![Irrigation system performance
• Conveyance efficiency
Ec = (Vf / Vt) x 100
• Application efficiency
Ea = (Vs / Vf) x 100
• Storage efficiency
Es = [Vs / (Vfc – Va)] x 100
Where
Vf = Volume of irrigation water that reaches the farm or field
Vt = Volume of irrigation of water diverted from the water source
Vs = Volume of irrigation water stored in the root zone
Vfc = Volume capacity at field capacity in the crop root zone
Va = Volume of water in the root zone prior to an irrigation event](https://image.slidesharecdn.com/adripresentation-181228054839/85/CLIMWAT-and-CROPWAT-Model-7-320.jpg)
![Cont…
• Scheme irrigation efficiency
• Overall irrigation efficiency
Eo = (Ec x Ea x Es ) x100
• Effective irrigation efficiency
Ee = [Eo + (FR) x (1 - Ea)] x100
Where
FR = fraction of surface runoff , seepage, and deep percolation that is recovered](https://image.slidesharecdn.com/adripresentation-181228054839/85/CLIMWAT-and-CROPWAT-Model-8-320.jpg)
![Solution
• Water conveyance efficiency, Ec = 100 x (Vf/Vd) = 100 x (110/140) = 78.5%
• Water application efficiency, Ea = 100(Vs/Vf)
Water delivered to the field = (110 x 8 x 3600) / 1000 = 3168 m3
Water stored in the root zone = 3168 – 435 = 2733m3
= 100 x (2733 x / 3168) = 86.26%
• Water storage efficiency, Es= 100 x (Vs/Vrz)
Water holding capacity of the root zone = 20 x 1.85 = 37 cm
Moisture required in the root zone = [37 – (37 x 50)/100] x 1.65 x 10,000
= 3052.5 m3
= 96.3%](https://image.slidesharecdn.com/adripresentation-181228054839/85/CLIMWAT-and-CROPWAT-Model-11-320.jpg)
CLIMWAT and CROPWAT Model
- 1. Lecture on CLIMWAT and CROPWAT model Date: 9th August, 2018 at ADRI, Patna Er. Pawan Jeet Scientist (LWME) Division of Land and Water Management ICAR-Research Complex for Eastern Region, Patna
- 2. ? • Weather and Climate • Irrigation and drainage • Infiltration and percolation • Precipitation and rainfall • Potential ET and Reference ET • Irrigation efficiency and water use efficiency
- 3. Water Cycle/Hydrology cycle = Change in storage
- 4. Water balance components Input/Source Output Change in storage - = • Precipitation • Groundwater • Surface water • Irrigation • Runoff • Infiltration • Percolation • Interception • Evaporation • Evapotranspiration • Groundwater Recharge • Moisture
- 5. Input • Irrigation: artificial application of water to soil for proper plant growth and crop production (Israelsen, 1950) • Irrigation efficiency: volume of water required for consumptive use by the crop for its growth to the volume of water delivered from the source • Irrigation efficiency Irrigation system performance Uniformity of water application Response of crop to irrigation
- 6. Classification Irrigation Efficiency Irrigation system efficiencies Conveyance efficiency Application efficiency Storage efficiency Distribution efficiency Farm or crop use efficiency Water use efficiency Transpiration efficiency Farm water use efficiency
- 7. Irrigation system performance • Conveyance efficiency Ec = (Vf / Vt) x 100 • Application efficiency Ea = (Vs / Vf) x 100 • Storage efficiency Es = [Vs / (Vfc – Va)] x 100 Where Vf = Volume of irrigation water that reaches the farm or field Vt = Volume of irrigation of water diverted from the water source Vs = Volume of irrigation water stored in the root zone Vfc = Volume capacity at field capacity in the crop root zone Va = Volume of water in the root zone prior to an irrigation event
- 8. Cont… • Scheme irrigation efficiency • Overall irrigation efficiency Eo = (Ec x Ea x Es ) x100 • Effective irrigation efficiency Ee = [Eo + (FR) x (1 - Ea)] x100 Where FR = fraction of surface runoff , seepage, and deep percolation that is recovered
- 9. Crop response to irrigation • Crop water use efficiency CWUE = Yg / ET • Transpiration ratio (dry matter basis) TR = ET / Yg • Irrigation water use efficiency IWUE = Yg / IR Where Yg = Economic yield ET = crop water use IR = irrigation water applied
- 10. Questions A stream of 140lps was diverted from a canal and 110 lps were delivered to the field. An area of 1.65 ha was irrigated in eight hours. The effective depth of root zone was 1.85 m. The runoff loss in the field was 435 m3. Available moisture holding capacity of the soil is 20 cm/m depth of soil. Determine the water conveyance efficiency, water application efficiency, water storage efficiency and irrigation was started at a moisture extraction level of 50 percent of the available moisture.
- 11. Solution • Water conveyance efficiency, Ec = 100 x (Vf/Vd) = 100 x (110/140) = 78.5% • Water application efficiency, Ea = 100(Vs/Vf) Water delivered to the field = (110 x 8 x 3600) / 1000 = 3168 m3 Water stored in the root zone = 3168 – 435 = 2733m3 = 100 x (2733 x / 3168) = 86.26% • Water storage efficiency, Es= 100 x (Vs/Vrz) Water holding capacity of the root zone = 20 x 1.85 = 37 cm Moisture required in the root zone = [37 – (37 x 50)/100] x 1.65 x 10,000 = 3052.5 m3 = 96.3%
- 12. Irrigation water losses Serageldin (2010)
- 13. Reasons for poor irrigation efficiency • Non-stop flow of water to the field when the amount of water needed has been delivered • Absence of volumetric supply of water from the water source to the field • Non measurable soil moisture level at the time of irrigation
- 14. Cont… • Improper field levelling which cause poor water distribution across the field • Excessive slopes which cause high runoff losses • Application of water not based on intake characteristics of the soil
- 15. Improving irrigation efficiency • Less stress on water resources, less losses of water and nutrients to groundwater and surface water resources • Minimise irrigation inputs while continuing to improve production and overall profits • Allow a greater area to be irrigated with a given volume of water
- 16. Cont… • Modernization of Irrigation Projects • Promotion of Efficient Irrigation Practices • Promotion of Micro‐Irrigation Systems
- 17. Cont… • Crop Diversification • Deficit Irrigation • Conjunctive Use of Surface and Ground Water
- 18. Improving irrigation efficiency practices Crop Selection Irrigation Scheduling Irrigation Method Source of Water
- 19. Soil moisture • Water contained in the vadose zone of subsurface • Major component of soil hydrology that influences the exchange of heat and moisture between the atmosphere and land surface • Forecasts of runoff, flood, groundwater recharge and evapotranspiration
- 20. Applications of soil moisture Soil Moisture Drought monitoring Climate science Flood forecasting Groundwater recharge Land Atmosphere processes Ecological status Agronomy
- 21. Soil moisture measuring equipment's Thermostat weight method Measure the electrical resistance Hydrogen atoms that changes with time Changes in frequency of signals due to the dielectric properties of the soil Changes in the dielectric properties of the soil at microwave frequencies Soil moisture tension
- 22. Evapotranspiration (ET) ET Lysimeter ETc = Kc x ETo
- 23. Questions Following data given below Crop grown: Sorghum Length of total growing season: Base period = 120 days ETo = 6.0 mm/day Kc = 0.78 Calculate ET crop.
- 24. ET Measurement Evaporation • U.S. Weather Bureau Class A Pan Evaporimeter • ISI Standard Pan • Sunken Evaporation Pan • USGS Floating Pan • Piche Evaporimeter Lake Evaporation = Pan Coefficient x Pan Evaporation, or ETo = Epan x Kpan
- 25. Questions Following data are given below Type of pan: Class A evaporation pan Water depth in pan on day 1 = 150 mm Water depth in pan on day 2 = 144 mm Rainfall (during 24 hours) = 0 mm K pan = 0.75 Calculate ETo.
- 26. Conte… Percolation • Single ring infiltrometer • Double ring infiltrometer
- 27. Measurement of ET • Thornthwaite • Blaney-Criddle, FAO-24 • Hargreaves • Christiansen-Hargreaves Pan Evaporation • FAO-24 Pan Evaporation • Penman FAO-24 • Penman-Monteith • Radiation Method Model • CROPWAT
- 28. Penman Monteith equation Where, Lv = Volumetric latent heat of vaporization (Lv = 2453 MJ m−3) ETo = Water volume evapotranspired or reference ET (mm s−1) Δ = Rate of change of saturation specific humidity with air temperature (Pa K−1) Rn = Net irradiance (W m−2) G = Ground heat flux (W m−2) cp = Specific heat capacity of air (J kg−1 K−1) ρa = dry air density (kg m−3) δe = vapor pressure deficit, or specific humidity (Pa) ga = Conductivity of air, atmospheric conductance (m s−1) gs = Conductivity of stoma, surface conductance (m s−1) γ = Psychrometric constant (γ ≈ 66 Pa K−1)
- 29. CLIMWAT • Climatic database to be used in combination with the computer program CROPWAT. • Used to calculate crop water requirements, irrigation supply and irrigation scheduling for various crops for a range of climatological stations worldwide. • CROPWAT requires local climatic data, but if these are not available the software can use a representative station from the CLIMWAT database.
- 30. Conte… Long-term monthly data of seven climatic parameters • Mean daily maximum temperature (°C) • Mean daily minimum temperature (°C) • Mean relative humidity (%) • Mean wind speed (km/day) • Mean sunshine (hours per day) • Mean solar radiation (MJ/m2/day) • Monthly rainfall (mm/month) • Monthly effective rainfall (mm/month)
- 31. CLIMWAT Input
- 32. Weather observation networks in India • Automatic Weather station : 675 • Automatic rain gauge : 1289 • Agro-met Unit : 130 IMD data availability • Rainfall • Temperature (Min/Max) • Humidity • Radiation • Wind speed • Evaporation
- 33. CROPWAT • Crop water requirements and irrigation requirements based on soil, climate and crop data • Allows the development of irrigation schedules for different management conditions and the calculation of scheme water supply for varying crop patterns. • can also be used to evaluate farmers’ irrigation practices and to estimate crop performance under both rainfed and irrigated conditions.
- 34. Importance • Monthly, decade and daily input of climatic data for calculation of reference evapotranspiration (ETo) • Possibility to estimate climatic data in the absence of measured values • Decade and daily calculation of crop water requirements based on updated calculation algorithms including adjustment of crop- coefficient values
- 35. Conti… • Calculation of crop water requirements and irrigation scheduling for paddy & upland rice, using a newly developed procedure to calculate water requirements including the land preparation period • Interactive user adjustable irrigation schedules • Daily soil water balance output tables • Easy saving and retrieval of sessions and of user-defined irrigation schedules • Graphical presentations of input data, crop water requirements and irrigation schedules
- 36. CROPWAT input
- 37. Conte…
- 40. Crop parameters
- 41. Soil parameters
- 44. Selection of cropping pattern
- 46. Problems Calculate field water supply, when following data is given Crop: Maize Cultivated area = 1 ha Plant coverage: 100% Reference ET = 7.216 mm/day Average crop coefficient (Crop Kc) = 1.20 Effective rainfall = 2 mm Irrigation efficiency = 70% Crop Water Requirement (CWR) = ? Irrigation Requirement = ? Field Water Supply for one hectare = ?
- 47. Solution Crop Water Requirement (CWR) = Reference ET x Crop Kc = 7.216 x 1.20 = 8.659 mm/day Irrigation Requirement (NIR) = CWR – Effective rainfall = 8.659 - 2 = 6.659 mm/day Field Water Supply/ha = (Area converge x IR)/ irrigation efficiency = 1 x 6.659 x 1.428 = 95.07 m3/day
- 48. References • FAO 56: "Crop Evapotranspiration - Guidelines for computing crop water requirements” • FAO 33: "Yield response to water“
- 49. The success of any Irrigation Technology needs people Who design & build it Who live it Sleep it Dream it Believe it and build great future plans for it 49
- 50. Thank You!