Model output uncertainty of a coupled pathogen indicator–hydrologic catchment model due to input data uncertainty

A conceptual model of Escherichia coli behaviour in catchments, the EG model, coupled with a standard hydrological model has been previously developed and tested. This paper presents an analysis of the uncertainty of the modelled pathogen concentrations and loads due to uncertainties in the models data inputs. The data collected at three different large Australian catchments were used. Firstly, uncertainties in the models input data, i.e. hourly rainfall, monthly potential evapotranspiration, catchment size and daily surface pathogen deposition rates, were assessed. Random and systematic sources of errors were taken into account. It was found that systematic errors in rainfall and random errors in pathogen deposition rates have the biggest impact on uncertainty in the models output.