Climate change impacts on potential evapotranspiration, drought, and runoff in eastern Australia

Shi, Lijie

Climate change impacts on potential evapotranspiration, drought, and runoff in eastern Australia

Shi, Lijie

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Publication Type:: Thesis
Issue Date:: 2021

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Field	Value	Language
dc.contributor.author	Shi, Lijie
dc.date.accessioned	2021-10-20T01:27:54Z
dc.date.available	2021-10-20T01:27:54Z
dc.date.issued	2021
dc.identifier.uri	http://hdl.handle.net/10453/151153
dc.description	University of Technology Sydney. Faculty of Science.	en_US.UTF-8
dc.description.abstract	As one of the most arid continents, Australia is exposed to drought and water scarcity. The changing climate is likely to intrigue more drought occurrence and make water scarcity more severe. In this context, it is important to investigate the influence of climate change on drought and water availability in Australia. This study aimed to investigate the possible change of potential evapotranspiration (ETp), drought occurrence, and runoff under future climate scenarios, thus providing useful information to mitigate the adverse impacts of climate change on crop production and water resource management. In specific, four inter-related studies were carried out based on widely used empirical ETp models, random forest method, statistical indices, standardized precipitation evapotranspiration index (SPEI), Xinanjiang model, and a three-way analysis of variance. Findings from these studies suggested that: (1) radiation based models including Jensen-Haise, Abtew, modified Makkink, and Turc and temperature-based model Hargreaves were able to reasonably estimate ETp rates, capture its temporal evolution, and periodically oscillation; (2) random forest-based ETp models generally outperformed empirical ETp models which required the same climatic inputs; (2) ETp was likely to increase in the future and the increase could be mostly explained by the increase in temperature and solar radiation; (3) Droughts, especially for moderate and severe droughts were also likely to increase and the increases in spring and winter were larger than that in summer and autumn. The increase in ETp explained more of the change in drought than the decrease in rainfall did; (4) There were obvious decreases in spring and winter runoff whereas the mean changes in summer and autumn runoff were subtle. The changes in runoff were consistent with the pattern of changes in rainfall and the difference in ETp inputs barely influenced runoff projection; (5) GCMs, RCPs, or their interaction generally were the dominant factors resulting in uncertainty in the projections of ETp, drought, and runoff in future climate scenarios. This study confirmed the increase in air evaporative demand, drought occurrence, and water scarcity in eastern Australia and highlighted the necessary to for farmers and policy makers take measures to adapt to the changing climate. The possible measures include cultivating drought-resistant varieties, adjusting the planting structure, improving the capability of drought forecast, and changing the seeding windows accordingly.	en_US.UTF-8
dc.format	Thesis (PhD)
dc.language.iso	en_US	en_US.UTF-8
dc.relation	https://opus.lib.uts.edu.au/bitstream/10453/151153/2/02whole.pdf
dc.rights	The author owns the copyright in this thesis including all reproduction and reuse rights for the work. The work may not be altered without the permission of the copyright owner. Attribution is essential when quoting or paraphrasing from this thesis.
dc.rights	au.edu.uts.lib/ppc
dc.rights	info:eu-repo/semantics/openAccess
dc.title	Climate change impacts on potential evapotranspiration, drought, and runoff in eastern Australia	en_US.UTF-8
dc.type	Thesis
utslib.copyright.status	open_access	*

Abstract:

As one of the most arid continents, Australia is exposed to drought and water scarcity. The changing climate is likely to intrigue more drought occurrence and make water scarcity more severe. In this context, it is important to investigate the influence of climate change on drought and water availability in Australia. This study aimed to investigate the possible change of potential evapotranspiration (ETp), drought occurrence, and runoff under future climate scenarios, thus providing useful information to mitigate the adverse impacts of climate change on crop production and water resource management. In specific, four inter-related studies were carried out based on widely used empirical ETp models, random forest method, statistical indices, standardized precipitation evapotranspiration index (SPEI), Xinanjiang model, and a three-way analysis of variance. Findings from these studies suggested that: (1) radiation based models including Jensen-Haise, Abtew, modified Makkink, and Turc and temperature-based model Hargreaves were able to reasonably estimate ETp rates, capture its temporal evolution, and periodically oscillation; (2) random forest-based ETp models generally outperformed empirical ETp models which required the same climatic inputs; (2) ETp was likely to increase in the future and the increase could be mostly explained by the increase in temperature and solar radiation; (3) Droughts, especially for moderate and severe droughts were also likely to increase and the increases in spring and winter were larger than that in summer and autumn. The increase in ETp explained more of the change in drought than the decrease in rainfall did; (4) There were obvious decreases in spring and winter runoff whereas the mean changes in summer and autumn runoff were subtle. The changes in runoff were consistent with the pattern of changes in rainfall and the difference in ETp inputs barely influenced runoff projection; (5) GCMs, RCPs, or their interaction generally were the dominant factors resulting in uncertainty in the projections of ETp, drought, and runoff in future climate scenarios. This study confirmed the increase in air evaporative demand, drought occurrence, and water scarcity in eastern Australia and highlighted the necessary to for farmers and policy makers take measures to adapt to the changing climate. The possible measures include cultivating drought-resistant varieties, adjusting the planting structure, improving the capability of drought forecast, and changing the seeding windows accordingly.

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