Multi-tool Assessment of Energy Balance Consequences of Reservoir Construction for Hydropower Generation in the Tropical Andes

Abstract:

In many tropical countries, topographic and climatic conditions permit the installation of hydropower infrastructure, considered cleaner and with fewer environmental impacts than other alternatives for power generation. Such is the case of Colombia, where approximately 70% of the nation's electricity comes from hydropower generation. In recent decades, multiple neotropical watersheds have been targeted of reservoir building, and these developments generally involve direct changes in surface characteristics over large areas, including not only the establishment of new water bodies, but also modifications in land use and vegetation cover in surrounding areas. These changes can potentially lead to atmospheric and ecological changes that may result in unaccounted environmental consequences of this kind of infrastructure. In this work, we use a suite of in-situ observations and remote sensing products to characterize changes in surface energy balance in the surroundings of three recently installed hydropower projects in the tropical Andes of Colombia. We compare the response of the energy budget components, biophysical properties, and meteorological variables before and after the establishment of reservoir lakes using in-situ measurements and MODIS, ERA5 and GEDI data. Overall, our results indicate changes in evapotranspiration and albedo due reservoir building, with consequent effects in temperature over flooded areas. However, these changes are not strong enough to significantly modify surface energy budget in surrounding areas beyond the flooded area, beyond changes from land use in this region. In addition, due to the humid climate in this region, changes in energy budget do not alter precipitation regimes significantly, like other studies have shown. More generally, Our results highlight the utility of remotely-sensed products to assess the collective effects of major surface changes on local-to-regional energy balances and its associated ecological, hydrological and atmospheric processes.