5 A Case Study of Uncertainty: Applying GLUE to EUROSEM J.N. QUINTON 1 , T. KRUEGER 2 , J. FREER 3 , R.E. BRAZIER 4 AND G.S. BILOTTA 5 1 Lancaster Environment Centre, University of Lancaster, Lancaster, UK 2 School of Environmental Sciences, University of East Anglia, Norwich, UK 3 School of Geographical Sciences, University of Bristol, Bristol, UK 4 School of Geography, University of Exeter, Exeter, UK 5 School of Environment and Technology, University of Brighton, Brighton, UK 5.1 Introduction At the time of writing, it is 10 years since Morgan et al. (1998a) published their paper describing the European Soil Erosion Model (EUROSEM). Since then the model has been downloaded by over 700 scientists from 64 countries worldwide. It remains one of the few truly dynamic and distributed soil erosion models. The concepts behind EUROSEM date back over 20 years. It was first proposed at the Workshop on Erosion Assessment and Modelling held in Brussels in December 1986. At that workshop, Chisci and Morgan (1986) were critical of the mod- els being developed in the US and believed that there was a potential to utilise process-based research from within the European Community to develop something better. They set out six design requirements: (1) to enable the risk of erosion to be assessed; (2) to be applicable at field and catchment scales; (3) to allow the contribution of sediment and solutes from the land surface to water bod- ies to be determined; (4) to provide reliable esti- mates of erosion and solute concentrations for comparison with acceptable standards; (5) to oper- ate on an event basis; and (6) to be useful as a design tool for selecting soil protection measures. This was the basis for a collaborative research programme to turn these requirements into real- ity. In all the EUROSEM project ran from 1988 through to 1994, supported by two tranches of funding from the EU, and was also a core compo- nent of two further EU-funded projects: Modelling Within Storm Sediment Dynamics (MWISED) and Soil Productivity Indices and Erosion Sensitivity (SPIES). The first operational versions of the model were released in 1992, with further releases in 1994 and 1998. The model has also influenced the development of other erosion models, notably the Limburg Soil Erosion Model (LISEM: De Roo et al., 1996). An Italian team lead by Lorenzo Borselli is currently developing a new version of the model, incorporating new process descriptions originating from more recent process research and the outputs of the MWISED project (Borselli et al., 2008). There have been a number of attempts to eval- uate EUROSEM against measured data. Quin- ton (1994, 1997) evaluated the model against data from the Woburn Erosion Reference Experiment (Quinton & Catt, 2004). Quinton selected param- eters to which the model was most sensitive and sampled four values of each from measured distri- butions and applied the model to single storms. The results demonstrated, for the first time, that Handbook of Erosion Modelling, 1 st edition. Edited by R.P.C. Morgan and M.A. Nearing. © 2011 Blackwell Publishing Ltd. 9781405190107_4_005.indd 80 9781405190107_4_005.indd 80 10/15/2010 10:17:06 PM 10/15/2010 10:17:06 PM