In order to provide a suitable means for the tidal prediction of the Changjiang Estuary and its adjacent area and for the open boundary conditions of tidal flow numerical model of the Changjiang Estuary, accuracy of NAO.99Jb was evaluated. The feasibility of providing open boundary conditions for tidal flow numerical model of the Changjiang Estuary was studied. The results show that the NAO.99Jb model can accurately simulate the propagation of the tide outside the Changjiang Estuary and its adjacent area; The NAO.99Jb has good accuracy outside the Changjiang Estuary, but has lower accuracy inside the Changjiang Estuary; It is feasible for using the tidal level predicted by NAO.99Jb as the open boundary condition of the tidal flow numerical model of the Changjiang Estuary, and the accuracy is good, which can be further popularized and applied.

As an important part of rural energy, small hydropower plays an important role in driving rural economic development and promoting energy saving and emissions reduction. However, there is a lack of scientific guidance in the process of optimal operation of small hydropower stations in most areas. This paper takes the Mengdong River basin as an example to establish a cascade optimal operation model of small hydropower stations based on runoff simulation. The Xinanjiang (XAJ) model is combined with Manning's formula to establish a semi-distributed hydrological model for simulating the influence of reservoir operation on runoff. The successive approximation dynamic programming method is used to achieve optimal operation by considering the actual operating characteristics of small hydropower stations. The results demonstrate that the semi-distributed hydrological model has a good performance in the river basin. The changing pattern of simulated and measured runoff processes is basically consistent, and the Nash-Sutcliffe efficiency coefficient and coefficient of determination between the measured and simulated series are 0.86. The optimal operation model can reduce the spillage water effectively, which improves the utilization efficiency of water energy. Meanwhile, the optimal operation can match the actual intra-day features of small hydropower, indicating its feasibility in applications.

Continued land development around the world has accelerated the construction of impervious surfaces, thereby changing the hydrological cycle of the natural environment itself, resulting in frequent urban waterlogging disasters. Due to its own limitations, the old city not only cannot reasonably utilize rainwater resources, resulting in a waste of rainwater resources, but also is often in the predicament of flooding every time when it rains. Taking the Nandajie area of the old city of Xifeng District in Qingyan City, Gansu Province as an example, the construction effect of different LID measures in each return period was simulated through SWMM modeling. The best LID measures suitable for the study area were selected. The results show that the reduction effect of the combined measures is the best, the reduction rates of the total runoff and the peak runoff are over 68.71% and 68.90%, respectively, the peak time is delayed between 10-15 minutes, and the reduction rate of the overload of the pipe network decreases with the increase of rainfall return period. The research results provide reference for optimization of LID measures in the old urban areas of Northwest China.

In view of the fact that traditional neural network models can hardly make full use of the topological relationship of the backward forward information of dam deformation monitoring time series data, while the bidirectional long short-term memory (BiLSTM) can effectively learn the backward forward information, a combined dam deformation prediction model BES-BiLSTM was proposed based on bald eagle search algorithm optimized bidirectional long short-term memory neural network. Firstly, the bald eagle search algorithm was used to optimize parameters of the model. Secondly, the bidirectional learning feature of BiLSTM was used to train the model to enhance the correlation between the data. Then, the settlement value of a concrete dam hydropower station was taken as example 1 for dam deformation prediction based on the BES-BiLSTM model. Another concrete dam horizontal displacement value was taken as example 2 to verify the model performance. Finally, the prediction results of the BES-BiLSTM model were studied in comparison with those of the traditional long and short term memory neural network (LSTM) model and the BiLSTM model. The results show that the BES-BiLSTM model has stronger fitting and prediction capabilities than the single traditional LSTM and BiLSTM models, which can be used for deformation prediction of concrete dams and slopes.

In order to response the request of hydraulic digital twin, this paper studied how it implement in long linear engine hydraulic project so that the manage system can show any position and any changes of the project. The data linkage inquiry method in both two and three dimension and the shortest distance algorithm innovatively were proposed based on BIM, GIS and geological profile graph. It is implemented through data fusion, data structure design, software design etc., which can make digital scene and geological profile graph's view move and inquire together. The user can immediately acquire mileage, geological conditions, design section, construction and operating state through moving and pre-clicking the cursor. It's proved in a certain water diversion project that the project manager can inquire and acquire real-time project information immediately by using this method without inspect the whole engineering. This method lays the foundation of real-time data inquiry, engineering safety intelligent analysis and production operation management, which implement engineering digital twin to some extent.

In order to study the viscoelastic properties of hydraulic asphalt concrete, bending creep tests under different temperatures and stress conditions were carried out. The Burgers model was used as a constitution model for the viscoelastic mechanical behavior of hydraulic asphalt concrete, and a nonlinear fitting of the test data was carried out by the most rapid descent iteration method to obtain the fitting curves and Burgers model parameters under different test conditions. By analyzing the variation law of the parameters, the function equation of the parameters with temperature and stress was established by using Origin polynomial fitting function. The creep behavior of hydraulic asphalt concrete was predicted. The test results show that the Burgers model optimized by the most rapid descent method can better fit the test curve, and the fitted correlation coefficients are all greater than 0.996, especially in the isokinetic creep stage, the fitted curve is closest to the test curve; Under the condition of constant stress, the parameters of the Burgers model decrease with the increase of temperature; Under the condition of constant temperature, the parameters E₁ and E₂ increase with increasing stress, and the parameters η₁ and η₂ decrease with increasing stress.

The nonlinear equation was established for the incipient motion of sediment under constant flow, including Reynolds number, Hiltz number and sediment erosion intensity. Based on cusp catastrophe theory, this experimental process focused on the main factors affecting incipient motion of sediment and bottom riverbed scouring, and considerd different flow intensity conditions. The Reynolds number of sand particles from other experiments was used in the nonlinear equation of this study to verify the influence of Reynolds number. The theoretical value calculated by this formula has a strong consistency with the test value, after comparing the results and data. Therefore, this nonlinear equation can basically meet the requirements for predicting the scouring intensity of fine sediment.

For the transmission line distributed traveling wave fault ranging system, this paper proposes a distributed fault location matrix algorithm of transmission lines based on traveling wave time difference information. The algorithm uses the principle of double-ended traveling wave ranging to construct the lower triangular fault location matrix by combining the monitoring node data two by two. The nature of matrix rank was used to select the fault point area and calculate the fault location distance simultaneously. The matrix zeroing algorithm was set to accelerate the find of matrix rank. The distance correction algorithm was set to improve the accuracy of positioning results. The applicability and reliability of the distributed traveling wave fault location matrix algorithm for transmission lines were verified by modeling and simulation with PSCAD and MATLAB software. The necessity of the corrected zeroing algorithm and the significant improvement of the distance correction algorithm on the fault location accuracy were demonstrated by comparison during the operation.

In order to improve the accuracy of runoff prediction, based on the control variable method and the daily runoff data of Lanzhou hydrometric station from August 2001 to December 2019, the models of the LSTM, ARIMA, SVR and XGBoost were used to establish 12 model schemes, including single model, EMD decomposition and reconstruction, EMD decomposition and reconstruction after removing noise components, and evaluation indicators of the 12 schemes were compared. The results show that the EMD sequence decomposition and reconstruction technology and noise component elimination based on Hurst exponent are helpful to improve the prediction accuracy. Compared with the single model, the R_RMSE of the model constructed by the former decreased by 15.16% on average, and that of the latter decreased by 28.49% on average. Among the 12 schemes, EMD-SVR-ARIMA with noise components removed is the best model.

Based on the monthly data of precipitation and average temperature from 36 reference meteorological stations in the six basins in Yunnan Province, 11 climate models published by CMIP6 were used to simulate and predict the change process of meteorological elements in six basins. Three model integration technologies were used to improve the simulation ability and evaluate the suitability of each model and integration method. The optimal method was chosen to predict the possible trend of climate change in six basins under the scenario of SSP2-4.5 in the future. The results showed that precipitation and temperature would increase gradually in the near, middle and long term in the six basins of Yunnan Province. Precipitation might increase significantly after 2060, and temperature might increase significantly after 2050.