TY  - JOUR
A1  - Breuer, Lutz
A1  - Willems, Patrick
A1  - Bormann, Helge
A1  - Bronstert, Axel
A1  - Croke, Barry
A1  - Frede, Hans Georg
A1  - Gräff, Thomas
A1  - Hubrechts, Lode
A1  - Kite, Geoffrey
A1  - Lanini, Jordan
A1  - Leavesley, George
A1  - Lettenmaier, Dennis P.
A1  - Lindstroem, Goeran
A1  - Seibert, Jan
A1  - Sivapalan, Mayuran
A1  - Viney, Neil R.
T1  - Assessing the impact of land use change on hydrology by ensemble modeling (LUCHEM) : I: model intercomparison with current land use
N2  - This paper introduces the project on 'Assessing the impact of land use change on hydrology by ensemble modeling (LUCHEM)' that aims at investigating the envelope of predictions on changes in hydrological fluxes due to land use change. As part of a series of four papers, this paper outlines the motivation and setup of LUCHEM, and presents a model intercomparison for the present-day simulation results. Such an intercomparison provides a valuable basis to investigate the effects of different model structures on model predictions and paves the ground for the analysis of the performance of multi-model ensembles and the reliability of the scenario predictions in companion papers. in this study, we applied a set of 10 lumped, semi-lumped and fully distributed hydrological models that have been previously used in land use change studies to the low mountainous Dill catchment. Germany. Substantial differences in model performance were observed with Nash-Sutcliffe efficiencies ranging from 0.53 to 0.92. Differences in model performance were attributed to (1) model input data, (2) model calibration and (3) the physical basis of the models. The models were applied with two sets of input data: an original and a homogenized data set. This homogenization of precipitation, temperature and leaf area index was performed to reduce the variation between the models. Homogenization improved the comparability of model simulations and resulted in a reduced average bias, although some variation in model data input remained. The effect of the physical differences between models on the long-term water balance was mainly attributed to differences in how models represent evapotranspiration. Semi-lumped and lumped conceptual models slightly outperformed the fully distributed and physically based models. This was attributed to the automatic model calibration typically used for this type of models. Overall, however, we conclude that there was no superior model if several measures of model performance are considered and that all models are suitable to participate in further multi-model ensemble set-ups and land use change scenario investigations.
Y1  - 2009
UR  - http://www.sciencedirect.com/science/journal/03091708
U6  - https://doi.org/10.1016/j.advwatres.2008.10.003
SN  - 0309-1708
ER  - 
TY  - JOUR
A1  - Bormann, Helge
A1  - Breuer, Lutz
A1  - Graff, Thomas
A1  - Croke, Barry
T1  - Assessing the impact of land use change on hydrology by ensemble modelling (LUCHEM) IV : model sensitivity to data aggregation and spatial (re-)distribution
N2  - This paper analyses the effect of spatial resolution and distribution of model input data on the results of regional-scale land use scenarios using three different hydrological catchment models. A 25 m resolution data set of a mesoscale catchment and three land use scenarios are used. Data are systematically aggregated to resolutions up to 2 kill. Land use scenarios are spatially redistributed, both randomly and topography based. Using these data, water fluxes are calculated on a daily time step for a 16 year time period without further calibration. Simulation results are used to identify grid size, distribution and model dependent scenario effects. In the case of data aggregation, all applied models react sensitively to grid size. WASIM and TOPLATS simulate constant water balances for grid sizes from 50 m to 300-500 m, SWAT is more sensitive to input data aggregation, simulating constant water balances between 50 m and 200 m grid size. The calculation of scenario effects is less robust to data aggregation. The maximum acceptable grid size reduces to 200-300 m for TOPLATS and WASIM. In case of spatial distribution, SWAT and TOPLATS are slightly sensitive to a redistribution of land use (below 1.5% for water balance terms), whereas WASIM shows almost no reaction. Because the aggregation effects were stronger than the redistribution effects, it is concluded that spatial discretisation is more important than spatial distribution. As the aggregation effect was mainly associated with a change in land use fraction, it is concluded that accuracy of data sets is much more important than a high spatial resolution.
Y1  - 2009
UR  - http://www.sciencedirect.com/science/journal/03091708
U6  - https://doi.org/10.1016/j.advwatres.2008.01.002
SN  - 0309-1708
ER  -