Branco river stage gradient determination and Amazon hydrologic studies using GPS water level measurementsCheng, K. C.Calmant, StéphaneKuo, C. Y.Tseng, H. Z.Shum, C. K.Seyler, FrédériqueSilva da, J. S.GPS hydrologyriver stage gradientsatellite altimetryThis study presents the result of a demonstration of Global Positioning System (GPS) hydrologic studies in a remote area. A GPS campaign was conducted using a GPS-equipped vessel and a GPS buoy to measure water level along Rio Branco, a tributary of the Amazon. The GPS water level data agree well with river gauge data and with ENVISAT radar altimeter measurements. The GPS-estimated river stage gradient of Rio Branco is 5.75 +/- 0.48 cm/km with 99% confidence, which is higher than previous estimates. This result also agrees well with ENVISAT altimetry results.2009texthttp://www.documentation.ird.fr/hor/PAR00004141oai:ird.fr:PAR00004141Cheng K. C., Calmant Stéphane, Kuo C. Y., Tseng H. Z., Shum C. K., Seyler Frédérique, Silva da J. S. Branco river stage gradient determination and Amazon hydrologic studies using GPS water level measurements. Marine Geodesy, 2009, 32 (3), p. 267-283.