Application of flexible-structure hydrological models in different runoff generation regions

The choice of an appropriate model to be applied to a given catchment for hydrological simulation is a challenging task in hydrology research. To address this issue, extensive research efforts have been devoted to the use of flexible-structure models in recent years. Four typical conceptual models and four flexible-structure models were applied to eleven Chinese catchments divided into the saturation excess, infiltration excess and mixed runoff generation regions. The results show that, in the saturation excess runoff generation region, it is difficult to improve the simulation accuracy by using the flexible-structure models. However, these models can be used to investigate the effect of model components on the simulation results and remove unreasonable model structures for this region. Although the flexible-structure models are able to produce the improved simulations in the infiltration excess runoff generation region, they present less systematic characteristics and cannot accurately represent full hydrological processes. Generally, the flexible-structure models exhibit unstable performance and poor versatility. However, these models are easy to build and modify, and have contributed to the identification of key processes of the runoff generation and concentration. Therefore, the flexible-structure models can be used as an efficient and robust tool for hydrological simulation.