The bedload sediment transport in the compound channel is affected by the presence of emergent rigid vegetation, and there were few studies available on this topic. The laboratory experiments and theoretical analysis were used to investigate the effect of emergent rigid vegetation in parallel arrangement on the threshold Shields number and the bedload transport intensity. The results show that the presence of emergent rigid vegetation in parallel arrangement increased the threshold Shields Number by 97.2%, and the bedload transport intensity reduced by more than 80%. The modified Engelund Formula that was applicable to the emergent rigid vegetation in parallel arrangement conditions was developed to calculate the bedload transport intensity. The formula was shown to have a high accuracy by applying it to the other studies.

Integrating reclaimed water into water supply system is a strategic measure to alleviate the problem of water resource shortage. Aiming at the uncertainty and stability existing in the optimal allocation of multiple water sources including reclaimed water, Monte Carlo simulation and interval two-stage robust stochastic optimization were coupled to build the optimal allocation model of multiple water sources under the condition of multiple uncertainties. The uncertainty represented by the form of interval and probability distribution in the process of water supply and water demand was effectively handled. The variable random value of water resources allocation and the recourse cost were balanced, and the system’s risk was controlled. The water resources allocation schemes were obtained under different scenarios. The improved model was applied to water supply area in Linfen Basin-Jincheng Qindan river watershed of Shanxi large water network. Based on the comprehensive analysis of regional water efficiency and water loss under different scenarios, the joint allocation scheme of multiple water sources under different utilization rates of reclaimed water was obtained, which provides a reference for decision makers to consider the optimal allocation scheme of reclaimed water under uncertain conditions.

Aiming at the evaluation of water resources security in China, combined with the characteristics that support vector machine (SVM) has good classification effect on small samples and nonlinear problems, the sparrow search algorithm (SSA) was used to optimize the penalty factor (C) and kernel function parameters (g) of the SVM. The support vector machine model optimized by the sparrow search algorithm (SSA-SVM) was used for regional water resources security assessment. A case study was carried out in a certain area of Luoyang City. The results show that the evaluation grade obtained by SSA-SVM method and T-S fuzzy neural network method are basically consistent, the SSA-SVM model has the characteristics of fast searching speed, and not easy to fall into local optimum, which can be used for regional water resources security evaluation.

The supersaturated total dissolved gas (TDG) is mainly caused by the discharge of high dam spillway, excess oxygen production of plant photosynthesis and sharp increase in water temperature, which may directly lead to fish and aquatic organisms suffering from gas bubble disease (GBD) or even death. In order to explore the measures to mitigate the adverse effects of supersaturated TDG, under different aeration conditions, the swirl mixing aeration mode has an obvious effect on the release of supersaturated TDG, its effect is slightly stronger than that of pinhole aeration method, and the aeration rate has the greatest impact on the mass transfer coefficient of supersaturated TDG, followed by the aeration depth, and the aeration diameter is the smallest. The relationship between supersaturated TDG mass transfer coefficient and aeration rate, aeration diameter and aeration depth is obtained, respectively. The average error is within ±6.25%. The research results provide a data basis for mitigating the adverse effects of supersaturated TDG.

In order to improve the water environment carrying capacity of Nanchang during the dry period, this paper constructed a water environment model at the lower end of the Ganjiang River and proposed an optimal scheduling scheme. The results show that the optimal scheduling water levels for the Ganjiang main river and its four downstream branches-the main, the north, the middle, and the south-were between the minimum ecological water level and the alert control water level, and that the scheduling time was within 1.11 days when the flow rate was less than 1 020 m³/s. Conversely, when the flow rate was greater than 1 020 m³/s, the alert control water level was the flood control limit water level. The optimal scheduling water levels of the main river and the four branches were between the minimum ecological water level and the flood control limit water level, and the scheduling time was within 4-7 d. It was suggested that each branch barrage hub should be operated close to the alert control water level to ensure that the water quality of the river control section meet the standard, and to maintained the maximum amount of water resources available in Nanchang.

Conventional and wetting triaxial experiments were carried out on coarse grained materials for dam construction with a large static and dynamic triaxial tester. The dynamic characteristics of coarse grained materials after wetting deformation were studied, and the results were compared with those of conventional triaxial dynamic experiments. The experimental results show that the dynamic characteristics of coarse grained materials are greatly affected by wetting deformation, and the dynamic performance parameters of coarse grained materials are attenuated to a certain extent. The Hardin-drnevich model parameters of the two experiments were compared and analyzed. It was found that wetting deformation had a significant effect on k₂ and λ_max, and the numerical values were attenuated, but the effects on n and k₁ were not significant.

Considering the characteristics of inversion problems of concrete face dam, including high dimensionality, complex calculation and excessive calculation time, the orthogonal experimental design was used to construct the learning sample composed of the combination of permeability coefficient and the water head of pressure measuring point. The nonlinear mapping relationship between the water head at monitoring points and permeability coefficient was established by general regression neural network (GRNN), and the particle swarm optimization (PSO) algorithm was used to search for the smoothing factor σ suitable for the specific project to improve the generalization and convergence speed of the model. The PSO-GRNN model for the inversion of the permeability coefficient of concrete face dam was established, and was applied on an engineering example. The results show that the value of permeability coefficient obtained by inversion based on the model is reasonable, and the maximum relative error between the calculated value of water head at monitoring points obtained by seepage analysis and the measured value is 3.64%, and the accuracy meets the needs of engineering.

With the continuous accumulation of dam deformation monitoring data and the continuous increase of deformation measuring points, it often takes a lot of time to predict all deformation measuring points, which is easy to cause the problem of untimely feedback. Therefore, the fuzzy C-means clustering algorithm (FCM) was introduced to partition the dam according to the similarity of deformation laws. The whale optimization algorithm (WOA) was used to optimize the parameters of long short-term memory neural network (LSTM), and a dam deformation prediction model based on FCM-WOA-LSTM was established. The measured deformation data of a concrete double-curvature arch dam was used as sample data for prediction, and the prediction results were compared with those of LSTM model and SVM model. The results show that the average absolute error (M_MAE), mean square error (M_MSE) and root mean square error (R_RMSE) of the prediction results of FCM-WOA-LSTM model are the smallest among the three models, and the three evaluation indexes of the fitting section are close to those of the prediction section, respectively. Compared with the existing models, the FCM-WOA-LSTM model has higher prediction accuracy and better applicability.

For the long-distance water supply project where the pump station pressurizes before the high point and gravity flows after the high point, when the end valve is closed in a straight line in case of power failure in an accident, a longer valve closing time is required to meet the pressure control standard, which virtually increases the scale of the protective measures and increases the investment. In order to solve this problem, a broken line valve closing rule is proposed to reduce the volume of protective measures while optimizing the pressure. The characteristic line method is used to check each scheme through FORTRAN programming, and the general rule is summarized by analyzing the influencing factors of the main parameters. The case results show that the broken line valve closing can reduce the volume of protective measures and reduce the project cost compared with the straight line valve closing within the same valve closing time under the premise of ensuring that the pressure meets the requirements.

For the pressurized water supply project of a long distance, large flow and high lift pumping station, the pump trip was simulated. Combined with the characteristics of the engineering terrain, the combined protection method of air-cushion surge chamber and one-way surge tank was proposed. And then the sensitivity analysis of the closing rule of the valve after the pump and the throttle orifice of the surge chamber was carried out according to the requirements of pipeline pressure control. The results show that the air cushion surge chamber could effectively protect the water hammer of the pump trip and the water hammer of valve shutdown caused by the rapid closure of the pump valve. The one-way surge tank solved the problem of local high pressure caused by the continuous water refill of the air cushion surge chamber, and protected the safety of the high point pipe section. The combined protection scheme could significantly reduce the volume of air cushion surge chamber and saved the engineering cost. In addition, the closing rule of the pump valve and the throttle orifice area of the air cushion surge chamber has a great impact on the water hammer pressure of the pipeline. Too fast valve closing or too large throttle orifice area will lead to the positive pressure of the pipeline exceeding the standard. Too slow valve closing or too small throttle orifice area will lead to large negative pressure in the pipeline. The specific project needs to be optimized in combination with transition process simulation. For this project, after simulation and optimization, the diameter of the throttle orifice was 0.8m, and the valve of the pump was closed by 5s straight line, and the results met the requirements of regulation guarantee calculation.