Probabilistic uncertainty assessment of phosphorus balance calculations in watershed

Water quality studies in reservoirs, rivers, lakes, and entire river basins include increasingly often mass balance calculations. In comparison with hydrological studies where water balance models are traditionally frequently used, water quality investigations are typically faced with essentially higher uncertainty. This study presents an approach to the assessment and propagation of this uncertainty, with a case study on a river reach with three-point source polluters, substantial throughflow, and non-point components. A computational implementation using spreadsheets was used, which allows the use of probabilistic models in close contact with environmental data bases.