water pollution-pt.1

global distribution

-oceans Cover 71% of earth’s surface
-oceans Contain 97% of all earths water
-Only 3% of water on earth’s surface is fresh
-Nearly 65% (two thirds) of this 3% is fresh water in the ‘deep freeze’ in the ice sheets

WATER CYCLE

precipitation

moisture that reaches the surface in the form of rain, sleet, snow or hail

surface run-off:

precipitation that flows over the grounds surface, eventually finding its way into streams, rivers and other water bodies

interception:

precipitation that doesn’t reach the earth’s surface dure to being obstructed by trees and plants

infiltration:

:precipitation soaks into the sub-surface soils and moves into rocks through cracks and pore spaces.

through-flow:

down slope movement of water through the soil, roughly parallel to the ground surface

groundwater flow:

slow horizontal movement of water through rock

evaporation:

water from oceans, seas and other water bodies is changes from water droplets to water vapour (invisible gas) in the atmosphere due to heat

transpiration:

evaporation or diffusion of water from plant leaves

condensation:

water vapour converted back to liquid (water droplets) or solid (ice particles) due to a decrease in temperature with increasing height by air currents, e.g., clouds

WATER SUPPLY

surface water:

water in lakes, rivers, and swamps

Grounds water:

water in the soil, ad in rocks under the surface of the ground

Aquifers:

-water stored in porous rocks under the grounds
-Varying layers of permeable + impermeable rock trap water in permeable rock
-Folded layers of rock present, so water accumulates most in the down fold
-Permeable rocks extending on the surface receive new supplies of rainwater
-Water is stored in the limestone and sandstone rocks below the water table
-Mechanical pumps, or human labour are used to rise water on the surface

Artesian aquifers:

-an aquifer in which the water is under pressure
-Water from a well sunk into an artesian aquifer will rise to the surface without the need for a pump

potable

safe to drink

Reservoirs:

-an artificial lake used as a source of water supply, usually created behind a dam or by the side of a river (bankside reservoirs)

Service reservoirs:

-a reservoir where portable water is stored. E.g., water tower and cistern

wells

-a hole bored or dug into a rock to reach the eater stored in it

rivers

-a large natural stream of water flowing in a channel to the sea, a lake, or another river.
-They provide surface transfers of water to low-land areas where farms and villages, towns and cities are concentrated.

Desalination:

removal of salt from sea water by:

Distillation:

-water is boiled and release as vapour, leaving salt behind
-the vapour is then condensed as liquid water and can be used
-10-30% efficient and ususes a lot of energy
-Provision of energy and salt water (brine) is a source of pollution

Reverse osmosis:

-pumping water at high pressure through a fine membrane
-30150% efficient and requires lesser energy than distillation

WATER QUALITY AND AVAILABILITY

water rich countries

-countries with plentiful fresh water supplies:
-some are large countries with plenty of land for rain to fall on, Russia, Canada, China etc. and some have the worlds greatest revers flowing through them, Amazon, Yangtze, Mississippi.
-However, big areas do not ensure water availability, Australia, Argentina, Sudan, due to containing substantial areas of desert within its borders.

water poor countries

-countries with scare fresh water supplies
-dominated by desert countries
-except Singapore and Mauritius since they receive high precipitation totals, but they are tiny islands states that have only small areas for rain to fall on

water conflict

-conflict between countires, states or groups over an access to water

physical water scarcity

-not enough water to meet both human demands and those of ecosystems to function effectively
-arid regions frequently suffer from physical water scarcity
-it also occurs where water seeps abundant, but resources are over-committed.

economic water scarcity

caused by lack of investment in water infrastructure or insufficient human capacity to satisfy the demand of water in areas where the population cannot afford to use an adequate source of water

unlike rural areas, urban areas have higher access to safe drinking water because:

-cities are more wealthy places with factories and offices
-on average, people’s incomes are higher
-easier to put pressure on the politicians or leaders to make improvements.
-wealthy people are more likely to live in cities
-water pipes are easier and cheaper to build when lots of people live together