Mapping of Maximum and Minimum Inundation Extents in the Amazon Basin 2014–2017 with ALOS-2 PALSAR-2 ScanSAR Time-Series Data

Abstract

Seasonal inundation is an important effect that governs the distribution of ecosystems in the tropics. In the Amazon Basin, the seasonal flood pulse causes a difference in high and low water levels that can exceed 15 m. The associated flood duration and extent play an important role in land-atmosphere carbon exchange and affect the ecosystem's carbon pool that originates from organic matter transported from upland and flooded forests. Studies of wetlands inundation across the Amazon Basin have utilized dual season mosaics from JERS-1 and wide-swath ScanSAR data from ALOS PALSAR to characterize inundation across the basin. This study builds upon past efforts with JERS-1 and ALOS PALSAR and uses ALOS-2 PALSAR-2 ScanSAR data to generate annual maximum and minimum inundation extent maps over the full Amazon Basin for the period spanning November 2014-October 2017. The study uses decision tree classification to create a maximum and a minimum inundation extent map for each year over this time period. The results show that a generalized algorithm that fits the entire basin has an 86% overall accuracy compared with a classification made for a local region from the same PALSAR-2 datasets. Comparisons with previous full-basin inundation maps by other L-band radars shows similar results for inundated areas during maximum inundation. The maps derived previously from JERS-1 and ALOS PALSAR show 7.3% and 6.9% inundated vegetation, respectively, and this study using PALSAR-2 shows values ranging between 5.5% and 7.0% across the three study years. Comparisons between the stage data across the basin and acquisition dates/periods for JERS-1 and PALSAR-2 show that the sensors capture the nature of the maximum and minimum flooding across the basins but have not successfully captured the exact maximum and minimum flood levels that have been recorded in the stage data. The inundation maps are publicly available under a Creative Commons (CC BY 4.0) license Abstract: Seasonal inundation is the tropics. In the Amazon Basin levels that can exceed 15 m. The a atmosphere carbon exchange an matter transported from upland Amazon Basin have utilized dua ALOS PALSAR to characterize in JERS-1 and ALOS PALSAR an maximum and minimum inun spanning November 2014-Octo maximum and a minimum inun show that a generalized algorith with a classification made for a previous full-basin inundation m areas during maximum inundat show 7.3% and 6.9% inundated values ranging between 5.5% and data across the basin and acquisi capture the nature of the max successfully captured the exact m stage data. The inundation map license from the Alaska Satell Keywords: SAR; inundation; de from the Alaska Satellite Facility.

Amazon Hydrology From Space: Scientific Advances and Future Challenges

“…Rosenqvist et al. (2020) generated annual maximum and minimum inundation extent maps over the Amazon using ALOS‐2/PALSAR‐2 ScanSAR, in line with previous inundation maps by L‐band JERS‐1 and ALOS/PALSAR radar classifications of the inundation (Chapman et al., 2015). At the regional scale, Bourrel et al.…”

“…The use of multi-temporal SAR coverage, such as the ScanSAR mode of ALOS/PALSAR, provide variations of flood extent at the scale of floodplain units, for example, Curuai floodplain along the lower Amazon River (Arnesen et al, 2013), Mamiraua floodplain (Ferreira-Ferreira et al, 2015) or inundation patterns in central Amazon (Pinel et al, 2019;Resende et al, 2019). Rosenqvist et al (2020) generated annual maximum and minimum inundation extent maps over the Amazon using ALOS-2/PALSAR-2 ScanSAR, in line with previous inundation maps by L-band JERS-1 and ALOS/PALSAR radar classifications of the inundation (Chapman et al, 2015). At the regional scale, Bourrel et al (2009) mapped the floods in the Bolivian Amazon from SAR C-Band microwave data of RADARSAT and ERS-2.…”

Expressive riverine fluxes over Amazon floodplain units revealed by high resolution 2D modelling

“…This is not a trivial mapping and the different approaches have led to disagreements, as shown by the comparison documented in Fleischmann et al (2022). We used two basin-scale databases that consider periods of maximum and minimum inundation Rosenqvist et al, 2020). The Hess mapping (hereafter called HESS) , one of the most widely used in the validation of hydrologic-hydrodynamic models in the Amazon basin, depicts wetland inundation and vegetation for the central Amazon basin based on JERS SAR imagery for the flood and low-water periods -May 1996 and October 1995 (available at https://daac.ornl.gov/LBA/guides/LC07_Amazon_Wetlands.html).…”

Dynamics of Methane in Mangrove Forest: Will It Worsen with Decreasing Mangrove Forests?

“…Particularly, technologies that can detect soil inundation even with soil covered by cloud/vegetation have been well developed. They involve analysing the contribution of double-bounce intensity to the total back-scattering intensity of the L/P band SAR data used for regionalizing CH 4 emissions in various wetland studies [117][118][119][120][121][122].…”