Abstract
Karst trough valleys are prone to flooding, primarily because of the unique hydrogeological features of karst landform, which are conducive to the spread of rapid runoff. Hydrological models that represent the complicated hydrological processes in karst regions are effective for predicting karst flooding, but their application has been hampered by their complex model structures and associated parameter set, especially so for distributed hydrological models, which require large amounts of hydrogeological data. Distributed hydrological models for predicting the Karst flooding is highly dependent on distributed structrues modeling, complicated boundary parameters setting, and tremendous hydrogeological data processing that is both time and computational power consuming. Proposed here is a distributed physically-based karst hydrological model, known as the QMG (Qingmuguan) model. The structural design of this model is relatively simple, and it is generally divided into surface and underground double-layered structures. The parameters that represent the structural functions of each layer have clear physical meanings, and the parameters are less than those of the current distributed models. This allows modeling in karst areas with only a small amount of necessary hydrogeological data. 18 flood processes across the karst underground river in the Qingmuguan karst trough valley are simulated by the QMG model, and the simulated values agree well with observations, for which the average value of Nash–Sutcliffe coefficient was 0.92. A sensitivity analysis shows that the infiltration coefficient, permeability coefficient, and rock porosity are the parameters that require the most attention in model calibration and optimization. The improved predictability of karst flooding by the proposed QMG model promotes a better mechanistic depicting of runoff generation and confluence in karst trough valleys.
Highlights
Karst trough valleys are very common in China, especially in the southwest
The QMG model proposed in this study has a two-layer structure, including a surface part and an underground part, with the former mainly performing the calculation of runoff generation and the confluence of the surface river, while the latter performs the confluence calculation of the underground river system
The number of parameters in a distributed hydrological model is generally large, and it is important to perform a sensitivity analysis of each parameter to quantitatively assess the impact of the different parameters on model performance
Summary
Karst trough valleys are very common in China, especially in the southwest. These karst areas are water scarce because their surfaces store very little rainfall, but it is a protential birthplace for floods. The Qingmuguan karst trough valley for example, floods used to happen here constantly. The simulation and prediction of karst flooding events in these karst trough valleys like the study area are both important and urgently needed. System Hydrologue Europeen, ‘SHE’, a: History and Philosophy of a Physically-based, Distributed Modelling System,J. System Hydrologue Europeen, ‘SHE’, b: Structure of a Physically based, distributed modeling System, J.
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