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Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

With the construction and operation of cascade reservoirs in large basins, the research on short-term optimal operation of cascade reservoirs has received more and more attention. However, the optimization problem contains many variables and complex constraints, and its model modeling and solution are more and more difficult with the expansion of the reservoir group. Although traditional optimization methods or intelligent optimization methods can obtain optimal solutions that meet relevant objectives and constraints, the results under the optimization algorithm are often too biased towards the target value, resulting in large volatility and randomness, which is difficult to meet the actual scheduling needs. In view of this, this paper proposes the construction technology of power station output scenario based on the historical dispatching results, cluster analysis and other data mining methods, considering the scheduling period, business type, scheduling period length, scheduling objects and other scenario elements, and forms the output scenario set by mining typical output scenarios based on a long series of historical operation data. On this basis, a short-term optimal operation method of cascade reservoirs based on the output scenario set is proposed. Through the case study of Shaxi cascade reservoirs, it is found that compared with the traditional optimal operation method, the scenario method proposed in this paper can not only obtain the output process that meets the actual operation requirements, but also shorten the calculation time relatively, which verifies the feasibility and practicality of this method. The research results have a good reference significance for short-term optimization scheduling of cascade reservoirs in other basins. [ABSTRACT FROM AUTHOR]

Wading projects are likely to bring about changes of the original hydrodynamic conditions of the river, and this may further affect the flood discharge capacity of the river course. Thus, it is of great significance to study the flood risk of the river course with or without the wading projects, so that we can well maintain the project, regulate river course and ensure regional flood control security. Based on the random simulation of four uncertain factors, namely peak flood discharge, initial water level, river course roughness and dike elevation, this paper analyzed the stress of aqueduct under flood action, and then calculated the water surface line of the river. Combined with theforce conditions and water surface line calculation results, the conventional Monte Carlo method and the Monte Carlo method based on Latin hypercube sampling were both used to calculate the flood risk of river course with or without an aqueduct. The results show that: 1 When the water level in Gangqian Aqueduct is 0.5, 1.0, 1.5 and 2.0 m, the flood discharge capacity of Qingfeng Mountain stream, compared with its designed discharge of 1 200 m³/s, respectively decreases by 36.68%, 27.87%, 19.00% and 10.05%. 2 In the case of having no aqueduct in its river course, the flood risk of Qingfeng Mountain stream course is 0.007. In the case of having Gangqian Aqueduct in its river course, when the water level in the aqueduct was 0.5, 1.0, 1.5 and 2.0 m respectively, the flood risk of Qingfeng Mountain stream course is 0.34, 0.045, 0.016, 0.012 in turn. 3 Keep the water level in Gangqian Aqueduct at the highest value within the safe range. When the discharge of Qingfeng Mountain stream exceeds 1 600 m³/s, the flood risk of its river course still rises significantly with the increase in the flood flow. Therefore, in this case, Gangqian Aqueduct would have to be scrapped to ensure the flood discharge capacity of Qingfeng Mountain stream. 4 Both the conventional Monte Carlo method and the Monte Carlo method based on Latin Hypercube Sampling are suitable for assessing the influence of aqueduct on flood risk of river course, and the latter has better convergence. In summary, building adueducts in river courses would have a negative impact on the river courses' flood discharge capacity. It results in the flood discharge capacity of the river course being lower than the designed discharge, and further, led to the flood risk of river course increasing. To a certain extent, raising water level in the aqueduct can reduce the flood risk of river course. The fairness of water use is one of the key factors to be considered in the balanced allocation of water resources. Aiming at the problem that the fairness of water use in the basin is not considered enough in the different industries, an evaluation method based on multi-factor Gini coefficient in different industries is proposed. The Gini coefficient between industry water consumption and industry scale is used to represent industry water fairness. The comprehensive Gini coefficient of water use in the basin is calculated based on the proportion of water consumption in each industry to represent the fairness of water use in the basin. Taking the Yellow River Basin as an example, this paper calculates the Gini coefficient and analyzes the variation of the fairness of water use of different industries in nine provinces of the Yellow River Basin from 1980 to 2020. Take 1995 and 2005 before and after the integrated water regulation of the Yellow River as examples, the impact of integrated water regulation on the fairness of water use in the basin was compared and analyzed. The results show that over the past 40 years, the fairness of water use in domestic, industry, urban public, and agriculture were "highly fair", "relatively fair", from "highly fair" to "relatively fair", and from "relatively fair" to "highly fair", respectively. The proportion of agricultural water use exceeds 70%, and the Gini coefficient of watershed water use is mainly affected by agricultural water use, the comprehensive Gini coefficient of economic and social water use in the basin is 0.16-0.25 from 1980 to 2020, which is in a downward trend, indicating that the fairness of economic and social water use in the basin has gradually improved, changing from "relatively fairness" to "highly fairness" . The fairness of water use for domestic and agriculture is gradually improved, and the fairness of public water use in industry, especially in urban areas, has decreased significantly. This is mainly because the differences in water use quotas for domestic and agriculture between 9 provinces in the basin have decreased, while the differences in water use quotas for the tertiary industry have increased. The integrated water regulation of the Yellow River has effectively controlled the total water use in the basin, promoted the improvement of agricultural water use efficiency and the reduction of water quota differences between provinces, and improved the fairness of agricultural water use and water use in the entire basin. [ABSTRACT FROM AUTHOR]

With the development of industrialization and urbanization, untreated domestic sewage, industrial sewage and pollutants of surface runoff in the rainy season are discharged into the river system, leading to the serious urban water pollution. Due to the complexity and variability of the sources of urban polluted water bodies and environmental conditions, the current river restoration focuses on the rapid recovery of water quality, but does not fundamentally clarify the source of pollution, and does not consider the restoration of river water ecosystem damage. It leads to the fact that urban river is characterized with poor ability of self-purification and imperfect biodiversity, meanwhile, it is difficult to maintain and continuously improve water quality. This paper systematically illustrates the development process and inherent science of the concept of near naturalization restoration and urban sponge city. Both of them have separate characteristics, the concept and measures of which have commonality with the urban river restoration. The ecological restoration under the guidance of near-naturalization concept is beneficial to restore the hydrological continuity of river channels, to reshape the meandering and winding landscape of rivers, to increase the biodiversity index, making full use of their original ecological functions and values. Whereas, the concept of sponge city can effec tively reduce surface runoff, purify, accumulate, utilize rainwater and alleviate the discharge of pollutants into river or water bodies. They also contribute to the mitigation of flooding risk and improvement of river dredging and drainage functions. In addition, this paper summarizes the near-naturalized and sponge city part from the project carried out in Fuyang City, Anhui Province. Through the combination technology of "source control, pollution interception, dredging, water diversion and management", ecological restoration makes the near naturalization and sponge city integrated, which also emphasizes the construction of food chain system and greening management in the river channels. The two concepts focus on the restoration of self-purification capacity of the river and the reconstruction of ecosystem integrity, emphasize the treatment and reuse of rainwater resources, achieving the harmonious development of urban ecological restoration and landscape. Finally, to ensure the sound cycle and sustainable development of urban water ecosystem, the paper develops the direction of urban river restoration under the concept of near naturalization and sponge city intersection based on the current advanced environmental remediation and administration of domestic and foreign countries. It mainly includes two aspects: one is that the river restoration should be implemented in combination with the over-all planning of urban areas, making the river channel construction as an organic component of urban landscape; the other one is to gradually establish the evaluation indicators and standard for urban river restoration, including the traditional water quality indicators and those indicators related to the biological habitat and biodiversity. [ABSTRACT FROM AUTHOR]

Under the background of building a new power system based on new energy, the traditional decentralized small hydropower controller is more and more difficult to meet the construction needs of distributed small hydropower. In this paper, a distributed small hydropower controller based on ARM+DSP dual-core heterogeneous chip AM2732 is developed, which uses ARM to realize small hydropower control management, fast network transmission and integrity certification of transmission information, and uses DSP to realize small hydropower data acquisition and analyze the processing. According to design requirements, this paper introduces the overall design and hardware and software structure of distributed small hydropower controller. In particular, it focuses on the two key technologies of dual-core information exchange and remote communication integrity certification based on national secret algorithm. Finally, the field application of distributed small hydro-power controller shows that it not only has good functions of small hydropower regulation and communication, it can also support the development needs of new power grids such as small hydropower micro-grid. [ABSTRACT FROM AUTHOR]

As an important propaganda position of China's water conservancy, the core journals of water conservancy play an important role in promoting the development of China's water conservancy science and technology. In order to further enhance the influence of water conservancy journals in China, this study takes the journal " China Rural Water and Hydropower" as an example, combined with the bibliometric indicators of the journals in the past five years, this paper puts forward the following measures: ➀ closely track major national water conservancy research projects; ➁ Strengthen the solicitation of research papers on macro policies; ➂ Strengthen the solicitation of technical application papers and improve the quality of engineering technology papers; ➃ Fully utilize the Council platform to expand the influence of journals ; ➄ Give full play to the role of the editorial board in running the journal. [ABSTRACT FROM AUTHOR]

In recent years, the water level in Poyang Lake has repeatedly reached a record low in dry seasons, which has led to increasingly prominent economic and social development and ecological and environmental protection issues. In order to identify the law of water level changes of Poyang Lake and quantify the degree of contribution of different influencing factors on the changes in the water level of Poyang Lake, this paper uses Mann-Kendall test and polynomial regression analysis methods to quantitatively analyze the change trend of water level of Poyang Lake and its causes. In this paper, Xingzi Station and Hukou Station are taken as the water level and flow representative stations of Poyang Lake respectively, and Jiujiang Station is taken as the representative station of the mainstream of the middle and lower reaches of the Yangtze River. First, the long-term observed data of the Yangtze River Basin and Poyang Lake from 1981 to 2021 are selected for case studies. The main influencing factors of the water level changes of Xingzi Station on the Poyang Lake are identified by correlation analysis. The trend characteristics of the water level of Poyang Lake are analyzed by the Mann-Kendall test method. Finally, the degree of contribution to the changes in the water level of Poyang Lake during the dry season is quantified based on the water volume relationship. The results show that the changes in Poyang Lake's water level from the perspective of water volume are mainly affected by the total water volume of Jiujiang Station and Hukou Station. In 1981 before the Three Gorges Reservoir was built, the lowest water level of Poyang Lake had shown a significant downward trend. After the reservoir was built, the lowest water level of Poyang Lake in the normal storage period rose by 0.44 m com-pared with the initial storage period, indicating that the water supply regulation of the Three Gorges Reservoir in the dry season alleviated the downward trend of the water level of Poyang Lake in the dry season to some extent. Impoundment of the Three Gorges Project is not a key factor affecting the decrease in water level in the dry season of Poyang Lake, with a contribution of 35.4%, but is mainly affected by the comprehensive factors such as decreased water and cutting under the river bed, with a contribution of 64.6%. In addition, the water supplement of the Three Gorges Reservoir has a positive effect on the increase in water level of Poyang Lake in the dry season, with a contribution of 20%, and the contribution of factors such as the cutting of the riverbed and the reduction of other incoming water is -120%. The study can provide scientific basis and guidance for formulating countermeasures for low and dry water levels of Poyang Lake in the dry season and improving water resources and water environment carrying capacity of the lake area. [ABSTRACT FROM AUTHOR]

Based on deep learning, precipitation prediction has been a hot topic in hydrological research in recent years. Monthly precipitation data is a typical small sample data that cannot meet the demands of deep learning for large datasets. Therefore, this paper proposes an improved method for predicting monthly precipitation using a Long Short-term Memory Network (LSTM) by integrating the ideas of signal decomposition and boundary correction. First, to address the " end effect" of sequence decomposition, this paper uses the waveform feature matching extension method to expand the boundaries of the original sequence. Then, the original sequence is decomposed twice by using Extreme-point Symmetric Mode Decomposition (ESMD) and Variational Mode Decomposition (VMD). ESMD is used to extract different sorts of scale information of the monthly precipitation sequence, obtaining several model components with decreasing frequencies and one residual component. After cutting off the most severe extension parts that "pollute" the internal data of each sub-sequence, VMD further smooths the high-frequency components. Finally, LSTM is applied to each sub-sequence for prediction, and the predicted results are reconstructed to obtain the final prediction. The monthly precipitation in Badong County, Hubei Province is selected as an example for verification. Through model comparison analysis, the results show that compared to traditional single SVM and LSTM models, the prediction model combining signal decomposition algorithm has more advantages in monthly precipitation prediction; The method of boundary correction is incorporated into the combined model by using the ESMD algorithm improves the overall prediction accuracy of the model. The prediction effect of high-frequency components is a key factor determining the accuracy of combined model prediction. The method proposed in this paper not only performs the best on the selected evaluation indicators but also significantly improves the fitting effect of extreme data points. In particular, even when facing a small sample dataset, the Nash-Sutcliffe Efficiency coefficient (NSE) of monthly precipitation prediction can reach 0.960 0 by using this model. [ABSTRACT FROM AUTHOR]

Based on the survey data of hydropower immigrants in Yantan, Guangxi, the combination empowerment method and Topsis model are used to quantify the sustainable livelihoods composed of three abilities, and variance analysis is used to explore the impact of follow-up supports and their specific measures on the sustainable livelihoods for the overall and three types of immigrant households in order to evaluate the effectiveness. The results show that the overall sustainable livelihood level of immigrant households is lower than the medium level, and the sustainable livelihood level of non-poor households, general poverty alleviation households and low-income poverty alleviation households decreases successively. Comprehensive assistance has significantly improved the sustainable livelihoods of overall immigrant households. The involvement of specific measures has different effects on the sustainable livelihoods for different immigrant households, among which education and training have significant effects on the improvement of the sustainable livelihoods of three types of immigrant households. The number of measures involved has a significant impact on the sustainable livelihoods of non-poor households and low-income poverty-stricken households, but has no meaningful impact on ordinary poverty-stricken households. This paper expands the research methods in the field of of evaluating the effectiveness of follow-up support for immigrants, which can provide a basis for accurately and efficiently promoting immigrants support. [ABSTRACT FROM AUTHOR]

With the post epidemic economic recovery and development, Liaoning Province experienced a severe electricity shortage in 2021. This article is based on a systematic analysis of the current situation of hydropower development and the degree of hydropower resource development and utilization in Liaoning Province, pointing out the problems, construction opportunities, advantages, and disadvantages faced by current hydropower development; Based on the relevant planning achievements of hydropower development in Liaoning Province for many years, this paper analyzes the planning situation of conventional hydropower stations and pumped storage power stations that can be constructed in the future in Liaoning Province; By analyzing specific cases of using upstream and downstream reservoirs to construct pumped storage power stations, suggestions for ensuring the development of hydropower in Liaoning Province are proposed, providing reference for the hydropower construction in Liaoning Province in the new era. [ABSTRACT FROM AUTHOR]

Slope has an important effect on the runoff production process. Slope correction of runoff curve number in the SCS-CN runoff production model is important to improve the model prediction accuracy, In order to conduct an investigation of the effect of average watershed slope in the runoff production process, in this paper, based on Huang's slope modification formula, the first 40 out of 70 rainfall runoff measurements in the study area from 1955 to 1981 were used as the validation data, and a1 and a2 parameters in Huang's slope modification formula were re-determined, so as to propose the slope modification formula of the CN value for the study area under three different antecedent moisture conditions, and then the SCS-WJG method, which is of good applicability to the region, was established and compared to the SCS-CN look-up table method, and the SCS-Huang method, which is a direct transfer of the Huang's slope modification formula. The conclusion is as follows: the λ-value of the initial rainfall loss rate determined using the ergodic method is 0.09, so the standard value of 0.2 is not applicable to the study area. After comparing the size of the CN values obtained by the three methods, it is found that the CN value obtained by the SCS-Huang method is the largest, followed by the SCS-CN look-up table method, and the smallest is obtained by the SCS-WJG method, so the CN value obtained by the SCS-WJG method is more suitable for the study area as shown in the simulation results. Comparison of the SCS-CN lookup table method and the SCS-Huang method reveals that the NSE of the SCS-Huang method is lower and the RMSE is higher; therefore, it is necessary to propose a slope correction formula for the CN value applicable to the study area and establish the SCS-WJG method. When λ = 0.09, the NSE of the SCS-CN lookup table method, and the SCS-Huang method are -2.85 and -3.25, respectively, while the NSE of the SCS-WJG method is increased to 0.86, and the RMSE of the SCS-WJG method is reduced by 77%, and 78%, respectively, compared with the first two methods. The simulation accuracy of the SCS-WJG method is significantly better than that of the remaining two methods, indicating that the SCS-WJG method has good regional applicability and can provide a reference for the simulation of runoff production in small watersheds. [ABSTRACT FROM AUTHOR]

Considering that the statics/dynamics analysis about the large emersed radial gate are always over-simplified by previous investigations, in this paper, the static and dynamic characteristics of single gate and gate-dam system are analyzed and compared in detail using the ANSYS finite element software. A finite element model (FEM) of gate-dam system considering seal friction, supporting hinge system and prestressed anchor cable is established based on the instantaneous opening condition of spillway radial gate of a hydropower station. The research results show that: in terms of statics, the two sides of the water seal have little influence on the stress distribution of the steel structure components in the gate, with a maximum difference of 14.08%; Also, more reasonable stress distribution of fixed hinge is obtained from gate-dam system comparing with that of single gate; Besides, the anchor block affects the overall displacement of the gate prominently, and the degree of effect can be sorted as: the overall displacement of the single gate < the integrated displacement of the gate dam without the prestressed anchor cable < the overall displacement of the gate dam with prestressed anchor cable. In terms of the dynamics analysis, frequency of the gate structure is reduced by the water seal when fluid-structure interaction effect is taken into account; And the prestressed anchor cable has little influence on the dynamic characteristics of gate-dam system. [ABSTRACT FROM AUTHOR]

After long-term operation of a generator, the stator winding will gradually experience aging or electrical corrosion, and scientific experimental analysis methods are needed to diagnose the health status of equipment. By analyzing the leakage current data of stator winding DC withstand voltage tests of multiple large tubular generators, this paper proposed an insulation performance evaluation method and measures to prevent winding breakdown; according to the electrical corrosion and high operating temperature of stator winding of wall mounted structure, we studied a series of innovative designs and processes for stator renovation, and conducted finite element simulation calculation of stator temperature field. The temperature rise test data shows that the operating temperature of the generator after stator modification is effectively reduced, and there is significant reduction in temperature deviation at each measuring point. The research results are close to the simulation calculation values, proving that the new process adopted for stator transformation is effective and feasible. [ABSTRACT FROM AUTHOR]

The lack of some hydrological data or short hydrological sequences makes it difficult to predict the power generation capacity of small hydropower stations, and this paper summarises three prediction methods: ARIMA model, LSTM model, and large and small hydropower station correlation method, in order to effectively solve this problem. Taking Ni'ao Gia Ga power station in Gannan area as an example, with the actual power generation data of the power station in 2022 as the test standard, and based on the power generation and water inflow data from 2015 to 2021, ARIMA model, LSTM model and large and small hydropower station correlation method are successively used to predict the power generation capacity of small hydropower stations in this area. The results show that the correlation method of large and small hydropower stations using the flow of large hydropower stations as the relevant factor can effectively predict the amount of water coming from small hydropower stations, and then get the prediction results of power generation with higher accuracy, which is obviously better than the ARIMA model and the LSTM model, and it can be popularised and applied in similar areas. [ABSTRACT FROM AUTHOR]

In order to deeply analyze the drought and flood disaster response patterns of Tuojiang River Basin under the background of climate anomalies, this paper reconstructs the time series of drought and flood disaster of Tuojiang River Basin in the Qing Dynasty, and analyzed its related data with mathematical statistics, mutation test, power spectrum cycle analysis, ADF and Granger causality test, etc., to explore the occurrence patterns of drought and flood disasters in the Tuojiang River Basin in the Qing Dynasty and its climate driving force factors. The results show that, during the Qing Dynasty, 208 drought and flood disaster occurred in the Tuojiang River Basin, with an average of one drought and flood disasters occurring every 1.29 years. There were more flood disasters than drought disasters, with a total of 21 persistent flood and drought disasters and an overall high level of severity of disasters. Drought and flood disasters were interspersed frequently, and there were also drought and flood disasters coexisting during the same year. Drought and flood disasters were concentrated in a chain-like distribution from 1800 to 1910.The number of disasters peaked in the middle of the Qing Dynasty, and mega-disasters were concentrated in the middle and late Qing Dynasty. The year 1863 was an important mutation point for drought and flood disasters, after which the number of disasters increased significantly. Drought and flood disasters in the Qing Dynasty were significantly correlated with the average annual sunspot number, and continuous disaster events were more frequent around sunspot extreme years.The change cycle of drought and flood disasters is about 2.5 a, which is strongly consistent with the ENSO cycle. The number of drought and flood disasters in the Tuo River Basin was significantly higher during ENSO event years. With a lag period of 1a, sunspot activity and ENSO events are the main climatic triggers of drought and flood disasters changes. The research results not only fill the research gap of drought and flood disasters mechanism in the Tuojiang River Basin under climate change, but also enrich the knowledge of spatial and temporal distribution pattern and regularity of drought and flood disasters in the Yangtze River Basin. It provides a useful reference for strengthening the scientific use of water resources and disaster prevention and mitigation, and also provides an important reference for the flood and drought prevention and ecological civilization construction in the Tuojiang River Basin. [ABSTRACT FROM AUTHOR]

It is very easy to encounter the phenomenon of water and mud gushing during construction and excavation of tunnel through karst area. How to choose appropriate anti-seepage measures to reduce the seepage flow of tunnel has always been a hot issue. In this paper, a three-dimensional finite element model of complex strata in karst area is established based on a water diversion project . Three anti-seepage measures, namely back-filling concrete on the roof of the tunnel, grouting ring around the tunnel and concrete cutoff wall, are mainly considered. The change law of pore water pressure and seepage flow of the tunnel during tunnel excavation is studied, and the influence of permeability coefficient of the cutoff wall and grouting ring on seepage characteristics is analyzed. The results show that the concrete cutoff wall has a great influence on the distribution of pore water pressure in the tunnel, the water level between the cutoff walls decreases obviously, and the grouting ring around the tunnel has the greatest influence on the seepage flow of the tunnel, and the quality of the grouting ring should be ensured during construction. The pore water pressure increases with the increase of the horizontal distance from the tunnel center, and increases first and then decreases with the increase of the vertical distance from the tunnel center. With the increase of the permeability coefficient of the grouting ring or the cutoff wall, the pore pressure growth rate in the area of the grouting ring or the wall decreases gradually, and the seepage flow of the tunnel increases continuously. [ABSTRACT FROM AUTHOR]

Based on the "air-land-water" integrated model system and multi-level collaborative architecture of the basin, this paper proposes a technological system for a non-point source pollution forecasting and warning platform for the Pengxi River basin, and a non-point source pollution forecasting and warning platform for the Pengxi River basin has been established. By automatically collectting and processsing meteorological data, and invoking the meteorological model, land model, hydrodynamic model, and water quality model driven by the control center, the platform can make hourly simulated forecasts of land surface runoff and the flow of pollutants such as TN, TP and NH3-N for the next 3 to 15 days, and warn about the risk of pollutant fluxes, providing technical support for the intelligent basin management and comprehensive control of non-point source pollution. [ABSTRACT FROM AUTHOR]

Water body extraction from high-resolution remote sensing images often results in incomplete and discontinuous extraction results due to factors such as complex types of ground objects and narrow rivers. To address these challenges comprehensively, combined with the spectral and texture characteristics of the water body itself, this paper proposed an innovative method for water body extraction and optimization in high-resolution remote sensing images that combines global features and local interconnection. The proposed method integrates the intrinsic spectral and textural features of water bodies, adopting a strategy of initial extraction followed by optimization and skillfully blending global and local communication features. Firstly, linear tributaries are recognized based on the initial water extraction results using multiscale Frangi filtering and the OTSU segmentation algorithm and river replenishment is applied to these linear features, resulting in preliminary optimization results. Then, a locally interconnected disconnection continuation algorithm is introduced to connect disjointed segments in the preliminary optimization results ingeniously. The final stage involves the extraction of water body segments using K-means clustering, and topology inspection and spectral inspection are performed with the accurate optimization results to achieve verification and screening of blocky water bodies. Then, rigorous checks are conducted to validate and filter block-shaped water bodies, ensuring the precision of the extraction results. Experimental results validate the outstanding performance of this method, particularly in the extraction of small tributaries, resulting in a substantial improvement in optimization accuracy. Introducing the disconnection continuation algorithm enhances the completeness of river extraction and fortifies the overall robustness of water body extraction. Comparative analysis with other methods reveals an overall accuracy improvement of 1.04% and 1.50%, along with an increase in comprehensive value by 5.84% and 8.28%, respectively. It can be used as a means to effectively improve the post-processing of water body optimization and improve the integrity and accuracy of water body extraction. [ABSTRACT FROM AUTHOR]

Because the thermal conductivity of freezing soil is hard to measure, in order to clarify the influence of temperature on thermal conductivity, a hyperbolic model with three parameters was proposed to describe the relationship between thermal conductivity and negative temperature in this paper. Then, the performance of the new hyperbolic model was verified by the measured thermal conductivity coefficients and three widely used models, and a sensitivity analysis of model parameters was performed. The results show that the hyperbolic model can accurately predict the change pattern of soil thermal conductivity during the freezing process. Among these four models, the proposed hyperbolic model has the smallest root mean square error and relative error. The model parameters are closely related to the fine particle content and decrease as the initial volume moisture content increases. Considering the new model can accurately simulate the variation of thermal conductivity with subzero temperature, it can provide a basis for coupled heat and mass transfer in cold regions. [ABSTRACT FROM AUTHOR]

This paper analyzed the pre-stressing mechanism of the steel wire and the damage process of the pipeline, and proposes a method of PCCP wire broken warning and alarm threshold assessment based on mechanical simulation analysis. The PCCP finite element model was established by ABAQUS program, and the complete construction process including laying bedding, installing pipelines, backfilling in steps was simulated, and the stress state of pipeline prestressing steel wires, steel cylinders and pipe core concrete was calculated under nearly 100 working conditions with different depths of burial and different design working pressures. It was proposed to take the maximum permissible number of broken wires of the pipe core concrete cracked under the action of water hammer as the early warning threshold for the bursting of the pipeline, and the maximum permissible number of broken wires in the limit state of the buried bearing capacity of the pipeline as the alarm threshold for pipe bursting, and analyzed the relationship between the PCCP wire broken warning and the alarm threshold under different working pressures and burial depths. [ABSTRACT FROM AUTHOR]

Cavitation phenomenon and hump instability characteristics are the main factors affecting the safe and stable operation of the centrifugal pump unit. In this paper, based on the numerical calculation and model test results of two impeller schemes of a large centrifugal pump unit, the cavitation performance and hump instability characteristics were comparatively analyzed to explore the correlation between the two. At the same time, the hump generation mechanism and the role that cavitation performance played in it were analyzed. The numerical results show that due to cavitation, a hump instability phenomenon appears on the H-Q performance curve in the numerical results. In addition, the impeller with excellent cavitation performance has a uniform pressure distribution on the blade surface in the small flow area and a reasonable minimum pressure distribution, and its hump instability characteristics are significantly improved. The model test results show that under normal operating conditions of the pumping station, by increasing the ratio of plant cavitation coefficient σp to incipient cavitation coefficient σi, the hump margin increases when the impeller cavitation performance is improved. The results show that there is a positive correlation between cavitation performance and hump instability characteristics. The improvement of impeller cavitation performance in the small flow zone reduces the degree of cavitation, the flow in the impeller passage can be improved, hydraulic efficiency can be increased and hump instability characteristics can be improved. The study results provide design reference for the safe operation of large centrifugal pump. [ABSTRACT FROM AUTHOR]

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Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Aiming at the shortcomings of the existing methods of energy efficiency management level evaluation for hydropower stations, this paper introduces Analytic Hierarchy Process (AHP) method and Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) method into the evaluation process. The evaluation index system of energy efficiency management of hydropower station is constructed by considering the three aspects of economy, safety and management comprehensively. In order to overcome the shortcomings of the nine scale method, the paper uses the exponential scale method to determine the weight of each index. What's more, TOPSIS method and expert scoring method are used to score the quantitative indicators and the qualitative indicators, respectively, so as to further realize the comprehensive evaluation of the hydropower station energy efficiency management level. An actual hydropower station is taken as an example to analyze and calculate the score of the energy efficiency management level of the hydropower station from 2018 to 2022.The results show that the energy efficiency management level of the hydropower station is on the rise. [ABSTRACT FROM AUTHOR]

The traditional monitoring model for concrete dam displacement often ignores analyses of pertinent information within the residual sequence, leading to suboptimal predictive performance for dam displacement. The purpose of this paper is to improve the accuracy of prediction models. To address this issue, a dual-layer displacement prediction model for concrete dam, which considers signal residual amendment, is proposed. Firstly, influential factors affecting dam displacement are selected based on the statistical model of traditional concrete dam displacement. Secondly, the sparrow search algorithm (SSA) is employed to determine the hyperparameters of extreme learning machines (ELM) in order to establish the single-layer prediction model SSA-ELM, which yields single-layer model displacement prediction values for dams. Next, the Variational Mode Decomposition (VMD) technique along with the Minimum Sample Entropy (SE) and correlation analysis is utilized, the residual sequence is decomposed and reconstructed. Finally, by using the SSA-ELM model to correct the reconstructed sequence and combining the corrected values with the single-layer model displacement prediction values, the dual-layer prediction model SSA-ELM-VMDr+ is constructed, allowing for the final displacement prediction values. The engineering validation of the model demonstrates that the dual-layer prediction model exhibits higher prediction accuracy and stronger generalization ability compared with other models. Moreover, the model effectively extracts valuable information from the residual and overcomes noise interference. This paper provides a new reference for dam safety monitoring, health service diagnosis and management operations. [ABSTRACT FROM AUTHOR]

In order to propose an accurate and rapid method for the determination of the permeability coefficient of clay in the core of an earth-rock dam, this paper establishes an ellipsoidal horizontal flow model for the seepage flow based on CPTU, which is suitable for the evaluation of the horizontal permeability coefficient of compacted soil. It firstly reviews the previous research results of soil permeability coefficient estimation based on CPTU, and then, from the practical perspective, analyzes and deduces the simple mechanical model of pore water pressure distribution generated by the soil injected by the probe. After the measured data are compared, it concludes that the distribution of negative exponential function has a strong correctness. Then an evaluation method of permeability coefficient based on ellipsoidal horizontal seepage model is derived. It is proved by an engineering example that the method in this paper improves the previous methods in theory and calculation accuracy, and has a good prospect in engineering application. [ABSTRACT FROM AUTHOR]

In order to meet the downstream water demand in the open channel water transfer project, this paper considers it necessary to formulate the control scheme in advance. The design of feed forward control scheme is often complicated, and there are many influencing factors, which make it difficult for dispatchers to make decisions quickly. Based on the storage compensation method, this paper applies feed forward control to the section from Diaohe control gate to Jialihe control gate of the middle route of South-to-North Water Transfer Project. Based on the calculation results of storage compensation, the relationship between the initial flow, water diversion flow and feed forward control time is analyzed, and a fast calculation formula of feed forward control time with single and double variables is established. The influence of different factors on the downstream water level deviation of storage compensation control is explored, and the functional relationship between the initial flow, water diversion flow and the maximum deviation of the downstream water level is obtained. In order to solve the problem that the deviation of the downstream water level under the original storage compensation control is too large in the extreme working condition of engineering operation, the feed forward control of the channel pool is carried out by using the secondary storage compensation rule, which effectively reduces the downstream water level deviation. [ABSTRACT FROM AUTHOR]

In this paper, a numerical simulation model of the flow field inside the diaphragm valve is established based on the k-ε turbulence model (where k represents the turbulent kinetic energy and ε represents the turbulent dissipation rate). The mass flow at the inlet and static pressure at the outlet are used as the numerical calculation conditions, and the accuracy of the model is verified through experiments. Based on this, the model is applied to analyze the internal flow characteristics and pressure field distribution of the valve body under different import flow rates (2.787-33.273 kg/s), and an accurate quantitative relationship between import flow rate and valve body head loss is established. The results show that: 1 the numerical simulation can better predict the head loss of the valve body under different flow conditions. When the inlet flow numbers are 5.546, 11.091 and 16.637 kg/s respectively, the relative errors between the experimental and numerical simulations are only -6.433%, 4.619%, and 7.264%. 3 With a constant inlet flow, the static pressure decreases from inlet to outlet in flow passage. Flow contraction caused by the blockage of the valve wall and the flow impinging on the diaphragm creates a large static pressure gradient in the valve body. 4 After water passes through the narrow flow channel on the valve wall, a cavitation zone and reflux phenomena occur downstream of the valve body. The cavitation zone appears mainly in the 1/3 fluid domain away from the outlet. As the inlet flow increases, the vortex in the downstream of the valve body intensifies and the reflux phenomenon becomes more significant, but the scope of the reflux zone does not increase significantly. 2 After verifying the accuracy of the model, this paper studies the valve body's internal flow characteristics and pressure field distribution under 18 different inlet flow conditions. The model establishes a relationship between the inlet mass flow Q and the head loss ΔP of the valve body. For Reynolds numbers from 37 927-21 5984 and inlet mass flow Q from 2.787-15.428 kg/s, the fitting equation is ΔP = 2 076.31Q - 7 567.49 (R² = 0.964). For Reynolds numbers from 240 097-467 009 and inlet mass flow Q from 17.141-33.273 kg/s, the fitting equation is ΔP = 5 688.02Q - 67 317.39(R² = 0.993). These results are useful for hydraulic calculations in irrigation systems. [ABSTRACT FROM AUTHOR]