Vegetation and hydrogeomorphic features of a large lowland river: NDVI patterns summarizing fluvial dynamics and supporting interpretations of ecological patterns

Abstract

The interactions among hydrogeomorphic features of large lowland rivers regulate the spatio-temporal fluvial dynamics and influence the occurrence and understanding of the ecological patterns in these systems. We studied the hydrogeomorphic features that explain the fluvial dynamics of the Paraná River floodplain and investigated the usefulness of NDVI patterns in summarizing this dynamics. Information layers related to elevation, drainage network, geomorphic units, runoff dynamics, and NDVI patterns of the study area were generated from multi-source remote sensing data and fieldwork measurements. All these layers were integrated and analysed in a GIS environment, and the statistical association among them was corroborated. In our study area, the interaction among hydrogeomorphic features determined a centrifugal flooding pattern through which inundation occurs when water from remote courses, fluvial lakes, and secondary tributaries reaches the main channel. The areas closest to the main channel are flooded only when it overflows. Five NDVI patterns statistically different in terms of their means and standard deviations were identified and characterized. These NDVI patterns were significantly associated with elevation, geomorphic units, and runoff dynamics highlighting their usefulness to characterize the fluvial dynamics and to support the understanding of the ecological patterns.