Resilience Strategies for Flash Flooding

The United States is facing increasingly frequent and intense precipitation events and ever higher damages from flooding each year due to climate change and urbanization. Communities, counties, and states are responding by upgrading stormwater and sewage systems with a growing emphasis on strategies to become more resilient to flooding. This paper outlines resilience strategies for flash flooding, with an emphasis on riverine and precipitation-caused flooding. For each strategy, the paper will discuss primary and co-benefits, and associated costs. Costs and benefits will vary based on local conditions and climate projections. A case study of Philadelphia’s green infrastructure plan, Green City, Clean Waters, provides an example of an applied comprehensive green infrastructure plan based on a cost-benefit analysis. The paper concludes with high-level insights and a list of publications and interactive tools available to start building resilience to flooding.

Key Takeaways

  • Heavier and more intense precipitation nationwide, compounded by urban development, is projected to lead to more frequent and severe flooding by the end of century.
  • Unless communities adapt, intense precipitation will cause greater stormwater runoff, agricultural runoff, and sewer system overflows that threaten water quality and public health.
  • Green infrastructure and open space conservation manage precipitation by retaining and infiltrating, and sometimes treating excess stormwater onsite.
  • Green infrastructure can be integrated in urban and suburban landscapes in the form of street trees, permeable pavement, rain gardens, rainwater harvesting, and detention structures.
  • In addition to reducing flood damages, benefits of green infrastructure include energy savings, reduced sewer costs, improved public health, spaces for recreation and environmental benefits.