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The United States is increasingly becoming an urbanized nation. According to the most recent U.S. Census estimates, approximately 80% of the U.S. population lives in urban areas. Urban populations rely on robust infrastructure systems of transportation, utility services, housing, and more. As regions become progressively developed, water systems such as rivers and streams are diverted, channeled, or cut off and replaced with impervious surfaces such as roads, buildings, and parking lots. The combination of a loss of natural waterways and increased impervious surfaces creates a compounded problem of impeded stormwater drainage and a need for more careful planning and infrastructure to manage storm runoff. Oceana Francis, Ph.D., P.E., Department of Civil and Environmental Engineering and Sea Grant College Program, University of Hawaii at Manoa, recently completed a research project, “Stormwater Drainage Design and Best Management Practices with Applications to Roadways and Climate Change,” that discusses best practices in addressing these issues.  University of Hawaii is part of the Pacific Southwest Region University Transportation Center, and Professor Francis one of the Center’s affiliated researchers.

While comprising a small percentage of regional surface area, roadways play a significant role in stormwater runoff. According to a 2014 Department of Transportation report, transportation-related runoff plays a significant role in water quality impairment, contributing to stormwater’s position as the only growing source of water pollution. In urban environments, a storm drainage system is critical in collecting and discharging stormwater to a neighboring body of water without causing adverse effects. In addition to this drainage system, there are additional measures implemented to actively mitigate stormwater destruction, which can be classified as storage and infiltration types. Some examples of these include constructed wetlands, pervious payments, or rain gardens--all of which contain techniques to mimic natural filtration processes. Combining many practices can improve the levels of pollutant removal and runoff reduction.

Professor Francis’ study found that not enough is known about stormwater management program efficacy. Current best practices are not evaluated consistently, which has resulted in insufficient information on the efficacy of different runoff management practices. This lack of adequate evaluation has led to programs selecting management systems that have not been tested for efficacy and thus lead to further poor management of runoff. Professor Francis concludes that greater communication is needed between stormwater experts and state and local agencies. Communication could include public education, knowledge sharing between industries, trainings, and more. The findings, funded by a Pacific Southwest Region (PSR) University Transportation Center grant, resulted in the development of a five-module training program designed to educate both the general public and local and regional officials on stormwater problems and best practices in creating stormwater runoff management systems.

The five-module course begins by introducing the concept of stormwater management, including key terms and definitions, and an overview of the main components of stormwater management systems. It then moves into greater detail about the different types of runoff, how runoff is generated, and common problems that arise due to excess runoff. The participants engage in a group activity where different management systems are introduced, and participants must choose which systems would be most appropriate to use for a variety of scenarios. The role of climate change is discussed in relation to future considerations for stormwater management. Further instruction is provided on general principles of stormwater and roadway design as it relates to runoff. The program wraps up with a short discussion of the principles and a course evaluation.

Stormwater runoff presents a major ecological, urban design, and roadway concern, especially in an increasingly urbanized society. Presenting information to the public and local leaders creates opportunities to develop more educated and comprehensive discourse on the subject. As city planners and the public become more invested in the topic, more strategic stormwater planning can be anticipated, which one hopes will continue to benefit city residents for generations to come.