PROBABILISTIC UNCERTAINTY ASSESSMENT OF PHOSPHORUS BALANCE CALCULATIONS IN A WATERSHED

Water quality studies in reservoirs, rivers, lakes, and entire river b asins include increasingly often mass balance calculations. In compari son with hydrological studies where water balance models are tradition ally 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 stu dy on a river reach with three point source polluters, substantial thr oughflow, and non-point components. A computational implementation usi ng spreadsheets was used, which allows the use of probabilistic models in close contact with environmental data bases.