WHAT YOU DON’T KNOW CAN HURT YOU: RIVERSMART COMMUNITIES AND THE IMPORTANCE OF FLUVIAL GEOMORPHOLOGY ASSESSMENTS IN MASSACHUSETTS
A careful assessment of the wide array of FGM metrics can give researchers insight into patterns of erosion and deposition, stream power, flood risks, habitat health, and future changes. Such data can be used to define sites with high erosion or inundation risk, or to delineate the boundaries of the river corridor within which human activities are likely to interfere with channel avulsion, meandering, flooding, and riparian functions that are necessary to river stability. A large number FGM assessment tools and protocols have been developed, and vary in approach, goal, ease of use, and output. Most depend on in-situ observations by field crews, but improvements in remote-sensing technologies and GIS analysis methods present new opportunities for watershed-wide FGM assessments that cover a larger area at less cost than field-based methods.
In this paper we analyze a variety of stream geomorphic assessment protocols in order to both educate residents and municipal leaders who would benefit from a better understanding of this field, as well as to inform the future development of an official Massachusetts protocol. Additionally, we explore available ArcGIS tools that can be used to extract FGM parameters from digital elevation models (DEMs). Results derived from DEMs of different resolutions and from different sources, including digital orthophotograph and LiDAR datasets, are compared. Field-based FGM assessment data is used as a baseline for comparison.