Land Use Change Impacts to Flows and Hydropower at the Southern Fringe of the Brazilian Amazon: A Regional, Empirical Study of Land-Water-Energy Nexus Dynamics

Abstract:

Land use/cover change (LUCC) has occurred extensively in the Brazilian Amazon rainforest-savanna transition. Agricultural development-driven LUCC at regional scales can alter surface energy budgets, evapotranspiration (ET) and rainfall; these hydroclimatic changes impact streamflows, and thus hydropower. To date, there is only limited empirical understanding of these complex land-water-energy nexus dynamics, yet understanding is important to developing countries where both agriculture and hydropower are expanding and intensifying.

To observe these changes and their interconnections, we synthesize a novel combination of ground network, remotely sensed, and empirically modeled data for LUCC, rainfall, flows, and hydropower potential. We connect the extensive temporal and spatial trends in LUCC occurring from 2000-2012 (and thus observable in the satellite record) to long-term historical flow records and run-of-river hydropower generation potential estimates. Changes in hydrologic condition are observed in terms of dry and wet season moments, extremes, and flow duration curves. Run-of-river hydropower generation potential is modeled at basin gauge points using equation models parameterized with literature-based low-head turbine efficiencies, and simple algorithms establishing optimal head and capacity from elevation and flows, respectively. Regression analyses are used to demonstrate a preliminary causal analysis of LUCC impacts to flow and energy, and discuss extension of the analysis to ungauged basins.

The results are transferable to tropical and transitional forest regions worldwide where simultaneous agricultural and hydropower development potentially compete for coupled components of regional water cycles, and where policy makers and planners require an understanding of LUCC impacts to hydroclimate-dependent industries and ecosystems.