In order to explore the impact of river level and total rainfall duration on the drainage performance of rainwater pipe network, an integrated SWMM generalized model of pipe network and river in a certain industrial park was constructed. Based on the rainfall events with a return period of 5 years and the total rainfall duration of 2 h and 24 h, the drainage conditions of rainwater pipe network and river in industrial parks with different initial river levels were simulated and analyzed. The results show that when the initial river level is low and the outlet is free outflow, river level has little impact on the drainage performance of the rainwater pipe network. When the outlet is submerged, with the increase of the initial river level, the proportion of overloaded pipelines and overflow nodes in the drainage system increases, the overload time and overflow time are prolonged, the peak flow of outlets and pipeline nodes decreases, and the peak flow of node which is closer to outlet decreases more sharply. Based on the same rainfall return period and the initial river level, compared with the short duration rainfall, the proportion of overloaded pipelines and overflow nodes in the long-duration rainfall is larger, the overload time and overflow time are longer, and the peak flow of outlets and pipeline nodes decreases greatly. When designing the storm water drainage system with river-pipe network, it is advisable to check the drainage performance of storm water drainage system for 24 h rainfall and different river levels.

The change of hydrological situation and the operation scheduling of the downstream of the hub make the water level at the inlet and outlet of the fish channel change at all time, and the fish channel is running improperly. The insufficient inlet water depth will cause water drop and hinder the backtracking of fish. The integrated model was used to analyze the hydraulic characteristics under different water level combinations at the inlet and outlet of the fishing channel. The results show that the hydrodynamic changes of the fish tunnel tank chamber are mainly concentrated in the pool chamber near the inlet, and the greater the influence is closer to the downstream. When the inlet water level decreases, the water drops at the inlet and it is difficult for fish to trace; When the inlet water level rises, the inlet velocity slows down rapidly. In view of the design inlet flow velocity is 0.60 m/s-1.00 m/s, the maximum drop between the outlet of the fish channel and the inlet water depth is recommended to be controlled at 1.00 m. At the same time, appropriate water replenishment measures should be taken according to the water depth of the inlet to form effective lure flow rate at the inlet, and there is a good linear relationship between the supplementary water flow and the inlet water depth.

To analyze the impact of the construction of the Hengsha Dongtan (Phase 6-8) project on the Yangtze River Estuary, a two-dimensional tidal flow model was established using Delft3D, and tidal level and velocity calibration verification was conducted using existing hydrological data from 2008 and 2016. Based on the hydrological conditions in normal and flood years, the hydrological conditions, such as tidal volume, tidal level, and flow field in the main tributaries of the Yangtze River Estuary before and after the implementation of the Hengsha Dongtan Phase 6-8 Project were simulated. The results show that under two flow conditions, the construction of the Hengsha Dongtan Phase 6-8 project has a relatively small impact on the rising and falling tide flows of the main tributaries of the Yangtze River Estuary. The variation of high and low tide levels in the Yangtze River Estuary does not exceed 0.01 m, and the variation of high and low tide levels in the water area where the project is located does not exceed 0.02 m; The project has no significant adverse impact on the large-scale flow field structure of the Yangtze River Estuary. The rising tide velocity of the Beigang Waterway and Beigang Beisha Jiahong has decreased, with a maximum decrease of 0.03 m/s in Beigang Waterway and 0.02 m/s in Beigang Beisha Jiahong. The rising tide velocity of the Hengsha Channel and the North Channel of the Yangtze River Estuary has remained basically unchanged. Under the current riverbed terrain and engineering boundary conditions (all of the Hengsha East Beach project has been completed), there is a northwest southeast channel on the northeast side of the beach surface. The northern edge of the eighth phase project and the northern edge of the downstream sand body have a high ebb tide velocity, with a maximum velocity of 1.5 m/s or above, which is not conducive to the stability of the Hengsha East Beach regulation project.

The fan-shaped central revolving gate is a new type of gate with a significantly different flow pattern from the traditional gate. In order to study the hydrodynamic pressure characteristics of the fan-shaped central revolving gate, model experiment was conducted on the different opening coefficients of the gate based on the 60 m span gate of Wusongjiang regulation project and its energy dissipation design conditions, and the time-average pressure, average fluctuation amplitude, pulsation intensity and spectral characteristics under different opening coefficients were analyzed. The results show that the time-average pressure of the gate blade is positive pressure at each opening coefficient, and the overall pulsating pressure amplitude is relatively stable. The pulsating pressure of each measuring point is close to normal distribution under different opening coefficients. The pulsation intensity changes with the change of the opening and measuring point position. With the increase of the opening coefficient, the pulsation intensity presents a trend distribution of decreasing first and then increasing, and the pulsation intensity belongs to the low-frequency pulsation. The change of the measuring point position in the width direction will affect the pulsation intensity of the measuring point, and the center line pulsation intensity can be used instead of the whole gate pulsation intensity.

Based on the daily precipitation data of 38 meteorological stations in the Huaihe River Basin from 1961 to 2020, the consecutive dry days (CDD) were selected. The variation characteristics of CDD and its response to 12 circulation index at different time scales were analyzed by using M-K trend test, principal component analysis, the lag correlation analysis and cross wavelet transform. The results indicate that the spatial distribution of CDD in Huaihe River Basin had obvious seasonal characteristics. It was high in the west and low in the east in summer, and high in the north and low in the south in spring, autumn and winter. In the past 60 years, the changes of CDD in different seasons were also different. The CDD increased in most stations and the basin tended to become dry in autumn, but the CDD decreased in all stations and drought slowed down in the basin in winter. The CDD with different time lags had good correlations with the WP, SOI and Nino4, and the strongest correlation with Nino4. The Nino4 had a significant strengthening effect on the CDD with a lag of 4 and 5 months, and a significant weakening effect on the CDD with a lag of 10 and 11 months. The significant influence of Nino4 on CDD was mainly concentrated in the resonance period of 10-15 months, and there was a significant negative correlation between Nino4 and CDD. The finding is prone to useful for drought prediction and water resources management in the future.

The groundwater level in the deep foundation pit project close to the river shows a dynamic characteristic of long-term low water level but high water level during flood season. Foundation pit dewatering leads to the complexity of the seepage field in the surrounding stratum environment, destruction of enclosure structures, accidents include piping and instability at the bottom of the pit. Therefore, this paper simulated the excavation-precipitation process of deep foundation pit project based on the HS-Small constitutive model, analyzed the sensitivity of precipitation influencing factors (precipitation depth, mode, rate and water stop curtain) to the surrounding environment deformation and their relationship. Compared the analysis results with the measured results, it can be found that the settlement of the top of the foundation pit, the soil outside the pit and the surrounding buildings gradually increases, and the dewatering has a more obvious influence on the deformation during the excavation and dewatering of the foundation pit; Fractional precipitation can effectively reduce the settlement deformation of surrounding buildings and ground surface; It is recommended that the dewatering depth of foundation pit should be controlled within 0.5-2.0 m below the bottom plate; The precipitation rate has a relatively small impact on the total settlement of the surrounding environment, but has a great impact on the settlement rate. When the precipitation rate reaches the optimal value, it is beneficial to the stability control of the foundation pit. The embedded depth of water-proof curtain in this project is more than 30 m, which has no obvious effect on controlling the settlement of surrounding buildings. The research results can provide reference for the dewatering design and construction of similar deep foundation pit projects closed to the river.

In order to study whether the original design flow can be met after the lining scheme of sections of a long distance non-pressure diversion tunnel is changed, the flow capacity of typical sections of the tunnel was analyzed by model test and theoretical calculation. There are 4 tunnel diameters and 2 roughness in the typical section of the tunnel. In order to meet the conditions of similar resistance, different materials were compared and tested, and the roughness was determined. Through testing and analyzing the flow capacity and flow characteristics at three operating conditions, it is concluded that the flow can be safely passed under operating condition 1, and the clearance margin of some tunnel sections under operating condition 2 is insufficient, with the minimum margin of 14.39%. Most tunnel sections under operating condition 3 do not meet the safety flow. Comparing the test and theoretical calculation, the results of the two are relatively close, and the test value is relatively safe, which can provide a theoretical basis for the construction and operation of the project.

The proposed Longweizhou junction is a low-head hydro-junction project that focuses on navigation, flood control, water resources, and protection of the aquatic ecological environment. There are two continuous bends upstream and downstream of the dam site, and the straight section where the dam site is located is also short, so the river boundary conditions are not conducive to smooth flood discharge after the project. To demonstrate and optimize the general layout of the proposed hydro-junction, an integrated hydraulic-physical model with a scale of 1∶80 was adopted. On the basis of hydrodynamic similarity verification, a detailed experimental study was conducted on the discharge capacity of the hydro-junction, revealing the characteristics of flow velocity distribution and flow distribution in the original design scheme under typical flood conditions, clarifying the shortcomings of the original scheme and corresponding optimization ideas, putting forward the measure of cutting the side beach to improve discharge capacity. The optimized scheme test verified that the discharge capacity could meet the design requirements. The research results may serve as reference for the design of this project and other similar projects.

Aiming at analyzing the mechanism of slope failure and evolution propagation induced by typhoon and rainstorm, a numerical simulation of the safety state of a slope was carried out based on the measured rainfall data during various typhoons in Fujian Province of China. For the slope before instability, Monte Carlo method was used to calculate the real-time failure probability and reliability index and reveal the transient change characteristics of the seepage field and plastic zone of the slope. For the slope after instability, Herschel-Bulkley-Papanastasiou (HBP) model was used to describe the rheological characteristics of the slope using the SPH method. The propagation process of landslides was analyzed in terms of velocity and accumulation characteristics. The results show that the rainfall is the key factor to induce slope instability. When the slope failure occurs, the sliding speed of the leading edge can reach 15 m/s. This study provides a reference for the early warning and disaster prevention and mitigation of slope engineering under extreme conditions.

In order to study the water logging risk in lakeshore urban caused by the blocking drainage effect (BDE) of Poyang Lake, the "regulation and storage model" was used to elucidate the BDE of Poyang Lake on inner river drainage in Changnan District and to explore the impact of Poyang Lake on waterlogging risk of lakeshore urban. By defining the Index of Blocking Drainage (IBD) which quantifies the BDE, the main controlling factors that affect the IBD was explored and the response relationship between them was quantified. The results show that the main controlling factors affecting the IBD include rainfall intensity, water level of outer river, drainage capacity and storage space. There is an obvious quadric curve relationship between rainfall intensity and the IBD, and 11.67 mm/h is the inflection point of the curve. There is a four-quadrant risk diagram relationship between the IBD and the water level of outer river. The decrease frequency of the IBD increases with the increase of drainage capacity. The effect of reducing the IBD by improving the drainage capacity of Changnan District is obviously reduced when the rainfall intensity exceeds 11.67 mm/h. The IBD of the same rain intensity decreases gradually with the increase of storage space. The effect of reducing the IBD of Qingshanhu District by increasing the storage space is obviously reduced when the rainfall intensity exceeds 15.83 mm/h. The water logging risk in lakeshore urban caused by the DBE of Poyang Lake can be effectively reduced by appropriately improving the drainage capacity, reducing the proportion of impervious ground and increasing the adjustable storage space, but the ability to deal with extreme rainstorm events remains limited.