Dissertation
Experimental and modeling techniques for accurate measurement of wind drift and evaporation losses to improve water application efficiency of moving sprinkler irrigation systems in Washington
Doctor of Philosophy (PhD), Washington State University
01/2019
Handle:
https://hdl.handle.net/2376/107840
Abstract
Over half of the irrigated land in the US, 11.5 million ha, is irrigated with center pivot and linear move systems, considered as efficient pressurized irrigation methods. Still, there is enormous room to enhance their performance. Because of their ubiquity, minor improvements in their efficiency could have large global impacts. We used experimental and modeling approaches to study and enhance the water application efficiency (WAE) of these systems through accurate measurement of wind drift and evaporation losses (WDEL). A low-elevation spray application (LESA) system was evaluated against a typical mid-elevation spray application (MESA). Two data-analysis techniques, linear mixed modeling (LMM) and artificial neural networks (ANN), and three WDEL measuring methodologies: standard catch can test (CC), electrical-conductivity method (EC), and physical-based mathematical approach (PM), were evaluated to quantify and screen out the best possible combinations to improve WAE. The LESA and MESA results revealed that nearly 21% more water needs to be pumped by the MESA than LESA to get the same amount of water to the ground with the catch can study, and 17.5% as determined through the drainage lysimeters. WAE differences between LESA and MESA were high in the dry and warmer months (July) and reduced in spring and winter. Wind speed and vapor pressure deficit (VPD) were the primary drivers to determine WAE for MESA and VPD for LESA. Mixed modeling was used with these drivers to estimate WAE with an accuracy of 3% and 10% respectively. Similarly, ANN models were trained with an error of 2% compares to a 5% error using LMM. The testing outcomes revealed that ANN models can predict the output with accuracy as low as 1%, and the LMM models with 14%. WDEL measuring techniques showed that the three techniques gave mean WDEL values statistically not equal though the CC and EC were close enough and the nighttime CC and EC mean WDEL were not significantly different (p>0.05). The PM and EC WDEL values were highly correlated to the VPD while the CC values with the wind speed. These inferences could help policymakers in saving water, energy, and improve the profit-margins for growers.
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Details
- Title
- Experimental and modeling techniques for accurate measurement of wind drift and evaporation losses to improve water application efficiency of moving sprinkler irrigation systems in Washington
- Creators
- Abid Sarwar
- Contributors
- R. Troy Peters (Advisor)Claudio O. Stockle (Committee Member)Jennifer C. Adam (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Biological Systems Engineering, Department of
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Number of pages
- 152
- Identifiers
- 99900581813801842
- Language
- English
- Resource Type
- Dissertation