IRRIGATION WATER USE EFFICIENCYEFFICIENCY

ByR.D. Singh

DirectorNational Institute of Hydrology

Roorkee

INTRODUCTION

Irrigation accounts for over 80% of total t ithd lwater withdrawals

A huge amount of capital invested in major & medium irrigation projectsmajor & medium irrigation projects

The food production increased from 50 mThe food production increased from 50 m tonnes (1951) to about 252 m tonnes(2025-16 crop year) by expanding the(2025 16 crop year) by expanding the irrigated area.

INTRODUCTION (contd…)

Major concerns in irrigated agriculture is the poor water use efficiency which is estimated to b b t 38 t 40% f l i i ti dbe about 38 to 40% for canal irrigation and about 60% for ground water irrigation schemes.

The food grain requirement by 2050 AD is estimated at 450 million tonnesestimated at 450 million tonnes.

A i it i t id i i ti tArea wise it is necessary to provide irrigation to at least 130 m ha for food crops alone and in an area of 160 m ha for all crops to meet thearea of 160 m ha for all crops to meet the demands of the country in 2050 AD.

INTRODUCTION (contd…)

CWC estimates that the ultimate irrigation potential that can be created from surface and

d t ld b b t 139 9ground water sources would be about 139.9 million ha

In the majority of river basins in India, the present utilization is high and in the range ofpresent utilization is high and in the range of 50 to 95%.

Therefore, the great challenge for the coming decades is increasing water use efficiency and g yto achieve higher productivity of water.

OBJECTIVES

To discuss some of To suggest feasible To discuss some of the issues related to poor irrigation

options to increase the irrigation to poor irrigation 

efficiency efficiency in agriculture.

IRRIGATION EFFICIENCY

Irrigation efficiency is d f

From the water supply point (dam, river canal

Used to express the effective utilization

composed of different efficiencies, all related to different elements in

river, canal, groundwater) to the farmer’s field, the following efficiencieseffective utilization 

of irrigation water.different elements in water distribution and water application within

following efficiencies can be identified.• canal conveyance efficiency application within 

irrigation projects.y

• field application efficiency 

IRRIGATION EFFICIENCY (contd…)

Canal conveyance eff. (ec)

expresses the efficiency of water transport determined by soil types and irrigation system such as

lined or unlined canals, operation and maintenance ofwater distribution structures along irrigation canals etc.

Field application eff. (ea)

determined by the irrigation methods used at farm level determined by the irrigation methods used at farm level

Overall irrigation scheme efficiency (eo)

eo = ea *ec

MAJOR ISSUES CONCERNING WATER USE EFFICIENCY

Allocation Sl d tiAllocation and optimum use of available

Slow adoption of improved irrigation technologieswater, technologies

Low performance of many irrigation systems due to variety of shortcomings such as:•inadequate system design,

The most obvious manifestations of these shortcomings are:•gaps in created potential and utilization,

•unreliable main system water supply,inadequate system design,

•system layouts that do not adequately reflect existing conditions

•inappropriate governance arrangements,

•use of traditional irrigation

supply,•water wastage and poor maintenance practices

gmethods

MAJOR ISSUES CONCERNING WATER USE EFFICIENCY …

The contribution of public surface irrigation has been on decline due to unreliable supplies and poor maintenance of the public irrigation infrastructure.

Growth of well irrigation & more intensive exploitation of GW have been at the expense of irrigation from tanks and other so rcessources.

Low irrigation efficiencies can also be attributed to the lack of measurement devices in irrigation systems to measure themeasurement devices in irrigation systems to measure the water flows and the lack of data on cropping pattern.

There is a need for continuous monitoring of data on flowsThere is a need for continuous monitoring of data on flows, crops, state of system repair, and agricultural practices.

Irrigation also causes environmental problems including drainage, salinisation, habitat change, & human health

SCOPE FOR IMPROVING IRRIGATION EFFICIENCY

Traditional irrigation technologies viz. border and flood irrigation usually result in substantial water losses and limited uniformity in water distribution.

It is estimated that 10% increase in the present level of water use efficiency can bring an additional 14 m ha area under irrigation from existingcan bring an additional 14 m ha area under irrigation from existing irrigation capacities in the country

It is also reported that the water use efficiency can be increased up to 65% in an unlined open channel system.

Efficient design & proper maintenance of irrigation systems, use of modern irrigation technologies, conjunctive use of SW & GW, reuse of escaped water, innovative participatory approaches at community level, andwater, innovative participatory approaches at community level, and integrating agricultural activities for efficient application of irrigation water offer potential for increasing the water use efficiencies in irrigation

OPTIONS FOR IMPROVING IRRIGATION WATER USE EFFCIENCY

The useful ways for

These practices Th fways for 

enhancing th i i ti

practices mainly aim at:

The success of these 

approachesthe irrigation efficiency i l d

Augmentation of water supply

approaches depends on the level of theirinclude 

several on‐f d ff

demand management of 

crops

level of their integration and socio‐economic 

farm and off‐farm 

i

crops

water saving through various

dimensions of a given locality

practices through various practices

USEFUL PRACTICES FORPRACTICES FOR IMPROVINGIMPROVING IRRIGATION G ONWATER USE EFFCIENCY

Improvement in water conveyance, application & management

Poor condition of water conveyance, distribution and control structures in surface irrigation systems coupled with poor management results in huge wastage ofwith poor management results in huge wastage of water through uncontrolled flow and seepage losses.

Hence, focus should be contemplated on improving upon the existing water control & management structures including lining of the canals efficient waterstructures including lining of the canals, efficient water conveyance through pipes & better irrigation methods

Hydraulically efficient water conveyance, application & distribution systems coupled with geometrically efficient irrigation layouts will complement to the premise of enhancing water use efficiency

Improvement in water conveyance, application & management…

Investment in wells in canal command should be encouraged for better recharge and conjunctiveencouraged for better recharge and conjunctive use practices

Water User Associations (WUAs) should be involved in the decision making so that the gmaintenance of the structures will be made easy

WUAs should also devise comprehensive accounts of water supply to clients from rivers, canals & groundwater in the irrigation schemes.

Watershed Management Programmes

In regions, where lot of rain water flows down the streams during monsoon season, the technologies at W/S scale which promote precipitation water use & enhancescale which promote precipitation water use & enhance water supplies at local level should be seen as proactive approach for water management

Watershed management essentially aims at harnessing & efficiently utilizing available water resources through:

• promotion of in-situ soil and water conservation,p ,• water harvesting and storage, and• recharge to ground water.

Watershed Management Programmes…

A WMP may have one or several in-situ measures depending on topography, nature p g p g p y,& depth of soil, rainfall intensity & amount, infiltration & water holding capacity of g p ysoils, and land use etc.

Studies indicate that raising of bunds to aStudies indicate that raising of bunds to a height of 25-30 cm around the fields could store nearly 90% of total rainwater in-situstore nearly 90% of total rainwater in-situ

Tanks Management

There are about 12,85,000 tanks with varying sizes in the country with a storage capacity of about 50 m cum.

The tanks are deteriorating resulting in poor performanceperformance.

R t i th t diti l t b diRestoring these traditional water bodies through partial desilting and promoting water harvesting should receive majorharvesting should receive major developmental support.

Tanks Management…

Catchment treatment including supply channel maintenance is important in getting the rainfall runoff to the tanks.

Non-system tanks should be converted into system tanks by linking the river systems wherever possible so that surplus water during heavy rains can beso that surplus water during heavy rains can be diverted to the tanks easily.

Tank-chain should be restored to facilitate for the diversion of water from upstream tanks to d kdownstream tanks.

Conjunctive Use of Water

The excessive withdrawal of ground water has led to declining water table in many regions

This declining trend in water table can be arrested by increased use of canal water in conjunction withwater in conjunction with groundwater

In regions with poor quality groundwater the use of poor qualitygroundwater, the use of poor quality ground water in conjunction with canal water in appropriate proportions would help in checking the rising water table

IMPROVED IRRIGATION METHODS

Drip and sprinkler irrigation are considered as the leading water saving technologies in irrigated agriculture

Drip irrigation also facilitates application of fertilizers with irrigation water for efficient gutilization of fertilizers by crops

Studies indicate that drip irrigation results in water saving ranging between 30 - 70% and yield increase as high as 100% in some crops under specific locations

IMPROVED IRRIGATION METHODS…

Similarly, there is almost 30% saving of water with sprinkler irrigation systemwater with sprinkler irrigation system.

In India, the area covered under drip and sprinkler irrigation in 2004 was about 6 sp e gat o 00 was about 6lakh ha and 15 lakh ha respectively

Improved surface irrigation methods like level furrows dead level basins alsolevel furrows, dead level basins also provide high application efficiency

IRRIGATION USE EFFICIENCY90

Surface100

60

70

60

80Surface

Sprinkler

Drip

Drip

50 4060

30 35

30 20

Surface

Sprinkler

Drip

0

On-Farm Irrigation Scheduling Based on Soil Moisture Monitoring

Application of precise quantities of irrigation water at right time ensures airrigation water at right time ensures a high efficiency of water use by crops

A tendency to over-or under-irrigate results due to absence of information about soildue to absence of information about soil moisture status down the soil profile

Therefore, irrigation water management requires a combination of soil moisture qmeasurement & some method of irrigation scheduling

On-Farm Irrigation Scheduling Based on Soil Moisture Monitoring…

Soil moisture readings can detect if there is a water shortage that can reduce yields, or if there is excessive water application that can result in water logging wastage of water and nutrients belowcan result in water logging, wastage of water and nutrients below the root zone through deep percolation and surface runoff of tail water.

Use of soil moisture sensors or tensiometers which provide soil ppotential are quite handy and easy for use by farmers

Studies indicate that irrigation scheduling based on tensiometerg greadings can save water by about 24%

System of Rice Intensification (SRI)

SRI technology involves use of certain management practices which provide bettermanagement practices which provide better growing conditions for rice plants, particularly in the root zone, than those grown traditionallyin the root zone, than those grown traditionally

Four components of SRI include early planting (12 days old single seedlings, wider spacing), li it d i i ti (2 3 d th ftlimited irrigation (2-3 cm depth after appearance of hairline cracks, weeding and application of more compost and building soilapplication of more compost and building soil organic matter content

System of Rice Intensification (SRI)…Multiple benefits of SRI includes saving of irrigationMultiple benefits of SRI includes saving of irrigation water (about 600 to 700 mm through intermittent irrigation as against 1200–1500 mm in conventional

) imethod), less seed rate, less nursery area, better soil aeration, enhanced yield and control of malaria

SRI is being practiced in TN, AP, & Karnataka in South India and sporadically followed in few Eastern states like Tripura & Assam

Up scaling this innovative approach throughout the country alone could sustain the irrigated rice cultivation y gin future.

Laser Aided Precision Land Leveling

Unevenness in the soil surface adversely affects the uniform distribution of wateraffects the uniform distribution of water in the fields

Precision land leveling with the help of laser leveler results in reduction in time

d i f i d i iand quantity of water required to irrigate the field

It also results in more uniform distribution of water and soil moisture indistribution of water and soil moisture in the field for better crop growth.

Laser Aided Precision Land Leveling…

Results of the demonstrations conducted at farmers fields show thatconducted at farmers fields show that laser aided land leveling saved 10-20% irrigation water in different20% irrigation water in different crops

Therefore, precision land leveling will be of great use for improvingwill be of great use for improving application and distribution efficiency specially in water scarceefficiency specially in water scarce region

Mulching

Application of It helps in water ppstraw mulch improves the water use

psaving by reducing the evaporation losses from the soil

efficiencyfrom the soil surface

Mulching also keeps the weed down thereby

A few reports on the effect of mulching on water use in rice-wheat system reveal that mulching helps iny

reducing the evapotranspiration losses by

mulching helps in saving of water in the range of 25 to 100 mm resulting in less number of irrigations

d d i i i tiweeds and reducing irrigation time by about 17%

Deficit Irrigation Practices

Crop is exposed to aCrop is exposed to aDeficit irrigation is a way of maximizing water use efficiency for higher yields per

Deficit irrigation is a way of maximizing water use efficiency for higher yields per

Crop is exposed to a certain level of water stress either during a period that have little impact on

Crop is exposed to a certain level of water stress either during a period that have little impact on g y p

unit of irrigation water applied

g y punit of irrigation water applied

pyield or throughout the whole growing season

pyield or throughout the whole growing season

Resulting yield reduction may be small compared with the benefits

Resulting yield reduction may be small compared with the benefits

However, this approach requires k l d f

However, this approach requires k l d fwith the benefits

gained through diverting the saved water to other crops for which water

with the benefits gained through diverting the saved water to other crops for which water

knowledge of crop yield response to water stress & water retention capacity of the soil

knowledge of crop yield response to water stress & water retention capacity of the soilnormally would not

be availablenormally would not be available

the soilthe soil

Virtual Water Trade

It is an indirect way of water demand management

When a country imports a tonne of grains, it is also importing "virtual water", i.e. the water required to produce that crop

Trade in virtual water generates water savings for importing countries

Virtual water trade can help mitigate water scarcity if water-short countries can afford to import food from water-abundant countries

However, large water exporting countries may influence the policies of recipient countries

Therefore, there is a strong need to develop a set of principles/rules governing virtual water trade otherwise conflict may prevail over cooperation

Reducing Wastage along the Food Chain

A large part of grains produced perishes right on the farm, in storage, during transport and during consumption

Minimizing losses and wastage along the food chain will reduce the need for an additional food productionduring consumption. production

Thi ill h l i t ili

A combination of policy measures including investment support in post-harvest technologies, food processing industry This will help in curtailing

the water use in agriculture

p g yand supermarkets, as well as strategic efforts to educate the public about how to practically contribute to the

i f freduction of food wastage is necessary.

Share of irrigation water in total demand isO

NS Share of irrigation water in total demand is

bound to decrease in future due to more pressing and competing demands from other

t

USI

O sectorsAs such, the question of improving present level of water use efficiency in general and for

CL

U

eve o w e use e c e cy ge e d oirrigation in particular assumes a great significance in perspective water management planning

ON

C planningTechnological improvements in irrigation & farming systems have increased opportunities f i i

CO for water management in agriculture

Modern irrigation technologies, particularly sprinkler and drip irrigation increase watersprinkler and drip irrigation, increase water use efficiency

. In‐situ water conservation measures are veryNS…

. In‐situ water conservation measures are very effective in building up soil moisture to sustain vegetation growth during dry spells and they also contribute to ground water recharge

SION contribute to ground water recharge

Soil moisture monitoring coupled with irrigation scheduling can play a vital role in saving irrigation 

t

CLUS water. 

Renovation and desilting of tanks, construction of check dams and similar small storage structures for 

CONC g

rain water harvesting are the promising strategies for artificial recharge of ground water

Drainage problems can be prevented and alleviatedC Drainage problems can be prevented and alleviated by integrated use of canal and groundwater, adapting land use to the natural drainage conditions, canal lining and land leveling etclining and land leveling etc.