HR: 1340h
AN: H23E-1178    [Abstracts]
TI: Channel Slopes on Amazon Basin Rivers From the SRTM DEM
AU: * Hendricks, G
EM: ghendric@ucla.edu
AF: Department of Geography, University of California, Los Angeles, 1255 Bunche Hall, Los Angeles, CA 90095
AU: Alsdorf, D E
EM: alsdorf@geog.ucla.edu
AF: Department of Geography, University of California, Los Angeles, 1255 Bunche Hall, Los Angeles, CA 90095
AB: Changes in surface water storage (S) and discharge (Q) are poorly known globally but are critical for constraining the terrestrial branch of the water cycle. To date, only the SRTM mission provides global measurements of both surface water area and elevation. However, little is known about the instrument performance for collecting delta-S and Q. The Amazon Basin is a particularly appealing target given its sparse gauge density, lack of continuous and reliable slope data that can be used in the estimation of discharge, and complexity of flow hydraulics. We have used SRTM elevation data in conjunction with flow distance to estimate water surface slope for the area 0S-8S, 72W-54W. Using a 3rd order polynomial fit to the distance-elevation data, slope values of the mainstem Amazon range from less than 0.5 cm km-1 downstream of Obidos to 4.10 cm km-1 3000 km upstream of this location. The central Amazon slope ranges from 1.86 cm km-1 to 3.10 cm km-1 from Manaus to the Rio Japura (about 800 km upstream). Local slopes for specific gauge locations were achieved using both a linear fit to the data and the polynomial fit. The slope value at Itapeua, about 430 km upstream of Manaus, was found to be 3.22 cm km-1 using a linear fit, and 2.65 - 2.79 cm km-1 using a 3rd order polynomial fit, for a reach of 24 km. The slope value for Manacapuru, about 90 km upstream of Manaus, was determined to be 3.56 cm km-1 using a linear fit and 1.97 - 2.12 cm km-1 for a reach of 70 km centered on the local gauge. This slope is used in the Manning equation (n = 0.03) with depth values from navigation charts and river width measured from JERS-1 SAR imagery to yield discharge values for Manacapuru of 93,500 m3 sec-1and for Itapeua of 81,900 m3 sec-1. The observed discharge value at the Manacapuru gauge is 96,300 m3 sec-1 over an 11-day average in February for the years 1973-1991. The average observed discharge value for Itapeua is 83,100 m3 sec-1 for the same time period.
DE: 1836 Hydrologic budget (1655)
DE: 1860 Runoff and streamflow
DE: 1894 Instruments and techniques
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting