Development Induced Changes in Stream Channel Morphology and Considerations for Future Management of Water Resources

Water resource management is becoming a necessity as more of the nation's wetlands and headwater streams are being impacted by development. An important management tool for protecting water resources is avoidance and minimization of direct impacts, which is mandated through federal and state regulations. Fixed width stream buffers and storm water management to treat non point source pollutants and control discharges are two additional management tools used protect water resources. These methods can be effective, but may neglect to address specific indirect impacts to stream stability, wetland function, and the function of the system as a whole. Indirect effects of development within a watershed include the changes to the stream's hydrograph and internal stresses, which induce morphological changes to stream channels over time. In 2001, two projects that used avoidance and minimization of direct impacts to the greatest extent practicable during the planning and design process were constructed. One project converted 73 acres of forested land adjacent to a large forested wetland system, which provides habitat for rare threatened and endangered species to commercial development; the other converted 45-acres of mixed pasture, open and forested land and sparse residential development adjacent to wetlands and a headwater stream to commercial development. Construction of both projects was completed in February 2004. The headwater stream that receives runoff from the development site was monitored for stream stability and water quality during and after construction to document changes in stream morphology resulting from the changes in the watershed. The monitoring program will continue for several years to measure and evaluate trends in the morphological changes. The goal of this study is to develop a tool that allows water resource managers and regulators to better control indirect impacts to water resources by considering the characteristics of the watershed and stream morphology when determining the appropriate avoidance and minimization strategies to protect water resources.