Planning and Communicating Risk for Nonstationary Natural Hazards
Abstract: This work
investigates the probabilistic behavior of the time to occurrence of natural hazards
that exhibit nonstationarity through time with special attention to floods. Chapter one
combines existing theoretical and empirical results from the literature to provide the
first general, comprehensive description of the probabilistic behavior of the return
period and reliability under n... read moreonstationarity for the case of floods. Findings indicate
that under nonstationarity, the underlying distribution of the return period exhibits a
more complex shape than the exponential distribution under stationary conditions.
Chapter two provides an introduction to the field of hazard function analysis (HFA) for
flood events under nonstationary conditions, and demonstrates how HFA can be used to
characterize the probability distribution of the return period and the reliability - two
primary metrics in hydrologic design. This is the first paper to explicitly link the
probabilistic properties of a flood series (X) with failure times (T) associated with a
particular infrastructure design. This work shows that HFA is a relevant and useful
approach for characterizing nonstationary flood series, and can provide engineers with
tools to support hydrologic design decisions under nonstationary conditions. Chapter
three investigates the suitability of HFA to characterize a wide class of nonstationary
natural hazards whose peaks over threshold (POT) magnitudes are assumed to follow the
widely applied Generalized Pareto (GP) model. Such natural hazards might include: wind
speeds, landslides, wildfires, precipitation, streamflow, sea levels, and earthquakes.
The hazard function equations are derived for a natural hazard event series (X) whose
POT follows the 2-parameter GP distribution. The derived model and HFA are used to
compute reliabilities and average return periods associated with nonstationary behavior
of the original hazard series. These generalized results for a wide class of natural
hazards are consistent with the results in Chapters 1 and 2 for floods: nonstationarity
adds complexity to computation of traditional design metrics and changes the shape of
the probability distribution of the return period. General implications for planning and
design of nonstationary natural hazards are
Thesis (Ph.D.)--Tufts University, 2016.
Submitted to the Dept. of Civil Engineering.
Advisor: Richard Vogel.
Committee: Daene McKinney, Kaveh Madani, and Casey Brown.
Keywords: Environmental engineering, and Water resources management.read less