Characterization of complex fluvial systems using remote sensing of spatial and temporal water level variations in the Amazon, Congo, and Brahmaputra Rivers

Abstract

The Surface Water and Ocean Topography (SWOT) satellite mission will provide global, space-based estimates of water elevation, its temporal change, and its spatial slope in fl uvial environments, as well as across lakes, reservoirs, wetlands, and fl oodplains. This paper illustrates the utility of existing remote sensing measurements of water temporal changes and spatial slope to characterize two complex fl uvial environments. First, repeat-pass interferometric SAR measurements from the Japanese Earth Resources Satellite are used to compare and contrast fl oodplain processes in the Amazon and Congo River basins. Measurements of temporal water level changes over the two areas reveal clearly different hydraulic processes at work. The Amazon is highly interconnected by fl oodplain channels, resulting in complex fl ow patterns. In contrast, the Congo does not show similar fl oodplain channels and the fl ow patterns are not well defi ned and have diffuse boundaries. During inundation, the Amazon fl oodplain often shows sharp hydraulic changes across fl oodplain channels. The Congo, however, does not show similar sharp changes during either infi lling or evacuation. Second, Shuttle Radar Topography Mission measurements of water elevation are used to derive water slope over the braided Brahmaputra river system. In combination with in situ bathymetry measurements, water elevation and slope allow one to calculate discharge estimates within 2 . 3% accuracy. These two studies illustrate the utility of satellite-based measurements of water elevation for characterizing complex fl uvial environments, and highlight the potential of SWOT measurements for fl uvial hydrology.

Age, extent and carbon storage of the central Congo Basin peatland complex

“…While supra-annual river flooding cannot be excluded 19 , the peatlands of the Cuvette Central can be considered ombrotrophic-like peatlands due to their low-nutrient status and heavily rainwater dependent water tables. This is consistent with past satellite-only studies suggesting that these wetlands are largely hydrologically independent from regional rivers 20,21 , and with our radiocarbon dates suggesting that peat accumulation began with an increase in regional precipitation.…”

Present to future sediment transport of the Brahmaputra River: reducing uncertainty in predictions and management

“…The monthly coefficient of variation (CV) of column 3 reflects a variation around this mean due to fluctuating daily values, which we use to define lower bound and upper bound deviations (column 2) (b) Not used in the sensitivity analysis Present to future sediment transport of the Brahmaputra River: reducing uncertainty in… 519 located in Bangladesh. Jung et al (2010) (1969) is the only one reporting monthly sediment loads, we include it for illustrative purposes in Fig. 2a, b.…”

“…To overcome this lack of data, recent studies have focused on extracting basin data from satellite imagery, including river data (e.g. Jung et al 2010;Woldemichael et al 2010;Mersel et al 2013) and land cover and land use data (Prasch et al 2015), but these methods still cannot fully replace in situ measurements. To the best of our knowledge, Coleman (1969) is the only author who has published series of average monthly discharge data coupled with simultaneous sediment data.…”

A review of applications of satellite SAR, optical, altimetry and DEM data for surface water modelling, mapping and parameter estimation

“…InSAR has been used to calculate the changes in water levels using satellite altimetry data for calibration (Kim et al, 2009;Jung et al, 2010). To obtain the displacement phase used to obtain the change in water height, all other signals are removed.…”

“…SRTM data measure surface level which over river channels is equivalent to water levels when the land water boundary is delineated. Jung et al (2010) used in situ (bathymetry and cross-sectional) data and SRTM DEM water levels to derive water surface slope and to calculate the discharge of the Brahmaputra River. The crosssectional water level was obtained by fitting a first-degree polynomial function to the SRTM data elevation.…”