Water-Topic 8 first half
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- hydrologic cycle
- water cycle
- describe the hydrologic/water cycle
- solar energy (insolation) changes liquid or solid water to water water, and gravity pullls water down.
- what is the ultimate source of most water on land
- the evaporation of the oceans' water
- what four things can happen to water when precipitation falls on it?
-
1. water retention
2. infiltrattion
3. tunoff
4. evapotranspiration - water retention
- precipitation can be stored or retained on the land surface as ice or snow, or on the leaves of trees and other plants
- infiltrate
- precipitation sinks into the upper parts of earths lithosphere under the influence of gravity
- subsurface water
- all the water beneath earths surface
- runoff
- when precipitation flows over earths surface
- evapotranspiration
- precipitation is evaportated or transpired back into the atmosphere
- how much precipitation is put back in the atmopshere by evaporation or transpiration
- about 2/3
- how is the other 1/3 returned?
- by runoff
- how does the slope of the land affect infiltration?
- the stepper the slope of earths solid surface, the less infiltration or seepage
- how does saturation affect infiltration?
- the more saturated the loose materials at earths, the less infiltration
- 2 zones that earths surface is divided into
- zone of saturation and the zone of aeration
- zone os saturation
- where the pores or openings between solid partiles are filled with water
- zone of aeration
- where the pores are partlyfilled with air and partly filled with water
- which zone is on top
- aeration
- water table
- the interface between the two zones
- subsurface water below the water table
- ground water
- porosity
- the percentage of open spaces in a material compared to its total volume
- affect of porosity on infiltration
- the greater the porosity, the greater the amount of infiltration that can occur
- shape affect on porosity
- rounded particles have greater porosity than other shapes
- packing affect on porosity
- the more closely packed the particles, the lower the pososity
- sorted
- if all the particles in a material are about the same size
- unsorted
- if the particles are mixed sizes
- sorted/unsorted affect on porisity
- the more unsorted the particles, the lower the porosity
- affect of size alone on porosity
- none; a material with large particles may have the same porosity as one with smalller particles if teh shape, packing,, and sorting of both particles sizes are about equal
- permeability
- the ability of a material to allow fluids such as water to pass through
- permeability rate
- the speed at which fluids will flow through a material
- affects on permeability
- how well connected the openings are
- in loose particles, the large the particle size...(permeability rate and inflitration)
- the faster the permeability rate and infiltration
- why?
-
vegetation intercepts falling precipitation
reduces speed of precipitation and gives the ground more time to absorb the water - capillarity
- the attractive force between water molecules and the surrounding earth materials that stops some water from moving downward during infiltration
- water that is stored in small openinings in the zone of aeration
- capillary water
- what causes water to move up from the water table, against gravity, towards earths surface in the zone of aeration
- capillarity?
- what is this upward movement of water called?
- capillary action/migration
- when the particle size gets smaller, capilarity and capilary migration...
- becomes greater
- when the size of particles increases and the size of pores increases, capillarity..
- is reduced
- how does vegetation affect infiltration
- more vegetation=more infiltration
- when can surface runoff occur? (4)
-
1. the rate of precipitation exceeds the rate of infiltration
2. the pore space is saturated w/ water
3. the slope of a surface is too great to allow infiltration to occur
4. the water on the surface has not evaporated or sublimated into a gas - stream discharge
- the volume of water flowing past a certain spot in a stream in a specific amount of time
- the greater the runoff the ___the stream discharge
- greater
- what is the largest source of moisture for teh atmosphere?
- ocean water
- what is the primary source of water for the local water supplies?
- precipitation