The Mitigation Potential of Buffer Strips for Reservoir Sediment Yields: The Itumbiara Hydroelectric Power Plant in Brazil

Marta Luz,Lindsay Beevers,Gabriela Medero,Diego Nascimento,Alan Cuthbertson,Viviane Dias

doi:10.3390/w8110489

Abstract

Soil erosion and deposition mechanisms play a crucial role in the sustainability of both existing reservoirs and newly planned projects. Soil erosion is one of the most important factors influencing sediment transport yields, and, in the context of existing reservoirs, the surrounding watersheds supply both runoff and sediment yield to the receiving water body. Therefore, appropriate land management strategies are needed to minimize the influence of sediment yields on reservoir volume and, hence, the capacity of power generation. In this context, soil erosion control measures such as buffer strips may provide a practical and low-cost option for large reservoirs, but need to be tested at the catchment scale. This paper represents a study case for the Itumbiara hydroelectric power plant (HPP) in Brazil. Four different scenarios considering radially planted buffer strips of Vetivergrass with widths of 20 m, 40 m, 100 m and 200 m are analyzed. A semi-distributed hydrological model, SWAT, was used to perform the simulations. Results indicate a reduction of sediments transported to the reservoir of between 0.2% and 1.0% per year is possible with buffer strip provision, and that this reduction, over the life of Itumbiara HPP, may prove important for lengthening the productivity of the plant.

Highlights

Soil erosion and subsequent land degradation is recognized as an internationally important issue that has significant environmental and socio-economic impacts
When accelerated sediment erosion occurs in upstream river basins, it can result in detrimental impacts to downstream engineering infrastructure—in particular, reservoirs impoundments and associated hydropower operations [4]
The first three years were used as a warm-up period to minimize uncertain initial conditions, as the Soil and Water Assessment Tool (SWAT)

Summary

Introduction

Soil erosion and subsequent land degradation is recognized as an internationally important issue that has significant environmental and socio-economic impacts. Focusing on water related processes at the watershed scale, eroded sediment is transported across the land and into receiving water bodies from where it is conveyed through river systems, eventually depositing within the linked fluvial-estuarine-coastal system. In fluvial systems with large anthropogenic interventions (e.g., hydropower dams and reservoirs), sediment deposition can be exacerbated by large impoundments that act as sediment sinks within the watershed. Water 2016, 8, 489 of flood flows, reduced potential for hydropower production, less water for irrigation supply, or any combination of these) [1]. Inappropriate cultivation practices often accelerate erosion rates and thereby increase sediment movement from the land surface and subsequent transport in streams and rivers. When accelerated sediment erosion occurs in upstream river basins, it can result in detrimental impacts to downstream engineering infrastructure—in particular, reservoirs impoundments and associated hydropower operations [4]

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