Abstract
The partial runoff is complicated in semi-arid and some semi-humid zones in terms of what the runoff generates in partial vertical positions. The partial runoff is highlighted by horizontal soil heterogeneity as well. How to identify the partial runoff and develop a variable threshold for runoff generation is a great difficulty and challenge. In this work, the partial runoff is identified by using a variable active runoff layer structure, and a variable soil water storage capacity is proposed to act as a threshold for runoff generation. A variable layer-based runoff model (VLRM) for simulating the complex partial runoff was therefore developed, using dual distribution curves for variable soil water storage capacity over basin. The VLRM is distinct in that the threshold for runoff generation is denoted by variable soil water storage capacity instead of infiltration capacity or constant soil water storage capacity. A series of flood events in two typical basins of North China are simulated by the model, and also by the Xinanjiang model. Results demonstrate that the new threshold performs well and the new model outperforms the Xinanjiang model. The approach improves current hydrological modelling for complex runoff in regions with large deficiencies in soil water storage.
Highlights
Reliable and accurate flood forecasts by rainfall–runoff models are of importance for efficient reservoir operation, river management, flood control [1], and warning [2,3,4]
The vertical partial runoff issue commonly existing in regions with a large deficiency in soil water storage are characterized
The vertical and horizontal distribution curves for relative soil water storage capacity are constructed to characterize the non-uniformity of the soil water deficiency over the catchment
Summary
Reliable and accurate flood forecasts by rainfall–runoff models are of importance for efficient reservoir operation, river management, flood control [1], and warning [2,3,4]. As a basic theory supporting flood forecast, runoff generation theory is a hot pot for hydrological research worldwide. Great efforts have been implemented to develop the runoff generation theory [5], providing beneficial insight to analyze the underlying hydrological processes. A range of hydrological models are developed based on the runoff generation theory. The runoff concept facilitates the development of famous models, such as the TOPography based hydrological MODEL (TOPMODEL) [7], and the variable infiltration capacity model (VIC) [8]. TOPMODEL is a semi-distributed conceptual rainfall–runoff model that takes advantage of topographic information related to runoff generation. The concept of runoff generation method is to compute storage deficit or water table depth at any location [9,10]
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