Mercedes Gelós presentó en el 7th Symposium on Phosphorus in Soils and Plants, edición Impact of phosphorus on environmental quality and on biodiversity


ON THE PREDICTION OF PHOSPHORUS FLUXES IN THE SANTA LUCÍA BASIN UNDER DIFFERENT LAND USE AND MANAGEMENT PRACTICES USING SWAT MODEL. Mercedes Gelós1,2, Natalia Neighbur2, Pablo Kok1,2, Luciana Badano2, Florencia Hastings1,2, Eliana Nervi 2,3, Jimena Alonso2,4, Rafael Navas 2,5, Willem Vervoort 2,6, Walter Baethgen2,7

1 Dirección Nacional de Calidad y Evaluación Ambiental, Ministerio de Ambiente, 2.Grupo de Modelación Integrada de Cuencas Uruguay., 3. INIA FPTA 358, 4.Instituto de Mecánica de los Fluidos e Ingeniería Ambiental, Facultad de Ingeniería, Universidad de la República., 5. Departamento del agua, Centro Universitario Regional Litoral Norte, Universidad de la República, 6. School of Life and Environmental Sciences, The University of Sydney, 7.International Research Institute for Climate and Society, Earth Institute, Columbia University.

Theme 5: Impact of phosphorus on environmental quality and on biodiversity

Several actions have been carried out in the Santa Lucia River basin (1.343.300 ha) in order to reduce the impact of anthropogenic pressure and improve water quality. Environmental models may be used as supportive tools when assessing the effect of local actions at a basin scale. To have a better understanding of which is the best combination of strategies and management guidelines that may result in an improvement of water quality, a SWAT model was built in the Santa Lucia River basin for the 1983-2019 period. In this context, the objective of this work is to present the progress made in the development of the model and to describe the scenarios in which phosphorus fluxes can be predicted with the implemented tool. Local data was collected and used as an input for the model: DEM, cartographic and physicochemical representative soil data and 2015 land use map, crop rotation sequences, fertilization dates and doses, point source discharges. Climatological forcing was built with 41 rainfall stations and one agro climatological station. Eight flow gauges were used to calibrate and validate the model using sequential uncertainty fitting algorithm (SUFI-2). The model performance was evaluated using Nash-Sutcliffe efficiency (NSE) and Kling-Grupta efficiency (KGE), obtaining values between 0.65 and 0.82 and between 0.68-0.87 respectively. This tool can predict phosphorus fluxes between soil and water for various scenarios such as sub superficial phosphate fertilization, vegetative mining, buffer zones, land use changes, downstream dilution effects of reservoirs, which will support decision making in water and soil resources planning in Uruguay.