Diagnosing water variations within the Amazon basin using satellite data

Abstract

.[1] The components of the Amazon water budget and their spatiotemporal variability are diagnosed using monthly averaged remote sensing-based data products for the period September 2002-December 2006. The large Amazon basin is divided into 14 smaller watersheds, and for each of these sub-basins, fresh water discharge is estimated from the water balance equation using satellite data products. The purpose of this study is to learn how to apply satellite data with global coverage over the large tropical regions; therefore several combinations of remote sensing estimates including total water storage changes, precipitation and evapotranspiration. The results are compared to gauge-based measurements and the best spatiotemporal agreement between estimated and observed runoff is within 1 mm/d for the combination of precipitation from the GPCP and the Montana evapotranspiration product. Mean annual precipitation, evapotranspiration and runoff for the whole basin are estimated to be 6.3, 2.27 and 3.02 mm/d respectively but also show large spatial and temporal variations at sub-basin scale. Using the most consistent data combination, the seasonal dynamics of the water budget within the Amazon system are examined. Agreement between satellite based and in situ runoff is improved when lag-times between sub-basins are included (RMSE from 0.98 to 0.61 mm/d). We estimate these lag times based on satellite-inferred inundation extents. The results reveal not only variations of the basin forcing but also the complex response of the inter-connected sub-basin (SB) water budgets. Inter-annual and inter-SB variation of the water components are investigated and show large anomalies in northwestern and eastern downstream SBs; aggregate behavior of the whole Amazon is more complex than can be represented by a simple integral of the forcing over the whole river system.

Large‐scale hydrologic and hydrodynamic modeling of the Amazon River basin

“…[] based on 756 pluviometric stations; 6.3 mm/day from Azarderakhsh et al . [] based on the Global Precipitation Climatology Project (GPCP) gauged and remote sensing data; 5.8 (5.2–8.6) mm/day by Marengo [] based on several rain gauges, remote sensing, and reanalyses‐based data. ET rates are also comparable with values obtained in other studies, although there are large differences between them: 2.27 mm/day by Azarderakhsh et al .…”

“…ET rates are also comparable with values obtained in other studies, although there are large differences between them: 2.27 mm/day by Azarderakhsh et al . [] using global remote sensing‐based products; 4.3 mm/day by Marengo []; 3.23 mm/day by Ruhoff [] using MOD16 remote sensing product but including the Tocantins basin; and 3.2 mm/day (at Negro basin), 2.9–3.8 mm/day, and 2.6–3.0 mm/day using modeling results by Getirana et al . [], Costa and Foley [], and Beighley et al .…”

“…These models, when used in forecast systems, may help to reduce population vulnerability to natural hazards, particularly in the Amazon River basin, where extreme hydrological events have occurred in the past few years, such as the floods of 2009 and 2012 and the droughts in 1996, 2005, and 2010 [ Chen et al ., ; Tomasella et al ., ; Marengo et al ., ; Espinoza et al ., ; Marengo et al ., ]. Furthermore, complementary to observational studies [e.g., Frappart et al ., ; Azarderakhsh et al ., ; Alsdorf et al ., ], simulation models can support the understanding and quantification of different Amazon hydrological processes such as evapotranspiration, soil and groundwater storages, and river‐floodplain hydrodynamics [e.g., Costa and Foley , ; Trigg et al ., ].…”

Seasonal variability of tropical wetland CH<sub>4</sub> emissions: the role of the methanogen-available carbon pool

“…Although independently GRACE and inundated fraction (Prigent et al, 2007) provide proxies for wetland water volume, a better understanding of basin-scale hydrology could ultimately be achieved via a sythesis of all available hydrological parameters (e.g. Azarderakhsh et al, 2011).…”

Surface Freshwater Storage Variations in the Orinoco Floodplains Using Multi-Satellite Observations

“…Large South American rivers, such as the Amazon, Parana and Orinoco, are characterized by extensive floodplains, with an important effect at the basin scale [9][10][11][12]. In these basins, a flood occurs as a single event (i.e., flood pulse) that lasts for months [13].…”