Assessing the hydrological impacts of hydropower boom in the Amazon River basin using high resolution modeling

Abstract:

Given the ongoing and planned hydropower development projects in the Amazon River basin, appalling losses in biodiversity and river connectivity are inevitable. With the growing consensus of the hydrological impairment caused by hydropower dams and the untethered plans of hydropower development in the Amazon, it has become increasingly imperative to better understand the changing downstream dynamics caused by a hydropower dam thereby anticipating the environmental and social losses, including those caused by water impoundment, sediment accumulation, resettlement of populations, and reduced fish productivity. Our present understanding of the collective impact of existing hydropower dams on the entire basin as a whole is fairly limited. In this study, we address the issues identified above by implementing a recently developed integrated river-floodplain-reservoir hydrodynamic model, CaMa-Flood-Dam, which allows us to mechanistically investigate the climate- and human-driven changes in the entire Amazon River basin at a spatial resolution of 3 arc-minutes (~5 km), while mainly focusing on the existing dam-induced changes in the Amazonian floodplains. We implement an optimized reservoir operation scheme to realistically represent the dam-induced changes in the model and maximize energy production while also following the common practice of water management through different seasons. Initial analysis indicates significant changes in the surface water dynamics both downstream and upstream regions of the existing dams, created by the dynamic interplay between floodplain topography and river flood cycle. Significant changes in the Amazon mainstem are also expected in further analysis. This study opens multiple pathways to understand the complex hydrological interaction of dam operations with the natural regime while also providing important insight towards sustainability of the ongoing hydropower development under climate change in the future.