The document discusses the global water cycle and water usage. It notes that 71% of the Earth's surface is water, with 97% being salt water and 3% fresh water. Most fresh water is frozen or located underground. It then outlines different components of the water cycle like precipitation, evaporation, runoff, and percolation. It also summarizes different sources of water like rivers, lakes, groundwater, and wells. The document concludes by discussing issues like water pollution, conservation efforts, and solutions to water scarcity.
20. According to the World Health Organization,
more than 1 billion people lack access to a
clean, reliable source of fresh water.
A shortage of clean, fresh water is one of
the world’s most pressing environmental
problems
21. When a water supply is polluted or
overused, everyone living downstream
can be affected.
22. Global Water Use
There are three major uses for water:
agricultural use, industrial use and
residential use.
67%
19%
14%
Agriculture
Industrial
Residential
24. Water Conservation
As water sources become
depleted, water becomes
more expensive.
This is because wells must be
dug deeper, water must be
piped greater distances, and
polluted water must be
cleaned up before it can be
used.
26. Irrigation
a method of providing plants with water from sources
other than direct precipitation.
high-pressured overhead sprinklers are the most
common form of irrigation. (inefficient – up to 80%
evaporates)
29. Water Conservation in Agriculture
Most of the water loss in agriculture comes
from evaporation, seepage, and runoff
Drip irrigation systems deliver small
amounts of water directly to plant roots by
using perforated tubing.
30. Industrial Use
Industry accounts for about 19 percent of the water
used in the world, Water is used to manufacture
goods, to dispose of wastes, and to generate power.
31. Most of the water that is used in industry is used to
cool power plants.
Power-plant cooling systems usually pump water
from a surface water source such as a river or a
lake, carry the water through pipes in a cooling
tower, and then pump the water back into the
source.
32. Water Conservation in Industry
Recycling of cooling water and wastewater.
Instead of discharging used water into a nearby
river, businesses often recycle water and use it
again.
37. Water Conservation at Home
Water-saving technology, such as low-flow
toilets, can also help reduce household water
use.
Water their lawns at night to reduce the amount
of evaporation.
41. Water treatment removes elements such as
mercury, arsenic, and lead, which are poisonous
to humans even in low concentrations.
42. Pathogen
a virus, microorganism, or other substance that
causes disease.
Pathogens are
found in water
contaminated by
sewage or animal
feces, but can be
removed with water
treatment.
44. Water Management Projects
– bringing in water to make a dry area habitable
– creating a reservoir for drinking water,
– generating electric power, which then allows
people to live and grow crops in desert areas.
45. Water Diversion Projects
To supply dry regions with water, all or part of a river
can be diverted into canals that carry water across
great distances.
46. Dams
A dam is a structure that is built across a river to
control a river’s flow.
About 20 % of the world electrical energy is
generated using this method.
49. Desalination
The process of removing salt from ocean water.
Because desalination consumes a lot of energy,
the process is too expensive for many nations to
consider.
55. Sources of Water Pollution
Point-source pollution is pollution that
comes from a specific site.
56. Nonpoint-source pollution is pollution that
comes from many sources rather than from a
single specific site.
This silt-laden runoff from a residential area contains not only soil and clay particles
from nearby construction, but also is likely to contain small amounts of lawn chemicals,
oil, grease, gasoline, and even residues from recent highway de-icing.
60. water is filtered and treated to make the water
clean enough to return to a river or lake.
Wastewater Treatment Plant
61. Eutrophication
Nutrients are an essential part of any aquatic
ecosystem, but when lakes and slow-moving
streams contain an abundance of nutrients,
they are eutrophic.
62. The process of decomposition uses up
oxygen, and as oxygen levels decrease, the
types of organisms that live in the water
change over time.
63. Artificial Eutrophication
a process that increases the amount of
nutrients in a body of water through human
activities, such as waste disposal and land
drainage.
The major causes of eutrophication are
fertilizer and phosphates in some laundry
detergents.
64. Algal Blooms
In bodies of water
polluted by
phosphorus, algae
can form large floating
mats, called algal
blooms.
65. Thermal Pollution
a temperature increase in a body of water
that is caused by human activity and that
has harmful effect on water quality and on
the ability of that body of water to support
life.
66. Thermal pollution can cause large fish kills if the
discharged water is too warm for the fish to survive.
If the temperature rises even a few degrees, the
amount of oxygen the water can hold decreases.