Pradeep Purandare
Making our irrigation systems compatible with the
demands of the 21st century is the real challenge before us. While
technology is not everything, refusal to learn lessons from experience is also
resulting in continued inefficiencies in canal automation. Irrigation projects
need to change with times and all that is needed is a systemic approach.
Discussions on efficient use of water in
agriculture many a times take an elitist turn. Farmers are generally blamed for
the in-efficient use. The systemic issues are either down played or completely
ignored. It is taken for granted that “all is well” regarding physical system
that conveys water from source to farm.
Maharashtra is one of the progressive,
industrialized and urbanized states of India. A close examination of the nature
of irrigation projects, their potential, utilisation and the irrigation
efficiencies bring out the need for modernising irrigation systems.
Case of Maharashtra
Though surface water allowed to use by the
interstate water tribunal is 1,16,467 MCM, as much as 55% of that volume of
water is available in Konkan area where there are constraints in making use of
the same. Maharashtra, therefore, could, so far, create only 38% design live
storage. Though most of the irrigation projects in Maharashtra have been
designed only for irrigation, water use for irrigation in 2020-21 was
58.6%. The remaining 41.4 % water was used for non-irrigation purpose,
which includes domestic, industrial and others. The ‘others’ category which
remains undefined and strangely 15% of water use is categorised under this
‘others’ category. Around 15.6% water gets lost in the rivers and 16.7% of the
water gets evaporated.
Irrigation – Potential and Utilisation
Maharashtra has so far completed 3877 state sector
irrigation projects, which includes 87 Large, 297 Medium and 3493 Minor
projects. The State has created 73.494 lakh ha irrigation potential as against
the Ultimate Irrigation Potential of 85 lakh ha. The actual irrigated area of
state sector projects was 41.6 L ha (77%). Information of local sector projects
is not available. These projects unfortunately fall in the “built &
forgotten” category – absence of management being the main reason.
The average actual Irrigated Area of state sector
projects is only 45.4% of created Irrigation Potential if well-irrigation is
not considered. With well irrigation it increases to 69%. Theoretically
speaking, well irrigation is an accident. It is not provided for in the
planning. The capital as well as recurring expenditure on well irrigation
is done by farmers themselves. On an average the area under sugarcane (483000
ha) in the command is 60% of the average area under sugarcane in the whole
State.
Dams do not get filled up to their full capacity;
the average actual live storage being 64%. This happens due to two reasons.
First, in order to make project feasible, inflated availability of water is
considered. Second, there is authorised /unauthorised upstream abstraction of
water due to additional medium & minor irrigation projects and farm ponds
in the catchment of the project. Water impounded anywhere by any means for any
purpose have an equivalent downstream effect; water management being a zero-sum
game.
Overall Project Efficiency
It is required to understand that Overall
Project Efficiency (OPE) is a product of efficiencies of all
components. It is determined as given below
OPE = Emc * Edyy* Eminor* Efc* Efarm (where, Emc means efficiency
of main canal, Edy means efficiency of distributary; Eminor means
efficiency of minor; Efc means Efficiency of field channel
and Efarm means Field Application Efficiency). Every component
is important. Any component with low efficiency brings down the OPE.
|
Component |
Efficiency |
|
|
Lined canal |
Unlined canal |
|
|
Main canal |
0.95 |
0.85 |
|
Distributory |
0.9 |
0.85 |
|
Minor |
0.9 |
0.85 |
|
Field Channel |
0.9 |
0.85 |
|
Field application |
0.75 |
0.75 |
|
OPE |
0.52 |
0.39 |
Main Canal, Distributary and Minor together form
the main system (Fig-1). It is generally under govt control. Responsibility of
field channel and on-farm irrigation is with farmers. But, where Water Users
Association (WUA) is formed, the minor is also handed over to WUA.
As per MMISF rules, 2006, WRD, GOM has prescribed
the following component wise efficiencies. The Overall Operating Efficiency for
lined and unlined canals is 52% & 39% respectively. That simply means if
100 units of water is released at canal head, only 52% water would be delivered
at root zone in case of lined canals. In the case of unlined canals, a similar
figure would be 39%..
It should be noted that the component wise
efficiencies considered above are `design’ values! Actual values may be even
50% of the design values depending upon the physical status of canals. The
point to be seriously noted is: The present type of canals are highly
inefficient with 75 to 80 percent water being lost in conveyance. The
design efficiency of govt controlled lined & unlined Main System (i.e. Main
Canal, Distributory & Minor) works out to 77% & 61% respectively.
Since this Main System is not adequately maintained
and properly managed, WUAs / farmers don’t get promised quota of water in
planned number of rotations, at right time, at proper place for declared
duration. Hence, the anarchy in the command of irrigation projects! This
mismanagement adversely affects irrigation on farm and performance of WUAs too.
Conventional inefficient Main System and pressurised irrigation on farm is a
weird combination which seldom works without the support of well-irrigation.
In view of above, it is high time the state should
seriously think about modernization of its irrigation projects.
Fig-1: Main System
Current Characteristics and Constraints – how to
overcome them
Large scale public sector irrigation projects in
Maharashtra provide water not only for irrigation but even for non-irrigation
[drinking, domestic, industrial, etc] purposes. They are expected (but not
designed for) to simultaneously achieve multiple and at times, even competitive
/ conflicting objectives. Existing irrigation projects in Maharashtra are upstream
controlled, manually operated, mostly open channel systems without any
arrangement for operation of Head Regulators & Cross Regulators based on
Real Time data. Their present performance is obviously an outcome of their
original nature and inherent characteristics. It would not be correct to expect
something for which the system is not designed.
Measuring devices on Canals and DISNET in almost
all projects are not provided/constructed. If at all there are measuring
devices, it is quite likely that they may be suffering from common problems,
namely, wrong design, improper location, defective construction, poor
Maintenance and Repair (M&R) and unreliable records. The situation
regarding Water Meters on pipelines of non-irrigation schemes is not very different.
There appears to be no systemic and systematic plans for provision,
installation, maintenance, repairs and calibration of water meters in adequate
numbers
Cross bund to get ‘proper level’
Irrigation projects in Maharashtra are
basically Upstream Controlled Systems. Such systems work as per the
logic of supply side management. Water level upstream of control element (e.g.
Cross Regulator) is maintained. Changes in discharge are initiated at the
upstream end by the system operators who obviously take decisions of their own
convenience. Needs and demands of water users are seldom considered. Decisions
taken by the bureaucracy are thrust upon the users. Majority of users,
therefore, usually get inadequate volume of water mostly at wrong time for
unpredictable duration. This is the main reason behind the dismal performance
of Water Users Associations. Though Participatory Irrigation Management (PIM)
has been accepted in Water Policy and provided for in the Acts & Rules, the
conventional Main System is just not compatible for PIM simply because it has
not been designed, from engineering point of view, for such a paradigm shift.
Downstream controlled systems, on the contrary, work as per the logic of demand
side management. They are designed for Participatory Irrigation Management.
Water level downstream of control element is maintained. Changes in discharge,
in an already filled canal, are initiated at the downstream end by the users /
WUAs. They start taking water, their demand gets transmitted upstream through
water itself and finally the system responds by releasing matching discharge.
It is designed for “On Demand” logic from engineering point of view. For
example, dynamic regulation on Majalgaon Project was one of the variants of
downstream control systems! It is necessary to revisit Majalgaon Project where
this concept was introduced way back in early 1990s.
HR and CR not in use
Therefore, it is proposed that a new project may be
designed, on pilot basis, using principles of Downstream Control systems.
Further, Mains system can be modernised through many other measures too. Unless
the Main System is modernised and its characteristics are changed, there would
not be any significant improvement in its performance. Main System with
facilities to control, regulate, measure water level and discharge are
immediately required. Better the Main System, better will be the Water Management, Governance
& Regulation (WMGR) which, in turn, would help improve actual
use of water by different utilities.
Some possible solutions
1. Modernising Regulators and Gates
·
Provide motorised HR
& CR gates and protect, maintain and operate them by respectively
implementing Water Laws, creating Special Gates M & R Mobile Units and
appointing trained system operators.
·
Replace conventional HR
gates by Distributors and conventional CR gates in main canal by automatic
gates and that in Distributaries by Duckbill or Diagonal weirs.
·
Introduce Supervisory Control And Data Acquisition
(SCADA) on main canals of major projects to start with.
Go for a “proper mix” of above 3 solutions
together. It is proposed that pilot projects may be taken up to try above
solutions.
1. Modernisation of Measuring Devices
There could be three ways, as follows, to improve
the situation.
·
Provide measuring devices
on a large scale. Do flow measurement as per WALMI Publication No 36, MWRRA’s
Technical Manual for Water Entitlement, MMISF Act, 2005 & Rules, 2006 and
MWRRA Act, 2005.
·
Switch over to indirect
measurement of water. Requirement of measuring devices can be reduced if
conventional HR gates are replaced by Distributors. These structures release
known & constant discharge. Volume can be obtained only by measuring the
time for which that discharge is given.
Go for a “proper mix” of above 2 solutions together
Proposed Roadmap for switching over to Volumetric
Supply systems
Volumetric Supply demands reasonably well
maintained and operated system with conveyance losses and filling time within
permissible limits. It requires functional gates of HR & CR with Q-tables
to control and regulate water levels and discharge; functional, accurate and
calibrated Measuring Devices (MD); trained canal operators in adequate numbers
for operation and maintenance of gates, MDs and to keep reliable records of
flow measurement; special Gates & MD Repairs Mobile Units for prompt
and adequate Maintenance and Repair.
Conclusion
Volumetric Supply (VS) is an accepted principle.
The issue of `Why’ & `What’ parts of the systems have already been
addressed in State Water Policy and several publications. But the bigger
dilemma is – How? When? To what extent? By whom? At what cost?.
Introducing Volumetric supply systems at individual Water User Association’s
level is comparatively easy. Introducing them at project level is a real challenge.
What is necessary and warranted is a Systemic Approach.
New systems would also generate new opportunities
which include, industrial production of HR & CR gates, duckbill weirs,
measuring devices & water meters and provision, installation, maintenance,
repairs, calibration, automatic data collection, etc. CTF, SRO &
Distributors can be manufactured by local small / medium industrialists after
some training. It’s a very big business opportunity for our entrepreneurs. They
can also take up Annual Maintenance Contracts & calibration work; Gates
Directorate / workshop have experience of developing radial gates; Agreements
with international companies can also be done for transfer of technology
Modernisation is eminently possible. How to make
our irrigation systems compatible with demands of 21st century is the real
challenge before us. Technology is not everything! Agreed! But
indifference and refusal to learn lessons is also not correct. Water sector and
especially, the irrigation projects need to change with times. There are global
examples too. National carrier in Israel, California Aqueduct in USA &
Provence-de-canal in France are some of the best examples of Main System
with canal automation.
References
WRD, GOM, Water Resources Management,
11.1 Irrigation, Report of Integrated State Water Plan committee, 2017
Pradeep Purandare, Making Irrigation
Systems Compatible & Amenable to Modern Concepts and Improving
Institutional & Legal Arrangements, A submission to the drafting
Committee for National Water Policy on 27.1.2020
Pradeep Purandare
Retired Associate Professor, WALMI, Aurangabad.
Expert and Member, State Level Committees and
Expert Panels
Blog: jaagalyaa-thewhistleblower.blogspot.in,
M 9822565232, E-mail: pradeeppurandare@gmail.com
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