Grade 11 Chapter 4 Module Earth Science : Water Resources
2. Water resources are natural resources of water that are potentially
useful. Uses of water include agricultural, industrial, household,
recreational and environmental activities. All living things require water
to grow and reproduce.
Water is normally perceive as restricted to its liquid form as seen in the
rivers, ocean, and the water that we drink.
The current problem on water pollution has resulted in the emergence
of commercial potable drinking water bottles.
Water is now considering one of the world's most expensive
3. Earth is the only planet where water in its liquid form exists. In other
planets, water occurs in the form of ice or vapor. As seen from space, Earth
looks mostly blue and white because of water, snow, ice, and clouds on its
surface. The part of the Earth's subsystem containing the oceans, lakes,
streams, underground water, and snow and ice is the hydrosphere. It makes
up about 71% of the Earth's surface.
However, water is also present in other subsystems. It exists as water vapor
in the atmosphere, as an important constituent of minerals in the
geosphere, and a fundamental component of living organisms in the
biosphere. The existence of water in the different subsystems is part of the
4. The hydrologic cycle, also known as water cycle, is the movement of water around
the Earth's surface and its subsystems. The cycle consists of interconnected
pathways and reservoirs.
There is a mass balance in the cycle, which maintains the total amount of water.
Fluctuations may occur on a local scale, such as the occurrence of flood and
drought, but these are balanced out on a global scale.
Heat coming from the sun provides energy for the movement of water. It causes
evaporation or the process in which liquid water changes into vapor. Transpiration is
the evaporation of water from the leaves and stems of plants, which contributes to
about 10% of the water vapor in the atmosphere. In high altitudes, ice can directly
transform into water vapor in a process called sublimation.
5. Rain that falls into the land surface penetrates the soil in a process
called infiltration. When the soil becomes saturated, rainwater may
flow over land as surface runoff and will join other bodies of water
such as streams, lakes, and oceans.
6. Hydrogeology is the field of geology that deals with the distribution, availability,
and flow of groundwater in aquifers. Scientists who specialize in this field are
called hydro geologists. They also study groundwater contamination and how it
affects the other subsystems. To become a hydro geologist, one must first obtain
s bachelor's degree in geology or environmental science, and then pursue
further studies or training in hydrogeology.
7. The total amount of water in the planet,
also known as Earth's water budget,
generally remains constant through
time. Water moves and changes in form,
but is neither created nor destroyed.
Only a very small percentage is added
to the hydrologic system by volcanic
eruptions and meteors from space.
Most of the water on Earth today have
been cycling through the hydrologic
system for billions of years.
8. -97.5% Ocean
·(68.7%) from glaciers, (30.1%) from groundwater, (0.8%) form
permafrost, surface water, and atmospheric water.
The surface water in rivers, lakes, swamps, soil moisture, living things,
atmospheric water vapor, ground ice, and permafrost, constitute only
about 0.4% of the total freshwater supply or less than 0.02% or the total
water on Earth.
9. An ocean is a vast body of saline water. There is only one global or world ocean and
it covers 71% of earth. It is geographically divided into five distinct regions and into
numerous seas, gulfs, bays, and straits. Historically, the four recognized oceans are
the Atlantic Ocean, Pacific Ocean, Indian Ocean, and Arctic Ocean. In 2020, the
International Hydrographic Organization proposed the Southern Ocean. It is the
body if water surrounding Antarctica and is connected to the Pacific, Atlantic, and
Indian Oceans. The total volume of water in the world's ocean is about 1340
10. The saltiness of saltwater is called salinity. The major chemical elements
present in seawater are sodium and chlorine ions. Other natural elements are
also present in seawater varies from 33 to 37 parts per thousand. When it is
evaporated, three quarters of the dissolved material is comprised of NaCl
(common salt). The principal sources of the elements dissolved in seawater are
weathering and volcanic eruptions.
11. Surface Layer
The surface layer is the layer of a turbulent fluid most affected by
interaction with a solid surface or the surface separating a gas and a
liquid where the characteristics of the turbulence depend on distance
from the interface.
Three majors zone in the ocean
Large-scale density-driven circulation in the ocean, caused by
differences in temperature and salinity. In the north Atlantic, the
thermohaline circulation consists of warm surface water flowing
northward and cold deepwater flowing southward, resulting in a net
pole ward transport of heat.
13. Deep Zone
The deep sea or deep layer is the
lowest layer in the ocean, existing
below the thermocline and above
the seabed, at a depth of 1000
fathoms (1800 m) or more.
14. Most of the freshwater on Earth is stored in glaciers situated
in inaccessible areas such as the Polar Regions and High
Mountains. The readily available freshwater sources are the
surface water reservoirs and groundwater reservoir.
Glaciers and Ice Sheets
A glaciers is a permanent
body of ice which consists
largely of recrystallized
snow. An ice sheet, also
known as a continental
glacier, is a mass of glacial
ice that covers surrounding
terrain and is greater than
50,000 km2 (19,000 sq mi).
Permafrost is any ground that
remains completely frozen—
32°F (0°C) or colder—for at
least two years straight. These
permanently frozen grounds
are most common in regions
with high mountains and in
Earth's higher latitudes—near
the North and South Poles.
Permafrost covers large
regions of the Earth.
16. Surface water include the stream, lakes, and wetlands where water from
rainfall, melting snow and ice, and groundwater flows. They represent
0.3% Earth's total water resources. This resource is harnessed for
irrigation, recreation, transport, fishing, drinking, and hydropower.
Stream is a moving body of surface water that flows down slope toward sea
level because of gravity. Channels is clearly-defined passageways where
particles and dissolved substances are transported River is a stream with
considerable volume and well-defined channel.
The smaller stream called tributaries. Drainage basin or watershed is the land
area in which the water flows into particular stream. The line that separates
individual drainage basin is called drainage divide. Interface is the narrow,
elongated landform separating individual stream.
17. During heavy rain, water moves
downhill in process called
overland flow. After a short
distance, the water enters the
channels and becomes stream
flows. These processes aid the
transport of sediments and
carving of complex patterns
along their course.
The drainage area of world's
twenty largest river basins
range 1and 6 million km². In the
Philippines, the largest drainage
basin is the Cagayan River
Basin, which comprises a total
area of 27 280 km². This
drainage basin is bounded by
the Cordillera, Caraballo, and
Sierra Madre mountains ranges.
Lakes are the large inland bodies
of fresh or saline water. Its upper
surface is exposed to the
atmosphere and is essentially
Forms in places where water
collects in a low area(depression)
and behind natural or human
made dams. Ponds are small and
shallow lakes. Dams are barriers
constructed along streams to
contain the flow of water.
Water in lakes came from
streams, overland flow, and
Land areas where water covers the surface for significant period os
referred to as wetlands. They vary size from relatively large in flat
areas to small in steep areas. Wetlands are biologically diverse
environment filled with species that rely on both land and water for
survival. Wetlands constitute about 8.5% of the total land surface and
The largest wetlands in the Philippines is ligawasan marsh found in
provinces of Maguindanao, North Cotabato, and Sultan Kudarat.
20. The three types of Wetlands
Marsh is a shallow wetland around lakes stream and ocean where grasses
and reeds are dominant vegetation.
Swamp is a wetland with lush tress and vegetation found in low-lying areas
beside slow moving rivers.
Estuary is a partly enclosed coastal body of water where freshwater from
stream meets the saltwater from the sea.
Flood is a natural event in which an area that is usually dry is submerged
under water. It usually occurs when the rate of precipitation is higher than
the rate in which it could be absorbed by the ground or carried by streams.
It can also occur even during dry periods when natural or human made
22. Riverine flood
Occurs when a stream's discharge is greater than the capacity of the channel,
causing the stream to overflow.
are characterized by intense, high-velocity torrent of water that occurs in an
existing river channel with little to no notice.
Occurs when water overwhelms in low-lying areas along the coasts, usually due
to severe weather conditions.
Surface water flood
Occurs when heavy rainfall creates a flood event independent of an
23. Vegetation plays an important role in reducing flood intensity.
Plants can slow down the overland flow , giving the water enough time
to infiltrate the ground.
Vegetation and plants also decreases the amount of sediments that
could be eroded by surface runoff.
Groundwater is freshwater found in the rock and soil layers beneath
surface. The groundwater is the largest reservoirs of liquid freshwater
on Earth. It constitutes about 30.1% of the total freshwater.
Water-bearing rock layers called aquifers are akin to a "sponge"
which holds groundwater in tiny cracks, cavities, and pores between
Porosity is the total amount of empty pore spaces in the rock. It
determines the amount of groundwater that an aquifer can hold.
Sand and gravel have high porosity. Crystalline and basalt and diorite
have low porosity.
24. The movement of groundwater within the aquifer is also
controlled by the permeability of the material. Permeability is
the ability of the rock or sediments to allow water to pass
25. When a well is excavated in the ground, the first layer encountered is the
moist soil layer on the surface. Beneath this is a zone where the spaces
between the particles are filled mainly with air called the zone of
aeration or unsaturated zone. The layer beneath the zone of aeration is
the zone of saturation.
26. The boundary between the zone of aeration and the zone of
saturation is the water table. Directly above the water table is a
layer called capillary fringe, wherein groundwater seeps up to fill
the pore spaces in the zone of aeration via capillary action.
27. A reliable groundwater supply can be obtained from aquifers with good
porosity and permeability such as coarse-grained clastic sedimentary
rocks. An aquifer in which the groundwater is free to rise to its natural
level called unconfined aquifer. In unconfined aquifer , the water is
trapped and held down by pressure between impermeable rocks called
An artesian well is simply a well that doesn't require a pump to bring
water to the surface; this occurs when there is enough pressure in the
aquifer. The pressure forces the water to the surface without any sort of
When groundwater emerges to the ground surface, a spring is created.
Springs usually appear in place where is a decreases in permeability of
the underlying material.
28. There is an interaction between groundwater flow and stream.
There are streams that lose water downstream and dry up. In
this type of stream, the water flow underground and
contributes to the groundwater. This type of stream is called
losing or influent stream.
This stream is referred to as gaining or effluent stream. A
stream or segments of large streams could be influent or
effluent depending on the amount of available water.
29. Water resources helps to regulate climate, it shapes earth's
surface. Water bodies are habitat for humans, animals, plants and
marine animals. Water is very important for agriculture, cleaning,
cooking food and various activities.
30. There are 4 human activities affecting water resources.
1. Population growth, particularly in water short regions.
2. Movement of large number of people from the countryside to town
3. Demands for greater food security and higher living standards.
4. Increased competition between different uses of water resources.
5. Pollution from factories, cities and farmland.
The degradation of ecosystem is one of the serious threats, which occur due
to changes in landscapes, deforestation, conversion of natural landscapes
into farm or residential areas, urban growth, road-building, and surface
mining. These activities have led to too much soil and sediments delivered to
streams in the process of sedimentation. Mining of certain metals have also
caused surface water to become acidic, producing a discharge called acid
31. Water resource management is the activity of planning, developing,
distributing and managing the optimum use of water resources. ...
With the growing uncertainties of global climate change and the long
term impacts of management actions, the decision-making will be
even more difficult.