First results of soil and water bioengineering interventions to stabilise and control erosion processes in hydroelectric power plant reservoirs in Brazil

Reservoir banks are highly susceptible to erosion processes that result in a loss of stability. The main factors that cause erosion on reservoir banks are wave action and the oscillation of the water level. The aim of this study was to investigate four different soil and water bioengineering measures to stabilise and control erosion processes on the banks of reservoirs. The selection of plant species must follow various technical and ecological criteria. The study area is located at Itá hydropower plant. The development of the techniques and the used plants were monitored over a period of 28 months. Permanent plots were installed to assess plant development and erosion. When combined with support structures, the plants used were able to develop well. The average diameter and height of the plants increased in all sections. For the average plant height after 5 months, the best results were obtained in section A (1.32 m), and after 28 months the plants in sections C and B had an average height of 2.05 m and 2.01 m respectively. The greatest deposition occurred within the intervention zone, ranging from −6.4 cm/year (section A) to −0.6 cm/year (section D). For the pins 3/7, the largest soil deposition occurred in section B (−3.4 cm/year), while a soil loss (0.1 cm/year) was measured in section C. This confirms the positive technical effect of inert structures in combination with plants. The structures combined with vegetation, creates a barrier effect that protects the shore and enables the deposition/retention of sediments. • Soil and water bioengineering to mitigate erosion processes that lead to siltation and reduce the reservoir's lifespan. • The techniques work as living physical barriers against the action of waves dissipating their kinetic energy. • The intervention prevents the progression of erosion, the retreat of the bank and the loss of permanent preservation area.