Positioning Risk – Climate variability, Nonstationarity and Hydrological Extremes

Water and the Changing Climate
Chair: Jeanne VanBriesen (Carnegie Mellon University)
Global climate change is changing the frequency and magnitude of precipitation events in many regions, and further change is expected. Effects on precipitation-dependent events (drought, flood) as well as on rainfall-dependent systems (water supply, energy systems, agriculture) will challenge our study and management of hydrologic systems. This session will explore methods to study, model, and plan for hydrologic systems under changing climactic conditions.

\"Positioning Risk – Climate variability, Nonstationarity and Hydrological Extremes\"
Speaker: Ana Barros (Duke University)

The notion of positioning risk in the context of nonstationarity and future climate is based on the premise that the metrics of risk change conditional on climate regime. The IPCC defines climate regime as a state of the climate system that occurs more frequently than nearby states due to either more persistence or more frequent recurrence, that is a local maximum in the probability density function. First, Global climate Model simulations of past and current climate are analyzed against observations to assess the predictability of multi-decadal to century scale climate regimes relevant to hydrological extremes (precipitation and streamflow) in the Southeast US. Next, we separately address high and low precipitation statistics and space-time variability conditional on climate regime and physiography, and explore the development of a framework for adaptively positioning risk in the assessment of future extremes that also incorporates understanding of regional and local hydrology.