Global database of river width, slope, catchment area, meander wavelength, sinuosity, and discharge

1.Summary This document describes the database that accompanies the article submitted to Geophysical Research Letters by Frasson et al. The database is distributed as a set of shapefiles, containing polylines that define the geometry of river centerlines located between 60°N and 56°S, with attributes described below. The shapefiles are organized according to continent and further broken into major basins to allow for manageable file sizes. A more complete dataset is available in the netCDF format upon request (please email Renato Frasson at frasson.1@osu.edu). This database was partially funded by the Algorithm Definition Team contract to the Ohio State University, University of North Carolina at Chapel Hill, and Remote Sensing Solutions, Inc. 2.Polyline geometry The centerline geometry is defined by sets of points located approximately every 30 m based on the Global River Widths from Landsat (GRLW) database (Allen & Pavelsky, 2015; 2018). Each line describes a meander and features the following attributes. 3.Attribute description SegmentID: identification number of the river segment (segments are parts of a river delimited by confluences). lakeFlag: 0 – river, 1 – lake, 2 – river under the influence of tide, 3 – canal, 4 – unable to connect GRWL with HydroSHEDs, 5 – dam, -9999 – no data. Width: average width in the meander, disregarding small river widths assigned to locations undetected by Landsat but known to be inundated. Locations where no width could be produced are marked as -9999. Elevation: mean elevation from SRTM (90m) per river meander in meters. SRTM pixels are assigned to equally spaced points (every ~30m) over the river centerlines using the nearest neighbor approach. The average elevation of all valid points per meander is reported here. Locations where no elevation could be produced are marked as -9999. Slope: water surface slope in centimeter per kilometer. Slope is initially computed over 10 km reaches, then used to compute optimum reach lengths using a modified version of the equation proposed by LeFavour and Alsdorf (2005) in the form of RL=2σ /S, where RL is the optimum reach length, σ is the height uncertainty (5.51 m from LeFavour and Alsdorf, 2005) and S the initial slope estimate. Final slopes are computed over the optimum reach lengths using elevations assigned to the 30 m river points using either classic linear regression or the Theil-Sen estimator depending on which method produces the best coefficient of determination. Locations where no slope could be produced are marked as -9999. Meandwave: Meander wavelength in meters. This is computed by first smoothing the 30 m resolution river centerlines using a 5-point moving average and then identifying inflection points on the smoothed river centerlines. Finally, the meander wavelength takes the value of twice the distance between consecutive inflection points according to the definition given by Leopold and Wolman (1960). Sinuosity: Dimensionless sinuosity of each river meander computed the ratio of the length between meander endpoints measured along the river centerline to half the meander wavelength as defined by Leopold and Wolman (1960). catch_area: Catchment area was derived from flow direction and corresponding flow accumulation grids based on HydroSHEDS (Lehner et al., 2008). The flow accumulation grid describes, for any location (i.e. pixel), the number of upstream raster pixels that drain to that particular location. We translated flow accumulation given in number of pixels into catchment area (in m2) by multiplying the number of pixels flowing to a location by the average area of SRTM pixels according to the latitude of the centroid of the river segment. QWBM: mean annual flow estimated with the water balance model WBMsed (Cohen et al., 2014). Strpwr_len: stream power normalized by width (W/m). Strpwr_are: stream power normalized by area (W/m2). Acknowledgements Use of this database should be acknowledged appropriately. The WBM data used in this database were provided by Dr. Albert Kettner at INSTAAR, University of Colorado at Boulder. References Allen, G. H., and T. M. Pavelsky (2015), Patterns of river width and surface area revealed by the satellite-derived north american river width data set, Geophysical Research Letters, 42(2), 395-402, doi: 10.1002/2014gl062764. Allen, G. H., and T. M. Pavelsky (2018), Global extent of rivers and streams, Science, doi: 10.1126/science.aat0636. Cohen, S., A. J. Kettner, and J. P. M. Syvitski (2014), Global suspended sediment and water discharge dynamics between 1960 and 2010: Continental trends and intra-basin sensitivity, Glob. Planet. Change, 115, 44-58, doi: https://doi.org/10.1016/j.gloplacha.2014.01.011. LeFavour, G., and D. Alsdorf (2005), Water slope and discharge in the amazon river estimated using the shuttle radar topography mission digital elevation model, Geophysical Research Letters, 32(17), doi: 10.1029/2005gl023836. Lehner, B., K. Verdin, and A. Jarvis (2008), New global hydrography derived from spaceborne elevation data, EOS, TRANSACTIONS, AMERICAN GEOPHYSICAL UNION, 89(10), 93-94, doi: doi:10.1029/2008EO100001. Leopold, L. B., and M. G. Wolman (1960), River meanders, Geological Society of America Bulletin, 71(6), 769-793, doi: 10.1130/0016-7606(1960)71[769:RM]2.0.CO;2.