Promoting Porosity: Adaptation of Urban Roadways for Flooding and Climate Change

Using environmental and transportation data from a dense urban watershed in Honolulu, Hawaii, the use of porous pavement is investigated as a strategy for mitigation and adaptation to flooding events and increasing resilience to climate change. The potential for water capture to abate pollution and recharge aquifers is also considered. This research is motivated by the increased likelihood of flooding and demands for improved transportation resilience. Based on the impacts from a 2004 flood in Honolulu, installation of permeable asphalt pavements on residential streets with low-to-moderate traffic volumes, and 2% to 5% slope, flooding would be significantly reduced. With the highest absorption rate (90%), 1.8 trillion gal/year could be diverted, while, with a lower absorption rate (50%), 691 billion gallons would be captured. The transformation of roadways, culverts, stormwater infrastructure, and existing drainage systems requires a different approach to planning, designing, construction, and paving (or not) roadways. Adoption of nature-based transportation solutions and integration with low impact development standards by local governments are needed to reduce flood risk and improve environmental quality. Design criteria are reviewed in the context of a specific watershed but also for development and application of methods in other locations. Improved communications and collaboration between researchers, land use planners, and practitioners will further advance resilience through innovation and adaptation to climate change. Porosity is also a factor and requires appreciation for nature and understanding of the seepage and conveyance of new ideas.