Flooding dynamics on the lower Amazon floodplain: 1. Hydraulic controls on water elevation, inundation extent, and river-floodplain discharge

Conrado M. Rudorff*, John M. Melack, Paul D. Bates

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

63 Citations (Scopus)

Abstract

Modeling the routing of flood waters across large floodplains is challenging because flows respond to dynamic hydraulic controls from complex geomorphology, vegetation, and multiple water sources. In this study, we analyzed the topographic and hydrologic controls of inundation dynamics of a large floodplain unit (2440 km2) along the lower Amazon River. We combined land topography derived from the Shuttle Radar Topography Mission (SRTM) with underwater topography derived from an extensive echo-sounding survey to generate a seamless digital elevation model (DEM). Floodplain inundation was simulated using LISFLOOD-FP, which combines one-dimensional river routing with two-dimensional overland flow, and a local hydrological model. For the first time, accurate simulation of filling and drainage of an Amazon floodplain was achieved with quantification of changes in water elevation, flooding extent, and river-floodplain exchange. We examined the role of diffuse overbank versus channelized flows on river-floodplain exchange. Diffuse overbank flows represent 93% of total river to floodplain discharge and 54% of floodplain to river discharge. Floodplain discharge during high-water was four times higher than field observation values when the SRTM v.4 DEM with no correction was used for simulation because of a -4.4 m elevation bias originating from residual motion errors of the SRTM interferometric baseline. Key Points Topographic and hydrologic controls of inundation dynamics were analyzed Diffuse overbank flows represent 93% of total river to floodplain discharge Position of SRTM interferometric baseline is an important source of DEM error

Original languageEnglish
Pages (from-to)619-634
Number of pages16
JournalWater Resources Research
Volume50
Issue number1
DOIs
Publication statusPublished - Jan 2014

Keywords

  • Amazon River floodplain
  • digital elevation model
  • inundation modeling
  • river-floodplain discharge

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