DOI: 10.5066/p1ekdfl9
title: Hydraulic Channel Geometry of Selected Tidal Rivers in Coastal Massachusetts, 2024

description: 
The U.S. Geological Survey (USGS) collected elevation and location data at 24 selected river reaches along the coast of Massachusetts in 2024. These data were collected in cooperation with the Massachusetts Department of Environmental Protection (MassDEP) and the University of Massachusetts at Amherst (UMass Amherst). The 24 tidal rivers were selected based on the following criteria: spatial distribution along the coast, mean tidal range within 3 to 10 feet (Buzzards Bay National Estuary Program, 2017), upstream drainage-area size of under 30 square miles, and proximity to underserved populations (Commonwealth of Massachusetts, 2024). Channel bottom elevations were surveyed at 3 to 6 cross-section locations per reach; where possible, surveys were conducted upstream of tidal tributaries. Bridge or culvert structures were also surveyed at 18 of the 24 tidal river reaches. Structure surveys included measurements of important structural dimensions that include: height, width, and elevation of the opening or openings through which water would pass, elevations of the road or top of structure including any railings that would block the flow of water during normal or high flows, and cross sections of elevations of the channel bottom and associated top of bank areas both upstream and downstream from the structures.  

All surveys were conducted by wading, kayaking, or by canoeing the stream channel except for the Neponset River reach where an acoustic Doppler current profiler (ADCP) was used to collect river bottom elevations given the large size of the reach. Additional top of bank land-surface elevation points were collected on each side of the channel wherever possible. Structures were surveyed following techniques outlined in Taylor and Simeone (2021), while cross sections were surveyed to meet Level IV standards outlined in a U.S. Geological Survey Techniques and Methods report (Rydlund and Densmore, 2012). Elevations were measured relative to the North American Vertical Datum of 1988 (NAVD88) using real-time Global Navigation Satellite System (GNSS) techniques with Level IV positional-accuracy for cross sections and Level II positional-accuracy for all structures (Rydlund and Densmore, 2012). At some cross sections and structures and where tree-canopy cover created interference with direct GNSS observations, optical techniques including five-arc-second total stations were used to complete the survey (Noll and Rydlund, 2020). 

This data release includes 24 zip files containing measured land-surface and river bottom elevation points along cross sections as well as supplemental information documenting each location in photographs and sketches. A shapefile (.shp) and map (.jpg) are also included and show the locations of the 24 surveyed river reaches, associated tidal ranges, and locations of environmental justice areas. The zip file name for each tidal river reach is identified by the name of the tidal river reach followed by a three-letter acronym of the river name (e.g., ForestRiver_FOR.zip). Within each zip file are five categorical folders titled: “Control”, “Data”, "Notes”, “Photos”, and “Sketches”. These folders contain subfolders with data in comma-separated-values files (.csv) or images in .jpg format. The five categorical folders contain subfolders with an alphanumeric cross-section identification (e.g., FOR_ 0100, FOR_0200, FOR_0300, FOR_0400), where the letters indicate river name (e.g., Forest River is FOR) and the numbers indicate the cross-section number (e.g., 0100), which increase in the upstream direction of the river reach.  

Eighteen bridge or culvert structures were surveyed. In most cases, the structure itself as well as four accompanying cross sections (approach, upstream face, downstream face, and exit) are all surveyed in one job and the data included in a single .csv file (e.g., GLF_0200). In some cases, the approach, structure, and exit are treated as separate surveys and the data are in three separate .csv files. For example, the approach and exit cross sections for structure FOR_0100 are labeled as FOR_0101 and FOR_0099, respectively. Text (.txt) files are included in sub-folders and provide additional information on the surveyed cross sections. A data dictionary text file is attached below describing acronyms used in .csv files found in the “Data” and “Control” folders.