Study on optimization and combination strategy of multiple daily runoff prediction models coupled with physical mechanism and LSTM

•A type of model selection and combination strategy is proposed incorporating 16 different physically based models with LSTM technology.•A grouped model performance evaluation metric was proposed, which not only considers the performance of individual models, but also comprehensively evaluates the performance of a model group formed by multiple models.•It is found that the F score metric may not be suitable for evaluating model selection.