Description:

Water management and design engineering projects such as bridges, dams, and nuclear power plants often require detailed information on local extreme precipitation events.  For example, a high-hazard dam may be required to safely pass the Probable Maximum Flood (PMF).  A PMF is defined as the largest flood that can conceivably occur at a particular location at a particular time of year and is typically based on the Probable Maximum Precipitation (PMP).  A PMP is defined as the greatest depth of precipitation for a given duration meteorologically possible for a given size storm area at a particular location at a particular time of year.  Additionally, determining a robust hydrologic loading curve for some risk assessments requires the use of regional precipitation-frequency estimates.  In the past, federal agencies have provided support to the hydrologic design community through the production of Hydrometeorological Reports (HMRs) and the National Oceanic and Atmospheric Administration’s (NOAA) Atlas 14.  HMRs provide the basis for computing PMP at various durations and spatial scales, while NOAA Atlas 14 represents an atlas of at-site regional precipitation-frequency estimates of various durations out to the 1,000-year return period across most states.  Since the HMRs and NOAA Atlas 14 are not being updated regularly, states have started modernizing PMP and precipitation-frequency estimates using new datasets and methodologies, including numerical weather prediction (NWP) models.  Additionally, with limited fine resolution observed meteorological data, practitioners have looked to storm event data reconstruction developed by numerical weather models use in storm characterization and to calibrate and validate rainfall-runoff models.  There have been tremendous improvements in NWP capabilities during the past few decades, including increased efficiency, higher resolutions, and greater accuracy.  NWP models are now being run at spatial resolutions fine enough to simulate conditions at small watershed scales (e.g., 100s to 1000s of m).  The purpose of this session is to bring together experts developing NWP approaches and/or utilizing NWP output to address design engineering and water management challenges.  Abstracts are encouraged on topics such as generating PMPs and/or PMFs, rainfall-runoff model inputs, coupled atmosphere-hydrology simulations, frequency analyses, uncertainty analyses, and climate change projections.  This session will emphasize the critical link between scientists and engineers in transitioning to modern methodologies that support hydrologic design and decision making.