TY - JOUR

T1 - Use of expert elicitation to assign weights to climate and hydrological models in climate impact studies

AU - Sebok, Eva

AU - Henriksen, Hans Jorgen

AU - Pasten-Zapata, Ernesto

AU - Berg, Peter

AU - Thirel, Guillaume

AU - Lemoine, Anthony

AU - Lira-Loarca, Andrea

AU - Photiadou, Christiana

AU - Pimentel, Rafael

AU - Royer-Gaspard, Paul

AU - Kjellstrom, Erik

AU - Christensen, Jens Hesselbjerg

AU - Vidal, Jean Philippe

AU - Lucas-Picher, Philippe

AU - Donat, Markus G.

AU - Besio, Giovanni

AU - Jose Polo, Maria

AU - Stisen, Simon

AU - Caballero, Yvan

AU - Pechlivanidis, Ilias G.

AU - Troldborg, Lars

AU - Refsgaard, Jens Christian

PY - 2022/11/9

Y1 - 2022/11/9

N2 - Various methods are available for assessing uncertainties in climate impact studies. Among such methods, model weighting by expert elicitation is a practical way to provide a weighted ensemble of models for specific real-world impacts. The aim is to decrease the influence of improbable models in the results and easing the decision-making process. In this study both climate and hydrological models are analysed, and the result of a research experiment is presented using model weighting with the participation of six climate model experts and six hydrological model experts. For the experiment, seven climate models are a priori selected from a larger EURO-CORDEX (Coordinated Regional Downscaling Experiment - European Domain) ensemble of climate models, and three different hydrological models are chosen for each of the three European river basins. The model weighting is based on qualitative evaluation by the experts for each of the selected models based on a training material that describes the overall model structure and literature about climate models and the performance of hydrological models for the present period. The expert elicitation process follows a three-stage approach, with two individual rounds of elicitation of probabilities and a final group consensus, where the experts are separated into two different community groups: a climate and a hydrological modeller group. The dialogue reveals that under the conditions of the study, most climate modellers prefer the equal weighting of ensemble members, whereas hydrological-impact modellers in general are more open for assigning weights to different models in a multi-model ensemble, based on model performance and model structure. Climate experts are more open to exclude models, if obviously flawed, than to put weights on selected models in a relatively small ensemble. The study shows that expert elicitation can be an efficient way to assign weights to different hydrological models and thereby reduce the uncertainty in climate impact. However, for the climate model ensemble, comprising seven models, the elicitation in the format of this study could only re-establish a uniform weight between climate models.

AB - Various methods are available for assessing uncertainties in climate impact studies. Among such methods, model weighting by expert elicitation is a practical way to provide a weighted ensemble of models for specific real-world impacts. The aim is to decrease the influence of improbable models in the results and easing the decision-making process. In this study both climate and hydrological models are analysed, and the result of a research experiment is presented using model weighting with the participation of six climate model experts and six hydrological model experts. For the experiment, seven climate models are a priori selected from a larger EURO-CORDEX (Coordinated Regional Downscaling Experiment - European Domain) ensemble of climate models, and three different hydrological models are chosen for each of the three European river basins. The model weighting is based on qualitative evaluation by the experts for each of the selected models based on a training material that describes the overall model structure and literature about climate models and the performance of hydrological models for the present period. The expert elicitation process follows a three-stage approach, with two individual rounds of elicitation of probabilities and a final group consensus, where the experts are separated into two different community groups: a climate and a hydrological modeller group. The dialogue reveals that under the conditions of the study, most climate modellers prefer the equal weighting of ensemble members, whereas hydrological-impact modellers in general are more open for assigning weights to different models in a multi-model ensemble, based on model performance and model structure. Climate experts are more open to exclude models, if obviously flawed, than to put weights on selected models in a relatively small ensemble. The study shows that expert elicitation can be an efficient way to assign weights to different hydrological models and thereby reduce the uncertainty in climate impact. However, for the climate model ensemble, comprising seven models, the elicitation in the format of this study could only re-establish a uniform weight between climate models.

KW - EURO-CORDEX

KW - WATER

KW - UNCERTAINTY

KW - PROJECTIONS

KW - JUDGMENT

KW - FLOW

KW - SENSITIVITY

KW - ROBUSTNESS

KW - ADAPTATION

KW - PREDICTION

U2 - 10.5194/hess-26-5605-2022

DO - 10.5194/hess-26-5605-2022

M3 - Journal article

VL - 26

SP - 5605

EP - 5625

JO - Hydrology and Earth System Sciences

JF - Hydrology and Earth System Sciences

SN - 1027-5606

IS - 21

ER -