Location: Water Management Research
Project Number: 2034-13000-013-018-I
Project Type: Interagency Reimbursable Agreement
Start Date: Sep 1, 2024
End Date: Sep 30, 2027
Objective:
1) Evaluate deficit irrigation strategies for water conservation, 2) Measure and compare evapotranspiration (ET) in conventional and new trellised systems, and 3) Simulate water conservation if 30% of citrus production shifts to high yielding trellis systems and remaining lands are fallowed.
Approach:
For objective 1, we observed 20-30% deficit irrigation in a tangerine orchard in prior year field measurements in the watershed. Therefore, using modeling approaches, such as the integrated groundwater-land surface watershed model ParFlow-CLM, we will evaluate water savings if all tangerine and navel oranges are using 20% and 30% deficit irrigation within the watershed. This scenario analysis will be performed using the ParFlow-CLM calibrated against in-situ and remotely sensed evapotranspiration observations and groundwater level measurements in the watershed.
For objective 2, we will continue eddy covariance measurements of ET in conventional orchards: one with navel orange and one with tangerines. A new eddy covariance system will be installed in a trellised system within the Kaweah River watershed and the measured ET will be compared to the conventional citrus systems. Differences in total ET and water use dynamics between the conventional and the trellised systems will be determined and then will be applied in modeling assessment of water conservation by land fallowing in objective 3.
For objective 3, the ParFlow-CLM model will be used to estimate water conservation if 30% citrus production shifts to high yielding trellised systems and remaining lands are fallowed. Grower reports claim that the trellised system can increase citrus production by 300-400% on a per acre basis. Considering that the citrus market is near saturation and the growers’ goal is not unlimited increase in production, they could fallow up to 70% of the citrus lands if trellised citrus can be implemented at scale. Simulation scenarios can include: A) 30% land remains in citrus production, under irrigation, using the trellised system and remaining 70% land fallowed with natural vegetation cover such as shrubs without irrigation, B) 30% land remains in citrus production, under irrigation, using the trellised system and the remaining 70% land planted with small grain winter cover crop without irrigation plus groundwater recharge.
