The process of dike-break flood propagation in typical urban street is highly complex. The presence of buildings and trees groups in urban street profoundly alters the flood dynamics, impacting the drainage capacity of the area. In this study, a generalized sink model representing a typical urban street was established, including trees groups, buildings, sidewalks, and stormwater drainage systems. The study measured the fluctuation of water levels within the street block and the pressure variation in the pressurized stormwater drainage network during the dike-break flood propagation. Furthermore, it conducted a comparative analysis to assess the influence of different arrangements of trees groups on the maximum water depth in buildings and the discharge capacity of the pressurized stormwater drainage network. Dike-break floods give rise to large-scale water leaps and the formation of thin layer water sheets near the buildings under the influence of buildings, water tank sidewalls, and tree groups. The water leap zones exhibit lateral migration and superposition on the sidewalks during the flood propagation, gradually dissipating and disappearing in the longitudinal direction of the street. In the presence of tree groups, the water levels significantly decrease in buildings and downstream street, while the discharge capacity of the pressurized stormwater drainage network shows a slight improvement as the road’s flood-carrying capacity increases. The pressure in the main pipes fluctuates due to the switching of the grate inlet drainage mode and the hydraulic transition process in the branch pipes. The research findings not only provide valuable validation data for numerical simulations but also offer theoretical guidance for urban flood management and landscape design.

Hydraulic transients in long-distance pressurized water pipelines significantly impact their normal operation. This study develops a one-dimensional mathematical model for pressurized water pipelines using the method of characteristics and incorporates water hammer equations for dual-pipeline systems. The model is validated with experimental data, and simulations are conducted under real engineering conditions, focusing on valve closure operations. The analysis examines the transient responses for varying valve closure times (T) and the effect of installing surge tanks. Results show that increasing valve closure time and installing surge tanks both mitigate water hammer impacts. Specifically, when valve closure time exceeds 300 seconds, surge tanks reduce maximum pressure below the pipeline’s tolerance (Pmax) and decrease the number of nodes experiencing damaging negative pressures. This model effectively simulates hydraulic transients in dual-pipeline systems and provides a foundation for developing protective measures for pipeline operations.

The shoal area of the lower Yellow River in China is not flooded with water during the dry season, so various plants can grow. When floods overflow the plains in the flood season, the complexity of water resistance is increased due to the resistance to water flow by vegetation, which directly affects flood discharge in the beach area. The drag force coefficient (C_D), Manning’s roughness coefficient (n), and Darcy-Weisbach resistance coefficient (f) are commonly used to characterize vegetation drag force. Such studies are commonly conducted in clear water, but flood water in the lower Yellow River is generally muddy. In order to study the effect of the same sediment content and different sedimentation thicknesses on the resistance of muddy waters containing vegetation, this study conducted experiments in a flume (length = 28 m, width = 0.5 m, and height = 0.5 m) under different deposition thicknesses. The results showed that the vegetation drag force coefficient (C_D), vegetation roughness (n_b), and Darcy-Weisbach drag coefficient (f) all decreased logarithmically with increasing Reynolds number (Re) and Froude number (Fr). When Re > 30,000, under the conditions of different siltation thicknesses of vegetation, the vegetation roughness tended to stabilize near its minimum value. When the Reynolds number of the water flow is large (Re > 20,000), the variation of the Darcy-Weisbach drag coefficient f slows down with the Reynolds number Re. Logarithmic functions were established for the above resistance coefficients and flow coefficients, and the corresponding correlation coefficients were high, indicating that the conclusions were reliable.

In order to explore the relationship between groundwater levels and hydro-meteorological factors in Fengnan District, accurate estimation of groundwater levels in the area was undertaken. Real data on groundwater levels, water consumption, and rainfall from 2018 to 2021 in various townships within Fengnan District were selected. Utilizing the Principal Component Analysis method, the main influencing factors were extracted from the hydrological data of each township. Subsequently, a groundwater level calculation model was established using the CIWOABP(Cubic map - Intelligent weight adjustment - Whale Optimization Algorithm–Back Propagation) neural network in combination with these factors. The results indicate that: (1) Principal Component Analysis extracted a total of five principal components from various hydrological data in Fengnan District, namely, groundwater levels of monitoring wells #11 and #12, rainfall from rainfall station r1, and water consumption from Fengnan (FN) and Qianying (QY) towns. (2) The CIWOABP neural network was trained using 36 sets of actual measurement data and validated with 12 sets of simulated data. The mean absolute errors (MAE) for monitoring wells #11 and #12 were 0.19 and 0.23 respectively, and the mean squared errors (MSE) were 0.05 and 0.09 respectively. The model exhibited high computational accuracy and can be effectively employed to calculate actual groundwater levels. The research outcomes can provide theoretical and methodological insights for groundwater resource management in the North China Plain.

The study focuses on a key component of the Yangtze–Huaihe River Diversion Project—the Qiliqiao to Xincheng water supply pipeline section, which includes a megascale inverted siphon structure. A one‐dimensional mathematical model is developed to simulate water hammer phenomena in transmission pipelines containing the large siphon. A comparative analysis is conducted to evaluate the protective effects of linear and nonlinear valve closure strategies. The optimal valve closure scheme is explored by parameterizing the valve closing duration and buffering time. The impact of air valves installed near the inverted siphon during hydraulic transition processes is examined, and the transient variations of key hydraulic parameters during the entire valve closure operation are systematically characterized. Under long‐term operational conditions with Manning’s coefficient degradation, the designed pipeline maintains a hydraulic head surplus of 7.34 m, fully meeting long‐distance water supply requirements. Air valves effectively reduce the peak pressure magnitude by 80%. Under linear valve closure conditions, only the high‐elevation air valves exhibit significant exhaust behavior. In contrast, nonlinear closure strategies reduce the minimum internal pressure of the pipeline and suppress vaporization, thereby reducing the air valve discharge volume. Finally, the study identifies an optimal time coordination scheme by adjusting the closure timing of individual pumps and the interval between adjacent pump shutdowns.