Thesis (Ph. D.)--University of Adelaide, 1987. / Includes bibliographical references (leaves 146-152).

Flooding in semi-arid streams is highly variable but distinguished from its humid counterpart in terms of forcing conditions, landscape response, flood severity, and stream-aquifer connectivity. These floods have the potential for great benefit in a water-limited environment, but also great devastation when powerful floods encounter human infrastructure. This dissertation employs an integrative approach to address several facets of flooding in semi-arid streams. In particular, information from field sampling during flood events combined with modeling are used to evaluate the processes of post-disturbance sediment transport, flood routing, transient bank storage, and stream disconnection. The major findings show: (1) Suspended sediment composition in floods following wildfire depends on the number, timing, and intensity of preceding storms and flood events, implicating overland flow hillslope processes as a dominant mass wasting mechanism (2) Isotopic chemographs for two representative intense convective storm events demonstrate that the flash flood bore develops from predominantly high elevation event water that overcomes, incorporates, and pushes baseflow to the front of the hydrograph peak (3) Isotope information combined with a plug-flow model can simulate this flood bore mixing process simultaneously in two separate canyons in the basin in order to calculate the timing and quantity of flow; this could be a useful tool for watersheds that are not extensively instrumented, or for calibrating a more complex or distributed model, (4) For a stream connected to an underlying aquifer, a circulation pattern develops at the onset of flooding that causes an upwelling of antecedent water into the unsaturated zone, challenging the assumptions of one dimensional, lateral flow and transport into the streambank, and (5) For small stream-aquifer disconnections, large increases in infiltration, large decreases in seepage, and a dominantly vertical profile for floodwater were observed. This implies that a stream that supports a wide riparian corridor may be in danger of vegetation die-offs with even shallow depletions of the groundwater table.

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published_or_final_version / Biological Sciences / Doctoral / Doctor of Philosophy

Hundreds of international water institutions have been established over the last three decades in an attempt to address global water issues. Despite great efforts by these and other institutions, a significant percentage of the world's population still lacks access to clean water and sanitation facilities. Although billions of dollars have been spent on development, infrastructure and public health endeavors meant to tackle such issues, little research has been done to examine how these often influential organizations known as global water initiatives (GWIs) are addressing such urgent issues in the face of a rapidly changing climate. As water is central to the hydrological cycle, and affected by changes in climate, examining the role of GWIs in the use and translation of climate-change science may lead to better understanding of the mechanisms through which such organizations are linking climate change to their work in water management and governance. By examining 170 GWIs through two distinct phases of methodology, it was found that GWIs are addressing climate change issues through their work with water. Evidence presented in this research supports the claim that GWIs have adopted climate change as part of their overall operational frameworks and that their missions may be supported and ultimately achieved through the addition of climate-change science. While GWIs are shown to use climate-change science in setting objectives, and in decision making, it was also found that issues of cost, access, and utility remain as significant barriers. Findings presented in this study also suggest that intergovernmental and nongovernmental organizations, alongside professional societies dedicated to trades and disciplines related to water, are among the most important categories of GWIs, and as such, operate within a series of complex networks. This research also revealed that activities and outputs of GWIs enhance water management and governance, contribute to the world's knowledge base on water, and highlight the need to acknowledge GWIs as an important and prominent aspect of the global water dialogue.

Thesis (Ph. D. - Plant Sciences)--University of Arizona, 1986. / Includes bibliographical references (leaves 109-117).

Thesis (M. S. - Renewable Natural Resources)--University of Arizona, 1998. / Includes bibliographical references (leaves 134-138).