Branco river stage gradient determination and Amazon hydrologic studies using GPS water level measurements Cheng, K. C. /Calmant, Stéphane Kuo, C. Y. Tseng, H. Z. Shum, C. K. /Seyler, Frédérique Silva da, J. S. GPS hydrology river stage gradient satellite altimetry This 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. 2009 text https://www.documentation.ird.fr/hor/PAR00004141 PAR00004141 Cheng 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. 2009, 32 (3), 267-283 EN