The Effect of Water Hyacinth on Phytoplankton Biomass in a Hydropower Reservoir: A 3D Modelling Approach

Abstract

Eutrophication is a water quality issue around the world. However, its impacts in tropical developing countries are even stronger because of the temperature-dependent process rates and the lack of funding for efficient catchment measures. Alternative in-situ strategies need to be implemented to mitigate the most extreme effects of eutrophication such as toxic algal blooms, oxygen depletion and fish mortality. This paper investigates the use of water hyacinth (Eichornia crassipes) as a biofilter to reduce phytoplankton biomass in a hypereutrophic deep reservoir in Colombia. The effect was tested using a coupled hydrodynamic-ecological model in short term simulations. The results show that the model reproduces the hydrodynamic and ecological variables in selected sections of the system. The scenario for biofilter implementation suggests that an area of 100 ha covered with water hyacinth is required to decrease the level of health risk of cyanobacteria blooms in the reservoir. The use of such approaches can help decision makers to accurately assess the risks and costs of operating and maintaining a large biofilter.