Elisa Armijos

The optical properties of river and floodplain waters in the Amazon River Basin: Implications for satellite‐based measurements of suspended particulate matter

Satellite images can now be used to assess river sediment discharge, and systematic studies over rivers and lakes are required to support such applications and document the variability of inland water optical properties at the watershed scale. The optical properties of the Amazon Basin waters were analyzed from in situ measurements of the remote sensing reflectance (Rrs) at 279 stations and downwelling diffuse attenuation coefficients (Kd) at 133 stations. Measurements of the apparent optical properties, suspended particulate matter (SPM) contents, and characteristics and colored dissolved organic matter (CDOM) absorption spectra were performed during 16 cruises along the main Amazonian Rivers draining the Andes and for some tributaries. Surface-suspended sediment granulometry and mineralogy showed a stable distribution at the catchment scale, even over large distances and between tributaries. The particle number-size distribution was best described using a segmented distribution with a slope of 2.2 for the fine range (1–15 µm), and the CDOM absorption coefficient at 440 nm varied from 1.8 to 7.9 m−1. Overall, both Rrs and Kd were strongly correlated with SPM, although strong CDOM absorption limited the use of the blue spectrum. Reflectance saturation from blue to red was observed at approximately 100 g m−3, whereas the near-infrared (NIR) wavelength enabled the monitoring of the full SPM range (5–620 g m−3). In contrast, Kd showed no saturation for SPM from green to NIR, and a linear model was calculated. The use of the reflectance ratio was investigated and shown to improve the suspended sediment concentration retrieval performance.

Yields of suspended sediment and dissolved solids from the Andean basins of Ecuador

Abstract Water discharge and suspended and dissolved sediment data from three rivers (Napo, Pastaza and Santiago) in the Ecuadorian Amazon basin and a river in the Pacific basin (Esmeraldas) over a 9-year period, are presented. This data set allows us to present: (a) the chemical weathering rates; (b) the erosion rates, calculated from the suspended sediment from the Andean basin; (c) the spatio-temporal variability of the two regions; and (d) the relationship between this variability and the precipitation, topography, lithology and seismic activity of the area. The dissolved solids load from the Esmeraldas basin was 2 × 106 t year-1, whereas for the Napo, Pastaza and Santiago basins, it was 4, 2 and 3 × 106 t year-1, respectively. For stations in the Andean piedmont of Ecuador, the relationship between surface sediment and the total sediment concentration was found to be close to one. This is due to minimal stratification of the suspended sediment in the vertical profile, which is attributed to turbulence and high vertical water speeds. However, during the dry season, when the water speed decreases, sediment stratification appears, but this effect can be neglected in the sediment flux calculations due to low concentration rates. The suspended sediment load in the Pacific basin was 6 × 106 t year-1, and the total for the three Amazon basins was 47 × 106 t year-1. The difference between these contributions of the suspended sediment load is likely due to the tectonic uplift and the seismic and volcanic dynamics that occur on the Amazon side. Editor Z.W. Kundzewicz Citation Armijos, E., Laraque, A., Barba, S., Bourrel, L., Ceron, C., Lagane, C., Magat, P., Moquet, J.-S., Pombosa, R., Sondag, F., Vauchel, P., Vera, A., and Guyot, J.L., 2013. Yields of suspended sediment and dissolved solids from the Andean basins of Ecuador. Hydrological Sciences Journal, 58 (7), 1478–1494.

Preliminary Analysis of Potential for River Hydrokinetic Energy Technologies in the Amazon Basin

The Inter-American Development Bank (IDB) produced this report for the Sustainable Energy for All Americas initiative. A team of experts on Amazon hydrology from the Universidade Federal do Amazonas (UFAM) based in Manaus, Amazonas, Brazil carried out the work. This report analyzes existing hydrological data and other available information in order to determine high level feasibility for the deployment of River Hydrokinetic Energy technology in the Amazon River Basin. The investigation is based on an analysis of the ORE-HYBAM database (www.orehybam.org). Eight sites were chosen from the database and analyzed for velocity (water speed) and discharge data, while also considering existing Acoustic Doppler Current Profiler (ADCP) images. The first part of the report provides an overview of the database and data used, as well as of the performed analysis. The second part (results) describes the analysis via graphs and tables of detailed information about the sites investigated. It includes maps with the geographic distribution of the sites and associated data, Google Earth images from each site with an analysis of the river section, and ADCP images. The annex includes graphs showing the results of discharge and velocity analysis.