In order to meet the flood discharge and irrigation requirements of tributary channels, it is of great practical significance to master the water flow diversion characteristics of the three-branch river channel. Based on numerical simulation and physical model experiments, the water level changes, velocity distribution, and flow allocation characteristics at the mouth of three tributaries river under different branching angles were studied. The results show that for a three-branch river channel, the larger the branching angle, the smaller the flow velocity in the tributary is, and the flow allocation in the variable angle side gradually decreases, while the flow allocation in the fixed angle side and the main branch gradually increases. Based on dimensional analysis, a three-branch river flow diversion ratio calculation formula was obtained considering the Froude number at each branch inlet. The formula was verified, and it was found that the prediction accuracy of the formula for the flow diversion ratio of the tributary channels in a three-branch river system was good.

The permeability of karst medium is affected by multiple factors such as the geological characteristics of soluble rocks, the degree of karst development, and the fluid properties. The permeability coefficient estimation model of fractured rock mass is difficult to reflect the complexity of karst development, which makes it poorly applicable. Random Forest (RF), Support Vector Regression (SVR), CatBoost machine learning algorithm combined with Bayesian optimization algorithm were used to construct the permeability coefficient estimation model of karst media. The root mean square error (R_RMSE), mean square error (M_MSE) and coefficient of determination (R²) were used to verify the evaluation accuracy of the estimation model. The SHAP algorithm was used to analyze the dominant influencing factors of the permeability coefficient of karst media in machine learning model, and the influence of each influencing factor on the permeability coefficient of karst medium was clarified. The results show that the R_RMSE of the optimized SVR model is 0.128 8, M_MSE is 0.016 6 and R² is 0.74, which are better than the random forest and CatBoost models, and can better estimate the permeability coefficient of karst media. The SHAP diagram revealed that there were obvious differences in the permeability coefficient of karst media between different eigenvalues of each dominant factor, and the karst rate (BK), depth (Z) and filling content (AFC) of the borehole line were the main influencing factors of the permeability coefficient of karst media, and had a significant impact on the permeability coefficient of karst media. The SVR model has high estimation accuracy and strong interpretability, which provides a certain reference value for engineering applications in karst areas.

Water park is an important window of ecological civilization construction. Taking 20 national water parks as examples, using the public comment data, the CES dictionary of water park was constructed to analyze the public perception frequency and satisfaction of the CES during and after the COVID-19 pandemic. And then IPA model was used to evaluate water park. The results show that the public focus on water park are consumption, transportation, scenic spot environment and water conservancy engineering, and there are differences in different stages; The frequency of aesthetic value and recreation is the highest, and the frequency of inspiration service is the lowest. The frequency of popular science education is lower during the COVID-19 pandemic; The overall satisfaction is 80.51% during the COVID-19 pandemic and 82.15% after the COVID-19 pandemic ends; The future construction of water park in Henan Province should pay attention to social relations and science education service, while fully exploiting the potential of cultural history and spiritual service. The research is of great significance to the evaluation and planning and construction of water park.

Irrigation drainage is an inevitable accompanying process in agricultural irrigation, widely present in the irrigated farmlands of the northwest region of China. Due to poor water quality, if it is returned to the river channels, it will pose a threat to the water ecological environment of the basin. Taking the Huanghe South Bank Irrigation District in Hangjin Banner as the research object, a MIKE SHE distributed hydrological model was established to predict the drainage volume and available volume of the irrigation district. Cross-checking was conducted with the simulation results of hydrological models by using the water equilibrium method and the ratio of diversion to drainage method. The results show that under the current drainage system conditions, the multi-year average drainage volume is 48.21 million m³, and the available volume is 43.39 million m³; After the drainage system is upgraded and transformed, the multi-year average drainage volume is 49.20 million m³, and the available volume is 44.28 million m³. The drainage volume prediction results of each method vary slightly, but the overall difference is not significant. The simulation results by MIKE SHE's hydrological model and the average deviation is controlled within ±4%, while the relative error of the simulated drainage during the verification period is 3.7%. The MIKE SHE hydrological model performs well in simulating the drainage process of the irrigation district, which can provide reference for the resource utilization of irrigation district drainage.

To ensure the timeliness of frost resistance testing of hydraulic concrete and improve the safety of construction and operation of project, the methods for testing the frost resistance of concrete were systematically reviewed. The standard differences among slow freezing method, fast freezing method, single-sided freeze-thaw method and salt-resistant erosion method were compared. Two new trends were analyzed including the rapid detection technology of frost resistance based on the rapid freezing method and the rapid detection technology of concrete relying on process parameter control. The new ideas for rapid testing methods of frost resistance were proposed based on structures parameters of hardened concrete, accelerated destructive experiment, key process parameters of freezing and thawing. The concept of dedicated curves was established, and the specific procedures of the new methods was clarified. The work of all the above could provide new ideas for the frost resistance testing of hydraulic concrete.

Underwater topography serves as essential foundational data for river management and reservoir scheduling. The riverbed longitudinal profile is a significant topographical characteristic and is one of the key elements determining the flow velocity and water level variation along the river or reservoir. Based on the energy equation of flow, this paper employs the width-to-depth ratio /H and the relative depth of the section centroid H_c/H as indicators to quantitatively assess the cross-sectional morphology. The correlation relationship between the cross-sectional area, hydraulic radius, and the maximum water depth for a certain power station is established. An analytical method for inverting the longitudinal profile of deep pools of underwater topography before and after reservoir siltation under the control of water surface lines was proposed. Case study results indicate that the proposed method can quickly and accurately invert underwater topography after the siltation of rivers and reservoirs, providing a new approach for rapid determination of topography before and after reservoir construction.

In order to evaluate the applicability of the latest generation GPM IMERG satellite precipitation products in Jiangsu Province, the measured precipitation data of 73 ground stations were selected as references. Using statistical indicators and extreme precipitation index, the accuracy evaluation of GPM IMERG precipitation products were conducted from the perspectives of day, month, season, and their extreme precipitation monitoring capabilities were evaluated. The results show that the GPM satellite precipitation products have good observation effects in Jiangsu region. At the daily and monthly scales, their overall and regional data have a high correlation with ground station measured data (C_CC≥ 0.77), and the correlation becomes more significant with the increase of time scale. At the same time, the GPM satellites overestimate the measured precipitation, and the R_RMSE at the monthly scale is relatively higher. There are certain differences in the observation accuracy of GPM satellites in different seasons, and the winter observation effect is the best, with high correlation and the lowest observation error (C_CC=0.92, R_RMSE=26.37 mm, R_RB=23.4%). The GPM satellite has good ability to monitor extreme precipitation and can observe and describe the occurrence and intensity of extreme precipitation in Jiangsu region, especially in the southern Jiangsu region, with better observation effect.

Based on the hourly precipitation data (1980-2019) from 142 national stations in Hebei Province, Mann-Kendall (MK) trend and mutation test, K-means clustering, and hydrometeorologically homogeneous region methods were used to systematically analyze the temporal evolution characteristics and spatial distribution patterns of short-term extreme precipitation in Hebei Province. The results show that significant regional differences exist in interannual variation of short-term extreme precipitation, with an upward trend in high-altitude mountains and a downward trend in low-altitude plains/hills, marked by a 1996 change-point. Topography significantly influences patterns: the spatial extent decreases in plains and southern slopes but expands on northern slopes for 1 h and 3 h durations, indicating a shift towards mountainous areas. Seasonal differences are pronounced: winter/spring increases, while summer and autumn decreases significantly, with third-quarter Rx24h declining at 0.337 mm/a. The research results reveal the spatio-temporal differentiation law of short-term extreme precipitation in Hebei Province, providing a scientific basis for regional flood control and disaster reduction as well as adaptive management to climate change.

Aiming at the optimal dispatching problem of cascade hydropower stations in the lower reaches of the Jinshajiang River during the drawdown period, based on the analysis of the reservoir water balance, water level, discharge flow rate, and unit output, a daily-scale refined scheduling model was established by maximizing the total power generation of cascaded reservoirs and considering the actual scheduling requirements. The model was solved using the DPSA-POA algorithm. The effectiveness of the model and solution method was verified by the actual case. The results show that the proposed scheduling model can make full use of water resources and maximize the power generation in the drawdown period under the premise of ensuring the safe operation of each reservoir. Thus, it provides theoretical basis and technical support for the refined scheduling management of the cascaded reservoirs.

According to the prototype characteristic curve of the pump set, there will be a deviation between the theoretical value and the actual value when guiding the actual scheduling of the pumping station, which will affect the accuracy of daily scheduling and energy consumption evaluation. Therefore, taking Liyuzhou pumping station as an example, this paper proposes a method combining the measured data of the pumping station and the law of similarity to correct the prototype characteristic curve of the pump set. The flow optimization distribution model is established in terms of the actual operating conditions, and the difference of optimal flow distribution scheme of pumping station between the characteristic curve of the pump set before and after the correction is analyzed. The results show that the deviation between the actual operating head and the theoretical head is mainly concentrated in 8%-11%, and the deviation between the actual operating efficiency and the theoretical efficiency is mainly concentrated in 6%-9% when the prototype characteristic curve of the pump set is used. When the flow optimization distribution scheme is selected through the corrected characteristic curve of the pump set, the results are more in line with the actual operation situation, which can effectively strengthen the guiding role of the flow optimization distribution scheme of the pumping station on the actual scheduling.