This dataset contains topographic cross sections spanning the river channel, floodplain and valley walls for an approximately 500 meter (m) reach of the Kalamazoo River upstream of Plainwell, Michigan (MI). The five cross sections are oriented perpendicular to the valley axis and spaced evenly along the 500m reach to represent variability in channel and floodplain geometry. Bankfull hydraulic geometry attributes and complexity metrics were calculated for each cross section, as were floodplain inundation dimensions for flow stages at multiples ranging from 0.9 to 2.0 of the bankfull depth. The cross section data were extracted from a digital elevation model (DEM) comprising topographic and bathymetric data collected by several different methods. Bathymetric data in the river channel were collected in October, 2021 with a single beam sonar and Acoustic Current Doppler Profiler operated along two longitudinal transects and 48 cross-sectional transects, respectively. River bank topographic data were collected with a backpack-mounted terrestrial lidar unit concurrently with the bathymetric data. Floodplain elevations were obtained from aerial lidar data collected in 2015. All ground points from the respective datasets were projected to the same coordinate system and used to generate a DEM with 1m resolution covering the channel bed, banks, and floodplain, and valley walls through the reference reach. Cross-section data are provided in tabular and graphical form in an Excel spreadsheet. The data are also provided as individual CSV files for each cross-section (in a zipped archive), which contain X and Y coordinates in addition to elevations and cross-sectional distance values.The CSV files contain the same data as the Mecklenburg Excel files, but are provided additionally in that format to be readable by non-proprietary, open-source software and to provide the X,Y coordinate data for each transect point. The spatial location of the cross-sections is provided by an associated polyline shapefile contained in this data release. Cross-sections are named by their distance, in meters, downstream from the start of the reference reach.