161-2 Assessing Geomorphic Change in Puerto Rican Rivers: The Imprint of Damming on Fluvial Systems

Session: Dynamics of Natural and Built Environments

Presenting Author:

Authors:

Abstract:

Dam construction has markedly transformed river systems worldwide, yet the geomorphic consequences for upstream, especially at the river–lake transition zones (RLTZs) remain insufficiently explored. This study specifically assesses long-term geomorphic changes in the RLTZs of Puerto Rican rivers upstream of dams, employing an integrated dataset of historical maps and LiDAR-derived topography coupled with quantitative geomorphological metrics. By synthesizing cartographic archives with modern remote sensing techniques, we reconstruct historical channel and floodplain morphologies, providing a rigorous baseline for evaluating changes attributable to dam-related modifications.

Our approach enables precise quantification of morphological adjustments in the transition zones—including longitudinal slope changes, channel realignment, and spatial patterns of sediment deposition—across pre- and post-dam periods. Special emphasis is placed on detecting and characterizing backwater effects in RLTZs, such as increases in sediment accumulation, shifts in inundation frequency and valley-floor hydrodynamics, and associated modifications to channel and floodplain structures. The extent and magnitude of these transformations are found to propagate far upstream, impacting geomorphic and ecological processes in the transitional corridor well beyond the immediate dam site.

By integrating historical perspectives with high-resolution spatial analysis, this research addresses critical gaps in understanding how dams imprint on the geomorphology of upstream river–lake transition zones. The findings enhance our knowledge of fluvial–lacustrine interactions and provide science-based insights to guide sustainable reservoir management—including new strategies to predict and mitigate the persistent geomorphic and ecological impacts of dam-induced backwater fluctuations in RLTZs.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-10560

© Copyright 2025 The Geological Society of America (GSA), all rights reserved.