Linlin Li , Hang Li , Genguang Zhang , Defu Liu , Yao Xiao , Ying Liu , Jiahao Zou
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引用次数: 0
Abstract
Hyporheic exchange process is a common mode of surface water-groundwater interaction, involving the transport of substances, nutrients and energy, which is an important foundation for river ecology. However, the effect of riverbed deformation driven by weir in natural rivers remains unclear. In this study, the effect of local scour pit created by low-head weirs on hyporheic exchange process was studied by the coupled model of surface water-groundwater. While many studies assume static riverbed conditions, this study integrates a dynamic surface water model that accounts for sediment transport and evolving scour pits, while employing a steady-state representation for subsurface flow to reflect the gradual adjustment of hyporheic exchange. The variation of the local scour depth, hyporheic exchange flux, hyporheic zone pressure field and temperature response area were investigated under different weir height and flow discharge. The results showed that: (a) the increasing weir height significantly enhanced hydrodynamic effect, with the morphological changes in scour pits altering the distribution of hyporheic zone pressure field and further intensifying surface water-groundwater exchange; (b) when the weir height increased from 15 cm to 25 cm, the scour pit depth increased from 9 cm to 25 cm, the volume of the local scour pit increased by approximately 3.3 times, and the hyporheic exchange flux increased to a maximum value of 0.011 m2/s; (c) the peak downwelling Darcy velocity in the hyporheic zone increased from 0.0039 m/s to 0.0067 m/s as the flow discharge increased from 0.0621 m3/s to 0.1200 m3/s; (d) the scour pit formation altered the local bed topography, then influencing the hyporheic exchange pathways and rates; the peak downwelling Darcy velocity with the riverbed scouring effect was 2.5 times higher than that of the others, with the hyporheic exchange flux increasing by 1.5 times. This study can provide theoretical insights for optimizing low-head weir designs and water management in river ecological restoration.
期刊介绍:
Catena publishes papers describing original field and laboratory investigations and reviews on geoecology and landscape evolution with emphasis on interdisciplinary aspects of soil science, hydrology and geomorphology. It aims to disseminate new knowledge and foster better understanding of the physical environment, of evolutionary sequences that have resulted in past and current landscapes, and of the natural processes that are likely to determine the fate of our terrestrial environment.
Papers within any one of the above topics are welcome provided they are of sufficiently wide interest and relevance.