Citation:

Jalowska, A. Developing Intensity-Duration-Frequency (IDF) Curves from Modeled Meteorological Fields to Examine Extreme Precipitation Events Under Future Climate Scenarios. Invited talk at UNC Marine Science Department, Chapel Hill, NC, November 14, 2018.

Impact/Purpose:

invited talk at UNC Marine Science Department

Description:

Extreme precipitation causes flooding, landslides and erosion, which has important implications for watersheds, agriculture, urban and rural development, public infrastructure, and human health. Based on 38-year averages from 1980 to 2018, extreme precipitation events cause at least 12 casualties and $8.8 billion in damage across the U.S. each year. Analysis of U.S. historical climate records indicates that there has been an increase in frequency and intensity of extreme precipitation in Eastern U.S since the 1950s. Recent climate research suggests that the frequency and magnitude of extreme precipitation in the U.S. will continue to increase throughout the twenty-first century. Intensity-Duration-Frequency (IDF) curves are commonly used to account for extreme precipitation events in environmental and urban planning. The IDF curves estimate a frequency of occurrence of extreme precipitation events (rainfall amount within a given period) based on frequency analyses of the available historical observational data. Long-term observations of precipitation data are not available for many locations, motivating a need to develop models that can reasonably estimate hourly precipitation for historical and future periods. Here, we present extreme precipitation analyses for 3 cities (Cinncinati, OH; Raleigh, NC; Atlanta, GA) in the Eastern U.S., using observed data and dynamically downscaled 36-km and 12-km simulations of the Weather Research and Forecasting (WRF) model for a 23-year historical period (1988–2010). The results demonstrated that modeled meteorological data at 36-km resolution from WRF can be used with fidelity to represent historical extreme precipitation events at durations of 6 hours to 18 hours. With that confidence, same methodologies and analyses were applied to project future extreme precipitation probabilities for 75 years (2025–2100) by dynamically downscaling future climate projected by the Community Earth System Model (CESM) under Representative Concentration Pathways 4.5 and 8.5 (RCP 4.5 and RCP 8.5) to 36-km resolution. Under both future scenarios, long-term trends for precipitation reflect higher intensities but less frequent events. The eventual goal of this work is to include these techniques to build IDF curves in the EPA’s Storm Water Management Model (SWMM) and Climate Resilience Evaluation and Awareness Tool (CREAT), allowing public communities to aid in storm water management planning.

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