Date of Award:

8-2023

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Civil and Environmental Engineering

Committee Chair(s)

Alfonso F. Torres-Rua

Committee

Alfonso F. Torres-Rua

Committee

Lawrence Hipps

Committee

Belize Lane

Committee

Mac McKee

Committee

Burdette Barker

Abstract

The increasing global population and extreme weather events are putting pressure on agricultural water management to ensure high food production. One area greatly affected is grapevine cultivation in California, where factors like drought, regulations, and consumer sustainability concerns drive water resource usage changes. Fortunately, advancements in small unmanned aerial system (sUAS) technologies provide precise vineyard water management opportunities. These technologies enable the estimation of actual evapotranspiration (ET), vine water use, and vine water stress on a plant-scale, which is crucial for precision agriculture.

This research focuses on improving our understanding in three main areas. Firstly, it aims to generalize the estimation of green biomass (leaf area index - LAI) across different grapevine varieties, trellis management techniques, seasonal patterns, and climate regions within California’s Central Valley. This generalization helps in accurately estimating vine water use (transpiration) versus the total actual ET, which includes both the vine and interrow areas. Similar generalization schemes for biomass are explored in this aspect. Lastly, the study explores the correlation between sUAS information and direct measurements of vine water stress (leaf and stem water potential – LWP and SWP) in various vineyards across California. This correlation aids in generalizing the findings.

To conduct this research, a combination of ground measuremtns and sUAS imagery is utilized. Ground measurements include direct and time-synchronized LAI, LWP, SWP readings, and eddy covariance instrumentation. Optical, infrared, and thermal band imagery from Utah State University AggieAir sUAS is also employed.

The results of this study have significant implications for the precision management of vineyard blocks. The developed models, tailored to sUAS information, can be widely used in different vineyard practices and cultural settings within California and other arid regions worldwide. This research contributes to implementing practical solutions for water management in vineyards, ensuring sustainable and efficient agricultural practices.

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