Along Stream Profiles of Ohio River Discharge from Satellite Elevation Mapping
Abstract
SRTM DEM data are used to derive the surface slope of the Ohio River, which is then used to compute a continuous discharge profile along 1528 km of river flow-distance. The study reach extends from Montgomery Dam, Pennsylvania to Cairo, Illinois, the confluence of the Ohio with the Mississippi River. Flow distance data are derived from the DEM data with the use of Rivertools software and are slightly adjusted as dictated by USGS raster maps. Manning's equation is used to estimate velocity, with all parameters remotely sensed except depth and Manning's roughness coefficient, n. River widths are derived from land-use classification imagery (NLCD92) developed by the USGS Land Cover Institute. Channel width is computed at each pixel along a center line obtained by thresholding the Laplacian of an image containing the distance from each channel pixel to the nearest bank pixel. River depths are extrapolated from sparse in-situ stream gauge measurements with the use of a logarithmic algorithm that relates width, slope, and flow-distance. Discharge values are then computed every half-kilometer of river flow-distance. Standard deviations, interpreted as potential errors, of several parameters were calculated following the subtraction of 4^{th} order polynomial fits. Elevation standard deviation is 8.23 m, width is 135 m; depth is 1.15 m; and the resulting discharge standard deviation is 466 m3/s. The along stream profile of discharge is smooth, with a lower slope near the beginning of the study reach, and has some deviations from the 4th order polynomial indicative of local flow influences. Only one gauged discharge measurement is available for the SRTM time period (February 11-22, 2000) and our 4th-order discharge polynomial fit differs from this point by 5.1% (557 m3/s): the gauged value is 10973 m3/s, while that derived from the polynomial fit is 11530 m3/s. We are presently developing similar analyses of SRTM based water surface elevation and discharge for the Mississippi and Missouri Rivers.
state.edu/water/- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2006
- Bibcode:
- 2006AGUFM.H23A1460K
- Keywords:
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- 1855 Remote sensing (1640);
- 1860 Streamflow;
- 1880 Water management (6334);
- 1895 Instruments and techniques: monitoring