earth’s freshwater. This water is found within living organisms, including plants,animals and microorganisms.
biosphere and cellular functions
Water is vital for cellular processes, such as nutrient transport, waste removal and biochemical reactions. Plants use water for photosynthesis, while animals need it for hydration and metabolic function.
biosphere and soil moisture
Water in the biosphere also includes soil moisture, which supports plant life and contributes to the overall health of ecosystems.
how much groundwater and freshwater does the lithosphere make up?
Groundwater in the lithosphere makes up about 0.7% of all water and 20% of earth’s freshwater (it is stored in aquifers and soil moisture).
lithosphere and soil moisture
Soil moisture is the water held in the pore spaces between soil particles. It is essential for plant growth and can vary significantly depending on the soil type and climate.
lithosphere and water in rocks
Some water is also stored within the minerals and rocks of the earths crust, although this is a relatively small amount compared to groundwater.