Author(s): Nina Kilham
Linked Author(s):
Keywords: Floods; Hydroclimate; Suspended sediment; Remote sensing; MODIS; Landsat; Mekong River; Feather River
Abstract: Using directional statistics to map flood events on the Mekong and Feather Rivers for a period of record extending from 1910 to 2006 contrast two very different hydroclimates with different flood producing mechanisms and timing (M = 239 JD, R = 0. 96, d° = 1. 56 for the Mekong; M = 67, R = 0. 69, d° = 3. 94 for the Feather). MODIS and Landsat images acquired for recent large floods—September 14, 2001 and January 14, 1997 on the Mekong and Feather Rivers respectively—were analyzed using linear spectral mixture analysis for suspended sediment concentrations as a surrogate measure of the source of inundating waters i. e., the relative proportions of channel and floodplain water contributing to the flood. Results for the Mekong River were then used in conjunction with subwatershed areas generated from the HYDRO1k DEM to estimate increases in inundation height due to local (non-channel derived) water contributions to the floodplain. Local water contributed 15% of the inundated area on the Mekong and 28% on the Feather for regions selected for analysis. Contributions from direct precipitation on first- through third- order subwatersheds contributing to the Mekong floodplain yield an increase of between 13-126 cm in the flood height, depending on basin characteristics such as lag time and storage area. A comparison of resulting inundation patterns on these two rivers demonstrates: 1) the influence of largescale long-period climatic processes such as the El Nino Southern Oscillation on inundation patterns; 2) the need for measurements and incorporation into models of non-channel water sources which contribute to floods and; 3) the potential use of remotely derived suspended sediment concentrations as inputs to and for verification of models of floodplain hydrology.
Year: 2007