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  2. 2.  Irrigation engineering  Necessity of irrigation  Scope of irrigation engineering  Benefits of irrigation engineering  Ill-effect of irrigation  Irrigation development in india  Types of irrigation system  Soil-water plant relationship  Classification of soil water  Soil-moisture content  Depth of soil water available to plants
  3. 3.  IRRIGATION:-Irrigation is defined as the process of artificially supplying water to soil for raising crops.  IRRIGATION ENGINEERING:- It is the science dealing with planning, designing, construction, operation and maintenance of various irrigation works
  4. 4.  Inadequate rainfall  Non-uniform rainfall  Growing number of crops during year  Growing perennial crops  Growing superior crops  Increasing the yield of crops  Insurance against crops
  5. 5. Engineering aspect Agriculture aspect Management aspect
  6. 6.  It involves the development of source of water for irrigation and arrangement for the conveyance of water from the source right up to agricultural fields. a) Storage ,diversion or lifting of water. b) Conveyance of water to the agricultural fields. c) Application of water to agricultural fields. d) Drainage and reliving water – logging. e) Development of hydropower.
  7. 7.  It involves the timely and systematic application of irrigation water to the agricultural fields. It deals with following points: 1) Proper leveling and shaping of the agricultural fields. 2) Soil investigation and classification of the agriculural land. 3) Provision of field channel. 4) Distribution of water uniformly and periodically. 5) Capacities of different soil. 6) Conservation of soil against erosion. 7) Choosing proper crop pattern. 8) Reclamation of waste and alkaline ands.
  8. 8.  It deals with the successful implementation and efficient management of both the engineering as well as the agricultural aspects of the project.  Following points are considered in this aspect:- 1) The farmers should be trained and educated. 2) The cultivation should be carried out in a scientific manner with due control on all the inputs so as to obtain the maximum yield. 3) The distribution of water to the farmers should be managed properly. 4) The agricultural land holding of the small farmers should be consolidated to increase the efficiency of irrigation. 5) Suitable measures are to be adopted to eliminate the ill effect of irrigation.
  9. 9. 1) Increase in crop yield 2) Protection from famine 3) Cultivation of crash crops 4) Elimination of mixed cropping 5) Increase in the wealth of country 6) Increase in prosperity of people 7) Generation of hydro-electric power 8) Domestic and industrial water suplly 9) Inland navigation 10) Communication facility 11) Canal plantation 12) Increase in ground water storage 13) Overall development of the country 14) Aid in civilization
  10. 10.  It is due to the excess irrigation and unscientific use of irrigation water may give rise to the ill-effects. some of the common ill-effect of irrigation are: 1) Water logging 2) Mosquitoes nuisance 3) Damp climate 4) Pollution of ground water
  11. 11.  Classification based on availability of water Irrigation system Flow irrigation Lift irrigation Perennial irrigation As per source Inundation irrigation Well irrigation Lift canal irrigation Direct irrigation Storage irrigation Combined irrigation
  12. 12.  The flow irrigation system can be further classified based on duration into two classes: 1) Perennial irrigation system 2) Inundation irrigation system  PERENNIAL IRRIGATION SYSTEM:- In this system water is supplied as per the crop requirements at regular intervals, through the crop period.  INUNDATION IRRIGATION SYSTEM:- In this system large quantity of water flowing in a river during flood is allowed to flood or inundated the land to be cultivated.
  13. 13. Major project (CCA >10,000) Medium project 10,000<CCA>2000 Minor project CCA<2000 (20 km²)
  14. 14.  The water added to a soil mass during irrigation ,is held in the pores of the soil mass, which is termed as soil water. It is classified as following:- 1) Gravitational water 2) Capillary water 3) Hygroscopic water
  15. 15.  SOIL MOISTURE CONTENTT:-The amount of water present in soil is termed as soil moisture content.  SATURATION CAPACITY:-It is the amount of water required to fill all the pore spaces between soil particles by replacing all air held in pore spaces.  FIELD CAPACITY:-The field capacity is the moisture content of the soil after free drainage has removed most of the gravity water.  PERMANENT WILTING POINT:-Permanent wilting point or the wilting coefficient is that water content at which plants can no longer extract sufficient water from the soil for its growth.
  16. 16.  TEMPORARY WILTING:- Temporary Wilting of plants usually occurs on a hot day, but the plants recover - from wilting in the cooler portion of the day or during the night without any addition of water to the soil. Thus, temporary wilting of plants may occur even without much reduction in the soil moisture content.  ULTIMATE WILTING:-Ultimate wilting of plants Occurs when they become completely wilted and dead after ultimate wilting has occurred, the plants do not recover from wilting even after the addition of water to the soil. The water content at which ultimate wilting occurs is termed as ultimate wilting point.  MOISTURE EUIVALENT:- Moisture equivalent is Defined as the percentage of moisture retained in an initially saturated sample of soil 10 mm thick after being subjected to a centrifugal force of 1000 times gravity for a period of 30 minutes.
  17. 17.  AVAILABLE MOISTURE:- The difference in Moisture content of soil between the field capacity and the permanent wilting point is called the available moisture.  READILY AVAILABLE MOISTURE :-It is that portion of the Available moisture that is most easily extracted by plants. It is approximately 75% of the available moisture.  SOIL MOISTURE TENSION:-The force per unit area that Must be exerted in order to extract water from the soil is known as soil moisture tension.
  18. 18.  In irrigation, it is essential to know the amount of water needed by crops.  This determines the quantity of water to be added by irrigation and rainfall and helps in day to day management of irrigation systems.
  19. 19.  DUTY:- Duty represents the irrigating capacity of a unit water. It relation between the area of a crop irrigated and the quantity of irrigation water required during crop growth. For example: If 5 cumec of water is required for a crop sown in an area of 5000 hectares, The duty will be 5000/5=1000 hectares/cumec.  DELTA:- It is total depth of water required for a crop during the entire period the crop is in the field and is denoted by Δ. The unit of delta is days.
  20. 20.  There are four types of duty: 1) GROSS DUTY:-It is the duty of water measured at The head of main canal. 2) NOMINAL DUTY:-It is the duty sanctioned as per Schedule of an irrigation department. 3) ECONOMIC WATER DUTY:-It is the duty of water Which results in the maximum crop yield. 4) DESIGNATED DUTY:- It is the duty of water assumed in an irrigation project for designing capacities of the channel.
  21. 21.  Let, D=duty in hectares ∆ = total depth of water supplied in meters B = base period in days 1) If we take a field of area D hectares, water supplied to the field corresponding to the water depth ∆ meters will be, = D x ∆ hectares – meters =D x ∆ x 104 cubic meters 2) For the same field of area D hectares , water is supplied at the rate of 1 cumec for the entire base period of B days , then the total quantity of water supplied to the field, =1 x b x 24 x 60 x 60 cubic meter =8.64 x 104 B cubic meter D = 8.64 B/ D meters
  22. 22.  CROP PERIOD:-It is the time in days, that a crop takes from The instant of its sowing to that of its harvesting.  BASE PERIOD:- The base period is the relation between he First watering and the last watering supplied to the land.  PALEO:- It is defined as the first watering before sowing the Crop.  GROSS COMMAND AREA(G.C.A):-It is defined as the total Area lying between drainage boundaries which can be commanded or irrigated by a canal.
  23. 23.  CUTURABLE COMMAND AREA(C.C.A):- It is that portion of G.C.A which is cultivable or cultivable.  CROP RATIO:- It is defined as the ratio of the land irrigated During the two main crop season rabi and kharif.  TIME FACTOR:- It is the ratio of number of days the canal has actually run to the number of days of irrigation Period.  CAPACITY FACTOR:- It is the ratio of mean supply to the Full supply of a canal.
  24. 24. 1) Method of irrigation 2) System of irrigation 3) Method of cultivation 4) Type of crop 5) Base period of crop 6) Climatic condition 7) Quality of water 8) Canal condition 9) Type of soil and sub soil 10) Time of irrigation
  25. 25.  Composed of two sub processes:- ◦ Evaporation occurs on surfaces of open water or from vegetation and ground surfaces. ◦ Transpiration is the removal of water from the soil by plant roots, transported through the plant into the leaves and evaporated from the leaf’s stomata.  Typically combined in mass balance equations because the components are difficult to partition. Evapotranspiration Evaporation Transpiration Open Water Soil Vegetation Surfaces Plants
  26. 26.  Potential ET (PET) is the amount of evaporation that will occur if an unlimited amount of water is available.  Actual ET (AET) is the actual amount of evaporation that occurs when water is limited. For large areas can use a mass balance approach to calculate (Eq. 4.5).
  27. 27.  Transpiration is the loss of water in the form of vapor from plants  Factors that affect transpiration rates  Type of plant  Wind  Plant Available Water: the portion of water in a soil that can readily be absorbed by plant roots. Amount of water released between field capacity (amount of water remaining in the soil after gravitation flow has stopped) and wilting point (amount of water in the soil at 15 bars of suction).
  28. 28.  Phase change of water from a liquid to a gas o Rate of evaporation is driven by the vapor pressure deficit. Function of: 1. The ability of air to hold water based on air temperature and relative humidity. 1. The energy in the water largely based on temperature. o Net evaporation ceases when the air has reached the saturation vapor pressure.
  29. 29.  There are two method for the measurement :  DIRECT MEASUREMENT METHOD 1. Tank and lysimeter method 2. Field experiment method 3. Soil moisture study 4. Integration method 5. Inflow and outflow studies  USE OF EMPIRICAL FORMULA 1. Penman method 2. Jensen –Haise method 3. Blanley Criddle method 4. Hargreaves method 5. Thornthwait method
  30. 30. ET R G K BP e e r n z z a 0 1 0 1 622( )[( * )( ) ( * )(. ) ( ) ] •More reliable for any length period daily, monthly, or seasonal. •If adequate data available.
  31. 31. AET0 = The evapotranspiration for grass reference crop = heat of vaporization Rn = net radiation G = soil heat flux = slope of the vapor pressure curve = psychrometric constant = density of air BP = mean barometric pressure e0 z = average saturated vapor pressure ez = actual vapor pressure * = (1+rc/ra) rc = surface resistance to vapor transport ra = aerodynamic resistance to sensible heat and vapor transport K1 = the dimension coefficient
  32. 32.  These irrigation efficiencies are brought about by the desire not to waste irrigation water, no matter how cheap or abundant it is.  The objective of irrigation efficiency concept is to determine whether improvements can be made in both the irrigation system and the management of the operation programmes, which will lead to an efficient irrigation water use.
  33. 33. APPLICATION EFFICIENCY E Water in root zone after irrigation Total volume of water applied a Total vol of water applied Vol of Tailwater Vol of deep percolation Total water applied . ( . . ) Ea is inadequate in describing the overall quantity of water since it does not indicate the actual uniformity of irrigation, the amount of deep percolation or the magnitude of under-irrigation. See diagrams in text.
  34. 34. Water Conveyance Efficiency E Water delivered to the Farm W Water of water diverted from a stream reservoir or well W c d s ( ) , ( ) Farm Water lost by evap And seepage Wd Ws
  35. 35. E Volume of water in the root zone after irrigation Volume of water needed in root zone to avoid total water moisture depletion s =WS/WN X 100
  36. 36.  Irrigation projects are planned, executed, owned, and operated by state governments. Irrigation projects are financed by state governments out of their own resources, market borrowing and loans and grants made available by the central governments. the beneficiaries in commanded areas derive considerable benefits from the project. It is , therefore, imperative that the beneficiaries pay for it. The fixation of such charges is known as assessment of irrigation water.
  37. 37. 1) Assessment on area basis or crop rate basis 2) Volumetric assessment 3) Assessment on seasonal basis 4) Composite rate basis 5) Permanent assessment
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