Hydroelectric plant effects and climate change/land use impacts on flow regime in the tropical headwater watershed

Abstract

The effects of hydropower plants (HPPs) and climate/land use change pose a threat to the natural river regime. Although some approaches distinguish the climate action from anthropogenic influence on hydrological regimes in large basins, few methods propose to separate the climate effects from the regulation consequences of unique/few dams. This paper presents a new method to quantify effects of HPP and climate change/land use under the main altered river regime components, which is based on flow duration curves. The method was applied in the Grande River (Brazil), which is regulated by a large reservoir (with surface area > 70 km2). The indicators of hydrological alterations and the range of variability approach indicated that all drivers' effects promoted a moderate alteration in five regime components. The Itutinga‐Camargos HPP implications were the major driver, with a contribution higher than 90% in every component, and it was responsible for a 0.28 × 109 m3 year−1 reduction in water superficial availability downstream. The flow regimes in headwater watersheds can be highly sensitive to dam operations, but other factors may aggravate their effects on river dynamics. The quantification of anthropogenic actions has possible applicability in other systems worldwide to assess the ecosystem services of flow regimes.