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Field Survey and Numerical Modeling of Hillslope Hydrological Processes over a Headwater Catchment in Hong Kong, China

Author(s): Qian Xu; Ji Chen; Liqun Sun; Mervyn Peart

Linked Author(s): Ji Chen

Keywords: Hillslope hydrology; One-minute time step; Soil properties; TOPMODEL; Overland flow

Abstract: This study aims to improve our knowledge of hillslope hydrology. Due to frequent heavy monsoon rainfalls in the rainy seasons and the steep topographic slopes, Hong Kong suffers the hazards of flash floods almost every year, and an improved understanding of hillslope hydrology is valuable for flash flood forecasting. To explore the hillslope hydrology, in Mid-2007, several automatic rain gauges and one automatic water level data-logger were installed at a headwater catchment in Hong Kong for providing rainfall and runoff data at the one-minute time step. Since then, several severe rainfall hyetographs and related runoff hydrographs have been obtained. To make use of the observed hydrological data, a numerical model, TOPMODEL, was used to simulate the hydrological processes. Further, to determine the model parameters, several field surveys have been conducted to collect land cover, soil properties, and hydraulic features of the catchment. Then, these data were used to investigate various aspects of the catchment's hydrology and in particular to study the catchment's precipitation and runoff process. The study result reveals there was a significant difference between overland flow and baseflow. For the hillslope hydrology, this study showed that the overland runoff appears rarely, and the subsurface flow formed a dominant part of the flash flooding hydrograph.


Year: 2013

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