Post on 04-Feb-2018
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Course Instructor
Engr. Afzal Ahmed
MSc Water Resource & Irrigation Engineering
UET Taxila
Sc Ci!il Engineering
UET Taxila
Irrigation Engineering CE"#$#%'$(
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Course ContentsWater Resources)
*lanning and de!elo+ment of ,ater resources +ro-ects. omestic/
Industrial/ Agricultural and other ,ater usages/ Water resources in*a0istan.
Irrigation:
e1nition and t2+es of irrigation. Merits and demerits of irrigation/Indus asin Irrigation S2stem (IBIS).
Canal Irrigation:
Elementar2 conce+t a3out canal head ,or0s/ selection of their site
and la2out/ ,eirs and 3arrages/ !arious com+onents and functions.
Measures ado+ted to control silt entr2 into canals/ silt e-ectors and
excluders. esign of ,eirs on +ermea3le foundations/ sheet +ilesand cut o4 ,alls. esign of irrigation channels/ 5enned26s and
7ace26s Theories. Rational methods for design of irrigationchannels. Com+arison of !arious methods. Com+uter Aided designof irrigation channels.
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Barrages and Headworks:
Canal head regulators/ falls/ 8umes/ canal outlets.
Cross drainage ,or0s) t2+es and functions. Canallining) ad!antages and t2+es. Maintenance ofirrigation canals.Monitoring of 8o,s"telemetr2 s2stem.
Irrigated Agriculture:
Soil",ater"+lant relationshi+. Water re9uirements ofcro+s/ dut2 of irrigation ,ater. elta of cro+s/consum+ti!e use/ estimation of consum+ti!e use/
methods used for assessment of irrigation ,ater.Irrigation methods and +ractices. Irrigationscheduling. Management of irrigation s2stems/+artici+ator2 irrigation management.
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Water logging and salinity:
Causes and e4ects of ,ater logging/reclamation of ,ater logged soils. rainsand tu3e ,ells. Causes and e4ects ofsalinit2 and al0alinit2 of lands in *a0istan.Reclamation methods. rainage net,or0 inirrigated areas.
Drainage:
e1nition/ 7and reclamation/ Surfacerainage/ Su3surface rainage/ Estimationof discharge ca+acit2 of Cross"drainage
structures/ is+osal of drainage e:uents.
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Text oo0
7insla2/ R.5. and ;ose+h/ .ill.
Reference oo0s?. 7insla2/ R.5. and ;ose+h/ .ill.
@. Siddi9ui/ I9tidar >./ Irrigation and
rainage Engineering/ xford Uni!ersit2*ress
. I93al Ahmed/ Irrigation Engineering and>2draulic Structures
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Water Resources
Cha+ter Bo $?
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IntroductionUtilisation of available water of a region for use of
a community has perhaps been practiced from the
dawn of civilization. In fact, the Harappa and
Mohenjodaro excavations have also shown
scientific developments of water utilization and
disposal systems. hey even developed an efficient
system of irrigation using several large canals. It
has also been discovered that the Harappancivilization made good use of groundwater by
digging a large number of wells.
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!f other places around the world, the earliest dams
to retain water in large "uantities were constructed
in #awa $#ordan% at about &''' () and in *adi
+arawi $gypt% at about -' (). he /oman
engineers had built log water conveyance systems,
many of which can still be seen today, 0anats or
underground canals that tap an alluvial fan on
mountain slopes and carry it over large distances,were one of the most ingenious of ancient hydro1
technical inventions, which originated in 2rmenia
around 3'''() and were found in India since &''
().
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7og ,ater con!e2ances2stem
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2lthough many such developments had ta4en
place in the field of water resources in earlier days
they were mostly for satisfying drin4ing water and
irrigation re"uirements. Modern day projects
re"uire a scientific planning strategy due to5
3. +radual decrease of per capita available water on
this planet and especially in our country.
-. *ater being used for many purposes and thedemands vary in time and space.
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*ater availability in a region 6 li4e county or state
or watershed is not e"ually distributed.
he supply of water may be from rain, surfacewater bodies and ground water.
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*ater resources project planning
he goals of water resources project planning maybe by the use of constructed facilities, or structural
measures, or by management and legal techni"ues
that do not re"uire constructed facilities. he latter
are called non1structural measures and may include
rules to limit or control water and land use which
complement or substitute for constructed facilities.
2 project may consist of one or more structural ornon1structural resources.
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*ater resources planning techni"ues are used to
determine what measures should be employed to
meet water needs and to ta4e advantage of
opportunities for water resources development, and
also to preserve and enhance natural waterresources and related land resources.
he scientific and technological development has
been evident during the twentieth century in major
fields of engineering. (ut since water resourceshave been practiced for many centuries, the
development in this field may not have been as
spectacular as, say, for computer sciences.
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However, with the rapid development of
substantial computational power resulting reducedcomputation cost, the planning strategies have seen
new directions in the last century which utilises the
best of the computer resources. 7urther, economic
considerations used to be the guiding constraint forplanning a water resources project. (ut during the
last couple of decades of the twentieth century
there has been a growing awareness for
environmental sustainability. 2nd now,
environmental constrains find a significant place in
the water resources project $or for that matter any
developmental project% planning besides the usual
economic and social constraints.
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8riorities for water resources planning
*ater resource projects are constructed to develop ormanage the available water resources for different
purposes. he water allocation priorities for planning and
operation of water resource systems should broadly be as
follows5 3. 9omestic consumption includes water
re"uirements primarily for drin4ing, coo4ing,
bathing, washing of clothes and utensils and
flushing of toilets.
-. Irrigation *ater re"uired for growing crops in a
systematic and scientific manner in areas even with
deficit rainfall.
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&. Hydropowerhis is the generation of electricity by harnessing the power
of flowing water.
:. cology ; environment restoration
*ater re"uired for maintaining the environmental health of aregion.
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(asin 6 wise water resource project
development
he total land area that contributes water to a river iscalled a *atershed, also called differently as the
)atchment, /iver basin, 9rainage (asin, or simply a
(asin. he image of a basin is shown in 7igure 3.
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2 watershed may also be defined as a geographic area thatdrains to a common point, which ma4es it an attractive
planning unit for technical efforts to conserve soil and
maximize the utilization of surface and subsurface water
for crop production. hus, it is generally considered thatwater resources development and management schemes
should be planned for a hydrological unit such as a
9rainage (asin as a whole or for a >ub1(asin, multi1
sectorially, ta4ing into account surface and ground waterfor sustainable use incorporating "uantity and "uality
aspects as well as environmental considerations.
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ools for water resources planning and
management
he policy ma4ers responsible for ma4ingcomprehensive decisions of water resources planning
for particular units of land, preferably a basin, are
faced with various parameters, some of which are
discussed in the following sections.
3. >upply of water5
a. Water available in the unit
i. /ain falling within the region. his may be utilized
directly before it reaches the ground, for example, the
roof 6 top rain water harvesting schemes in water
scarce areas.
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ii. >urface water bodies. hese static $la4es and ponds% and flowing$streams and rivers%, water bodies may be utilized for satisfying the
demand of the unit, for example by constructing dams across rivers.
iii. +round water reservoirs. he water stored in soil and pores of
fractured bed roc4 may be extracted to meet the demand, for
example wells or tube 6 wells.
b. Water transferred in and out of the unit
If the planning is for a watershed or basin, then generally the water
available within the basin is to be used unless there is inter basin water
transfer. If however, the unit is a political entity, li4e a nation or a state,
then definitely there shall be inflow or outflow of water especially that of
flowing surface water. /iparian rights have to be honored and extraction
of more water by the upland unit may result in severe tension.
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c. Regeneration of water within the unit(rac4ish water may be converted with appropriate technology to
supply sweet water for drin4ing and has been tried in many extreme
water scarce areas. *aste water of households may be recycled, again
with appropriate technology, to supply water suitable for purposes
li4e irrigation.
-. 9emand of water5
a. Domestic water requirement for urban population
his is usually done through an organized municipal water
distribution networ4. his water is generally re"uired fordrin4ing, coo4ing, bathing and sanitary purposes etc, for the
urban areas.
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b. Domestic and livestock water requirement forrural population
his may be done through individual effort of the users by tapping
a local available source or through co1operative efforts
c. Irrigation water requirement of cropped elds
Irrigation may be done through individual effort of the farmers or
through group cooperation between farmers, li4e 7armers?
)ooperatives. he demands have to be estimated based on the
cropping pattern, which may vary over the land unit due to
various factors li4e@ farmer?s choice, soil type, climate, etc.2ctually, the term AIrrigation *ater 9emandB denotes the total
"uantity and the way in which a crop re"uires water, from the time
it is sown to the time it is harvested.
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c. Industrial water needshis depends on the type of industry, its magnitude and the
"uantity of water re"uired per unit of production.
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Canals/unnelshese are conveyance structures for transporting water over long
distances for irrigation or hydropower.
hese structural options are used to utilise surface water to its maximum
possible extent. !ther structures for utilising ground water include
rainwater detentions tan4s, wells and tube wells.
2nother option that is important for any water resource project is
*atershed Management practices. hrough these measures, the water
falling within the catchment area is not allowed to move "uic4ly to drain
into the rivers and streams. his helps the rain water to saturate the soil
and increase the ground water reserve. Moreover, these measures reducethe amount of erosion ta4ing place on the hill slopes and thus helps in
increasing the effective lives of reservoirs which otherwise would have
been silted up "uic4ly due to the deposition of the eroded materials.
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Management tools for water resource
planning
he following management strategies are important for water resourcesplanning5
C*ater related allocation;re1allocation agreements between planning
units sharing common water resource.
C >ubsidies on water use
C 8lanning of releases from reservoirs over time
C 8lanning of withdrawal of ground water with time.
C 8lanning of cropping patterns of agricultural fields to optimize the
water availability from rain and irrigation $using surface and;or
ground water sources% as a function of timeC )reating public awareness to reduce wastage of water, especially
filtered drin4ing water and to inculcate the habit of recycling waste
water for purposes li4e gardening.
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as4s for planning a water resources project
he important tas4s for preparing a planning report of a waterresources project would include the following5
C 2nalysis of basic data li4e maps, remote sensing images,
geological data, hydrologic data, and re"uirement of water use
data, etc.C >election of alternative sites based on economic aspects
generally, but 4eeping in mind environmental degradation
aspects.
C >tudies for dam, reservoir, diversion structure, conveyance
structure, etc.
C >tudies for local protective wor4s 6 levees, riverban4
revetment, etc.
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C 7ormulation of optimal combination of structural and
non1structural components $for projects with flood
control component%.
C conomic and financial analyses, ta4ing into account
environmental degradation, if any, as a cost.
C nvironmental and sociological impact assessment.
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Punjab
he public irrigation infrastructure in the 8unjab consists of 3& barrages
- siphons across major rivers
3- lin4 canals and -& major canal systems over an
aggregate length of &:,ystem. It serves an area of D.
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Sindh
3: publicly owned irrigation systems, which receivewater from three barrages across the /iver Indus.
hese systems, with an aggregate length of 3D,''' 4m
of canals, serve an area of about indh, which serve a total area of over &.< million
hectares and have an aggregate length of about :,D''
4m.
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5*5
< publicly owned irrigation systems in the Indus (asin, whichserve
a total area of '.&: million hectares. hese systems receive
water from two headwor4s across /iver >wat and *arsa4
9am. In addition, there are six other canal systems, whichserve a total of '.3& million hectares of land.
2lso has over -'' canals called Gcivil canalsG, which are
community or privately owned. hese irrigate an aggregate
area of '.D& million hectares.
here are four surface drainage systems in 8 comprising of
:
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Balochistan
(alochistan has two canal systems, which receivewater from the Indus (asin >ystem through +uddu
(arrage and >u44ur (arrage, located in >indh. hese
canal systems serve a total area of '.&& million
hectares. !ne of these, the 8at7eeder )anal >ystem, has been improved recently. In
addition, there are :&3 independent publicly owned
small irrigation schemes, which serve '.3: million
hectares. here are a few privately owned smallirrigation schemes too.
= d t f
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=round,ater usage forirrigation
2n estimated :3. M27 of groundwater is pumpedannually in 8a4istan.
2ccording to a study, more than F' of the extracted
groundwater is used for
irrigation purposes. +roundwater reservoirs are
recharged from the rivers as
well as the seepage losses from the canals,
watercourses, farm channels and the fields.