Date of Award

2022-12-01

Degree Name

Doctor of Philosophy

Department

Environmental Science and Engineering

Advisor(s)

Hugo A. Gutierrez-Jurado

Abstract

In drylands, crop water use varies considerably where high temperatures and limited water availability constraints farming activities, and irrigation planning is essential for the efficient water use and long-term sustainability of agriculture. However, despite dwindling water supplies and the looming threat of more frequent and intense droughts, low-efficient irrigation (e.g., furrow and flooding) continues to be the most widely used method for water delivery into agricultural parcels. Transitioning into more sustainable agriculture requires knowledge of the period of productive vs. unproductive crop water use during the agricultural cycle. I developed a method using satellite images for partitioning evapotranspiration (ETa) into Evaporation (Ev) and Transpiration (Tr). The method was named Partitioning of Evapotranspiration Through Vegetation Index (PETVI). I verified the Ev and Tr estimates with independently measured ETa using Eddy Covariance (ECET), satellite-derived ET from the METRIC algorithm, point measurements of Ev using the Maximum Entropy Production (MEP) method, and Ev and Tr obtained from ECET using the underlying Water Use Efficiency (uWUE) method. We tested this approach on an experimental wheat plot in Mexico. Once I had validated PETVI, I used it in an agricultural valley located in Cuauhtémoc, Chihuahua, in a cornfield under three irrigation schemes (furrow, sprinkler, and drip), I also used PETVI in a pecan orchard located in the south of Texas to quantify the productive and unproductive water use. In all cases unproductive water use by the crops occur in the early season, due to a long-time interval between the first irrigation and the planting or resprouting of the crops. Because groundwater supplies early season irrigation, shortening the time between the first irrigation and planting or resprouting would decrease the total consumptive water use in these crops.

Language

en

Provenance

Recieved from ProQuest

File Size

p.

File Format

application/pdf

Rights Holder

Orlando Ramirez-Valle

Included in

Agriculture Commons

COinS