80 / 2023-12-31 21:41:30

The impacts of Mouth bar on Saltwater Intrusion in the Modaomen Estuary of the Pearl River Based on a Generalized Model

Modaomen Estuary; saltwater intrusion; mouth bar; numerical simulation; mechanism analysis

Salt water intrusion in the Pearl River Estuary is a serious threat to the water security of the Guangdong-Hong Kong-Macao Greater Bay Area, and is the focus of the Pearl River estuary management and disaster prevention as well as reduction projects. The Modaomen Estuary is the outlet of the Xijiang River, and mouth bar formed in its estuary plays a role in preventing salt water intrusion. However, under the influence of the estuarine regulation project, the evolution of mouth bar in the estuary was altered, which had an impact on the salt water intrusion. Therefore, analyzing the impact of mouth bar on the salt water intrusion in the estuary has important theoretical significance for estuarine projects, such as regulation of mouth bar in the estuary and efficient utilization of water resources. In this paper, Delft3D numerical model was used to build a generalized model of Modaomen estuary. Under different working conditions, the brine intrusion process in the ideal Modaomen estuary was numerically simulated under different conditions with or without mouth bar. Combined with the analysis and mechanism decomposition of single width salt flux in cross section, the dynamic mechanism of the effect of the evolution of mouth bar on saltwater intrusion was discussed. The effect of mouth bar on saltwater intrusion in dry season was explored. The results indicates that the mouth bar in Modaomen estuary significantly reduced the intrusion distance of the bottom saltwater, and the reduction effect is stronger at spring tide, reducing by 9 km, and its effect was related to the tide intensity. The presence of mouth bar increased the tidal oscillation transport and reduced the stable shear transport, and the effect was slightly weaker at neap tide than that at spring tide. Our study can contributed to the comprehensive regulation engineering for water resource exploit in the Modoamen estuary.Salt water intrusion in the Pearl River Estuary is a serious threat to the water security of the Guangdong-Hong Kong-Macao Greater Bay Area, and is the focus of the Pearl River estuary management and disaster prevention as well as reduction projects. The Modaomen Estuary is the outlet of the Xijiang River, and mouth bar formed in its estuary plays a role in preventing salt water intrusion. However, under the influence of the estuarine regulation project, the evolution of mouth bar in the estuary was altered, which had an impact on the salt water intrusion. Therefore, analyzing the impact of mouth bar on the salt water intrusion in the estuary has important theoretical significance for estuarine projects, such as regulation of mouth bar in the estuary and efficient utilization of water resources. In this paper, Delft3D numerical model was used to build a generalized model of Modaomen estuary. Under different working conditions, the brine intrusion process in the ideal Modaomen estuary was numerically simulated under different conditions with or without mouth bar. Combined with the analysis and mechanism decomposition of single width salt flux in cross section, the dynamic mechanism of the effect of the evolution of mouth bar on saltwater intrusion was discussed. The effect of mouth bar on saltwater intrusion in dry season was explored. The results indicates that the mouth bar in Modaomen estuary significantly reduced the intrusion distance of the bottom saltwater, and the reduction effect is stronger at spring tide, reducing by 9 km, and its effect was related to the tide intensity. The presence of mouth bar increased the tidal oscillation transport and reduced the stable shear transport, and the effect was slightly weaker at neap tide than that at spring tide. Our study can contributed to the comprehensive regulation engineering for water resource exploit in the Modoamen estuary.