Modelling the impact of sediment management on the trophic state of a tropical reservoir with high water storage variations
Camila Cristina Souza Lira, Pedro Medeiros, Iran Eduardo Lima Neto
Abstract
Eutrophication of lakes has affected society in many regions, particularly in water scarce environments where: i) low runoff reduces the self-purification potential of water bodies; ii) water supply relies on surface reservoirs, which are susceptible to nutrient enrichment. This work presents an assessment of the impact of the silted sediment management on the trophic status of a tropical surface reservoir with intense temporal variability of water storage. A complete mixing model describing the total phosphorus budget in the water and sediments was used, based on semi-empirical formulations. The sediment reuse as soil fertilizer has been proposed to increase productivity in small scale agriculture, which should also enhance the water quality by removing the nutrient-enriched sediment from lakes. Model application for a 40-years period indicate that sediment management may improve water quality, changing from poor to acceptable trophic state during roughly 10% of the time when the reservoir is not empty.