Abstract
Hydrological models for regions characterized by complex runoff generation process been suffer from a great weakness. A delicate hydrological balance triggered by prolonged wet or dry underlying condition and variable extreme rainfall makes the rainfall-runoff process difficult to simulate with traditional models. To this end, this study develops a novel vertically mixed model for complex runoff estimation that considers both the runoff generation in excess of infiltration at soil surface and that on excess of storage capacity at subsurface. Different from traditional models, the model is first coupled through a statistical approach proposed in this study, which considers the spatial heterogeneity of water transport and runoff generation. The model has the advantage of distributed model to describe spatial heterogeneity and the merits of lumped conceptual model to conveniently and accurately forecast flood. The model is tested through comparison with other four models in three catchments in China. The Nash–Sutcliffe efficiency coefficient and the ratio of qualified results increase obviously. Results show that the model performs well in simulating various floods, providing a beneficial means to simulate floods in regions with complex runoff generation process.
Highlights
Rainfall-runoff models are basic and important tools for flood forecasting [1,2,3]
The performance of simulation is collectively tested by using the relative error of total runoff depth (RER), the relative error of flood peak (REP), the error of peak appearance time (ET) and Nash–Sutcliffe efficiency coefficient (NSE)
For Xiuwu Basin, almost all the flood peaks and the total runoff depths are simulated well by the model (SVHM) in terms of that most of the RER and REP are found within the permissible error in flood forecast [36] (Table 2)
Summary
Rainfall-runoff models are basic and important tools for flood forecasting [1,2,3]. Reliable and accurate flood forecasts by rainfall-runoff models are important for efficient reservoir operation, river management, flood control and warning [4,5,6,7,8]. The variable layer-based runoff model (VLRM) [3] try to simulate runoff generation process based on a new partial saturation-excess concept, which captures the complex runoff even the unsaturated zone is not totally saturated but neglects the infiltration-excess surface runoff component. It is urgently needed to develop a new framework to couple the infiltration-excess and saturation-excess runoff through considering the spatial partial runoff issue and the heterogeneity of water transmission between the two processes Toward this end, the objectives of this investigation are to: (1) identify the vertical process of infiltration and runoff generation; (2) develop a new vertically mixed runoff model by a probabilistic coupling method; and (3) integrate the vertical mixed approach to a hydrological model and test the performance through a comparison with other four models over three catchments in typical semi-humid and semi-arid region
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