Satellite altimeter‐derived monthly discharge of the Ganga‐Brahmaputra River and its seasonal to interannual variations from 1993 to 2008

The Ganga‐Brahmaputra accounts for ∼25% of the total amount of freshwater received by the Bay of Bengal. Using daily in situ river discharge data along with altimetry‐derived river heights, the present study aims to produce a monthly data set of altimetry‐derived Ganga‐Brahmaputra River discharge at the river mouths for 1993–2008. First, we estimate the standard error of ENVISAT‐derived water levels over the Ganga to be 0.26 m, much smaller than the range of variability of ∼7 m, and consistent with the accuracy of altimeter measurements over large rivers. We then establish rating curves between altimetry‐derived water levels and in situ river discharges and show that TOPEX‐Poseidon, ERS‐2, and ENVISAT data can successfully be used to infer Ganga and Brahmaputra discharge.…