A Sustainable and Resilient Approach to Managing Flooding, Water Quality, and Ecosystems for Rivers and Streams

Rivers and streams provide stormwater conveyance and storage, habitat, food, navigation, recreation and aesthetic beauty. For these reasons, many of the largest and most populous cities in the world lie along rivers and coasts, and healthy productive waters are key to public health and prosperity.Over time, development has encroached on wetland, riparian buffer and floodplain areas causing cumulative impacts. Many systems are experiencing issues with increased flooding and erosion; adverse impacts to water quality from excess levels of nutrients, sediments, bacteria, oils and grease, and metals; and loss of habitat and declining health of flora and fauna.Cumulative impacts are often a result of inadequate site runoff requirements and standard floodplain management policies that allow floodplain filling to raise structures. Buildings, roads and conveyance channels are also allowed to be filled, allowing as much as a one-foot increase in protected floodways. These practices often lead to snowballing impacts, and ultimate flood stage increases can be significantly greater than one foot, especially in flat areas and floodplains.Integrated stormwater, riparian buffer and floodplain management programs offer sustainable opportunities to protect and enhance rivers and streams by considering all water as a resource to be managed rather than disposed. This approach provides multiple benefits and cost savings in a resilient manner to protect systems and support adaptation for climate change. Benefits include riverine and tidal flood control, erosion control and reduced sedimentation, water quality improvement, increased aquifer recharge, stormwater harvesting and alternative water supply, shoreline and ecosystem restoration, and public parks and amenities.This paper presents a sustainable approach from more than 32 years of comprehensive stormwater and river management program experience, including existing system retrofits, new development and redevelopment controls. It includes discussion of lessons learned and the refinement of standards and criteria over that timeframe. It includes references to multiple ongoing programs and with an example case study.The approach is founded on three key elements working together to leverage the benefits of each:Protection of onsite storage, floodplain storage and floodwaysProtection and management of onsite vegetation, riparian buffer zones and stream habitatIntegrated stormwater management approaches for stormwater quantity and quality