Author(s)

G. Gunkel, D. Lima, F. Selge, M. Sobral, S. Calado

Abstract

The multiple use of reservoirs is widely accepted, but there are frequent conflicts between water users based on ecological, economic and sociological concerns. The promotion of aquatic ecosystem services is a successful approach to advanced reservoir management. The main aquatic ecosystem services are goods and human benefits such as clean water and hydropower. The sustainability of aquatic ecosystem services must be the aim of a reservoir management plan, and hence adequate water quality and predominantly mesotrophic conditions are necessary. However, eutrophication processes are advanced in many tropical reservoirs, and re-oligotrophication is needed, as has been successfully implemented in temperate lakes. The eutrophication processes and re-oligotrophication potential of tropical reservoirs are significantly different from temperate ecosystems. Studies to quantify the impact of ecosystem services were conducted on the Itaparica reservoir, São Francisco River, Brazil, which is located in a semi-arid area. The main disturbance to tropical reservoirs is the change in water level due to hydropower operational conditions. Desiccated areas on the lakeshore have a high potential for nutrient release by sediment mineralization. An increase in the water level promotes the growth of some pioneer plants, such as the water pest, Egeria densa. Intensive net cage aquaculture can lead to an overcharge of the reservoir, and therefore the carrying capacity should be considered. Furthermore, sediment management and the abstraction and re-use for soil amendment has to be managed. The multiple water uses and sustainability of aquatic ecosystem services must be the aim of any reservoir management plan, and the eutrophic level is a key factor due to its impact on water quality.

Keywords

ecosystem service, reservoir, semi-arid area, water management, eutrophication