UNIVERSAL COLLEGE OF ENGINEERING & TECHNOLOGY

(Approved by AICTE, New Delhi & Affiliated to JNTUK, Kakinada)

DEPARTMENT OF MECHANICAL ENGINEERING

BASIC CIVIL & MECHANICAL

ENGINEERING
UNIT -3
Transportation, Water Resource &
Environmental Engineering
WINNY DASARI
ASST.PROFESSOR
 SYLLABUS
Transportation Engineering
 Importance of Transportation in Nation's economic development
 Types of Highway Pavements- Flexible Pavements and Rigid
Pavements - Simple Differences.
 Basics of Harbour, Tunnel, Airport, and Railway Engineering.
Water Resources and Environmental Engineering:
 Introduction, Sources of water- Quality of water- Specifications
 Introduction to Hydrology
 Rainwater Harvesting
 Water Storage and Conveyance Structures (Simple introduction to
Dams and Reservoirs).
Importance of Transportation in Nation's economic development
Transportation plays a crucial role in India's economic development. The country's vast
and diverse geography, coupled with its large population and growing economy, make
an efficient transportation system essential for various reasons:
1.Facilitating Trade and Commerce: Transportation networks, including roads,
railways, ports, and airports, enable the movement of goods and services across the
country. Efficient transportation systems reduce logistical costs and enable businesses
to access markets and resources more easily. This, in turn, promotes trade and
economic growth.
2.Connectivity: India's population is dispersed across urban and rural areas.
Transportation networks connect people to employment opportunities, healthcare,
education, and essential services. Improved connectivity leads to better economic and
social outcomes, reducing disparities between regions.
3.Industrial Growth: Transportation is a lifeline for industrial sectors, enabling the timely
delivery of raw materials and the distribution of finished products. Industries such as
manufacturing, agriculture, and construction heavily depend on efficient transportation
for their operations and supply chains.
4.Foreign Trade: India's international trade depends on transportation infrastructure,
particularly ports and airports. Efficient ports facilitate the export and import of goods,
contributing to the country's foreign exchange earnings and strengthening its global
trade ties.
5.Tourism: India's rich cultural heritage, diverse landscapes, and historical sites make it
a popular tourist destination. Good transportation infrastructure is crucial for the growth
of the tourism industry, which brings in revenue, creates jobs, and stimulates economic
development.
6.Rural Development: Rural areas play a significant role in India's economy. Efficient
transportation networks allow agricultural products to reach markets and consumers,
improving farmers' livelihoods and contributing to rural development.
7.Urbanization: As India experiences rapid urbanization, urban transportation systems
are critical for the efficient movement of people and goods within cities. Well-planned
urban transportation systems reduce congestion, pollution, and travel times, contributing
to a higher quality of life.
8.Job Creation: The development and maintenance of transportation infrastructure
create job opportunities in construction, maintenance, logistics, and related sectors.
These jobs are essential for economic growth and can help reduce unemployment.
9.Regional Development: Transportation can help bridge regional disparities by
facilitating investments in infrastructure and industries in less developed areas. It can
also promote the development of industrial corridors and special economic zones.
10.Access to Education and Healthcare: Efficient transportation systems ensure that
people have access to quality education and healthcare services, leading to a more
educated and healthier workforce, which, in turn, contributes to economic development.

In summary, transportation is a linchpin of India's economic development, serving as

the backbone of trade, commerce, connectivity, and development. As India continues to
grow and modernize, further investments in transportation infrastructure and systems
will be crucial to sustain and accelerate its economic progress.
 Types of Highway Pavements

There are two types of pavements based on design considerations i.e. flexible
pavement and rigid pavement. Difference between flexible and rigid pavements is
based on the manner in which the loads are distributed to the subgrade. Before we
differentiate between flexible pavements and rigid pavements, it is better to first know
about them. Details of these two are presented below:
Flexible Pavements
 Flexible pavement can be defined as the one consisting of a mixture of asphaltic or
bituminous material and aggregates placed on a bed of compacted granular material
of appropriate quality in layers over the subgrade.
 Water bound macadam roads and stabilized soil roads with or without asphaltic
toppings are examples of flexible pavements.
 The design of flexible pavement is based on the principle that for a load of any
magnitude, the intensity of a load diminishes as the load is transmitted downwards
from the surface by virtue of spreading over an increasingly larger area, by carrying it
deep enough into the ground through successive layers of granular material.
 Fig: Flexible Pavement Cross-section

Thus for flexible pavement, there can be grading in the quality of materials used, the
materials with high degree of strength is used at or near the surface. Thus the strength
of subgrade primarily influences the thickness of the flexible pavement.
Rigid Pavements
 A rigid pavement is constructed from cement concrete or reinforced concrete slabs.
Grouted concrete roads are in the category of semi-rigid pavements.
 The design of rigid pavement is based on providing a structural cement concrete
slab of sufficient strength to resists the loads from traffic.
 The rigid pavement has rigidity and high modulus of elasticity to distribute the load
over a relatively wide area of soil.

Fig: Rigid Pavement Cross-Section

 Minor variations in subgrade strength have little influence on the structural capacity
of a rigid pavement. In the design of a rigid pavement, the flexural strength of
concrete is the major factor and not the strength of subgrade.
Due to this property of pavement, when the subgrade deflects beneath the rigid
pavement, the concrete slab is able to bridge over the localized failures and areas of
inadequate support from subgrade because of slab action.
Difference between Flexible Pavements and Rigid Pavements
Basics of Harbour
In all types of the surface transport systems, water transport is almost as old as human
habitation on this globe. Man initially exploited the resources use in water transport as
means of travel from place of place. This resulted in the discoveries of new continents
and new resources and a need for large, better designed and equipped sea going
vessels was felt.
SEAPORTS / HARBOURS

A seaport is one which provides sheltered berthing for ships and has facilities for
embarking and disembarking of passengers, loading and unloading of varied cargo,
storing and sorting of various consignments and servicing of ships. A harbour is the main
component of a seaport which is a partially enclosed water area where the ships can
find refuge from storms and waves. Here, there are facilities for refuelling, repairs and
cargo handling in addition to other services. There are two classes of harbours, namely,
natural harbours and artificial harbours.

Chennai and Tuticorin harbours are artificial harbours where a portion of sea is enclosed
by the construction of suitable breakwaters
Mumbai and Cochin have natural harbours where the ships get protection by existing
islands, bays and mountains around the water spread. The wave action is minimized in
these enclosed areas. Harbours are further classified as military, commercial, fishing
and refuge harbours.
To fulfill its function, a harbour must satisfy the following three requirements.
1. The harbour should have sufficient depth of channel for the draft of vessels using it.

2. Sufficient protection for ships should be provided against destructive wave action.
3. The bottom of the harbour area should provide sufficient anchorage for ships against
high winds.

River ports serve for landing of freight from river boats and barges in up country
locations. Some river ports are developed at a river mouth for serving ocean traffic.
Kolkata (Calcutta) harbour is an example. Layout of an harbour is shown in Fig. 14.1.
A harbour requires extensive area for its operation. The extent of area depends on the
sizes, number and types of ships which it attracts. Considerable space is required for a
ship at anchor in a harbour basin. So the harbour basin has to be planned for receiving
the ships, anchoring them, mooring them to wharves for loading and unloading
operations and for guiding the ships out of the basin after loading operations.
Basics of Tunnels
Tunnels are underground constructions used for transportations.
The tunnels are defined as the underground passages that are used for the
transportation purposes. These permit the transmission of passengers and freights, or it
may be for the transportation of utilities like water, sewage or gas etc. The operations
and the constructions are carried out underground without disturbing the ground surface.
This operation is called as the tunneling.
Selection of Tunneling Route
The two main factors that help in the efficient route of the tunnel are the alignment
restraints and the environmental considerations. The underground, as we know is
heterogeneous in nature.
A proper inspection on the nature of soil, rock, the water table level, and all the
alignment restraints had to be made before fixing the route. The site chosen for
tunneling is such a way that the inconvenience and difficulty that is caused to the
environment in that area including living is minimum.

Advantages of Tunneling
The tunneling method gain certain advantages compared with other methods, which
are mentioned below:
•The tunneling procedure is more economical in nature, compared to open cut trench
method when the depth is beyond a limit
•The surface life or ground activities like transportation are not disturbed when
tunneling is undergone.
•The method ensures high-speed construction with low power consumption
•Reduces Noise Pollution
•These methods have freedom from snow and iceberg hazards, in areas of high
altitudes
•Surface and air interference is restricted for tunnels.
Tunneling Disadvantages
The tunneling method gains certain disadvantages, which is due to its complexity and
difficulty. Some of them are:
•The initial investment cost for commencing the tunnel is high compared to the open cut
method.
•Highly skilled and experienced designers and engineer team only will work best for this
operation.
•Higher and constant supervision from the start to the end of the tunneling project is
necessary without any compromise
•Highly sophisticated and specialized equipment are necessary to perform the tunneling
operations.

Basics of Air Transport

Air transport has grown to be a crucial part of the modern transportation systems in
India. The necessity of well-planned airports for efficient air transportation will increase
as the community grows and expands both in population and economic activity.
Airport engineering deals with the planning, designing, construction, operation and
maintenance of facilities like the landing and take off, loading and unloading, servicing,
maintenance and storage of aircrafts. The major phases of airport engineering are
planning, designing and construction of airports and operation and maintenance of
aircrafts.

FUNCTIONS OF AIR TRANSPORT

1. It saves travel time tremendously.
2. Long distance travel and reaching inaccessible areas become possible and easy.
3. It facilitates aerial photography.
4. It provides facility for rapid and efficient handling of cargo.
5. It provides uninterrupted service during defense operations.
6. It is highly useful in rescue operations during the natural calamities.
7. It links different cultures, people by linking the countries.
8. It acts as one of the sources of foreign exchange generation.
9. It encourages tourism in a better way.
10. It has provisions for telegraph and telecom services.
AIRPORTS
An airport is the place which provides facilities for safe landing, take-off movements of
aircraft and berthing on loading aprons, It has provisions for hangars, fuel storage and
lounges for passengers, cargo handling, etc.

AIRPORT PLANNING
An airport is a terminal facility for aircrafts. It is also known as an aerodrome. Aerodrome
serving international traffic is called an airport. It has customs, health and immigration
facilities. It is used for aircraft take off and landing. It also includes facilities for handling
passengers, cargo and for servicing aircrafts.

CLASSIFICATION OF AERODROMES
The aerodromes can be classified in the following heads.
1. International airports
2. General aviation aerodromes
3. Military aerodromes
The design, construction and layout of an international airport should confirm with the
standards laid by the International Civil Aviation Organisation (ICAO). This type of an
airport should be constructed in accordance with the universal requirements and should
cater increasing sizes and number of aircrafts.
The general aviation aerodromes serve on local service routes. They accommodate
flights for business and industry. They also facilitate local flying operations such as
industrial flying, aerial photography and agricultural flights for crop dusting. These
aerodromes mainly support domestic needs and can handle only a limited number of
aircrafts per day.
Military aerodromes include all aerodromes used by Navy, Army and Air Force.
Sometimes temporary aerodromes are also constructed for this purpose. In many
instances, civilian aerodromes have been used by the military and vice versa.

Basics of Railway Engineering

Railways form the most important mode of transport in India. Railways have brought
about many political, social and economic changes in the life of Indian people.
The network of Indian Railways is divided into nine zonal divisions for administrative
purpose. These are listed in Table 12.1.
COMPARISON OF RAILWAYS AND ROADWAYS
ADVANTAGES OF RAILWAYS
Railways have the following advantages over the other modes of transport.
(i) Encourage commercial unity
(ii) Ensure safe and comfort journeys
(iii) Stabilisation of the prices of commodities
(iv) Development of the nation
(v) Helps migration of people on a mass scale
(vi) Mobilising troops during war periods
(vii) Easy access to important places of tourist attractions
(viii) Large-scale movement of commodities
Water Resources and Environmental Engineering

 The term ‘sanitary engineering’ was originally used to describe the practice of those
 engineers who designed water and sewerage systems, and other public health
protection works.
 The area of practice then expanded when the society recognised that protection of
the air, land and water is necessary for all living things.
 Thus, in modern times the term environmental engineering has evolved to describe
the engineers’ increased emphasis on the biological, chemical and physical reactions
of the air, land and water environments and improved technology for reuse, recycle
and recovery measures.
 Although the environmental engineering disciplines are reasonably well established,
i.e. air, water supply, waste water, storm water, solid waste and hazardous waste, a
number of other specialty disciplines also exist. These include noise, radiology,
industrial hygiene and oceanography.
 Environmental engineering is that branch of engineering concerned with the
environment and its proper management. Traditionally, environmental engineers have
drawn their basic education and training from civil engineering programmes.
 Recently, environmental engineers have included course work and training in
professional areas including chemical engineering, microbiology, hydrology and
chemistry in order to broaden their perspective on potential solutions to environmental
problems.
SOURCES OF WATER
General
• Surface sources of water include rivers, streams, lakes ponds, etc.
• There is large variation in the water yield of such sources, which vary from season to
season.
• The development, reliability and quantity of water mainly depend on the following:
1. The selection of the site for collection works
2. Preparation and control of the catchment area
3. Type and choice of the reservoir
4. The treatment of the reservoir sites as well as operation of the reservoir
5. The design and maintenance of dams and dikes
6. The design, construction and maintenance of intake and outlet facilities

Drinking Water Supply Systems

Water may be supplied to the consumers by the following two systems:
(i) Continuous systems
(ii) Intermittent systems

(i) Continuous systems

In the continuous systems, water is available to the consumers for all the 24 hours of a
day. No doubt, this is the best system since water is available as and when it is needed,
but this leads to the waste of useful water. If there are some minor leakages, etc., in the
systems, great volume of water is wasted because of long duration of flow. In this
system, water is not stagnant in the pipe at any instant, and hence fresh water is always
available.
(ii) Intermittent systems
In this system, water is supplied to the consumers only during some fixed hours of the
day, say two to four hours in the morning and two to four hours in the evening. This is
the most common system adopted in India. This method is adopted when either
sufficient pressure is not available or when sufficient quantity of water is not available.
Under these conditions, various distribution zones of the city are supplied water by turn.
The normal supply timings may be between 6 a.m. to 10 a.m. and 4 p.m. to 8 p.m.,
though these timings may be changed to suit climatic or seasonal conditions.

Sources of Water
All sources of water can be broadly classified as:
(i) Streams
(ii) Lakes
(iii) Ponds
(iv) Rivers
(v) Reservoirs
(vi) Stored rainwater
These can be further divided as
(i) Springs
(ii) Infiltration galleries
(iii) Porous pipe galleries
(iv) Wells
1. Streams
Streams offer a good source of water except for the water of the first run-off. Sometimes
the run-off water while flowing over the earth gets mixed with clay, sand and mineral
impurities. All the suspected impurities can be restored in settling tanks up to a certain,
extent, but the dissolved impurities require special treatments. The steams generally
flow in valleys and are the main source of water supply to nearby villages on hill slopes.

2. Lakes
At some places in mountains, natural basins are with impervious beds are formed. Water
from springs and streams generally flows towards these basins and ‘lakes’ are formed.
The quantity of water in a lake depends on its basin capacity, catchment area, annual
rainfall, porosity of the ground, etc. The quality of water in large lakes is better than that
of in small lakes. Lakes situated at high altitudes contain almost pure water which can
not be used without any treatment. Lake water is usable for only those towns and cities
which are situated near them, such as Nainital.
3. Rivers
Rivers are born in the hills, when the discharge of a large number of springs and
streams combine together. In mountains, the quantity of water in rivers remains little,
and therefore, at such place these are called youthful rivers. But as the river moves
forward, more and more streams combine in it and increase its discharge. Therefore,
rivers grow bigger and bigger as they move forward due to increase in their catchment
area. River are the only surface sources of water which from which the maximum
quantity of water can be easily taken.

4. Ponds
These are depressions in plains, like those of lakes in mountains, in which water is
collected during the rainy season. Sometimes ponds are formed when much excavation
is done for house construction in villages, and embankments for road and railways.
Generally, the quantity of water is very small and contains large amount of impurities. In
villages, the used water mostly flows towards ponds which further contaminate its water.
The water of ponds is used for washing clothes, for bathing animals and for drinking.
5. Artificial Reservoirs
Generally, It is found that there is great variation in the quantity of river water during
and after the summer season. The discharge in some rivers remains sufficient to fulfill
the water demand in the hot weather, but in sonic rivers the flow becomes very small
and cannot meet the requirements of this season. In such cases, it becomes essential to
store water for the summer season. The water can be stored in the river by constructing
a hand, a weir or a dam across the river at such places where minimum area of land is
submerged in the water and the reservoir basin can be made cup-shaped in order to
have the maximum possible depth of water.

6. Shallow Wells
Construction of shallow wells
The shallow wells are constructed in the uppermost layer of the earth’s surface. They
obtain their water supply from the groundwater table as shown in Fig. 10.2. The
diameter of shallow wells varies from 2 to 6 metres. They may be lined or unlined from
inside. The lining is also called the steining and its thickness varies from 30 cm to 50 cm.
The Fig. 10.2 shows a shallow well with steining. The unlined wells are generally
constructed up to a maximum depth of about 7 metres or so.
7. Deep Wells
Deep wells obtain their quota of water from an aquifer below an impervious layer as
shown in Fig. 10.3. The theory behind the functioning of a deep well is based on the flow
of water from the outcrop to the site of the deep well. The outcrop is the place where the
aquifer is exposed to the atmosphere as shown in the Fig. 10.3 The entry of rainwater
takes place at the outcrop, and it reaches the site of the deep well. During its travel, the
water gets thoroughly purified; but it dissolves certain salts and may, therefore, become
hard. In such cases, some treatment would be necessary to remove the hardness of
water
Quality of water- Specifications
Water quality parameters are essential indicators used to evaluate the suitability and
safety of water for various purposes. These parameters include temperature, pH,
dissolved oxygen, turbidity, conductivity, and the presence of pollutants. They indicate
the physical, chemical, and biological properties of water.

Physical Water Quality Parameters

Physical parameters of water quality refer to the measurable characteristics of water
that are related to its physical properties. These parameters provide valuable insights
about the physical state and condition of water, which can have profound impact on its
general quality and usefulness. Some important physical water quality parameters
include:
1.Temperature
Water temperature affects various biological, chemical, and physical processes in
aquatic ecosystems. It can influence the solubility of gases, metabolic rates of aquatic
organisms, and the distribution of species.
2.Turbidity
Turbidity refers to the clarity or cloudiness of water caused by the presence of
suspended particles. High turbidity levels can affect light penetration in water bodies,
reducing photosynthesis and oxygen production. It can also impact the visibility of
aquatic organisms and interfere with their feeding and reproductive activities.
3.Colour
Water colour is an important visual indicator of its quality. It can be influenced by natural
factors such as dissolved organic matter or human activities like industrial discharges or
pollution. Unusual or significant changes in water colour can suggest the presence of
contaminants or pollutants.
4.Electrical Conductivity
Electrical conductivity measures the ability of water to conduct an electric current. It
gives an idea about the concentration of dissolved salts, minerals, and other
substances. Conductivity is an essential parameter for assessing water quality and can
indicate the presence of pollutants or changes in salinity levels.
 5.Total Dissolved Solids (TDS)
TDS refers to the combined content of inorganic and organic substances dissolved in
water. It includes minerals, salts, metals, and other dissolved particles. High TDS levels
can affect the taste and suitability of water for drinking, irrigation, or industrial
processes.
Chemical Water Quality Parameters
Chemical parameters of water quality are measures of the various chemical substances
present in water. These indicate the chemical composition of water, which include the
existence of natural and anthropogenic contaminants. Monitoring and analyzing these
parameters help in assessing the suitability of water for different purposes and identify
potential risks to human health and the environment. Some important chemical
parameters of water quality include:
1.Dissolved Oxygen (DO)
DO connotes the amount of oxygen dissolved in water. Low dissolved oxygen can incite
due to organic pollution, eutrophication, and other factors like the algal blooms.
These can inturn result in the deterioration of water quality and low DO can also cause
death of fish. A minimum DO of 4 ppm is necessary for the survival of fish.
2.Nutrients
Nutrients include nitrogen and phosphorus that are important for the plant growth.
However, excessive nutrient levels, often due to human activities like agriculture or
wastewater discharge, can lead to eutrophication. This process can cause harmful algal
blooms, oxygen depletion, and disruptions in the balance of aquatic ecosystems.
3.Heavy Metals
Heavy metals include lead, mercury, cadmium, and arsenic. These metals can easily
enter the water bodies via industrial discharges and mining activities. These metals are
toxic in nature. They can get accumulated and can lead to serious risks to human health
and aquatic life.
4.Chlorine and Chloramines
Chlorine and chloramines are commonly used disinfectants in water treatment
processes..
Monitoring their levels is important to ensure they are present in adequate amounts to
eliminate harmful pathogens while avoiding excessive concentrations that may cause
taste and odour issues or have adverse health effects.
5.pH
pH gives an idea about the acidity or alkalinity. It influences chemical reactions, the
solubility of minerals, and the effectiveness of water treatment processes. pH levels
outside the acceptable range can have detrimental effects on aquatic life and water
treatment systems.
6.Pesticides and Herbicides
These are chemical substances used in agriculture to control pests and weeds. They
can enter water bodies through runoff and have harmful effects on aquatic organisms.
Monitoring their presence and levels is crucial for ensuring water safety and protecting
ecosystems.
7.Organic and Inorganic Contaminants
Different Organic and inorganic contaminants may deteriorate water quality. These
contaminants include Industrial pollutants, pharmaceuticals, etc.
Identification of these contaminants is crucial for ensuring the water quality.
Water Quality Requirements
Water quality requirements refer to the set of standards, guidelines, or regulations that
define the acceptable quality and safety levels for different uses of water.

1.Drinking Water Quality Standards: These standards determine the maximum

permissible limits of physical, chemical, and biological contaminants in water. These
standards address parameters such as microbiological contaminants (bacteria, viruses),
disinfection byproducts, heavy metals, pesticides, nitrates, pH, turbidity, and many other
substances.
2.Recreational Water Quality Standards: These standards highlight the water safety
for activities such as swimming, bathing, and water sports.
3.Agricultural and Irrigation Water Quality Guidelines: These guidelines are related
to the water quality for use in agricultural irrigation. They address parameters such as
salinity, alkalinity, sodium adsorption ratio (SAR), and specific ion concentrations to
ensure that the water does not negatively impact soil quality, plant health, or crop
productivity.
4.Industrial Water Quality Requirements: Industrial water quality requirements vary
depending on the specific industrial processes and applications. These include pH,
suspended and dissolved solids, etc. These can impact the efficiency and safety of
industrial operations.

5.Environmental Water Quality Standards: Environmental water quality standards are

established to protect and preserve the health of natural water bodies and their
ecosystems.
Introduction to Hydrology
 Hydrology in civil engineering may be understood as the branch of engineering that
deals with the study of water resources. It is also commonly referred to as water
resources engineering.
 Precisely, engineering hydrology may be defined as the multidisciplinary
specialization of civil engineering that deals with the occurrence, circulation,
and distribution of water on Earth.

 Mostly, engineering hydrology is focused on the scientific study of the water cycle,
water resources, and water resource sustainability.
Importance of Hydrology in Civil Engineering

1. It is necessary for determining the maximum probable flood at the proposed

construction site. For example, dam construction.
2. It facilitates engineers and hydrologists for establishing the relation between surface
water of catchment and underground water resources.
3. It enables one to determine the flow over various hydraulic structures such as
spillways, highway culverts, urban storm drainage systems, etc.
4. It is important for studying the on-site drainage and seepage condition before the
commencement of any engineering construction.
5. The nature of variations of water flow, rainfall pattern, etc can be obtained from the
use of engineering hydrology applications.
6. It is necessary for determining the reservoir capacity to assure an adequate supply of
water for domestic and other purposes.
Application Area of Hydrology in Civil Engineering
The main application areas in the field of civil engineering can be listed as follows:
1. Irrigation Projects and Schemes.
2. Hydroelectric Power Generation Projects and Dam Constructions.
3. Water Supply Projects.
4. Disaster Prevention or Flood Control Projects.
Scope of Hydrology in Civil Engineering
1. Determination of Maximum Probable Flood:
The maximum probable flood at a proposed site can be determined by the techniques of
engineering hydrology.

2. Determination of Maximum Intensity of Storm:

The determination of the maximum intensity of the storm is necessary to determine the
drainage conditions at the site and to design the needed drainage systems.

3. Determination of Water Yield of Basin:

For the design and construction of various structures such as municipal water tanks,
reservoirs, inland navigation, etc; it is necessary to determine the yield of the basin i.e.
the occurrence, frequency, and quantity of water that can be obtained from the basin.
4. Ground Water Development Study:
Engineering hydrology facilitates the study of groundwater and its development.
Rainwater Harvesting
 Rainwater harvesting is the process of collecting, storing and then using rainwater as
an alternative or complementary source to mains water. Rainwater is usually
collected from rooftops and other hard surfaces which allow the volume of water to
run off into channels, guttering or downpipes which divert the water into a collection
tank and sometimes these are underground tanks.

 From there the water can be gravity fed or pumped into a system for use around your
home or business premises. Rainwater is commonly used for watering plants and
flowers, washing cars, flushing toilets and washing clothes. Filters can be added to a
system to remove certain contaminants from the water such as leaves and debris.
Broadly there are two ways of harvesting rainwater
1.Surface runoff harvesting
2.Roof top rainwater harvesting
Rainwater harvesting is the collection and storage of rainwater for reuse on-site, rather
than allowing it to run off. These stored waters are used for various purposes such as
gardening, irrigation etc. Various methods of rainwater harvesting are described in this
section.
1. Surface runoff harvesting
In urban area rainwater flows away as surface runoff. This runoff could be caught and
used for recharging aquifers by adopting appropriate methods.
2. Rooftop rainwater harvesting
It is a system of catching rainwater where it falls. In rooftop harvesting, the roof becomes
the catchments, and the rainwater is collected from the roof of the house/building. It can
either be stored in a tank or diverted to artificial recharge system. This method is less
expensive and very effective and if implemented properly helps in augmenting the
groundwater level of the area.
Advantages of rain water harvesting
(a) Promotes adequacy of underground water
(b) Mitigates the effect of drought
(c) Reduces soil erosion as surface run-off is reduced
(d) Decreases load on storm water disposal system
(e) Reduces flood hazards
(f) Improves ground water quality / decreases salinity (by dilution)
(g) Prevents ingress of sea water in subsurface aquifers in coastal areas 6
(h) Improves ground water table, thus saving energy (to lift water)
(i) The cost of recharging subsurface aquifer is lower than surface reservoirs
(j) The subsurface aquifer also serves as storage and distribution system
(k) No land is wasted for storage purpose and no population displacement is involved
(l) Storing water underground is environment friendly.
NECESSITY FOR RAINWATER HARVESTING
Rain water harvesting reduces the requirement to find clean water. Most commonly used
for flushing toilets and laundry, rain water can also be used for irrigation and much
more.
As for the sewer systems found in many developed areas – changing climate often
makes the pressure on the sewers much higher. Flooding of lower areas occur more and
more often in certain regions. Upgrading the capacity of sewers are expensive – so if
every household had a rain water tank in the ground, a lot of water can be captured,
rather than flooding the sewers.
Water Storage and Conveyance Structures (Simple introduction to Dams and Reservoirs)

A dam can be defined as an impervious barrier or an obstruction constructed across a

natural stream or a river to hold up water on one side of it, up to a certain level. As
shown in Fig. 6.1, the side on which water is getting stored is called upstream side and
the other side is called the downstream side. The stored water on the upstream side
constitutes the reservoir.
PURPOSE OF DAMS
The construction of a dam across a river results in the ponding of water on its upstream
side and this serves many useful purposes for mankind. They are as follows:
1. The stored water in the dam can be conveniently used for irrigation purposes.
2. The reservoir forms a very good source for water supply in areas where groundwater
source is inadequate.
3. If sufficient head of water is stored, then that can be used for power generation (hydel
power).
4. In case of heavy floods, if water is left unobstructed, the result will be very hazardous
involving irrecoverable loss of lives of human beings, animals, etc., and loss of property.
A dam across the river can act as a good flood-control measure by only letting out the
excess quantity of water.
5. A dam with its green surroundings forms an excellent place for recreation purposes
such as boating, swimming and water skiing.
6. The reservoir forms a good place for the breeding of fish, which is a considerable
wealth from dam. Fish are bred by the pisciculture department.
7. Besides the above-mentioned purposes, a dam serves many miscellaneous
purposes, such as adding beauty to the place where it is located and making it a place
of tourism importance. The atmospheric heat around the reservoir and its surroundings
is controlled well due to the large exposed area of water in the reservoir.

COMPONENTS OF A RESERVOIR
1. A dam across a river/valley forms a pool of water on the upstream side with necessary
sluices to let out water.
2. Irrigation canals taking off from one/either side of the dam with necessary outlets to
control the flow in the canal.
3. Spillway to let out the excess water from the dam which otherwise may result in
breach of the dam itself due to over storage of water. Therefore, the spillway acts as a
safety valve of the dam.
4. A good earthen bond in case of a totally artificially made reservoir.
5. Ancillary works like fish ladder, log chutes, etc.
CLASSIFICATION OF DAMS

1.1 Solid
Gravity Dams

1.2 Arch Dams

1. RIGID DAMS
1.3 Buttress
Dams

1.4 Timber &

DAMS
Steel Dams

2.1 Earth dams

2. NON-RIGID
DAMS
2.2 Rockfill
Dams