Investigation of the Impact of the Guangzhou-Lechang Expressway Segment at the Pajiang River Detention Basin to Its Normal Flood Prevention Operation

Based on the existing relevant information, the paper investigates the occupation situation of the segment of the Guangzhou-Lechang expressway in the Pajiang River detention basin and analyzes the relationship of the water conservancy facility construction to the planning of the detention basin. One-dimensional and two-dimensional mathematical models are established to evaluate the construction effect on flood control in the detention basin under the normal use condition of the Pajiang River. The results show that the construction occupies 0.09% regulation and storage volume of the detention basin, which leads to the following impacts to its flood prevention operation: the starting time of the detention basin delayed 3~12 minutes, the average discharge of the Jiangkouxun section in the main river of the Beijiang River increased 12m3/s, and the average discharges of the Tiechuang-ao section of the Pajiang River and the Changbu section of the Yuantan River in the detention basin decreased 14 m³/s and 13 m³/s, respectively. Meanwhile, the highest water level of the Jiangkouxu Station and the peak discharge of the Shijiao Station remain almost the same. Therefore, as the conclusion, the engineering construction of the expressway segment only produces a minor impact on flood control of the Beijiang River. This investigation provides the technical basis for evaluation of the impact to flood prevention by highway construction for similar projects and will be useful for decision-making of the relevant planning agencies.