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4.1 INTRODUCTION TO WATER SYSTEM, factor influence, lead to, lead to -…
4.1 INTRODUCTION TO WATER SYSTEM
Human activity impact on surface runoff and infiltration
agriculture
poor irrigation raised water table causing salinization
(Indus Plain Pakistan)
Ploughing increase infiltration
Waterlogging increase salinization
soil compacted may reduce pore size thus decreasing infiltration
deforestation
remove tree which acts as natural sponge (absorbing rainfall and facilitate infiltration)
surface runoff increases (more water reaches ground surface, higher surface runoff rates)
reduce evapotranspiration rates (less transpiration and evaporation occurs)
urbanization
convert vegetated surface with concrete, brick (impermeable)
precipitation converted to surface runoff which
reduces infiltration
current drainage system designed to move water quickly to river than before
increase risk of flooding (flash flood)
Storages and flow in the hydrological cycle
STORAGES:
Saltwater approximately 97.5% of the Earth's water storages:
Oceans
: Largest storage of water in liquid form 97.5%
Freshwater approximately 2.6% of the Earth's water storages:
Glaciers and Ice Caps
: Water stored as ice 79%
Groundwater (Aquifers)
: Long-term storage of water underground 20%
3rd pie chart:
Organism
: Water stored inside living organisms
Soil
: Water stored as soil moisture/water in soil 38%
Lakes
: Surface water bodies 52%
Rivers
: Surface water bodies
Atmosphere
: Water vapor and clouds
FLOW
Transfer (Movement of water without state change)
:
Advection
: Wind-blown movement of water vapor/horizontal transfer energy or matter by wind
Flooding
: Overflow of water onto land
Surface Runoff
: Water flowing over land
Infiltration
: Water moving into the soil
Percolation
: Water moving deeper into the ground/the process of a liquid slowly passing through a filter
Stream-flow/Currents
: Movement in rivers, oceans.
Transformation (Change in state of water):
Evapotranspiration (EVT)
: Combined evaporation from land and transpiration by plants
Evaporation
: Water changes from liquid to gas
Condensation
: Water vapor turns to liquid, forms clouds/ change of water from gas to liquid
Sublimation
: Solid (ice) to gas (water vapor) in the air without first melting into water
Precipitation
: Water falling as rain, snow, etc
Melting
: Ice to liquid water
Freezing
: Liquid water to ice.
Human impact on hydrological cycle
Example:
Extraction of water from storages
Effect of warming temperature on evaporation rate
Melting ice caps on ocean circulation
Growing population demand for agriculture and drinking water
Human change the hydrological cycle by:
Withdrawals (for domestic use, irrigation in agriculture and industry)
Discharges (adding pollutants to water such as chemicals from fertilizers)
Changing the speed of water flow and where it flow (building roads in cities, dams to make reservoir, canalizing)
Diverting rivers
Real world example
Ganges basin
Deforestation increases flooding as precipitation is not absorbed by vegetation
Aral sea
Intense irrigation almost stopped river flow, lowered the sea level, shurnk in area by 90% in the last 50 years
ocean circulation system
temperature
water density
ocean conveyor belt
high temperature, lower dense
high salinity, high dense
the denser water mass slip under less dense water mass
warm ocean current move water away from equator towards pole
cold ocean current move water away from cold region (pole) toward equator
salinity
high temp, high salinity due to high evaporation
water runoff from river cause salinity reduce
deeper ocean, high salinity
thawing iceberg = low salinity
freezing iceberg = high salinity
Upwelling (cold to warm)
bring nutrient to the water surface
stimulate the growth and reproduction of primary producer
high level of fisheries
Downwelling (warm to cold)
factor influence
lead to
lead to