Comparison of performance of twelve monthly water balance models in different climatic catchments of China

- We compared twelve monthly water balance models in 153 catchments in China.
- The climatic characteristic is the most important factor impacting model performance.
- Increasing model complexity does not guarantee a better model performance.
- Improvement of evaporation simulation has limited influence on model performance.

Multi-model comparison can provide useful information for model selection and improvement. In this study, twelve monthly water balance models with different structures and various degree of complexity are compared in 153 catchments with different climatic conditions in China. Generally, the GR5M model has the best performance, followed by the GR2M and WBM model. We investigate the relations between model performance and catchment characteristics and find that the climatic characteristic of a catchment is the most important factor impacting model performance. The models have better performance in wet catchments than in dry catchments. Large differences of model performance exist in dry catchments and model users should pay attention to model selection in dry catchments. In addition, we analyze the model performances among different models and conclude that increasing the model complexity does not guarantee a better model performance. Simple models can achieve comparable or even better performance than complex models. For the monthly simulation of hydrological processes, a two-parameter model is sufficient to achieve a good result. Moreover, by comparing the impacts of evapotranspiration simulation and runoff generation simulation on model performance, we find that evapotranspiration simulation has limited influence on the model performance. We suggest model builders focus on runoff generation process rather than evapotranspiration process to improve the performance of a monthly hydrological model.