Establishment of an Altimetric Reference Network over the Amazon Basin using Satellite Radar Altimetry (Topex Poseidon)
Pascal Kosuth(1) , Denizar Blitzkow(2) , and Gérard Cochonneau(3)
UMR TETIS (Cemagref-CIRAD-ENGREF),
Maison de la Télédétection, 500 rue JF Breton,
34093 Montpellier Cedex 5,
(2) University of São Paulo, Brazil, CP 61548 , CEP 05424-970 São Paulo, Brazil
(3) Institut de Recherche pour le Développement, Maison de la Télédétection 500 rue JF Breton, 34093 Montpellier Cedex 5, France
Satellite radar altimetry (Topex/Poseidon T/P) was used to establish a consistent altimetric reference network over the Amazon basin.
A methodology was developed to quantify maximum annual water levels (referred to the geoid, using EGM96 geoid model) at intersections between the satellite ground tracks and the river network. Maximum annual water levels (referred to the geoid) at hydrometric stations where then derived using longitudinal interpolation. Comparison with maximum annual readings at gauges allowed the determination of local orthometric heights at these stations. Altimetric leveling from Topex/Poseidon measurements has been realized for 97 hydrometric stations along 27 740 km of the Amazon hydrographic network.
Validation has been realized both by checking the overall hydraulic consistency of longitudinal river profiles at low and high river stages and by comparing, for 23 hydrometric stations, orthometric heights obtained from T/P measurements with values obtained from bi-frequency GPS positioning. Results show a good agreement between the two techniques (average root mean square error of 0.05 +/- 0.64m). This levelling method allowed the identification of discrepancies in direct geometric land leveling results from Brazilian and Peruvian networks.
These results are of major importance for the study of Amazon river flow dynamics and sediment transport.