Influenced by terrain and construction costs, the water flow of the flood drainage ditch outside the surrounding wall of the construction project in hilly regions should be minimized as much as possible. However, the capacity of existing or planned small reservoir in the low-lying areas of mountain flood gully outside the walls of construction projects is usually small and difficult to expand, which cannot meet the normal requirements of reservoir flood control. Aiming at this kind of engineering technical problems, this paper proposes a technical scheme with the construction of a small empty reservoir for flood prevention and drainage in construction projects. Compared with the normal reservoir flood regulating system, the storage capacity in this system can be greatly reduced, and the downstream flow reduction requirements can be met. The function and design points of the empty storage capacity peak cutting and flood regulating system are elaborated in detail combined with the actual engineering cases, which aim to provide important technical support and experience for the flood prevention and drainage project of small watershed in mountain and hilly regions.

The Gaoxin District and Jinshui District were selected as the representatives of the new and old urban areas of Zhengzhou to explore the evaluation indexes that affect the risk of rainstorm waterlogging in cities and the importance of each index, and a risk index evaluation system covering natural and social factors was established. The importance of each evaluation index in new and old urban areas was determined by using random forest model. The results show that for both new and old urban areas, the sensitivity of disaster-inducing environment is the most important first-level indicator. Among them, imperviousness and pipe density are the most important tertiary indicators for surface and subsurface disaster-preventing environments, respectively. The risk of disaster-causing factors is the least important for Jinshui District and Gaoxin District, and the importance of rainfall is much greater than that of rain type. The difference between the old and new urban areas is mainly reflected in the stability of disaster-bearing body, whose importance is 0.23 and 0.09 for Jinshui District and Gaoxin District. The conclusion can provide some reference for the prevention and control of rainstorm waterlogging disaster in Zhengzhou.

Based on the finite element method, this paper numerically analyzes the stress behavior and its adverse effects when diaphragm of dam foundation axis shifts downstream during operation, and proposes remedial measures and reference critical values. The results show that when the axis does not shift, diaphragm of dam foundation is only subjected to bending moment and produces local tensile stress, but its influence is not obvious. When the axis is shifted downstream and the offset is less than 30 cm, diaphragm of dam foundation is subjected to the combined action of pressure and bending moment, resulting in stress concentration and adverse effects. In the case of no other processing, when the axis does not shift and the offset is less than 15 cm, it can be temporarily not processed; If the axis offset to the downstream is more than 15 cm and not more than 27 cm (measured maximum offset), in the subsequent construction, the concrete base needs to be widened downstream at least 20 cm, which can reduce the tensile stress extreme of diaphragm of dam foundation and weaken the stress concentration, so as to improve the stress behavior of diaphragm of dam foundation. The finite element simulation provides a reference for the safety evaluation and treatment measures when diaphragm of dam foundation is eccentric.

In order to explore the feasibility of using waste concrete to dispose expansive soil and make it as roadbed filler, the waste concrete and expansive soil were mixed evenly according to the ratio of 96 : 4, 92 : 8, 88 : 12, 84 : 16, 80 : 20 and 76 : 24. The boundary moisture content, linear shrinkage rate, expansion force and compaction tests were carried out. The influence of curing time was considered in unconfined strength and CBR tests to explore the improvement effect of the selected materials. The experimental results show that the liquid limit and plastic index decrease first and then increase with the increase of waste concrete content, and the minimum value appears when the content is 12 %, while the plastic limit increases slowly. The linear shrinkage rate increases first and then decreases with the increase of dosage, and the linear shrinkage rate is the smallest when the dosage is 12 %. The expansion force under different curing periods decreases slowly with the incorporation of concrete. When the dosage is 12 %, the dry density of the treated expansive soil is greater than that of the plain soil, and the optimum moisture content is less than that of the plain soil. Considering various factors, 12 % is determined as the best dosage. Under this dosage, the unconfined compressive strength of the mixed soil can reach the peak value, and the bearing capacity of the treated soil is about 5 times that of the plain soil. The treated expansive soil can be used as roadbed filler.

With the acceleration of urbanization in China, the demand for water resources is increasing, and the leakage of the water supply pipe network has caused waste of water resources. Therefore, leakage control is imminent. The first is to accurately calculate the leakage of the pipe network, but the current methods have certain deficiencies. Based on the Kalman filter, this paper establishes an analysis model of pipeline network leakage, and uses the empirical formula of node leakage, standard Kalman filter (SKF) and innovation adaptive Kalman filter (IAKF) to calculate the leakage of the pipeline network, respectively. Taking the actual pipe network project as an example, the EPANET simulation was carried out, and the calculation results were compared. The results show that using both filtering algorithms is more accurate than the nodal leakage formula, and the result of the IAKF algorithm is better than that of the SKF algorithm. This provides a theoretical basis for accelerating the research on leakage control technology and implementing scientific and effective leakage control methods, which has certain significance for urban water saving and sustainable development.

After the operation of the Three Gorges Project, the process of water and sediment in the lower reaches of the reservoir changed greatly and led to the adjustment of the evolution law of the curved channel, which may have adverse effects on the stability of the river and the safety of flood control. Based on the measured data, the evolution law of the typical bends in the lower reaches of the reservoir and its main causes were analyzed. The results show that after the operation of the Three Gorges Project, the typical bends in the lower reaches of the reservoir all appear "cutting beaches", and the main reason is that the sediments enter each river reaches. The amount of sand, especially fine-grained sand, has been greatly reduced. The main reasons for the "skipping bends" in most of the bends in the Lower Jingjiang are that the variation coefficient of the monthly average runoff process is large and the bending radius of the bends itself is small. With the successive operation of cascade reservoirs in the main and tributaries of the upper reaches of the Yangtze River, it is expected that the variation coefficient of the monthly average runoff process in the lower reaches of the reservoir will continue to increase, which may lead to the occurrence of bends with relatively small bending radius that do not currently have "skipping bends".

Dispatching operation of hydropower station is in face of the large capacity and large units, unit control new scheduling features such as irregular more limits and more complicated operation requirements. To aim at power station safe, stable and economic operation, a model of economic operation inside the station was established to realize optimal load distribution of hydropower station units under various operation conditions. The optimal output range of each unit under different head was analyzed. The optimal load distribution rule of the power station was studied, and the economic operation model of the station was established. Based on the economic operation model of the station, the optimal load distribution table was designed. The optimal load distribution result table of the power station under different loads, different heads, and different unit commitment was proposed to guide the real-time economic scheduling of the power station. Taking Hongjiadu station as an example, the results show that the model can reasonably arrange the start-stop sequence and number of units according to the real-time load instruction, and give real-time start-stop suggestions of units. It can obtain the optimal load distribution combination of the proposed unit under various working conditions, reduce the monthly average water consumption rate by 0.18%, reduce the adverse working conditions such as frequent start-stop and frequent crossing of the vibration zone by 9.5%, ensure the efficiency of the unit operation, and improve the economic benefits of the power station.

Early and timely defect detection is essential to ensure the safe operation of hydraulic concrete structures. The deep learning-based computer vision method does not require complex manual feature engineering, and can automatically determine the category of structural defects in remote images, overcoming the shortcomings of traditional manual vision that are labor-intensive, subjective and prone to errors. Inspired by this, this paper proposes a deep learning-based defect detection method, which introduces attention mechanism into the ResNeXt50 network to adaptively recalibrate the channel-level feature responses, so that the model can pay more attention to the defect information in the image and enhance the feature extraction ability. Test results show that the proposed method can achieve an F1 score of 88.0%, and realize a good classification effect for common concrete defects.

The cluster forecasting model is a long-term forecasting physical model based on mathematical statistics. This method has been applied in the long-term forecast of the upper reaches of the Yangtze River. After years of practice, there is space for improvement in accuracy and efficiency of the model. This paper selected the upper reaches of the Yangtze River as the demonstration area for forecast, the monthly areal rainfall from June to August as the forecast object, and used the coincidence rate of anomaly symbol and the percentage of anomaly error as the test methods of the model. And then the construction process and improvement of the model were described. Finally, the improved model was used to forecast the monthly area rainfall in the upper reaches of the Yangtze River from June to August during 2020 to 2022. The prediction results show that the improved model has a great improvement in the anomaly sign agreement rate and the percentage of anomaly error, and it has been implemented easily, which has certain reference value.

The geometric characteristics of landslide are closely related to the rainfall infiltration process, which is the key internal factor to control the stability of rainfall-induced landslides. There are many rainfall-induced landslides in the Three Gorges Reservoir area, and it is of great significance to deeply reveal the body shape characteristics of rainfall-induced landslides (landslide whose stability is sensitive to rainfall in hydraulic engineering are generally referred to as rainfall-induced landslides) for the identification and prevention of landslide disasters in the reservoir area. In this paper, the data of 275 rainfall-type sedimentary landslides in the Three Gorges Reservoir area were collected, and their body shape characteristics were statistically analyzed. The rainfall-type landslides in the area are narrow and long, thin in thickness and gentle in slope. Combined with the numerical simulation of the rainfall infiltration process of typical landslides, it is found that the landslides of this type have a larger rain-receiving area and infiltrated rainwater is more likely to infiltrate the sliding bed, which makes the effect of rainfall more significant, and is not conducive to the stability of the slope under rainfall conditions.