Floodplain Reconnection in an Incised, Rural Stream in Central Virginia: Working with Geomorphic Processes to Achieve a Desired Restoration Outcome
Gene Haffey
Stantec Consulting, Inc.
Charlottesville, VA
Mike Adams
Stantec Consulting Inc.
Fairfax, VA
Floodplain connectivity, and its concomitant positive effect on stream corridor processes, has long been recognized as a critical element of restoring critical functions to degraded stream systems. Since land use, infrastructure, and other constraints often reduce the practitioner’s ability to fully engage floodplains, it is a welcomed circumstance when these constraints are largely absent. This was the case for a project where Stantec and its partners, GreenVest and EQR, embarked on a quest to restore nearly a mile of perennial stream and 13 acres of floodplain on an old cattle farm in Central Virginia. Past land use practices resulted in highly incised and entrenched streams severely lacking a floodplain to perform its energy dissipation duties. Without this critical feature, channel migration and bank erosion processes had taken over, further exacerbating the situation and introducing Nitrogen and Phosphorus to the system as a result. This presentation will highlight the design emphasis on floodplain processes as a principal objective for restoration and discuss how wood and multiple-thread channel configurations were used to drastically increase floodplain connectivity while simultaneously providing in- and near-stream habitat and supporting the reintroduction of native wetland plants to the landscape.
Topics covered will include how a detailed geomorphic assessment revealed an unnamed tributary to the South River, and its tributary, had incised into the valley bottom such that they were disconnected from the floodplain. Understanding the cause(s) of the current condition of the stream and landscape, and how ongoing riverine processes would continue to cause the channels to evolve, established the foundation upon which a restoration strategy could be built. Moreover, the project’s position in the landscape, including geology and an abundance of water produced by adjacent springs, affected design decisions and strategies. Linkages between these landscape features and design considerations will be discussed in detail, including how floodplain connection guided design decisions and how wood was used to support those objectives. Descriptions of the types of in- and near-stream wood structures and their design process will be provided. Preliminary results, including the nearly immediate observation of spawning evidence and stone roller mounds will be presented, as well.
About Gene Haffey
Gene Haffey is a Senior Restoration Designer at Stantec specializing in stream and wetland restoration, geomorphic stream design, process-based natural channel design, fluvial geomorphology, erosion rate prediction and nutrient load estimation utilizing the BANCS Model, and habitat assessments. Gene’s responsibilities include project management, technical review, river design, project scoping, geomorphic assessments, stream and watershed studies, and community outreach. He has been involved in all phases of stream restoration design including developing project goals and objectives, scoping, field data collection and survey, design calculations, development of plans and specifications, public meetings, permitting, construction oversight and monitoring.
Gene is trained in several different types of stream restoration techniques but primarily focuses on process-based natural channel and floodplain design. Gene serves as a Regional Technical Lead for Stream Restoration in the Mid-Atlantic region for Stantec. He also specializes in the planning, installation, and maintenance of various streamflow monitoring devices and continuous dataloggers in support of hydrology studies on streams and rivers across the United States. Gene loves flyfishing, snowboarding, and surfing all over the world, and playing soccer. He lives in Crozet, Virginia with his wife and two boys (5 and 6).
www.linkedin.com/in/gene-haffey-1a877829
About Mike Adams
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