Use of remote sensing for archaeological survey in the Lower Amazon Floodplain

Abstract

The extensive and dynamic floodplains of the Amazon Basin have seldom been explored from an archaeological perspective due to the dynamic processes of erosion and deposition that shape them. A frequent assumption is that most landforms of the whitewater floodplains have recently been reworked. To better understand where human activities may have left an archaeological record in these ecosystems, it is essential to enhance our comprehension of the floodplain's geomorphology. We seek to construct a method of mapping older fluvial levees, that are landforms where we suspect that archaeological contexts may be preserved. The format of the terrain's lateral accretion can be identified based on fluvial geomorphology. Due to the annual flooding of the landscape, it is hypothesized that the higher vegetation corresponds to elevated landscape positions of vertical accretion. This proposal was explored through data from remote sensing and ground truthing. We sought to identify this vegetation using different values of NDVI (Normalized Difference Vegetation Index) that may aid in locating levees and, consequently, pre-colonial archaeological sites. This study presents qualitative findings from ground-truthing conducted in the Alenquer floodplain region of the Lower Amazon. Even though our results are initial, they demonstrate successful identification of some levees and document a late Holocene archaeological site located on a levee. Our study suggests that despite the losses of portions of the floodplain to erosional processes, there is an archaeological record to be explored in the seasonally flooded forests that may improve our understanding of historical human relationships with these ecosystems.