Calculating Drip Irrigation Time for Citrus Orchard
This solution calculates the required operating time for a drip irrigation system based on orchard parameters and daily evaporation rates.
Irrigation Parameters
- Planting Spacing: $5 \, \text{m} \times 5 \, \text{m}$
- Daily Pan Evaporation: $6 \, \text{mm/day}$
- Pan Coefficient ($K_p$): $0.8$
- Wetting Factor ($W_f$): $0.6$
- Crop Coefficient ($K_c$): $0.6$
- Drippers per plant: 4
- Discharge per dripper: $4 \, \text{L} \, h^{-1}$
Step-by-Step Calculation
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Calculate Area per Plant:
Area ($A$) is determined by the spacing.
$ A = 5 \, \text{m} \times 5 \, \text{m} = 25 \, \text{m}^2 $
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Calculate Reference Evapotranspiration ($ET_o$):
Use pan evaporation and the pan coefficient.
$ ET_o = \text{Pan Evaporation} \times K_p $
$ ET_o = 6 \, \text{mm/day} \times 0.8 = 4.8 \, \text{mm/day} $
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Calculate Crop Evapotranspiration ($ET_c$):
Use reference evapotranspiration and the crop coefficient.
$ ET_c = ET_o \times K_c $
$ ET_c = 4.8 \, \text{mm/day} \times 0.6 = 2.88 \, \text{mm/day} $
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Calculate Daily Water Requirement per Plant ($V_{req}$):
Convert $ET_c$ to meters and multiply by area and the wetting factor.
$ ET_c (\text{meters}) = \frac{2.88 \, \text{mm/day}}{1000 \, \text{mm/m}} = 0.00288 \, \text{m/day} $
$ V_{req} = ET_c (\text{meters}) \times A \times W_f $
$ V_{req} = 0.00288 \, \text{m/day} \times 25 \, \text{m}^2 \times 0.6 = 0.0432 \, \text{m}^3/\text{day} $
Convert cubic meters to Liters ($1 \, \text{m}^3 = 1000 \, \text{L}$).
$ V_{req} = 0.0432 \, \text{m}^3/\text{day} \times 1000 \, \text{L/m}^3 = 43.2 \, \text{L/day} $
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Calculate Total Dripper Discharge per Plant ($Q_{total}$):
Sum the discharge of all drippers for one plant.
$ Q_{total} = (\text{Drippers per plant}) \times (\text{Discharge per dripper}) $
$ Q_{total} = 4 \times 4 \, \text{L/h} = 16 \, \text{L/h} $
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Calculate Irrigation Time ($T$):
Divide the total water requirement by the total discharge rate.
$ T = \frac{V_{req}}{Q_{total}} $
$ T = \frac{43.2 \, \text{L/day}}{16 \, \text{L/h}} = 2.7 \, \text{h/day} $
The time of operation for the drip irrigation system is 2.7 hours per day.
Important Questions from Micro Irrigation Methods
- From the performance evaluation of drippers, the discharge exponent value and the coefficient of variation were obtained as 0.5 and 0.04, respectively. The drippers are categorized as
- The average discharge, operating pressure and emitter constant of a drip emitter are 4 L h$^{-1}$, 110 kPa and 0.3, respectively. The type of emitter is
- A permanent matured orchard has a tree spacing of 4 $m\times5$ m. Each tree has a shading area of 40% to be irrigated with the 'pig tail' pattern multi-exit drip emitters. The effective wetting geometry of each emitter is 2 $m\times2$ m. The emitters have discharge constant and exponent of 0.3 and 0.6, respectively. The coefficient of variation of emitter discharge is 0.06. The average and minimum operating pressures are 120 kPa and 100 kPa, respectively. The emission uniformity of the emitters is ________ %.
- In a field test of drip irrigation system having an application efficiency of 90%, the minimum, maximum and average flow rates are found to be $45 \ L\cdot h^{-1}$, $65 \ L\cdot h^{-1}$ and $50 \ L\cdot h^{-1}$, respectively. The manufacturer's coefficient of variation of the emitter is 0.07. If there is one emitter per plant, the drip irrigation efficiency in percent is ______ [round off to 2 decimal places]
