Hydrol. Earth Syst. Sci. Discuss., https://doi.org/10.5194/hess-2019-3 Manuscript under review for journal Hydrol. Earth Syst. Sci. Discussion started: 15 January 2019 c Author(s) 2019. CC BY 4.0 License. A Multi-Objective Ensemble Approach to Hydrological Modelling in the UK: An Application to Historic Drought Reconstruction Katie A. Smith1, Lucy J. Barker1, Maliko Tanguy1, Simon Parry1, Shaun Harrigan2, Tim P. Legg3, Christel Prudhomme2,1,4, and Jamie Hannaford1,5 5 1 Centre for Ecology & Hydrology, Maclean Building, Benson Lane, Crowmarsh Gifford, Wallingford, Oxfordshire, OX10 8BB, UK 2 European Centre for Medium-Range Weather Forecasts, Shinfield Road, Reading, RG2 9AX, UK 3 Met Office, FitzRoy Road, Exeter, Devon, EX1 3PB, UK 4 Department of Geography, Loughborough University, Loughborough, LE11 3TU, UK 10 5 Irish Climate Analysis and Research UnitS, Department of Geography, Maynooth, Ireland Correspondence to: Katie A Smith (
[email protected]) Abstract. Hydrological models can provide estimates of streamflow pre- and post- observations, which enable greater understanding of past hydrological behaviour, and potential futures. In this paper, a new multi-objective calibration method was derived and tested for 303 catchments in the UK, and the calibrations were used to reconstruct river flows back to 1891, 15 in order to provide a much longer view of past hydrological variability, given the brevity of most UK river flow records which began post-1960. A Latin Hypercube sample of 500,000 parameterisations for the GR4J model for each catchment were evaluated against six evaluation metrics covering all aspects of the flow regime from high, median and low flows.