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26 nov16 irrigation_water_use_efficiency

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Irrigation Water Use Efficiency

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26 nov16 irrigation_water_use_efficiency

  1. 1. IRRIGATION WATER USE EFFICIENCYEFFICIENCY By R.D. Singh Director National Institute of Hydrology Roorkee
  2. 2. 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.
  3. 3. 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.
  4. 4. 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 andg y to achieve higher productivity of water.
  5. 5. 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.
  6. 6. 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 
  7. 7. 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 of water 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
  8. 8. MAJOR ISSUES CONCERNING WATER USE EFFICIENCY Allocation Sl d ti Allocation and optimum use of available Slow adoption of improved irrigation technologies water, 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 g methods
  9. 9. 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
  10. 10. 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
  11. 11. 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 their include  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
  12. 12. USEFUL PRACTICES FORPRACTICES FOR IMPROVINGIMPROVING IRRIGATIONG ON WATER USE EFFCIENCY
  13. 13. 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
  14. 14. 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 theg maintenance 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.
  15. 15. 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.
  16. 16. Watershed Management Programmes… A WMP may have one or several in-situ measures depending on topography, naturep g p g p y, & depth of soil, rainfall intensity & amount, infiltration & water holding capacity ofg p y soils, 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
  17. 17. 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.
  18. 18. 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.
  19. 19. 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
  20. 20. 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 efficientg utilization 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
  21. 21. 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 6sp e gat o 00 was about 6 lakh 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
  22. 22. IRRIGATION USE EFFICIENCY 90 Surface 100 60 70 60 80 Surface Sprinkler Drip Drip 50 40 60 30 35 30 20 Surface Sprinkler Drip 0
  23. 23. 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 moistureq measurement & some method of irrigation scheduling
  24. 24. 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 soilp potential are quite handy and easy for use by farmers Studies indicate that irrigation scheduling based on tensiometerg g readings can save water by about 24%
  25. 25. 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
  26. 26. 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 cultivationy g in future.
  27. 27. 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.
  28. 28. 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
  29. 29. Mulching Application of It helps in waterpp straw mulch improves the water use p saving by reducing the evaporation losses from the soil efficiency from 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 evapotranspira tion 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 ti weeds and reducing irrigation time by about 17%
  30. 30. Deficit Irrigation Practices Crop is exposed to aCrop is exposed to a Deficit 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 ong y p unit of irrigation water applied g y p unit of irrigation water applied p yield or throughout the whole growing season p yield 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 f with 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 soil normally would not be available normally would not be available the soilthe soil
  31. 31. 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
  32. 32. 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 y and 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.
  33. 33. Share of irrigation water in total demand isONS Share of irrigation water in total demand is bound to decrease in future due to more pressing and competing demands from other t USIO sectors As such, the question of improving present level of water use efficiency in general and for CLU eve o w e use e c e cy ge e d o irrigation in particular assumes a great significance in perspective water management planning ONC planning Technological 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
  34. 34. . In‐situ water conservation measures are very NS…. 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 alleviated C 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.

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