Presenter: Ms. Kathleen Moore, Ph.D. Candidate in Geography
Doctoral Advisors: Dr. Julia Jones (Geography, CEOAS) and Dr. William Jaeger (Applied Economics)
Abstract: Reservoir systems in the western US are managed to serve two main
competing purposes: to reduce flooding during the winter and spring, and
to provide water supply for multiple uses during the summer. Because
the storage capacity of a reservoir cannot be used for both flood damage
reduction and water storage at the same time, these two uses are traded
off as the reservoir fills during the transition from the wet to the
dry season. Climate change, population growth, and development may
exacerbate dry season water scarcity and increase winter flood risk,
implying a need to critically evaluate reservoir operations. Focusing on
the Willamette River Basin, Oregon, we used a dynamic programming
approach to social welfare maximization, and derived the optimal
reservoir fill path for both historical conditions and future scenarios
of climate and social change. Anticipated future increases in winter
flood risk and reductions in spring streamflow led to an optimal fill
path in which reservoir fill began earlier and proceeded more slowly,
compared to the optimal fill path derived under historical conditions.
The analysis finds that increased value of stored water associated with
increased demand for reservoir recreation or irrigation water for
agriculture will shift the initiation of optimal reservoir fill to an
earlier date and increase the likelihood of achieving full pool by the
end of May. Conversely, an increase in the costs of flooding driven by
land use change and development in the floodplain associated with
increasing population led to an optimal fill path in which reservoir
fill began later and the final optimal reservoir fill level was
decreased, compared to the optimal fill path under historical
conditions. These findings may contribute to policies for adapting
reservoir management to future changes in water supply and demand.This research was part of the
Willamette Water 2100 project.
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