WATER RESOURCES

Lesson 5 – Earth Science

 THE HYDROSPHERE
▪ The hydrosphere is one of the
Earth’s subsystems that constitutes
all the available water supply
present on Earth, in all its forms.
▪ Being the only planet inthe Solar
System with water existing in all
three (3) forms—solid, liquid,
and gas—it allows life to flourish
on the planet’s surface.
▪ Although the hydrosphere exists in
the other subsystems
independently, it comprises at
least 75% of the Earth’s surface.
THE EARTH’S WATER BUDGET
▪ The finite amount of water on
the Earth, slowly added by
volcanic eruptions and
meteors from space, that has
lasted for billions of years.
RESIDENCE TIME
▪ The average length of time spent by a water molecule in a reservoir.
Generally, water molecules in larger reservoirs have longer
residence time.
RESERVOIR TYPES AND
WATER FORMS
1. Saltwater Reservoir
▪ Saltwater constitutes at least
97% of the total water supply
on Earth.
▪ Because of its saltiness, it
must be distilled and refined
before it can be used for
consumption.
SALTWATER RESERVOIR
Ocean
A very large body of saltwater that surrounds the entire land
✓ The total volume of the world’s oceans is approximately 𝟏. 𝟑𝟓 × 𝟏𝟎𝟗
𝐤𝐦𝟑 .
✓ The Earth contains five (5)—or four (4), depending on the reference
material—oceans:
1. The Pacific Ocean divides Asia and the Americas.
2. The Atlantic Ocean divides the Americas, Europe, and Africa.
3. The Southern Ocean divides Antarctica and the rest of the world.
4. The Indian Ocean divides southern Africa and Southeast Asia.
5. The Arctic Ocean, the smallest ocean, occupies the North
geographical pole.
SALTWATER RESERVOIR
1.2. Salinity
The measure of a saltwater’s
saltiness.
✓ Ocean water has a varied
salinity between 33 and 37 ppm
(parts per million), mostly from
sodium chloride (NaCl) existing
as both sodium and chloride ions.
✓ Volcanic eruptions (both on the
surface and submarine)
contribute to the ocean’s salinity.
SALTWATER RESERVOIR
1.3. Major Ocean Zones / Saltwater Profile
• Surface Layer/Zone - Composed mainly of low-
density warm water that extends to a depth of 200 m
(only 2% of the total ocean water); home to most
marine life on Earth.
• Thermocline - The second layer, whose temperature
drops drastically with each succeeding depth, with
most borders at 1,500 m below sea level.
• Deep Zone - The deepest layer, whose temperature
is uniformly low, with at least 80% of the total saltwater
accounting it
SALTWATER RESERVOIR
1.4. Water Current
The movement of water caused by varying factors
• Surface Current/Circulation Movement of saltwater caused
by surface air currents, depending on the hemisphere, on the
surface zone, creating slow, broad drifts confined at depths of
50–100 m
✓ Northern hemisphere currents move in a clockwise direction
as seen from space.
✓ Southern hemisphere currents move in a counterclockwise
direction as seen from space.
✓ On a local point of view, water currents move in a clockwise
direction regardless of the hemisphere.
SALTWATER RESERVOIR
1.4. Water Current
The movement of water caused
by varying factors
• Thermohaline/ Deep
Currents Circulation/Current
Movement of water in the deep
zone caused by the active
processes within the zone
caused by differences in density,
which are controlled by both
temperature and salinity.
RESERVOIR TYPES AND
WATER FORMS
2. Freshwater Reservoir
▪ Most of the freshwater (a form
of water that is not saline) on
Earth are stored in glaciers
and ice sheets in regions
mostly inaccessible by man.
▪ The ones that are usable and
potable are found on shallow
surfaces and underground.
FRESHWATER RESERVOIR
2.1 Glacier
▪ A permanent body of solidified
water (i.e., ice) primarily
composed of recrystallized snow
compacted together.
▪ Glaciers form on land, and they
are made up of fallen snow that
gets compressed into ice over
many centuries. They move slowly
downward from the pull of gravity.
Most of the world's glaciers exist
in the polar regions, in areas like
Greenland, the Canadian Arctic,
and Antarctica.
FRESHWATER RESERVOIR
2.2 Ice Sheet
Mass glacial ice covering more
than 𝟓𝟎, 𝟎𝟎𝟎 𝐤𝐦𝟐 in total land
area, commonly seen in Greenland
and Antarctica.
An ice sheet is a mass of glacial ice
more than 50,000 square
kilometers (19,000 square miles).
Ice sheets contain about 99% of
the fresh water on Earth, and are
sometimes called continental
glaciers.
FRESHWATER RESERVOIR
2.3 Permafrost
Any part of the lithosphere and/or
the pedosphere that has been
frozen for more than two (2) years.
Mostly found in polar regions,
permafrost can be as deep as 150
m and has amassed storage of at
least 𝟑𝟎𝟎, 𝟎𝟎𝟎 𝐤𝐦𝟑 worth of
freshwater.
Permafrost is a permanently frozen
layer on or under Earth’s surface. It
consists of soil, gravel, and sand,
usually bound together by ice.
FRESHWATER RESERVOIR
2.4. Surface Water
streams, rivers, lakes and
reservoirs - collectively
referred to as surface water -
are important natural
resources for irrigation,
public supply, wetlands and
wildlife.
FRESHWATER RESERVOIR
2.4.1 Streams
A moving body of surface water flowing
downslope from higher elevations toward sea
level via clearly defined channels, carrying
dissolved substances and sediments.
✓ Land areas that allow water to flow into
streams are known as watersheds or drainage
basins.
✓ Stream and river waters contribute to
surface runoffs, aiding the transport of
sediments and dissolved substances.
✓ A stream has an interaction with
groundwater, depending on how the stream
water flows.
FRESHWATER RESERVOIR
2.4.2 Rivers
Streams with
considerably more
volume of surface water
flowing in well-defined
channels
✓ Rivers constitute at
least 0.0006% of the
global water supply
(about 1.6% of the
surface water supply),
estimating at around
𝟐,𝟏𝟐𝟎 𝐤𝐦𝟑 worth of
freshwater.
FRESHWATER RESERVOIR
2.4.3 Lakes
▪ Large inland bodies of water,
either fresh or saline. Essentially
flat on the water’s surface, it is
exposed to the atmosphere and
formed in places with deep
depressions (i.e., low areas) by
water being supplied by inlet
rivers and/or streams, overland
flow, and/or groundwater.
▪ Lakes are the largest surface
freshwater reservoirs, despite
freshwater being the smallest
water type on Earth.
FRESHWATER RESERVOIR
2.4.4. Wetlands
Land areas whose
surfaces are covered
primarily with water,
whose biological life
also adapted to its
presence (i.e., water).
Highly sensitive, any
changes in the wetlands’
waters drastically affect
life in them.
FRESHWATER RESERVOIR
2.4.5. Wetlands
✓ Wetlands have three
(3) types, depending
on its location and the
wildlife found in it:
o Marshes are shallow
wetlands found around
lakes, streams, and
oceans where grass
and reeds are the
dominant vegetation.
FRESHWATER RESERVOIR
2.4.5. Wetlands
o Swamps are
wetlands with lush
trees and vegetation in
low-lying areas beside
slow moving rivers.
Local wildlife had
adapted to the place’s
low oxygen content.
FRESHWATER RESERVOIR
2.4.5. Wetlands
o Estuaries are partly
closed coastal bodies of
water where freshwater
from streams meet the
ocean’s saltwater,
serving as home to
organisms capable of
adapting to such drastic
changes in salinity.
FRESHWATER RESERVOIR
2.5. Groundwater
Freshwater found in the rock and soil
layers deep within the soil’s surface.
As a freshwater source, it is the
largest liquid freshwater source, as
glaciers and ice sheets are the
largest solid freshwater source on
Earth.
✓ Groundwater sources can be seen
as hollow caves located
underground, or it can be encased in
stone layers. Such rock layers with
water are called aquifers.
WATER AS A RESOURCE
▪ Humans have depended on water
for years, and this is evident in the
way early settlements were
located: near coasts and
riverbanks.
▪ Coastal settlements provided fish
and seafaring, whereas
riverbanks were known to be near
floodplains where people
benefitted from agriculture.
▪ Even today, humans still depend
on water resources for food, water,
transportation, religious, and
recreational activities (Olivar et
al., 2018).
 HUMAN ACTIVITIES AFFECTING WATER QUALITY
1. Population growth
2. Migration from rural
settlements to urbanized
areas
3. Demands for greater
food security and higher
living standards
4. Increased competition
5. Pollution from factories,
cities, and farmlands
OTHER ACTIVITIES FOR WATER DEGRADATION
1. Sedimentation
Changes in the
environment that
degrade the local
ecosystems
Includes deforestation,
conversion of natural
landscapes into farms
and/or residential areas,
urban growth, road
building, and surface
mining.
OTHER ACTIVITIES FOR WATER DEGRADATION
2. Acid Mine Drainage - Mining of certain metals create acid
compounds once the water is exposed to such binding elements or
compounds.
OTHER ACTIVITIES FOR WATER DEGRADATION
3. Improper Waste Disposal
- Encourages pollutants to
accumulate, inciting pollution
to the affected area
Examples of Wastes:
1. Industrial wastes
2. Sewage
3. Runoffs containing harmful
chemicals, coming from
Farmlands, Factories and
Cities.
4. Chemical emissions from
vehicles and factories
OTHER ACTIVITIES FOR WATER DEGRADATION
4. Overexploitation of Known Water Supplies - Disrupting the
natural flow of water in an area by using more water than nature can
replenish
- Using more water than what is needed
OTHER ACTIVITIES FOR WATER DEGRADATION
5. Responses to Natural Phenomenon - Using more (or less) water in
cases when natural phenomena become aberrant, either from natural
or man-made causes
Examples of Natural Phenomena:
1. Severe Drought (El Niño)
- Forces people to pump more water or divert stream flows
- May use cloud seeding to induce rain, which deprives other areas
from rain
2. Severe Rains (La Niña)
- Induces sedimentation due to severe erosion in denuded landscapes
3. Climate Change and Global Warming
 THE REPUBLIC ACT NO. 8041 OF 1995
National Water Crisis Act addressed the Philippines’
water problems through an integrated water
management program and the development of new
water resources and conservation of identified
watersheds, among other provisions (Olivar et al.,
2018).