Hydroelectric Power

Developing countries around the world are expanding hydropower to meet growing energy demand.  The move away from fossil fuels is one to applaud, and cost effective alternatives are hard to come by.  The resulting impact on the environment locally may be compromised in an effort to protect the atmosphere of the planet, but the truth is that we jsut don't know.  What we do know is that there are a number of cities in the devloped and developing world that are significantly hampered by air pollution (Beijing and Dehli, to name two), and that needs to improve.
In the Brazilian Amazon, >200 dams are planned over the next 30 years, and questions about the impacts of current and future hydropower in this globally important watershed remain unanswered. In this context, a sutdy recently published in Science applied a hydrologic indicator method to quantify how existing Amazon dams have altered the natural flow regime and to identify predictors of alteration. The type and magnitude of hydrologic alteration varied widely by dam, but the largest changes were to critical characteristics of the flood pulse. Impacts were largest for low-elevation, large-reservoir dams; however, small dams had enormous impacts relative to electricity production. Finally, the “cumulative” effect of multiple dams was significant but only for some aspects of the flow regime. This analysis is a first step toward the development of environmental flows plans and policies relevant to the Amazon and other megadiverse river basins.