Projected Trends of Great Plains Extreme Rainfall Return Intervals Using CMIP5 LOCA Ensembles

Climate change, as it progresses through the 21^st century, is expected to affect the amount and frequency of rainfall events. These changes in peak rainfall return frequencies as well as periods between wetting rains will impact infrastructure, sediment loading, wildland fire, flood plain extent, and some elements of disaster planning.

Detectability of rainfall extremes is challenging due to the discontinuous nature of rainfall and non-local effects (e.g. flooding) whereby extreme rain in one location can impact hydrologic units downstream from the event. Likewise, single future scenarios due to isolated rainfall events cannot effectively capture the potential of extreme events for a given future time interval, especially under nonstationary climate change.

Our approach is to use CMIP5 LOCA ensembles regionally localized and aggregated by hydrologic units or climate zone divisions to assess changes in extreme rainfall event returns and the implication of those changes. Our results show that in some regions in the Central US and Great Plains, daily rainfall event totals currently having a 30-year return interval could equate return intervals as frequent as 15 years by the mid 21^st Century. We will present these results in the context of hydrologic modeling and planning for extreme events.