Taking double-discharge building in branching stream of Baiyang Lake as an example, the relationship between water level and discharge capacity of only spillway gate and overflow weir was determined by model test, and then the mutual influence between them was determined by numerical simulation. The method of combined model test and numerical simulation to determine the diversion ratio and discharge capacity were explored. Through this method, the diversion ratio of the spillway gate and the overflow weir and the water level under the gate and weir were obtained. Compared with the design value, the difference is very small within 6%. The results show that the discharge capacity of the spillway gate and overflow weir mainly meet the requirements.

Aiming at the problems of difficulty in determining the optimal parameters and low accuracy of the deep learning method in dam prediction, the sparrow search algorithm (SSA) was improved, and the parameters of the gated recurrent unit (GRU) were optimized by the improved sparrow search algorithm (ISSA). Then a dam deformation prediction model based on the ISSA-GRU was constructed, and this model was applied to the deformation prediction of the Longyangxia Dam of Qinghai Section in the upper reaches of the Yellow River. The results show that the dam deformation prediction model based on ISSA-GRU has higher prediction accuracy and stability, which can be used as a reference for dam deformation prediction.

In response to the inadequacies of traditional earthen and reinforced concrete flood walls that create barriers between urban areas and waterfront regions, which no longer meet the public's demands, the introduction of aluminum alloy flood walls in the Moon Bay flood control renovation project has been proposed. A transformation plan that combines modular flood walls with ecological embankments has been implemented. The post-renovation project has demonstrated excellent operational effectiveness, eliminating the oppressive feel of conventional flood defenses within the urban space. Furthermore, it seamlessly extends the urban landscape space to the water's edge, creating a unified and continuous landscape interface. This approach ensures flood safety while fostering a waterfront landscape with distinctive regional characteristics.

There are some problems in construction, such as inaccurate material parameters and unclear influence of shield operation parameters on ground settlement. Based on a water-rich sand layer shield construction diversion tunnel, an orthogonal experiment is designed by setting the index of ground surface settlement, and a three-dimensional numerical simulation is used to analyze sensitivity of different material’s parameter. Mechanical parameters of materials are inverted according to the observed settlement. The subsidence lines under different excavation pressures, different synchronous grouting pressures and different speeds of the shield are calculated. The result shows that the surface subsidence is most sensitive to the change of internal friction angle of sand layer. Increasing the internal friction angle of the sand layer and the elastic modulus of the lining will reduce the settlement. The speed of the shield has a great influence on the subsidence. Increasing the speed of the shield, the maximum settlement of the surface settlement curve will increase, and the width of the "settlement tank" will also increase. The maximum settlement and the width of "settlement tank" decrease with the increase of excavation chamber pressure or synchronous grouting pressure.

To explore the temporal and spatial distribution and attribution of mountain torrent disaster risk in Sichuan Province, the spatial distribution difference and high-risk areas of mountain torrent risk during 1990-2020 were studied by AHP and cluster analysis methods, and the changing characteristic and driving reason were investigated. The results show that the risk of mountain torrent disasters increased from the west to the east in Sichuan Province. High-risk areas mostly existed in areas with dense river networks and high exposure and vulnerability, such as Meishan, Zigong, Neijiang, Ziyang, Suining, Guangan and Nanchong. From 1990 to 2020, the risk of mountain torrents showed an increasing trend in Sichuan Province. The proportion of areas with high and above risk increased from 17% to 34%. Increased risk levels were concentrated in central Sichuan, and most of them were from moderately high and relatively high risk transformed into high risk. In the past 30 years, the risk of mountain torrents has shown a downward trend in Sichuan Province, while the greater GDP and population density had changed vulnerability and disaster prevention capacity, leading to increasing risk level of mountain torrents in local areas. The results can provide theoretical guidance and practical support for forecast and early warn in flood disaster and disaster prevention and mitigation in Sichuan Province.

In the condition monitoring of pumped storage units, vibration velocity signal is often integrated into the displacement signal, and then calculate characteristic values for unit evaluation. Taking the horizontal vibration velocity signal of upper bracket of a case unit under stable working condition as an example, the method of integrating velocity signal into displacement signal and the setting of filter parameters are studied. Furthermore, vibration signal in transient working condition is adopted for verification. The results indicate that a high-pass filter shall be used when the vibration velocity signal is integrated into the displacement signal under stable conditions, and the cut-off frequency of the high-pass filter can be set as per 0.2 times of the rotational frequency. Under transient conditions, there is a risk of over estimating unit vibration when using unfiltered displacement signals integrated from velocity signals to calculate characteristic values for unit safety assessment.

In view of the relatively serious drought in the Feiyun River basin in recent years, the inability to effectively utilize the regulating capacity of the counter-regulating reservoir, and the inability to effectively guarantee the timeliness and scientificity of the operation, which affect the water supply safety of nearly 6 million people in Wenzhou, the anti-drought operation model and data center of the Feiyun River basin are established. The real-time data of rainfall, water level, water supply flow and ecological flow of multiple reservoirs in the basin are quoted. The meteorological data including 1 h, 3 h, 6 h short-term and imminent grid forecast data, and 1 d, 3 d, 7 d, 15 d, 30 d, 90 d and other long-term rainfall forecast data are introduced. Combined with water and soil moisture in the basin, reservoir and basin evaporation, support vector regression (SVR) calculation method is used to develop a distributed digital twinning business system based on SPARK components, which realizes early warning of available water supply, drought-resistant water level early warning, drought-resistant days early warning and ecological flow early warning, increases the use of the anti-regulation storage capacity of 2.8 million cubic meters and the reserve storage capacity of 2.93 million cubic meters. Thus, it provides data basis and technical support for the drought-resistant decision-making, scientific scheduling and "four pre-" realization in the Feiyun River basin.

The flow field characteristics of vortex setting chamber (VSC) play a decisive role in its water and sediment separation performance. In order to clarify the influence of the inclination angle of the curved deflector on the flow field characteristics of VSC, the large eddy simulation and VOF method are used to study the three-dimensional flow field characteristics of the VSC when the inclination angles of the curved deflector are 5°, 10° and 15° respectively, and the flow field characteristics of the VSC with the plane deflector under the same inlet flow rate are compared. The results show that the use of curved cantilever deflector will increase the eddy current intensity in the VSC chamber and reduce the range of low velocity zone. The increase of the inclination angle can improve the stability of the air vortex, increase the strength and size of the air vortex, which is beneficial to the separation of water and sediment. The radial velocity in the cone area increases with the increase of the inclination angle, and basically points to the center of the VSC, which is conducive to the rapid transport of sediment to the bottom hole of the sediment discharge. The velocity of the overflow flow on the surface of the curved deflector is greater than that on the surface of the plane deflector, and the flow velocity on the deflector is the largest when the inclination angle is 15°.

In order to solve the problem that the current existing precipitation trend analysis methods cannot simultaneously detect precipitation trends in low and high value areas, this article introduces innovative trend analysis (ITA) and combines it with traditional trend analysis methods for analysis. Taking the station data of Yili River basin from 1961 to 2020 as an example, the ITA and Mann-Kendall (MK) series, Theil Sen and other seven methods are compared and analyzed. The results show that the annual precipitation of stations in Yili River basin, except Huocheng Station, Yining County Station and Zhaosu Station, increases significantly in other stations in high value areas, which is the same as the trend of annual extreme precipitation; The extreme precipitation intensity in the low and median areas of other stations shows an increasing trend, while the high value areas show a decreasing trend, and the overall trend is increasing; The ITA can reflect the range of rainfall changes and detect the trend changes of rainfall in low, medium, and high value areas. Therefore, the combination of ITA and traditional trend method to conduct trend analysis on the overall rainfall and rainfall in high and low regions simultaneously will help to more comprehensively analyze the precipitation change law of Yili River basin.

The study of classified water price can provide scientific basis for the rational formulation of agricultural water price, which is of great significance for guaranteeing the benign operation of irrigated areas and promoting the high quality development of regional agriculture. Taking grain and oil crops as the research object, two evaluation indexes of irrigation benefit apportionment coefficient and irrigation water output were selected to define the irrigation benefit apportionment coefficient by emergy theory. The agricultural water price share evaluation system of different crops was constructed based on entropy weight method, and the irrigation classified water price evaluation model was established and applied in Baojixia irrigation district of Xianyang City. The results show that the share coefficient of irrigation benefit was 0.42, the share of agricultural water price of grain and oil crops was 0.37, and that of cash crops was 0.63. For agricultural water supply at full cost, the agricultural water price of grain and oil crops was 0.485 yuan/m³, and that of cash crops was 0.827 yuan/m³. As for the water price of agricultural water supply operation cost, the agricultural water price of grain and oil crops was 0.377 yuan/m³, and that of cash crops was 0.641 yuan/m³.