Integrated lake and catchment phosphorus model - A eutrophication management tool. II: Application to Rutland Water

An integrated lake and catchment model was used to simulate reservoir volum e and phosphorus concentrations in Rutland Water over a period of seventeen years, taking into account changes in reservoir output and phosphorus sedi mentation resulting from the addition of ferric sulphate. Application of th e model for critical-period analysis and the setting of environmental targe ts and trigger values are discussed, and an example is given showing the im pact of changing reservoir output on the frequency distribution of phosphor us using an eighty-year set of river-discharge data. The impact of phosphor us removal at point sources in the catchment on phosphorus concentrations i n the river and reservoir is simulated and compared to results from SIMCAT- a steady-state model which was developed by the Environment Agency. Results are also compared with observed data following the implementation of the E C urban waste water treatment Directive, at the end of 1998.