Cleveland, Ohio has experienced a 16.3% increase in the number of days with precipitation in the top 1% of the daily total precipitation and an increase of 22.2% in the amount of rain falling in these very heavy precipitation events in 1981-2010 compared to 1961-1990 (GLISA 2016). Out of concern for the impact of this increased occurrence of extreme storms on flood resiliency and stormwater management, CRWP secured a NOAA Coastal Storms grant through Ohio Sea Grant at The Ohio State University in 2014 to evaluate the need for updating our recommendations for bioretention and permeable pavement designs and comprehensive stormwater, flood damage reduction, and riparian setback regulations.
This work supported updates to CRWP’s model comprehensive stormwater code and confirmed the value of adopting and implementing comprehensive stormwater, flood damage reduction, and riparian setback regulations for flood resiliency.  Please see this summary of CRWP code updates and rationale for more information.
North Carolina State University evaluated future performance of 3 bioretention cells and 3 permeable pavement bays using projections from University of Tennessee Civil Engineering Department/Oak Ridge National Laboratory for 2055-2059 based on Gao et al. 2012.  These data indicate that all studied bioretention cells will have increases in overflow (untreated flow to the storm system) in the future, but 2 of the cells will actually have increased runoff reduction.  One of the permeable pavement bays will have increases in surface runoff (water traveling untreated over the pavement surface into the storm system) and decreases in runoff reduction.  For the bioretention cells expected to have more overflow in the future, ponding depth or media depth would need to be increased or loading ratio would need to be increased to maintain overflow volumes in future condition.  For the permeable pavement bay with decreased performance in the future, the loading ratio would need reduced or the aggregate depth would need increased.  [Please see this summary for more information on this work - coming soon ].
Our team offered a training for engineers on permeable pavement and bioretention design on April 18, 2016 and one for planners, floodplain managers, and other interested parties on strategies for increasing flood resiliency on May 12, 2016.  Presentations are available in the sidebar for both trainings.