Water Saving Irrigation: Paper Presented in Wuhan, China
Technical
Issues for Water Saving Irrigation Development in Arid Region
Abstract
Irrigated agriculture, comprising 17
% of the total cultivated area and producing 40% of the world’s food, is a key
to meeting the food requirements of an increasing population (SIWI, 2005).
Irrigation, utilizing 70% of the fresh water supply and hence the largest water
consuming sector in the world, is facing pressure from not only other consumer
sectors like municipalities and industries but also from non-consuming sectors
with conflicting operation criteria such as power generation, recreation, and
flood control. Hence, efficient use of irrigation water, which is the key and
constraining input of the irrigated sector, is the most desirable thing to
strive for in arid and semiarid regions.
For any sustainable change from traditional flood
irrigation to water saving irrigation, it is essential to have a minimum
package of social, organizational, legal, economic and political arrangements
put in place or at least proposed for implementation. Initially, these packaged
conditions can be deduced from the available global experience gained in other
settings that can then be adapted for the local environment. However, with
time, as lessons from the relevant local experience become available, these
conditions can be adjusted and refined.
Water saving irrigation conveys a meaning of
reducing irrigation water requirements when compared to traditional irrigation
practices. Pressurized irrigation techniques are one set of such changes that
demand addressing many arising technical issues for letting new water saving
practices take their hold, particularly in the arid regions where water
scarcity abounds.
Similarly, after gaining access to laser technology
in irrigated agriculture and new knowledge gains in gravity irrigation
applications, some developed as well as underdeveloped arid contexts are either
moving away from pressurized irrigation or directly moving in from traditional
practices to a properly designed, less energy-dependent, more economical and
efficient gravity water saving irrigation methods. In either case, we need to
address technical issues within an appropriate institutional structure as well
as an incentive system to let such a change become a permanent reality.
This paper is mainly based on Pakistani experiences
in trying and testing both of the referred types of changes, pressurized as
well as improved surface irrigations, in the context of required basic non-technical
and the resulting technical issues. There have been, as happens in any context,
both failures and successes in introducing water saving irrigation practices.
These are worth mentioning and discussing so as to allow us to draw appropriate
lessons from them and adjust our strategies accordingly.
Since Pakistan
Finally, this paper briefly discusses new concepts
of global versus local efficiencies as it is bound to impact water saving
irrigation practices. The authors of this paper propose a third option that is
based on saving water through efficient irrigation practices and providing
water storage facilities at different levels of irrigation system. This concept
is presented for consideration that will address concerns for remaining
attached on to local efficiencies and not realizing tangible water savings or
keep insisting on only global efficiencies as a concept but refusing to heed
local concerns like water quantity, water quality, water reliability, water
resources planning, water allocation, water project design, energy needs for
water extractions and new set of management controls.
1.
Context: Water Saving Irrigation Development in Arid Region
1.1
Water Saving Irrigation: Possible Origin
There could be many
experts / institutions who can claim to take credit for using this terminology
but per the following web-site, the authors think it originated from China: (www.watertech.cn/english/Water%20Saving%20Irrigation%20Journal.ppt)
The Chinese
experts and institutions have persistently promoted this terminology since
1976. In the South Asian Sub-continent, water savings in irrigation applications
are mostly described as improving irrigation efficiency or efficiency
enhancement techniques.
In China, there is a bimonthly journal entitled
“Water Saving Irrigation” with its editorial office in the Wuhan University
(Website referred above). Approved by the Ministry of Water Resources in 1976,
this journal was originally named “Sprinkler Irrigation technique” but after 20
years, the same journal further evolved to opt the current title, Water Saving
Irrigation, to expand its scope to cover all potential avenues of irrigation
water savings by either sprinkler and micro-irrigation or other new and
advanced surface water saving irrigation techniques plus related research
findings.
Because of the extension of laser technology for
land leveling and efficiency enhancement in surface irrigation water
applications, both made possibly by new innovative techniques supported by
mathematical modeling, an old art of surface irrigation application has become
a full-fledged science itself. This is why, while discussing different options
for efficient water application development in irrigated agriculture,
irrigation water savings will not be confined just for pressurized irrigation
techniques.
1.2
Scope of Water Savings Irrigation Development in Arid Region
Irrigated agriculture is by far the largest consumer
of water in the world. This sub-sector accounts for about 84 % of total water
use in Asia , 72% worldwide and 87% in
developing countries (David, 2004).
According to the same source, average irrigation efficiency is less than
40% and it is even lesser where rice-based cropping systems are practiced.
These above figures are just average values for arid
and non-arid zones. Exclusively for arid and semi-arid regions, the share of
water consumption increases and irrigation efficiency tends to dip further
down. This is why development of water saving irrigation in irrigated arid
zones presents a huge potential for increasing additional water supply to meet
future needs in the emerging context of water scarcity.
1.3
Pakistan
|
Figure 2. Aridity status in
|
|
Figure 1, Aridity status in
|
1.4
Pakistan
In Pakistan, where
irrigated agriculture consumes about 97% of total available water in use, its
water crisis is a complex and multi-faceted phenomenon. Whereas in 1951 Pakistan
1.5
Pakistan and its Irrigation System
Indus Water Irrigation System (IBIS) is the largest
contiguous irrigation system in the world with the following main features as
reported by Bhatti, et al (2009):
v 3
large dams;
v 19
river barrages;
v 12
inter-river link canals;
v 45
large canal commands;
v 90,000
groundwater pumping units (recent figure is over 1.2 million tube-wells);
v 80%
of cropped area, about 18.09 ha, is irrigated;
v Total
IBIS flow is around 179 BCM; and
v At
present, 119.5 BCM water diverted to canal commands.
A schematic diagram (Figure 3) of this huge
contiguous irrigation system is presented by the Word Bank Report (2005) as
follows:
|
Figure 3. Indus
Basin Irrigation System (IBIS) within Pakistan
|
v Main
canal;
v Branch
canal;
v Secondary
or Distributary Canal;
v Minor
or sub-secondary canal;
v Watercourses;
v Branch
watercourses; and
v Farmers’
field ditches.
According
to a report (Kugelman & Hathaway, 2009), the canal system is estimated to
be 64,000 kilometers long and watercourses are also to be around 100,000 kilometers.
This
huge and complex network of irrigation has a direct impact on the allocated
water saving in irrigation. From mid-nineteenth century to-date, a system has
been developed that was designed for subsistent irrigated agriculture, but, at
present, ground realities have changed in favor of commercial agriculture that
demands different irrigation water management. As the old design parameters do
not fit these new realities of commercial agriculture, an intrinsic conflict is
brewing that may have to be addressed while planning water saving irrigation
development in this region.
1.6 Pakistan and Water
Management Conditions
A
World Bank Report (2006) has appreciated many strengths that exist for better
water management in Pakistan as listed below:
v Pakistan’s
water rights from the Indus Basin River System are clearly defined under the
Indus Water treaty of 1960;
v Provincial
water rights are agreed by all four stakeholders under the Water Apportionment
Accord of 1991;
v Rules
for further water distribution to secondary canals and Watercourse-outlets are
followed by all concerned; and
v Below
watercourse outlet, a turn system, locally termed as warabandi, is in practice to get canal water supplies equitably
based on land ownership.
However, there is still confusion for availing the
following opportunities to meet the demand of the changing nature of
agriculture in this arid and semi-arid region:
v Provision
of entitlements for groundwater extractions;
v Water
entitlements to be defined for new sources of water like spate irrigation
water; and
v Establishment
of good water governance to ensure accountability, transparency and
participation of all water users.
1.7
Brief History regarding Efforts directed for Water Saving Irrigation Practices
|
|
Over the last four decades, in order to create a
conducive environment for water saving irrigation at the farm level, Pakistan
has made concerted efforts to improve on and off farm conditions to improve
irrigation efficiency. This second stage of irrigation development starts from
the early seventies and it is still being pursued. A brief history of this
lower-level development is listed below:
v 1972-76,
USAID funded an experimental water management project in Punjab to demonstrate
irrigation water savings and productivity enhancement through individual as
well as integrated packages of land leveling, land reshaping, attempts at different
improved surface irrigation application techniques, watercourse improvements
and appropriate use of inputs;
v 1976-1982,
USAID funded another project that was termed Punjab Water Management Project;
v 1982-to-date,
through foreign funding as well as substantial government support, the National
program about On-farm Water Management, a well appreciated project by the water
users, remains active even today and its main focus has been lining and earthen
improvements of watercourses in all four provinces of Pakistan;
v Land
leveling activity remained part and parcel of this national program but its
progress remained well below that desired till the time that laser-controlled
land leveling technology became available for ensuring quality of the job
undertaken;
v During
the mid-eighties, the Command Water Management Project was initiated to do all
the activities that were defined under On-farm Water Management Project with
the additions, integration of activities and up-scaling at the secondary canal
level;
v From
mid-nineties to-date, another ambitious program is in hand where institutional
reforms have been introduced to have joint management by public irrigation officials and elected
representatives of farmers at all different levels: provincial, canal command,
secondary canal and watercourse levels.; and
v During
this period, other minor projects for trial and testing of improved surface and
pressurized irrigation techniques have been undertaken and even today, there is
a project on efficiency enhancement in hand where drip and sprinkler irrigation
demonstrations are being conducted in all four provinces of Pakistan.
1.8
Gaps in the way of Water Saving Irrigation Practices
For a Pakistani national, it is a bit embarrassing
to accept but reality remains that all the stated projects, with an exception
of watercourse improvement projects, could not achieve desired objectives
because of different gaps that exist such as the following:
Ø Knowledge
gap;
Ø Skill
gap;
Ø Input
support gap;
Ø Water
resource gap;
Ø Irrigation
management gap;
Ø Maintenance
gap;
Ø Political
will gap;
Ø Productivity
and productivity focus gap; and
Ø Trust gap.
3. Institutional Structure and Incentive
System for Water Saving Irrigation Development
On
the surface, it sounds as if such projects were the set of activities that were
undertaken without providing any proper institutional structure and incentive
system agreed and accepted by all stakeholders. There remained a clear absence
of political ownership to bring a desired change by securing respective
objectives of all such projects. Since productivity and profitability per unit
of water applied was neither monitored nor made a condition for such heavy
investments, outcomes related to water saving in irrigation remained an
illusionary goal only.
What
is an institutional structure? As defined by Douglass North (1993):
“Institutions are the humanly devised constraints that structure human
interaction. They are made up formal constraints (rules, laws, constitutions),
informal constraints (norms of behavior, conventions, and self imposed codes of
conduct and their enforcement characteristics. Together they define the
incentive structure of societies and specifically economies.” So, the institutional structure relates
to a framework based on all the legal, policy, regulatory measures that govern
how something works or functions.
In
this direction, some half-hearted efforts like water users associations and
institutional reforms in provincial irrigation sectors were made but again the
lack of political ownership and the lack of attention to other essential
ingredients of institutional structure made this whole exercise much less than
the expected outcome. Moreover, in almost all cases, there was no
accountability mechanism put in place to ensure enhancement in productivity and
profitability per unit of water as a precondition for ensuring sustainable
water saving irrigation development in Pakistan.
What
is the incentive system? The incentive system grows upon the
institutional framework and incentives are both positive and
negative. These drivers could include stimulus like water prices and
subsidies, market price controls or subsidies, enforcement or lack thereof
of the institutional framework, etc. Again because of missing political will
and powerful vested interests, these projects failed to provide needed
incentive system that could bring in economic and social responsibility to the
water users to use irrigation water efficiently.
The
process in the appendix builds on a system of supporting farmers with a water
supply, effective irrigation of a field, and support for high levels of
productivity. Providing a coordinated
and collaborative effort between agencies and farmers makes all willing to work
in the new system and enjoy the benefits.
Rewards for government personnel need to be included. The revamped farming and agency effort is a
great incentive.
For
a successful water saving irrigation development, therefore, as a first step,
there should be an institutional structure agreed upon by all stakeholders in a
participatory manner and that structure should be made functional too. Trying
to impose such structures from the top without any relevance to the working and
living environment of irrigation water users cannot go very far. Second part is
that incentive system should be in line with an objective to induce water
saving irrigation and it does not become an instrument to work against the real
spirit of set objective. While working with the water users, as a third part,
identify those incentives that they respond willingly and effectively.
3.0
Conceptual Framework for Water Saving Irrigation Development
Obviously a potential conceptual framework with a
built-in institutional structure and incentive system for water saving
irrigation development revolves around irrigation system that is selected to
apply water to crops. By placing an appropriate incentive system within its
conducive-environment of an opted institutional framework, the goal to
accomplish water saving irrigation or the introduction of efficient on-farm
irrigation practices does not remain an illusionary dream.
Generally, an irrigation system is perceived to have
one dimension being physical only. However, this is not true. A note prepared
by F. E. Schulze, former director of International Irrigation Management
Institute-Pakistan, states that an irrigation system has the following two
dimensions: (1) management and (2) physical. Therefore, a conceptual framework
for water saving irrigation will be based within a management dimension to
affect the performance of the physical counter-part. For elaboration, each
dimension of an irrigation system will be further divided into conditions,
activities and results as presented below:
3.1
Management Dimension of an Irrigation delivery and Application System
3.1.1 Management Conditions: These
management related conditions refer to the quality of persons involved,
availability of historic as well as real time data / information, public
irrigation extension services, private irrigation advisory companies,
appropriate farmers’ organizations, Institutional structures, incentive systems,
etc.
3.1.2 Management Activities: These
activities are focused on decision preparation and decision making aspects on
management. They also include monitoring and evaluation to feed-in the
management process to make adjustments. Some important examples of management
activities in the choice area include actions like: irrigation scheduling, selection of
appropriate water application system, stream size, decision-making to set
criteria for irrigation evaluation, application of measures to address water
quality concerns, etc.
3.1.3 Management Results: Compilation of
guidelines used for successful implementation of management activities are
management results. These guidelines of decisions taken under management activities
concerning irrigation water management for crops can include products such as a
manual for irrigation scheduling, check-list for selecting an appropriate
surface irrigation method and stream size for a furrow or border, guidelines to
avoid excessive over or under-irrigation, strategy for conjunctive use of
surface and groundwater, etc.
3.2
Physical Dimension of an Irrigation Water Delivery and Application System
3.2.1 Physical Conditions: These conditions
include facilities for water application (for example furrows, alternate
furrows, basin-borders, basins or pressurized irrigation methods), flow
measuring structures or devices, arrangement for water disposal, quality and
quantity of irrigation water source/(s), infrastructure for determining soil
water infiltration and depletion, types of crops being planted, etc.
3.2.2 Physical Activities: These
activities concern with aspects such as application of irrigation water at
field level, operation of available facilities for determining flow rate, infiltration
behavior and soil water depletion, etc.
3.2.3 Physical Results: Examples of
physical results is application, storage and disposal of certain amounts of
water at a certain time for a selected crop/(s) with a set goal to achieve
water saving irrigation
4. Salient Features of a Typical
Institutional Framework for Pakistan
Institutional
Framework
Available institutions have different roles to play at different stages of development and management of irrigation water saving. During the early stages of testing various scenarios and techniques for water saving, the research institutes and the universities associated with agricultural and irrigation practices would need to come up with water saving “packages” suitable for different agro-climatic zones keeping in view the soils, climatic conditions, spatial and temporal availability and quality of water, and local socio-economic conditions. In most countries, this task has already been accomplished although there is always scope for improvement and fine tuning, by making use of the latest developments.
The recommended practices and techniques will need to be tested and promoted through demonstration farms and dissemination of the findings to the farmers through media and meetings/seminars organized through local farmer bodies. At this stage, the role of agricultural and irrigation extension agencies would be crucial. It will be an opportune time for the Government and international development organizations to come up with suitable incentives for the private sector (importers of machinery and equipment, and service providers) and farmers in terms of, for example, tax and duty relief, and subsidies. This opportunity of active involvement of various institutions in irrigated agriculture must also be used to overcome the inherent shortcomings of irrigated agriculture in order to increase productivity. Use of improved seeds, adequate amount and mix of fertilizers, cultural practices, plant protection, improved post-harvest handling, and marketing of agricultural supplies and produce are few areas requiring interventions. Almost all institutions associated with agriculture sector would be associated with this task.
Available institutions have different roles to play at different stages of development and management of irrigation water saving. During the early stages of testing various scenarios and techniques for water saving, the research institutes and the universities associated with agricultural and irrigation practices would need to come up with water saving “packages” suitable for different agro-climatic zones keeping in view the soils, climatic conditions, spatial and temporal availability and quality of water, and local socio-economic conditions. In most countries, this task has already been accomplished although there is always scope for improvement and fine tuning, by making use of the latest developments.
The recommended practices and techniques will need to be tested and promoted through demonstration farms and dissemination of the findings to the farmers through media and meetings/seminars organized through local farmer bodies. At this stage, the role of agricultural and irrigation extension agencies would be crucial. It will be an opportune time for the Government and international development organizations to come up with suitable incentives for the private sector (importers of machinery and equipment, and service providers) and farmers in terms of, for example, tax and duty relief, and subsidies. This opportunity of active involvement of various institutions in irrigated agriculture must also be used to overcome the inherent shortcomings of irrigated agriculture in order to increase productivity. Use of improved seeds, adequate amount and mix of fertilizers, cultural practices, plant protection, improved post-harvest handling, and marketing of agricultural supplies and produce are few areas requiring interventions. Almost all institutions associated with agriculture sector would be associated with this task.
Assured supply of the required amounts of irrigation water at predetermined time is crucial for the success of irrigation water saving, as the supply of exact amount of water at calculated interval leaves no “reserve” moisture in the root zone to take care of subsequent delayed or inadequate supply. This would require strong governance in the distribution of water in case of shared water resources like surface water supplies through canals, and necessity of stand-by power arrangements in the case of local/independent water resources like groundwater or local pond/storage.
Individual
farmer water savings would be used by the farmer to initially provide water to
all the crops he is growing. If his
experience suggests he could plan additional area to crops, he would do so now
and for sure he would plan all the available land to crops for the next season.
When water supplies are adequate for the command, head farmers should stop
using excess water at the head and allow the water to become available to
middle and tail farmers. These farmers
should have adequate water supplies for their fields.
When
water supplies are more than adequate for the outlet command, then the farmers
can agree to allow additional water to reach outlets lower down the canal
command. If the canal command has
excess, they can sell or trade the water to farmers on other canal commands. If excess water is available then a reduction
in supplies for the canal command can be accomplished. Water savings would not be released to the
canal, but become available for diversions down the canal command.
5. Actual and Attainable Irrigation
Application Efficiencies
According
to personal communication with Dr. Ross Hagan, former staff of International
Irrigation Center, Professor Wynn Walker, current dean faculty of engineering
at Utah State University, used to make two statements: “(1) most of water
savings in irrigation will come from improved irrigation management practices
while irrigation methodology remains unchanged, (2) irrigation technology is
only helpful when you want to squeeze out the top 5-10 % of efficiency.” In
other words, if the efficiency is less than the attainable range, work to
change the management of current systems in use. To support these statements,
two tables depicting a general trend are presented from two different sources
from the United States.
Table
1. Actual application efficiencies as reported by Sterling and Neibling (1994)
|
|
Application
Efficiency (%)
|
Water required to put 1 inch in Crop-Root Zone
|
|
Surface Systems
|
|
|
|
Furrows
(Graded)
|
35 – 60
|
1.7 – 2.8
|
|
Corrugate
|
30
– 55
|
1.8
– 3.3
|
|
Border,
Level
|
60 – 75
|
1.3 – 1.7
|
|
Border,
Graded
|
55
– 75
|
1.3
– 1.8
|
|
Flood,
Wild
|
15 – 35
|
2.8 – 6.7
|
|
Surge
|
50
– 55
|
1.8
– 2.0
|
|
Cablblegation
|
50 – 55
|
1.8 – 2.0
|
|
Sprinkler System
|
|
|
|
Stationary
Lateral
(Wheel-
or Hand-Move)
|
60 – 75
|
1.3 – 1.7
|
|
Solid-set
Lateral
|
60
– 85
|
1.2
– 1.7
|
|
Center
Traveling Big Gun
|
50 – 67
|
1.5 – 1.8
|
|
Stationary
Big Gun
|
50
– 60
|
1.7
– 2.0
|
|
Center-Pivot
Lateral
|
70 – 85
|
1.2 – 1.4
|
|
Moving
Lateral (Linear)
|
80
– 87
|
1.1
– 1.2
|
|
Micro-Irrigation Systems
|
|
|
|
Surface
Drip
|
90
– 95
|
1.05
– 1.1
|
|
Sub-surface
Drip
|
90 – 95
|
1.05 – 1.1
|
|
Micro-spray
or Mist
|
85
– 90
|
1.1
– 1.2
|
Table 2a. Actual application
efficiencies as reported by Howel ( 2003 )
|
Irrigation Method
|
Field
Efficiency (Application)
(%)
|
Farm Efficiency (Application)
(%)
|
||||
|
|
|
|
||||
|
|
Attainable
|
Range
|
Average
|
Attainable
|
Range
|
Average
|
|
Surface Irrigation
|
|
|
|
|
|
|
|
*Graded Furrows
|
75
|
50 - 80
|
65
|
70
|
40 – 70
|
65
|
|
w/tail-water Reuse
|
85
|
60
– 90
|
75
|
85
|
-
|
-
|
|
*Level Furrows
|
85
|
65 – 95
|
80
|
85
|
-
|
-
|
|
*Graded Border
|
80
|
50
- 80
|
65
|
75
|
-
|
-
|
|
* Level Basin
|
90
|
80 – 95
|
85
|
80
|
-
|
-
|
|
Sprinkler
|
|
|
|
|
|
|
|
*Periodic Move
|
80
|
60 – 85
|
75
|
80
|
60 – 90
|
80
|
|
*Side Roll
|
80
|
60
– 85
|
75
|
80
|
60
– 85
|
80
|
|
*Moving big gun
|
75
|
55
- 75
|
65
|
80
|
60 – 80
|
70
|
|
Center Pivot
|
|
|
|
|
|
|
|
*Impact heads w/ end gun
|
85
|
75 – 90
|
80
|
85
|
75 – 90
|
80
|
|
*Spray heads wo/ end gun
|
95
|
75
– 95
|
90
|
85
|
75
– 95
|
90
|
|
@LEPA
wo/ end gun
|
98
|
80 – 98
|
95
|
95
|
80 – 98
|
92
|
|
Lateral Move
|
|
|
|
|
|
|
|
*Spray heads w/ hose feed
|
95
|
75 – 95
|
90
|
85
|
80 – 98
|
90
|
|
*Spray head w/canal feed
|
90
|
70
– 95
|
85
|
90
|
75
– 95
|
85
|
|
Microirrigation
|
|
|
|
|
|
|
|
*Trickle
|
95
|
70
– 95
|
85
|
95
|
75
– 95
|
85
|
|
*Subsurface Drip
|
95
|
75 – 95
|
90
|
95
|
75 – 95
|
90
|
|
*Micro-spray
|
95
|
70
– 95
|
85
|
95
|
70
– 95
|
85
|
|
Water table Control
|
|
|
|
|
|
|
|
*Surface Ditch
|
80
|
50
– 80
|
65
|
80
|
50
– 80
|
60
|
|
Subsurface Drain Lines
|
85
|
60 – 80
|
75
|
85
|
65 – 85
|
70
|
|
@LEPA stands for low energy precision
application
|
||||||
Table 2b. Attainable application
efficiencies by different irrigation methods (Solomon, 1988)
|
Type of System
|
Attainable
Efficiencies
|
|
Surface Irrigation
|
|
|
Basin
|
80 – 90%
|
|
Border
|
70 - 85 %
|
|
Furrow
|
60 - 75%
|
|
Sprinkler Irrigation
|
|
|
Hand Move or
Portable
|
65 - 75%
|
|
Traveling Gun
|
60 – 70%
|
|
Center Pivot and
Linear Move
|
75 – 90%
|
|
Solid Set Permanent
|
70 – 80%
|
|
Trickle Irrigation
|
|
|
With point source
emitters
|
75 – 90%
|
|
With line source
Products
|
70 – 85 %
|
Comparison
of data about pressurized systems presented in these three tables (Tables 1, 2a
& 2b) reveal an interesting trend: gap between actual and attainable is
very small in case of micro-irrigation as compared to different kind of
sprinkler irrigation systems. This gap is expected to be even wider if such
sprinkler systems are operated under hot and arid environments that exist in
many Asian contexts in general and Pakistan in particular. This is why some
resourceful farmers tried center-pivot systems in central Punjab but due to heavy
evaporation losses, they soon moved to laser leveled basin-borders and
level-bed-and-furrow irrigation systems. However, in slightly less hotter and
semi-arid cases in northern Punjab, sprinkler system for fruits and vegetable
crops has been successfully operated by some progressive farmers.
However
data comparison in given Tables 1 & 2 (a & b), show that the stated
performance gap exists across gravity and pressurized systems. This leads one to
observe that the performance of pressurized is more influenced by technical
issues like design of pipe flows, working of emitters, etc. whereas gravity
systems are more responding to, in addition to management dimension, spatially
varied flow over porous media and ever changing infiltration behavior from seasonal
as well as soil variability from point to point. Of course, there are a host of
other issues to be addressed but such dominant trends may help to prioritize
steps to be taken to address issues related to less than desired performances.
6. Case of Pressurized Water Saving
Irrigation Development in Arid Zones
6.1 Possible Issues under Pressurized
Water Saving Irrigation Development in Arid Regions
Review
of literature suggests to pay due attention to physical, economic and social
consideration while developing pressurized irrigation system in any context in
general but arid environment in particular. Different experts list the
following points for consideration:
A. Physical Considerations
} 1. Crops & Cultural Practices
} 2. Soils
} a.
Texture, Depth & Uniformity
} b.
Intake Rate & Erosion Potential
} c.
Salinity & Internal Drainage
} 3. Topography Slope & Irregularity
} 4. Water Supply
} a.
Source & Delivery Schedule
} b.
Quantity Available & Reliability
} d.
Water Quality - Chemical and Suspended Solids
} 5. Climate
} 6. Land Value and Availability
} 7. Boundary Constraints and Obstructions
} 8. Flood Hazard
} 9. Water Table
} 10. Pests
}
11. Energy Availability and Reliability
B. Economic Consideration
}
1. Capital Investment Required
}
2. Credit Availability & Interest Rate
}
3. Equipment Life & Annualized Cost
}
4. Costs & Inflation
}
a. Energy, Operation & Maintenance
}
b. Labor (Various Skill Levels)
}
c. Supervision & Management
}
5. Cash Flow
}
6. Efficiency Factors
C. Social
Considerations
} . Legal and Political Issues
} 2. Local Cooperation and Support
} 3. Availability and Reliability of Labor
} 4. Skill and Knowledge Level of Labor
} 5. Local and Governmental Expectations
} 6. Level of Automatic Control Desired
} 7. Potential for Damage by Vandalism
} 8. Health Issues
6. 2 Challenges for Water Saving
Irrigation using Pressurized Irrigation – Pakistani Experience (Shafique,
2009):
Government of Pakistan is doing the right thing by
encouraging farmers to try relatively more efficient pressurized irrigation
systems instead of traditional gravity or flood irrigation methods. Among the
pressurized systems, special emphasis remains on trickle / drip for point
irrigation that cuts almost 50% demand on existing water demand and increases
crop yield significantly. In this context, just to create demand for the
technique and to adapt the new water application systems, current planning is
to establish demonstration farms on 1500 acres in Punjab and 500 acres in each
of the remaining three provinces.
In addition to short-term objectives, a strategic
interest in such endeavor appears to be field testing for the sustainability of
such pressurized systems under an environment of medium to heavy soils in arid
and semi-arid region where gravity irrigation has been practiced over
centuries. As the current project is a second or third attempt in the
introduction of pressurized systems, common sense suggests that the new project
is based on lessons learned from the not-so-successful similar attempts made in
the recent past. This seems to be the reason that private vendors and companies
are being proposed to install such systems for demonstration in all four provinces
of Pakistan.
However, such a paradigm shift in the modality of
irrigation water application is not going to be an easy task. There will be
many challenges of different nature that must be addressed properly for making
this change irreversible.
If the establishment of demonstration sites is
limited to a part of a farm, it may be difficult to fully know the adjustments
required for fitting a pressurized system within a gravity water application
environment. Demonstration sites based on entire farms are essential to learn
about challenges that farmers will have to face in the existing environment of
multiple cropping patterns, different land uses and related cultural practices.
When farms are fully dedicated for crops like
vegetables, orchards or row crops like cotton, drip irrigation fits well.
However, the same does not hold right when seasonal vegetables and row crops
follow by say wheat or fodder. So, the second challenge would be that either
new cropping patterns come into being or some innovative combinations of
pressurized systems are introduced to suit the new arising situation.
Even if we have row crops, vegetables or orchards,
the nature of arid and semi-arid region is such that salinity will appear on
the soil surface between rows in no time. To avoid shifting of the salts to
adjacent plants, proper use of rain-water and occasional gravity / flood
irrigation may become a necessity to maintain good soil health. It appears that
a system that works well in sandier or tropical environment may need
appropriate adjustments to fit with medium to heavy soils located in arid and
semi-arid regions.
With proper adjustments, drip systems should work
well for orchards of mangoes, citrus, apple, guava, etc. However, when
inter-cropping is opted, for most citrus growers, having a sprinkler system in
place should help. In that case, however, the challenge is to design a circular
water application system that fits to rectangular fields. In the USA, some
center-pivot systems have been designed to do just that.
For planners and managers, another issue concerns
with the use of tube-well and canal water. For tube-well water, drip systems
will need either no or limited filtration arrangement whereas canal water must
have to have silt-free clean water to avoid clogging of drip lines and
emitters. On the other hand, most of the tube-wells in the Indus Valley pump
sodic water having high amounts of carbonates and bicarbonates. Such
groundwater creates sodic hazards in medium to heavy soils on one hand; the
deposits of calcium carbonates (lime) could clog emitters on the other hand.
This implies that groundwater has to be treated in most cases and de-silting of
canal water would be necessary for pressurized systems like sprinklers in
general and drip irrigation in particular. Handling treatment with say sulfuric
acid or tackling accumulated silt from different locations should be another
aspect for serious consideration.
Canal irrigation system of the Indus Valley is a marvel
of engineering and uniquely tailored for surface / gravity irrigation. Canals
are conduits for rationing water as per weekly turn system. Both canals and
tube-wells deliver water at much higher rates than any pressurized system that can
consume such flows. To address this challenge, a mushroom growth of on-site
water storages becomes another necessity. Obviously, there will be a lot of
work needed to make these options feasible and acceptable.
Of course, the next challenge concerns with a scenario
when we all switch to pressurized systems to avoid excessive application of
water using surface irrigation. In this case, what kind of remodeling will be
needed for existing water supply systems as well as the new ones to fit
efficient but slow-consumers of water at a farm or field level? Our researchers
and planners must start thinking to devise adjustments to handle the upstream
effects of pressurized irrigation systems. If proper plans are not thought
through and implemented, canals will silt up fast.
Similarly; researchers, managers and planners have
to come up with legal and physical flexibilities of making use of saved water
by opting pressurized systems. Will the head-end farmers be able to sell their
saved water to fellow farmers along the water supply system? This implies to
structural adjustments of water supply systems and nature of water rights in the
future.
Another challenge relates to the proposed strategy
versus an alternative one that has been tried in Egypt. In the latter context,
pressurized systems have been encouraged in areas that are beyond the existing
canal commands or generally termed as new
areas. The Egyptian approach seems more practical when compared with issues
that are associated with canals and / tube-well commands as described above.
Our planners and policy-makers should consider following the strategy by
declaring deserts of Thal, Cholistan, Thar and others similar areas for
pressurized irrigation systems only. This should encourage growing high-valued
crops and orchard plants where surface irrigation will cause water logging in
these zones within no time. In the meantime, required conditions can be created
to suit the adaptation of pressurized systems in canal and / tube-well
irrigated areas.
In order to make the pressurized systems financially
feasible, there is need to make marketing of agricultural products more
producer-tilted instead of being heavily in favor of middle-men. How can farmers invest in this new technology
when profitability in agriculture is restricted because of this odd marketing
environment?
Once profitability is ensured, our policy-makers
have to review the water rates like Abiana
and free-access to groundwater as incentives to switch to efficient water
application systems in agriculture. If seasonal irrigation charge per acre of a
crop in canal commands is less than the rate being charged per hour of a
tube-well in Punjab or free-access to groundwater with hardly paid power
charges say in Baluchistan, it would be very difficult to convince many to this
paradigm shift in agriculture.
Asking farmers to leave practices passed on from one
generation to other is a tough challenge to overcome. As the farmers are only
familiar with the old ways to apply irrigation, it is asking too much to happen
unless we create conducive environment for the change as stated above and
taking other critical steps that may include:
- Capacity
building of farmers on regular basis;
- Provision
of technical support systems;
- Availability
of spare parts;
- Regular
maintenance; and
- Un-interrupted
power supply at farm / field levels.
6.3 Potential Threats in the way of Drip
Water Saving Irrigation Development in Pakistan
} Middle-man infected marketing deficiencies;
} Difficulties associated with a change from water supply to water demand
system;
} Cropping patterns generally do not favor drip irrigation;
} Low priced canal water hardly encourages for its efficient utilization;
} Sodic and high pH groundwater can cause chemical clogging;
} Silt in canal water could cause clogging due to sand and algae;
} High-discharge
within short time does not fit to low-discharge for longer-time based drip
system;
} Arid environment within silt-clay environment;
} Unreliable power supply;
} Higher initial & operational costs;
} Absence of operation and maintenance services in private sector at
convenient locations; and
} No technical support infrastructure.
7.
Case of Gravity Water Saving Irrigation Development in Arid Zones
7.1
Issues Associated with Gravity Based Water saving Irrigation Development in
Arid Regions.
A close scrutiny of Tables 1 & 2 show that
actual application efficiencies compared to attainable efficiencies under
gravity based irrigation application systems are 30 to 50% lower. This is mostly
because surface irrigation is a much more complicated system than the
pressurized modalities as they have to deal with variable flows, types of soil,
roughness, compactness, soil-water depletion level, infiltration behavior and
similar other conditions. Of course, as stated earlier, improvement in gravity
irrigation technology will help to improve 10-15% performance but the main
enhancement in performance can come the way people manage their water resources
at the field level in both dimensions of time and space. This is why gravity
water saving irrigation development is possible, as it has been demonstrated in
western arid states of the United States where many water users are reverting
back to improved and efficient gravity irrigation application systems, but that
process requires a strategy that can help to make gravity based irrigation systems
equally efficient and cost effective for higher crop production
In view of the stated context, a detailed strategy
for gravity water saving irrigation development is being proposed that is
appended for record. However, a summary of this strategy is given in the next
section.
7.2 Strategy for Water Saving Irrigation
by Using Improved Gravity Irrigation Application Techniques
Improving water
management is a key strategy for saving water for irrigation in arid
regions. Beginning at the farm level, precision
leveled fields (often using laser controlled machines) are constructed and
level basins are designed for farmer management of irrigation
applications. Farmer cooperation and
agency dependable support also must be established. Level basins are designed and constructed for
use with beds, furrows, or other appropriate field configurations for specific
crops as farmers prefer.
Field design uses completion-of-advance design
theory to ensure farmers can observe irrigation advance and apply a target amount
of water to each basin. These irrigation
applications use the average expected flow delivered to the field and the
advance distance to apply the target irrigation of, for example, 7.5 cm. This allows farmers to measure the target
amounts of water applied for each irrigation.
Irrigation scheduling replenishes soil water as required by the
crop. Quantitative application of water
for each field on each farm, each watercourse, and each canal command is the
result.
Farm agricultural practices are assessed and needs
for inputs and agency support identified.
This assessment is conducted by expert and host country professionals to
determine the practices farmers will be encouraged to follow. The goal is to combine effective water
management and crop production practices that will produce optimum yields on
each level basin. Farmer cooperation and
participation with agency coordination will support the resulting productive
irrigated agriculture. Organizational
development processes will support the creation of these cooperative units of
required agencies and farmers for productive agriculture.
For an irrigation command, expert and host country
professionals will assess surface water and groundwater resources for irrigated
agriculture in the area. Timing,
storage, soil and water chemical status, and information for effective
management will be provided to a management unit. Because the minimum water requirement will be
diverted for irrigation, water logging and salinity will be prevented or managed
to be eliminate if already present. If
irrigation is already practiced, the extra water will remain in the canal or
river for downstream water users.
Conjunctive use of surface and groundwater will ensure only needed water
is used, and water logging and salinity is eliminated or controlled.
The Indus valley already under irrigation is
expected to provide extra water saved by better water management through having
farmers measure the amount of water applied to each field. Also, studies have shown that excess water
diverted and used for irrigation results in large amounts of water lost from
evaporation and non-beneficial use.
Also, water returning to the river often has increased substantially in
salinity making the return flow only usable if mixed with better quality
water. Examples of each are the large
amounts of water evaporated from waterlogged areas in existing irrigation
projects and the resulting increases in salinity. These areas also are lost for production at
great cost. When saline layers exist at
lower levels in a soil, water returning to the river may approach sea water
levels of salinity. Savings of water are
expected to be large in many irrigation projects while productivity increases
many-fold.
Organizational development processes are used to
change agencies to more effectively support irrigated agriculture and
farmers. Cooperation and coordination
between farmers, between agencies, and between agencies and farmers can and
have been achieved. These outcomes are
essential to the changes needed for saving water for irrigation.
7.3 Challenges for Gravity Based Water
saving Irrigation Development – Pakistani Experience
Switching
over to improved gravity based irrigation application systems, for that matter
even pressurized irrigation technology, is not an easy process. How fast this
shift occurs depends on the kind of crops being grown, rate of change towards
new commercial crops, process and technology to create necessary conditions for
demonstrating efficient irrigation applications techniques, skills and capacity
building focus to facilitate water saving irrigation development.
Over
the last four decades, Pakistan has made many efforts from gravity based
improved irrigation systems to pressurized irrigation systems to influence water
demand management at the field level. Some experiences regarding pressurized
irrigations have already been discussed under Section 6.2. Some examples about
new and improved gravity based water saving irrigation practices are presented here
for understanding the complicated nature of this process.
Traditionally,
there are roughly leveled basins of one or half acre fields. There is no
concept of appropriate stream size per unit width of these basins. Our fixed
flows and fix basin sizes usually do not match and as a consequence two to
three times extra water is applied to irrigate an entire basin when compared
with long but narrower level-borders designed to take in proper stream-sizes
per unit width. Shafique (1976) monitored such traditional wheat fields over an
entire crop season as given in Table 3:
Table
3. Seasonal irrigation application efficiencies on a traditional basin
(Shafique, 1976)
|
Serial No.
|
Date
|
Application Efficiency
(%)
|
Storage / requirement Efficiency (%)
|
|
1
|
12-22-1975
|
27
|
100
|
|
2
|
01-25-1976
|
52
|
100
|
|
3
|
02-08-1976
|
31
|
100
|
|
4
|
02-29-1976
|
61
|
100
|
|
5
|
03-07-1976
|
38
|
100
|
|
6
|
04-07-1976
|
56.4
|
100
|
Table
3 provides a general trend in the Indus Valley where most of irrigations apply two
to three times more water than the amount required at different stages of crops.
This happening does not mean that the farmers intentionally do so to lose their
crop nutrients, water and other related resources just to cause water-logging
and salinity conditions down-stream. They
do not have technical, organizational and required access to latest
developments to practice differently. Such a huge margin for water saving
irrigation does not just stop with one or two technical supporting gestures; it
requires providing all necessary conditions that help to improve managerial as
well as physical activities of an irrigation system to avoid over-irrigation.
As
a next step, different fields were precisely leveled and then narrower but
longer strips of borders were made with approximately the same area, with the previous
case of a traditional field, and about half an acre for growing wheat. Table 4
presents seasonal monitoring results about irrigation efficiencies on the
fields as provided below (Shafique, 1976):
Table
4. Seasonal irrigation application efficiencies on a level borders (Shafique,
1976)
|
Serial No.
|
Date
|
Application Efficiency
(%)
|
Storage/ requirement Efficiency (%)
|
|
1
|
01-24-1976
|
67
|
100
|
|
2
|
02-14-1976
|
100
|
95
|
|
3
|
02-28-1976
|
67
|
100
|
|
4
|
03-29-1976
|
100
|
65
|
Obviously,
water saving outcome is comparatively much more improved when compared with
traditional irrigation practice. However, there is still over irrigation during
Irrigation Events No.1 & 3. Usually, some over-irrigation under gravity
systems during early season is unavoidable as respective evapo-transpiration rate
is lower, roughness and infiltration is more likely to cause such eventuality.
Moreover, the over-irrigation is also caused because of weekly-turn system and
critical stage of crop growth during which a farmer refuses to take risks and
irrigates field crops when he could have waited for more days. Unless farmers
are helped to have on-farm surface storages and / or access to groundwater, such
risk-avoiding behavior will also contributes toward the over-irrigation
phenomenon even when you have conducive-conditions created to avoid such water
loss to an allocated share of a farmer.
Nafees
(2000), researcher from IWMI-Pakistan, monitored level-borders and
bed-and-furrow irrigation systems for two cotton seasons during 1995-96. After
failing to make use of center-pivot in a very hot and arid environment, a
progressive farmer in southern Punjab decided to use new gravity-based
irrigation techniques. This farm was first laser leveled and then different
plots were prepared for level-borders and level-bed-and-furrows to grow cotton.
Table
5 provides monitoring results of seasonal monitoring of two cotton plots of
level-borders. Interestingly, data shows almost similar trends in 1996 on
cotton plots to the data taken on wheat borders about two decades before as
presented in Table 4. In both cases,
application efficiencies are relatively higher than observed on traditional
roughly leveled basins (Table 3). However, there is also evidence coming forth
that under-irrigation was on the rise as storage efficiencies for some events
dropped.
As
per traditional practice, farmers keep on applying water to a plot till water
reaches near the tail-end, extension of such tradition to a level-border can
cause under-irrigation from time to time because water with narrower and
precisely leveled border reaches to the end faster. Therefore, there is need to
explain and train farmers to address this concern with organizational support,
both by public and private sectors, for informing about ways and mean to
determine proper cut-off time for advancing irrigation water.
Table 5. Seasonal application
efficiencies using level-basin borders (Nafees, 2000 and Shafique et al, 1997)
|
Event #
|
Application Efficiency (%)
|
Storage / Requirement Efficiency (%)
|
Distribution Uniformity (%)
|
|
Modality: Level-basin-border irrigation, S2-3, Year: 1996
|
|||
|
1
|
66.1
|
100
|
96.5
|
|
2
|
75.9
|
100
|
98.6
|
|
3
|
70.4
|
100
|
99.4
|
|
4
|
100
|
95.9
|
99.5
|
|
5
|
60.5
|
100
|
99.55
|
|
6
|
53.9
|
100
|
99.5
|
|
Modality: Level-basin-border irrigation, S2-4, Year: 1996
|
|||
|
1
|
76.1
|
100
|
89.0
|
|
2
|
54.7
|
100
|
97.3
|
|
3
|
23.1
|
100
|
98.2
|
|
4
|
58.8
|
100
|
98.6
|
|
5
|
76.5
|
100
|
98.4
|
From
Tables 6 & 7, it is evident that application efficiencies using level-bed-and-furrow
irrigation modality go up significantly. Except for the initial events,
application efficiencies of rest of the events are 100% and corresponding
storage efficiencies dropped, in other words, a consistent pattern of severe
under-irrigation during both monitoring seasons. This also indicates that new
water saving irrigation techniques are not an automatic “switch-on” phenomenon;
there is critical need to set proper management conditions, activities and
results to let new physical conditions selected be effectively operated through
physical activities to deliver physical results in the form of sustainable
practices of water saving irrigation development.
However,
there is an encouraging observation about high water distribution uniformity in
both gravity improved cases. This indicates a possibility that user-friendly
water saving irrigation development is within reach.
Table 6. Seasonal application
efficiencies by using bed-and-furrows (Nafees, 2000 and Shafique et al, 1997)
|
Event #
|
Application Efficiency (%)
|
Storage / Requirement Efficiency (%)
|
Distribution Uniformity (%)
|
|
Modality: Bed-and-furrow irrigation, Year: 1996, Field: S 2-1
|
|||
|
2
|
74.7
|
100
|
98.8
|
|
3
|
100
|
55.1
|
98.0
|
|
4
|
100
|
56.6
|
98.4
|
|
5
|
100
|
58.0
|
99.6
|
|
6
|
100
|
62.9
|
99.8
|
|
7
|
100
|
44.2
|
99.8
|
|
8
|
100
|
49.3
|
99.8
|
|
9
|
100
|
51.5
|
99.8
|
|
10
|
100
|
54.2
|
99.8
|
|
11
|
100
|
65.8
|
99.8
|
|
|
|
|
|
Table 7. Seasonal application
efficiencies using bed-and-furrows (Nafees, 2000 and Shafique et al, 1997)
|
Event #
|
Application Efficiency (%)
|
Storage / requirement Efficiency (%)
|
Distribution Uniformity (%)
|
|
Modality: Bed-and-furrow irrigation water application Year:
1996, Field: S 2-2
|
|||
|
2
|
66.9
|
100
|
99.2
|
|
3
|
100
|
78.6
|
96.7
|
|
4
|
100
|
60.8
|
98.8
|
|
5
|
100
|
57.6
|
99.5
|
|
6
|
100
|
53.8
|
99.6
|
|
7
|
100
|
60.2
|
99.6
|
|
8
|
100
|
56.5
|
99.7
|
|
9
|
100
|
48.5
|
99.5
|
|
10
|
100
|
71.6
|
99.7
|
|
11
|
100
|
68.4
|
99.7
|
|
12
|
100
|
67.3
|
99.8
|
In
spite of the fact that both improved gravity irrigation techniques experienced
under-irrigation but water stress was more pronounced in case of level
bed-and-furrow (within a level basin) system as compared to level borders.
However, water use efficiencies were still higher in the case of
bed-and-furrows compared to level border as presented in Table 8. It is clear
that while switching to new water saving irrigation techniques, both gravity as
well as pressurized system, supportive institutional structure and
objective-oriented incentive systems have to be put in place to make such changes
work.
Table 8. Water use efficiencies for
cotton during 1995-96 (Nafees, 2000 and Shafique et al, 1997)
|
Plot #
|
Total Depth of Water Applied (mm)
|
Yield per hectare (Kg)
|
Water Use Efficiency (Kg/m3 of water)
|
|
Year 1995
|
|||
|
S 4-2
(Bed-and-furrow)
|
532
|
2800
|
0.53
|
|
S 4-3
(Bed-and-furrow)
|
595
|
3291
|
0.55
|
|
S 4-5
(Level-basin-border)
|
750
|
2965
|
0.40
|
|
S 4-6
(Level-basin-border)
|
905
|
3133
|
0.36
|
|
Year 1996
|
|||
|
S 2-1
(Bed-and-furrow)
|
593
|
2964
|
0.50
|
|
S 2-2
(Bed-and-furrow)
|
677
|
3102
|
0.46
|
|
S 2-3
(Level-basin-border)
|
709
|
2450
|
0.35
|
|
S 2-4
(level-basin-border)
|
575
|
2569
|
0.44
|
During
the late eighties, while associated with the International Irrigation Center at
Utah State University, one of the authors conducted many field monitoring and
evaluation studies on laser-leveled basins in Utah as well as southern
Colorado. With proper management and physical conditions properly addressed, it
was found that gravity-based modalities were made as efficient as pressurized
irrigation systems. In Utah, a large leveled basin of 14 hectares, with an
inflow around 0.5 m3/ second, successfully replaced sprinkler
irrigation.
Similarly, in Colorado, large laser-leveled basins on lighter soil
were other success stories where higher water distribution uniformity and
application efficiencies were being achieved by irrigating furrows from both
sides. Another author spent many years in Arizona, in association with a team
from the Agricultural Research Service, to bring about even more astounding
success by changing farmers and related organizations to switch back to
non-energy dependent surface irrigation application techniques.
However,
in southern Utah and western Colorado, it was a different situation where
California State was subsidizing famers along the Colorado River in the Rocky Mountain
region with abundance of shale to switch to pressurized irrigation to check
salt-loaded return flows to the river. Since farmers in that region were
growing mostly traditional crops like fodder and subsoil was too shallow to
construct laser-leveled basin systems, the choice made a lot of sense. Skogerboe et al (1982) and Shafique et al (1983)
monitored many farms over three consecutive years. Infiltration behavior of
different soils on perennial and seasonal crops was so drastic that surface
irrigation was found difficult to perform better without proper organizational
support on unfavorable terrain for gravity irrigation.
So, a cautionary note that can be presented is
that a laser-leveled basin cannot be assumed an automatic alternative at every
location for pressurized systems Field and agronomic practices on ground have
an important role to play.
Even
if conditions for leveled basin irrigation exist, selection of an irrigation
modality also depends on the types of crops being grown. As cropping patterns
change, so are the modalities to apply irrigation water. Orange et al (2005)
published a report by comparing different crops and irrigation methods from
1972 to 2001 in California State. According to this report, a decrease in the
use of surface irrigation and an increase in the use of drip irrigation were
observed. The largest increase in drip irrigation was found in orchards and
vineyards. Similarly, the largest increase in sprinkler irrigation was in
vegetables. In 1972, about 80.5 % of the irrigated land of California was
served by surface irrigation whose share declined to 49.6 % in 2001. However,
these reductions in surface irrigation occurred because of corresponding
reduction in field crop acreage. From 1972 to 2001, areas planted for orchards
increased from 15% to 31 % and vineyard from 6% to 16 %. For field crops,
reduction in acreage was observed to be from 67% to 42 %. It is interesting to note that the percentage
per year for field crops over 29 years was reported to be only -0.04 percent in
one of the most advanced states in the world.
Realistically,
in developing arid regions, gravity based surface irrigation practices are
going to remain dominant features for a long time to come. So, an enormous
amount of water savings will result if different versions of laser-leveled
basins are supported with necessary support, capacity building and incentive
systems.
However,
for such improved surface irrigation systems, technical issues about the
timing, amount and how long to apply water is going to be critical for
sustaining such water saving irrigation development. One approach was surface
irrigation scheduling, based on water advance on a field, as proposed by
Wattenburger and Clyma (1989) and Shafique (1984). This strategy is based on an
improved scientific version of a traditionally used practice; it needs to be
further tested, made user-friendly and promoted. Similarly, based on local calibration
of advance functions, Shafique and Skogerboe (1987) suggested surface
irrigation scheduling to derive what would be required to apply a certain
amount of water by calculating cut-off time that is based on locally calibrated
advance and infiltration functions. However, transfer of such scheduling
techniques will need a change in water users’ attitude for efficient water
application and supporting organizations to provide all necessary management
and technical support as and when needed without having bureaucratic and
procedural road-blocks.
8. Water Saving Irrigation and Concepts
of Water Saving in Irrigation
For
many people, it may sound a bit contradictory to discuss water saving
irrigation development in an environment where the water saving concept is
being challenged and ridiculed. Donors have also started objecting to such
projects that aim to improve irrigation practices at the field level to achieve
higher irrigation efficiencies. There is a heated controversy going on,
particularly spear-headed by IWMI, about local versus global efficiencies.
Without
going into mathematical formulations, suffice it to say that the authors feel
no conflict between the two concepts. As a matter of fact, improved local
efficiencies help to lower such outcomes like water-logging and salinity. In
other words, non-beneficial evaporation is curtailed and as a consequence, global
efficiency may go even higher.
Another
point that the authors wish to make is that irrigation is meant to provide the right
quantity and quality of water at the right time without stressing plant growth.
How can people do so without setting management and physical conditions correctly?
Moreover, if productivity declines due to excessive seepage, causing
water-logging and salinity, there is injustice done to the primary objective of
providing irrigation water to plants. Clearly, this cannot be done without
following a conceptual framework presented to achieve water saving irrigation
development.
The
authors propose that we conserve surface / river-water on the following six
levels:
1.
Federal
level to conserve water to off-set the often sharply skewed river flows over
time;
2.
Provincial
level to conserve its allocated share that can be held back from water users
during the rainy season, maintenance closures and through positive incentive
systems;
3.
Canal
command level, by Area Water Boards in Pakistan, to do the same as the
provincial governments do at the higher level;
4.
Secondary
canal level, by Farmers’ organizations in Pakistan, to store surface water and
make supply adequate by incorporating groundwater extractions;
5.
Watercourse
command level, by Water Users’ organizations in Pakistan, to have local
community storage facility like FOs; and
6.
On-farm
water storages by individual water users to have good quality surface water as
and when required.
Once
such water conservation is achieved, there will be no need to allow seepage for
down-stream usage of bad quality water that has negative externalities like
water-logging and salinity. By encouraging water saving irrigation practices,
message that comes out is higher productivity and profitability per unit of
water, minimum dependence on relatively lower quality groundwater, lesser
dangers of water-logging and salinity and sustainable agriculture in all
regions in general and in arid and semiarid regions in particular.
9. Conclusions
Since
most of the developing arid regions predominantly grow field crops on flat
lands, if properly designed and operated with the right kind of institutional
structure and effective incentive system, different variation of surface
irrigation methods within laser-leveled basin appear to be a wiser option for
water saving irrigation. Moreover, at present, energy dependency and often its
limited availability and affordability within suppressed returns from field
crops, support to improved surface irrigation techniques for a sustainable
irrigated agriculture in arid region.
Even
though the growth of pressurized water saving irrigation development is
expected to be very slow, along with necessary institutional support and
structure, already identified technical issues may have to be addressed on a real
time basis for their wider and faster acceptability by the farmers when they
move into commercial agriculture. On the irrigation scheduling aspect, applying
an accurate amount of water as and when required by using pressurized systems is
less complicated when compared with surface irrigation technique. Still, there
is need to encourage irrigation advisory service, preferably in the private
sector, to make effective use of energy-dependent low and high pressure irrigation
techniques for cash crops like fruits, vegetable and flowers.
However,
in time, as commercial agriculture picks up in the developing arid context, a
switch to orchards, vegetables and floriculture will be a natural outcome. Like
in California, once horticultural areas starts increasing, on lighter soil
conditions, pressurized irrigation in general and drip irrigation development
will follow. However, these changes are going to be even slower in developing
arid regions as compared to developed countries because of poor marketing and
market access, almost free irrigation water, limited availability of
technology, skills, institutional support and built-in incentive systems.
To
create conducive physical conditions, land development companies with laser-controlled
leveling equipment should be encouraged in the private sector to avoid even
minor local undulations. Similarly, the private sector must be encouraged to
use surface irrigation scheduling and related advisory services to facilitate
measured and timely application of irrigation water for gravity systems to
secure high application, storage and distribution efficiencies.
Common
for both kinds of irrigation water application modalities, there will be
general questions asked: (1) When to irrigate? (2) How much deficit of soil
water is allowed and (3) How much / how long to apply irrigation water to
selected crops in a selected field? In other words, as a cliché goes, water
management is a misspelled phrase; it should have been water measurement to
place proper emphasis of such requirement.
On
water saving concepts, improving on-farm water use practices to secure higher
local irrigation efficiencies have no negative impact on the resulting global
efficiency on basin scale. On the contrary, improved local irrigation
efficiencies at farm level are expected to improve global efficiency even
further as such process is expected to lower hazards of non-beneficial evaporation
from water-logged areas. Moreover, water-logging and resulting salinity impact
on water and crop productivity and profitability in a significant way.
Degradation of water quality of extracted groundwater because of excessive
seepage may be another externality to live with. So, authors feel that these
two concepts should not be construed as part of a zero-sum game.
10. Recommendations
10.1 Pressurized Water Saving Irrigation
Development:
} Like Egypt’s new areas, pressurized irrigation should be exclusively
encouraged in Thal, Thar, Cholistan and rain-fed areas (Pothwar);
} For desert areas, on-demand water supply through private sector be
tested;
} Pilot testing of drip irrigation must cover a farm as a unit;
} Private sector, based on our experience of irrigation control structures,
must be mobilized for operation, maintenance, technical support (scheduling)
and capacity building;
} Legal coverage for trespassing be enforced to discourage vandalism;
} Foreign companies must be persuaded to have full technology transferred
for sustainable use of drip irrigation;
} Supply based canal system should try on-farm storages to suit drip /
pressurized irrigation;
} Different options for silt-disposal in canal-commands and chemical
treatment of mainly sodic groundwater be tried.
} Agro-based industry for vegetables, flowers and fruits should be considered a pivotal
component of this strategy as it is done in case of cotton crop;
} Pro-producer marketing options be tested;
} Different manuals for drip irrigation be prepared to facilitate this
change process;
} Reliable and affordable power supply should be ensured; and
} Till local production starts, hardware should be subsidized.
10.2
Gravity-based / Surface Water saving Irrigation Development:
v User-friendly flow measurement structures be installed to apply known
quantity of water;
v Guidelines be prepared for stream size per unit width of border or per
furrow as the case may be;
v For different soils and crops, optimum management allowed deficits be
derived through applied research and demonstration;
v For different soils and growth stage of crops, advanced based irrigation
techniques be tested and tried to make them further user-friendly and refined;
v Land development companies possessing technical skills and
laser-controlled leveling equipment be promoted;
v Irrigation advisory companies be encouraged to provide support for
ensuring timely and surface water saving irrigation techniques;
v For sustainable development, emphasis should go beyond water saving
irrigation to include productivity and profitability per unit of water applied;
v Capacity building to develop land and apply water for efficient outcome
must be pursued on continuous basis;
v Institutional structure and effective incentive systems be provided to
promote water saving practices; and
v For developing shared understanding for surface water saving irrigation
development, scientific processes be utilized to manage change by changing
individuals and organization in a positive direction.
11. References
Bhatti,
Asif M., Pongsak Suttinon and Seigo Naso. 2009. Agriculture water management in
Pakistan: A review and perspective. Society of Social Management Systems, Kochi
University of Technology, Kochi, Japan.
David, Wilfredo P. 2004. Water
resources and irrigation policy Issues. Asian Journal of Agriculture and
Development, Vol. 1, Issue 1, Pages 83 to 106, Philippines.
Douglas C. North. 1993. Economic
performance through time. Lecture to the memory of Alfred Nobel, December 9,
1993 by Douglas C. North, Nobel Prize winner.
Howell, Terry A. 2003. Irrigation
Efficiency. Encyclopedia of Water Science. Published by Marcel Dekker Inc., New
York, USA.
Huu,
Tie Lee & Hotomi Rankine. 2007. The future of forests in Asia and Pacific:
Outlook for 2020. UN Commission for Asia and Pacific, Ching Mai, Thailand.
ICIMOD.
2010. Pakistan: an introduction. South Asian Floods, ICIMOD, Nepal
Journal
of Water Saving Irrigation. A Microsoft Power-point document at the following
website:
Katoaka,
Yatsuka. 2002. Overview paper on water for sustainable development in Asia and
Pacific. Asia-Pacific Forum for Environmental development, Bangkok, Thailand.
Kugelman,
Michael and Robert M. Hathaway. 2009. Running on empty- Pakistan’s water
crisis. Woodrow Wilson International Center, Asia Program.
Nafees,
Hafiz M. 2000. A diagnosis of farmer-managed irrigation system’s performance.
Thesis submitted for Master of Philosophy in Water Resources Management, Center
of Excellence in Water Resources Engineering, University of Engineering and
Technology, Lahore, Pakistan.
Orang,
Morteza, Richard Snyder and Scott Matyac. 2005. Survey of irrigation methods in
California. DWR and UC Davis, California, USA.
Schulze,
F.E. (early nineties). Concepts in irrigation management and related research
Issues. Note prepared for the IIMI – Pakistan’s Consultative Committee, Lahore,
Pakistan.
Shafique,
M. S. 1976. Land leveling and watercourse improvements for Pakistan. MS thesis,
Colorado State University, Fort Collins, Colorado, USA.
Shafique, M. S., Gaylord V. Skogerboe, Jim Loftis,
Steven M. Schitlin, Peter H. Rude, Bahman Hatami and George Bargsten. 1983.
Monitoring and evaluation of on-farm water improvements in the Grand Valley
salinity Control Project during 1982 irrigation season. Report submitted to:
Soil Conservation Service, United States Department of Agriculture, Denver,
Colorado, USA.
Shafique, M. S. 1984. Zero-inertia model for
basin-furrow irrigation. PhD thesis, Colorado State University, Fort Collins,
Colorado, USA.
Shafique,
M. S. and Gaylord V. Skogerboe. 1987. Surface irrigation scheduling.
International Irrigation Center, Utah State University, Logan, Utah, USA.
Shafique,
M. S. 2010. Water Crisis and Potential Way out.
A policy paper prepared for Pakistan Tehrik-e-Insaf. Website: www.internationalhydropolitics.com.
Shafique,
M. S., N. Bukhari, I. M. Kalwij, M. Latif and M. M. Chaudhry. 1996. Improved surface
irrigation practices. Proceeding of National Conference on Managing Irrigation
for Environmentally Sustainable Agriculture in Pakistan. Report No. 18-3,
IIMI-Pakistan, Islamabad, Pakistan.
Shafique,
M. S. 2009. Challenges for pressurized irrigation. Published in the Daily Dawn
in the weekly magazine about Economic and Business Review, Karachi, Pakistan.
Shaikh,
B. A. and G. H. Soomro. 2006. Desertification: Causes, consequences and
remedies. Pakistan Journal of Agricultural Engineering & Veterinary
Sciences, 22(1), Pakistan.
Solomon,
Kenneth H. 1988. Irrigation systems and water application efficiencies. Center
for Irrigation Technology, California State University, Fresno, California,
USA.
Skogerboe,
Gaylord V., M.S. Shafique, Jim Jackob, Nestor Garrido, Gregory Briston and GeorgeBergsten. 1982. Monitoring and Evaluation of On-farm
Irrigation Improvements in the Grand Valley Salinity Control Project. Research
Report submitted to: Soil Conservation
Service, United States Department of Agriculture, Denver, Colorado.
Sterling R., and W. H. Neibling.
1994. Final report of the Water Conservation Task Force. IDWR Report, Idaho
Department of Water Resources, Boise, Idaho, USA.
SIWI. 2005. Let it reign:
The new water paradigm for global food security. Stockholm International Water
Institute (SIWI).
Wattenburger, P. L. and
W. Clyma. 1989. Level basin design and
management in the absence of water control, Part II: Design method for
completion-of advance irrigation. Trans.of ASAE, 32(2): 844-850, USA.
World
Bank Report. 2006. Better management of
the Indus Waters. Strategic Issues and Challenges. Washington, USA.
Appendix is contributed
by Wayne Clyma and these contents of this paper are influenced by the following
references:
Clemmens, A. J. 1998. Level basin design based on cutoof
criteria. Irrigation and Drainage
Systems, 12:85-113.
Clyma, W.; and Shafique, M. S.
2001. Basin-Wide Water Management
Concepts for the New Millennium. ASAE Paper No. 012051, American Soc. of Agri.
Engrs., St. Joseph, MI, 1-16.
Clyma, W., M.K. Lowdermilk and G.L.
Corey. 1977. A Research-Development Process for
Improvement of On-Farm Water Management.
Technos, 6(1):34-45.
Clyma, W., M. S. Shafique, and J. Van Schilfgaarde. 2003.
Irrigated Agriculture: Managing Toward Sustainability. In Encyclopedia
of Water Science, 1st
Ed.; Stewart, B. A. and T. A.
Howell, Eds.; Marcel Dekker, Inc. New York, pp. 437-442.
Dedrick, A.R.; Bautista, E.;
Clyma, W.; Levine, D. B.; Rish, .S. A. 2000.
The Management Improvement Program: a process for improving the
performance of irrigated agriculture.
Irrig. and Drng. Systems, 14(1-2):5-39.
Dedrick, A.R.; Bautista, E.; Clyma, W.; Levine, D.
B.; Rish, .S. A. 2000. The Management
Improvement Program: a process for improving the performance of irrigated
agriculture. Irrig. and Drng. Systems,
14(1-2):5-39. U. S. Water Conservation Laboratory.
FAO. 1996. Food production: The critical role of
water. Rome. 1996.
Jones, A. L. and W. Clyma. 1988. Improving the Management of Irrigated
Agriculture: The Management Training and Planning Program for Command Water
Management, Pakistan. Water Management Synthesis Professional Paper No. 3,
Colorado State University, Fort Collins, CO, 14 pp.
Layton, J., D. Levine and W.
Clyma. 1987. Irrigation advisory service development plan. CID/CSU Tech. Rept.
No. 3, Regional Irrigation Improvement Project, Ministry of Public Works and
Water Resources, Arab Republic of Egypt, Nov., 24 pp.
Levine, D. B. 1989. The team planning methodology: Shaping
and strengthening development management (Working Draft). Washington, D. C.:
Development Program Management Center (DPMC), Office of International
Cooperation and Development, U. S. Department of Agriculture.
Lowdermilk, M. K., W. Clyma,
L.E. Dunn, M.I. Haider, W.R. Laitos, L.J. Nelson, D.K. Sunada, C.A. Podmore,
and T.H. Podmore. 1983. Diagnostic Analysis of Irrigation Systems,
Volume 1: Concepts and Methodology. Water Management Synthesis Project Report,
Colorado State University, Fort Collins, CO., 188 pp.
Postel, S. 1992. Last oasis:
Facing water scarcity. W. W. Norton and Co., New York, 239 pp.
Appendix
Strategy for
Gravity- based / Surface Water Saving Irrigation Development
Introduction
Recent publications of national and international
organizations (Ref 1, Ref 2, Ref 3) emphatically emphasize that water food
shortages are becoming a recurring and emphatic condition facing the
world. Another accepted fact is that
water shortages are often part of the contributing factors and in some
instances the key factor creating the food shortages. Concerns and even fears of climate change
contributing to further water shortages also are growing. Thus, water shortages for food production or
even loss of basic water supplies for human and animal needs are considered an
impending or imminent condition.
Irrigated agriculture supplies more than half the
world’s food supply while representing less than half the area. This productivity level is cited as a major
value for irrigated agriculture.
Actually, the data demonstrates the inadequacy of irrigated
agriculture’s performance. Irrigation
easily increases yields by five times or more than rain-fed agriculture. In addition, good water management makes additional
water supplies and effective irrigation practices available to a large area of
the command of an irrigation project.
This area produces much more increases in production because much of the
area in an irrigation command previously received no water, small amounts and
irregular amounts of water with limited benefits to production. Additionally, an average of nearly 40% of the
irrigated area, currently is waterlogged and saline, becomes available for
substantial levels of productivity. The
need for improvement of performance in irrigated agriculture is urgent. This irrigated land that is waterlogged and
saline is an emphatic conviction of the mismanagement of irrigated agriculture.
Irrigated Agriculture Culture
The culture of irrigated agriculture in many
countries is farmers receive support from private, public, and government
agencies to grow crops for food and commercial purposes. A government irrigation organization provides
the water supply with varying levels of farmer participation. A government extension organization provides
information, services and support for growing crops. Credit, seeds, fertilizer and other supplies
are provided by private, public or government organizations. Independent units are not coordinated nor do
they usually provide collaboration or coordination of their support and
services. Farmers are not usually organized to collectively interact with any
of the units that help them. Farmers
often have regular and continuing conflicts with each other. Farmers and their supporting units often have
conflicts, and they attempt to exploit each other by direct or indirect
actions. Either the farmers or any unit
may sabotage the processes of growing food for personal or collective gain. For example, farmers my take more water than
the irrigation structure is designed to provide or use more time than a
rotation allots to them. These
continuing and levels of intensity of conflict makes effective irrigated
agriculture difficult. Most of the
individual units, such as irrigation and extension, are government
bureaucracies intent on competition for resources, authority, and control with
each other and with the farmers. Thus,
irrigated agriculture is a conflict bound entity.
Improving Irrigated Agriculture Process
Over a period of four decades, processes for
creating effective conditions for productive irrigated agriculture were
evolved. An important emphasis was a
process of creating understanding, and collaboration and coordination was evolved
between these units and between farmers, and between the farmers and the
units. First, an expert
interdisciplinary team was created and then combined with a host country
interdisciplinary team. This allowed individuals
with credibility and connections with each of the key units in irrigated
agriculture to become involved. The
experts provided world knowledge and experience of irrigated agriculture. The host country professionals provided
similar knowledge plus understanding of the local culture and conditions. These teams established communication with
the farmers to understand their farming operations, the performance of the
farming actions, and what issues and needs the farmers regularly
experienced. At the same time, relevant
support units were assessed for their actions and performance, and their
effectiveness in support of farmers. The
combined interdisciplinary teams accomplished a diagnostic analysis of the
performance of irrigated agriculture with documentation of good performance,
inadequate performance and the causes of the results. The communication established between the
farmers and host country professionals provided the basis for establishing a
new level of trust and understanding for future improved relationships. To benefit the most from the field study, a
formal report is prepared by the interdisciplinary teams, and a presentation of
the results to interested farmers and supporting units is provided.
Changing organizations and farmers is a difficult
task to accomplish. The planing for
change with the irrigated agricultural support units and the farmers is
accomplished in a facilitated, management support planning process (Ref.
Organizational Development Process).
Farm leaders and the manager of each unit (and sometimes some support
personnel) participate in the planning. Organizational development processes
bring the farmers and stakeholders in the change process together to understand
what changes are needed and plan how the changes will be accomplished. Interactions between the farmers and the
supporting personnel are active and interesting. Changing the actions of the key units to
address needs of farmers and providing collaborating and coordinating
activities with the farmers creates effective change. Plans for change, especially in the larger
government units, are presented at appropriate levels in the organization
including the policy level to achieve approvals for implementing change from
the policy to the field level. As the
plans are implemented, continuing reviews by the farmers and supporting units
make changes as needed and provides the ongoing collaboration and coordination
to successfully accomplish change.
Improving Farm Water Management and
Irrigated Agriculture
The necessary condition for improving water
management and food production is an effective field irrigation system. This condition is met with laser level fields
for growing crops. Farmers must be
convinced by demonstration that level basins are effective for irrigating and
growing crops. Fields leveled with laser
controlled equipment or precision leveling supervision is the necessary
condition for a level basin. Farmers
appreciate the reduced time of irrigation and the reduced amount of water
used. Level basins can produce flat,
furrowed, ridged rows or other arrangements for most crops.
The assessment of farm performance allows the
arrangement of credit, seeds, equipment, fertilizer, water supply and other
support for the needs to produce optimum levels of crop production. Information for tillage, planting, and other
practices also are provided to ensure optimum crop production. Irrigation applications are provided to
planned fields with completion-of-advance designs such that farmers apply
target amounts of water such as 7 mm.5,6 This quantitative
application of water allows farmers to use the criterion of advance distance to
apply measured amounts of water. Farmers
have been observed on all four continents to use advance distance to control
water applications to fields. Now
quantitative water application can be accomplished by farmers. Optimum food production and quantitative
water are the two key needs for improving irrigated agriculture. Applications of the process7
have occurred in Pakistan (Ref.), Egypt (Ref.), and the U. S. A. (Ref.)
The involvement of professionals working with
farmers provides an understanding of how irrigated agriculture is managed by
farmers and what the major needs for improvement are. Diagnostic analysis studies have been
conducted in many countries and the needs are a surprise to most processionals. The deficiency level of fertilizer use, the
amount of water unnecessarily applied to fields, the impact of waterlogging and
salinity on production in the command area, and many other areas where the
magnitudes of the conditions are measured are the source of the surprise. The complexity of interactions between
farmers and between farmers and agencies often are surprising. Professionals often are surprised at the
impact of traditional agency decisions on farmers’ abilities to grow a
productive crop.
Getting agencies and farmers to change often is a
difficult process. Professionals come
to know the impact of what they are doing, farmers explain what they need, or
agencies may explain what they really need, but the process produces
understanding and changes are agreed upon and actions planned. A better understanding of what is really
needed or what can be done to effectively meet a need also may be a key outcome
of the facilitated discussion and planning sessions. The farmers are impressed and appreciative of
the availability of critical inputs and services and agency personnel are
surprised and pleased at the commendations of farmers. These working relations are impressive in
their ability to support change.
Productivity increases and more area farmed with effective improvements
in water supply also produce support by all concerned with change. Farmers and the Irrigation Department
collaborate and coordinate in the delivery of irrigation water.
The improved water management provides another
benefit that is often surprising to professionals and farmers. Apply only the target amount of water needed
at each irrigation often reduces the demand for water by several
magnitudes. Instead of 18 or 35 cm of
water applied, farmers achieve an effective application of water with only 7
cm. The additional water is available
for irrigating more area with effective irrigations, can be used at the tail
end of the command area or on another watercourse or canal command. Water savings is a large benefit that makes
additional supplies available for other uses, and reduces the impacts of other
effects. Fertilizer and pesticide leaching are reduced, water-logging and
salinity conditions are improved while productivity is increased.
A long tradition has created a belief that water
could not be saved in an irrigated valley.8 This belief was based upon two erroneous
assumptions. First, that all the water
diverted for irrigation of a command area in excess of the required volume
entered the river as return flow.
Another assumption was that the quality of the return flow was nearly
the same as the water that was diverted.9 All irrigated valleys have unique surface and
subsurface patterns for return flow.
Thus, there can be variations in the conditions of return flow. Careful studies of some selected valleys have
shown that the volume of return flow is greatly reduce by evaporation and non-beneficial
use of a large volume of the return flow.
This is especially true of valleys with waterlogged areas and/or areas
with a high water-table near the surface (1 to 5 meters). These circumstances suggest approaching 80%
of the assumed return flow may be lost.
Further, the return flow that does occur may have salinity levels making
the water unusable for irrigation without dilution by better
quality river water.
The saline return flow may have limited or even negative value for irrigation
water.10
Improving the effectiveness of water delivered by
canals and watercourses provide water for effective irrigation of the command
area. Water saved does not have to be
delivered. Water saved by quantitative
application of water to fields provides additional water for the same use. This saved water can reduce the water
requirements for irrigation of a command area by several magnitudes. This is the most effective strategy for
saving water from irrigation.
Water deliveries by canals vary greatly, but often
are 25% more than the water requirement of an area. Poorly constructed and maintained
watercourses can lose 90% of the water in delivery from head to tail while the
average loss may be 50%. Studies of
field irrigation systems in many countries (Bangladesh, Chile, Egypt, India,
Nepal, Pakistan, Somalia, Sri Lanka, Thailand, and the U. S. A.) suggest field
application efficiencies vary widely and may range from 0 (specific to a fixed
turn system where farmers even irrigate fields that may not irrigation) to 100%
for individual irrigations. Many more
extensive studies have suggested an average of near 25% or less is a common
level of performance. Well-managed level
basins managed by completion-of-advance irrigation are expected to achieve 85%
application efficiencies. The
opportunities for saving water are very significant.
1 Former Head of
IIMI Sudan, Pakistan Tehreek Insaf’s Spokesperson on Water and Irrigation, Lahore, Pakistan
2
Water Resources Management Consultant and former ADB staff, Lahore , Pakistan
3
Water Management Consultant, and Professor Emeritus, Civil and
Environmental Engineering, Colorado
State University, Fort Collins, CO 80525.
4Director
General Agriculture (Water Management), Punjab (Retired), and water Management
Consultant South Asian Conservation Agriculture Network (SACAN), Lahore , Pakistan
5 Wattenburger, P.
L. and W. Clyma. 1989. Level basin
design and management in the absence of water control, Part II: Design method
for completion-of advance irrigation. Trans.of ASAE, 32(2): 844-850.
6 U. S. Water Conservation Laboratory.
7 Clyma, W. "Management
Strategies for Sustainable Irrigated Agriculture With Organizational Change To
Meet Urgent Needs”. Agri. Engr. Int.: the CIGR Jour. Sci. Res. and Development.
Invited Overview Paper. Presented at the
Special Session on Agricultural Engineering and International Development in
the Third Millennium. ASAE Annual
International Meeting/CIGR World Congress, July 30, 2002, Chicago, IL. USA.
Vol. IV. Sept., 2002.
8 Clyma, W.; and Shafique, M. S.
2001. Basin-Wide Water Management
Concepts for the New Millennium. ASAE Paper No. 012051, American Soc. of Agri.
Engrs., St. Joseph, MI, 16 pp.
9 Clyma, W., M. S.
Shafique, and J. Van Schilfgaarde. 2003. Irrigated Agriculture: Managing Toward
Sustainability. In Encyclopedia of Water Science, 1st Ed.;
Stewart, B. A. and T. A. Howell, Eds.; Marcel Dekker, Inc. New York, pp.
437-442.
10 Op Cite.
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