珠江口磨刀门月际尺度地貌演变研究

Study on the morphological evolution of the Modaomen Estuary in monthly scale

本文基于二维波流耦合泥沙数学模型对磨刀门河口月际尺度地貌演变进行了模拟研究。结果表明:(1)枯季,无波浪作用下,磨刀门河口总体呈淤积状态;波流耦合后,磨刀门河口整体由淤积转为以冲刷为主。洪季,无波浪作用下,磨刀门河口除西汊外均呈淤积状态;波流耦合后,拦门沙内坡与中心区转为冲刷状态,整体仍以淤积为主,但总淤积量减少;(2)月际尺度上,地貌变化幅度为厘米级,洪枯季具有明显差异。不考虑波浪作用下,磨刀门河口洪、枯季均以淤积为主,但洪季淤积幅度更大;波流耦合后,磨刀门河口呈洪淤枯冲的格局;(3)空间上,拦门沙外坡洪淤枯冲,拦门沙顶洪季淤积、枯季变化不大,内坡洪枯季均为冲刷。此外,拦门沙内坡以径潮流作用产生的底切应力为主,外坡以波浪作用引起的底切应力为主。

The 2 Dwave and current coupled model is established and applied to simulate the morphological evolution of the Modaoment Estuary in monthly scale.The main findings are as follows：（1）In the dry season,the siltation dominates in the estuary without wave,however,siltation turns into erosion in the estuary with current and wave coupled.In the flood season,the siltation dominates in the estuary without wave except erosion in the west main tributary,with current and wave coupled,the siltation still dominates except that siltation turns into erosion in the inner slope and center of the mouth bar with the amount of the siltation reduced.（2）The magnitude of the monthly morphological change is centimeter level with the significant seasonal variation.The siltation dominates in the Modaomen Estuary without wave both the dry season and the flood season,with the larger siltation in the flood season.After the wave and current coupled,siltation dominates in the flood season while erosion dominates in the dry season.（3）Spatially,the outer slope of the mouth bar is silted in the flood season,and eroded in the dry season,the inner slope of the mouth bar is eroded both the flood season and the dry season,the top of the mouth bar is silted in the flood season and little changed in the dry season.In addition,the tidal induced bottom shear stress is dominant in the inner slope of the mouth bar,and wave induced bottom shear stress is dominant in the outer slope of the mouth bar.