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  • ZHAO Zuo-zhang, CHEN Jin-song, PENG Er-rui, LI Rong-liang, WU Da-zhen
    China Rural Water and Hydropower. 2023, (6): 202-208.
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    With global resources and environmental problems becoming more and more prominent, soil salinization has received widespread attention, and about 8% of the world’s land is threatened by salinization. China is a country where soil salinization is relatively serious, and the saline soil area accounts for 1/10 of the global saline soil area, and in recent years, under the influence of natural and human factors and other conditions, the soil under salinization stress is still developing, which seriously affects other aspects such as arable land resources, crop yield, and agricultural development. Therefore, it is of practical importance to improve the quality of saline soils and crop yields using economically rational and efficient management measures. This paper summarizes the causes and sources of soil salinization, and reviews the management pathways of saline soils from four aspects: irrigation and drainage measures, physical regulation, chemical improvement, and biological measures, to provide references for further research on saline soils management.

  • LI Jie, CUI Dong-wen
    China Rural Water and Hydropower. 2023, (11): 1-9.
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    This paper evaluates the spatial equilibrium status of water resources in Yunnan Province from 2006 to 2022 and 2025 scientifically, and proposes a water resource spatial equilibrium evaluation model based on social network search (SNS) algorithm, mountaineering team optimization (MTBO) algorithm, bi-directional gated loop unit (BIGRU) optimization, and bi-directional long short-term memory (BILSTM) network optimization. First, 15 indicators are selected from three aspects of water resources support, water resources pressure and water resources regulation to build the evaluation index system and grade standard of water resources spatial balance, and the samples are generated by linear interpolation and random selection methods to build BiGRU and BiLSTM fitness function. Secondly, the principles of SNS and MTBO algorithms are briefly introduced. SNS-BIGRU, MTBO-BIGRU, SNS-BILSTM, and MTBO-BILSTM models are constructed by using SNS and MTBO to optimize the number of neurons in the hidden layer of BiGRU and BilSTM and the learning rate (hyperparameter). The robustness of four models, including SNS-BIGRU, MTBO-BIGRU, SNS-BILSTM, and MTBO-BILSTM, is verified through different sample sizes and 10 consecutive runs. Finally, SNS-BIGRU, MTBO-BIGRU, SNS-BILSTM, and MTBO-BILSTM models are used to evaluate the spatial balance of water resources in Yunnan Province from 2006 to 2022 and 2025, and the evaluation results are compared with those of SNS-Support Vector Machine (SVM), MTBO-SVM, and fuzzy comprehensive evaluation methods. The results show that: ① the models such as SNS-BIGRU have good recognition accuracy and robustness. SNS and MTBO can effectively optimize the hyper-parameter of BIGRU and BILSTM, and improve the prediction performance of BIGRU and BiLSTM. ② SNS-BIGRU and other four models evaluate the spatial balance of water resources in Yunnan Province from 2006 to 2011 as “unbalanced”, from 2012 to 2013 as “relatively unbalanced”, from 2014 to 2018 as “critical equilibrium”, from 2019 to 2022 as “relatively balanced”, and by 2025, it can basically reach the level of “balanced”. There is a 3-year difference in the evaluation results of the four models compared to SNS-SVM, MTBO-SVM, and fuzzy comprehensive evaluation methods. The model method constructed and proposed in this paper serve as a reference for the spatial balance evaluation of water resources.

  • XUE Lian-qing, ZHOU Tian-wen, LIU Yuan-hong, YANG Li-juan
    China Rural Water and Hydropower. 2023, (7): 1-7.
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    To improve the prediction accuracy of monthly runoff, this paper proposes a prediction model based on a two-stage decomposition strategy. First, the original runoff sequence is decomposed into trend terms, seasonal terms and residual terms through the Seasonal-trend decomposition using Loess(STL), and then the residual items with strong randomness are further decomposed through the Variational Mode Decomposition (VMD) to eliminate noise. Three machine learning models, namely, Long-Short Term Memory (LSTM) networks, Convolutional Neural Network (CNN) and Support Vector Regression (SVR), are used to predict each component one by one, and the monthly runoff prediction result is a linear set of the predicted values of each component. Taking Shimen Station in Lishui Basin as the research object, indexes such as Mean Absolute Error (MAE)、Mean absolute percentage error (MAPE) and Nash Efficiency (NSE) were selected to comprehensively evaluate the model prediction accuracy, and combined with the SHAP(Shapley Additive explanations) interpretable machine learning method to explore the input characteristics in the optimal model contribution to runoff prediction results. The result shows that the overall prediction accuracy of LSTM and CNN is better than that of the SVR model, but the change in prediction accuracy caused by the difference in the model structure is smaller than that caused by the difference in input items; the contribution of each decomposition component in the optimal model STL-VMD-LSTM to the prediction results is better than that of other input characteristics.

  • XU Yi, ZENG Yan-li, LIU Min-zhi, LIU Tian, ZHANG Xuan, WU Wei, ZHOU Xing-chi
    China Rural Water and Hydropower. 2023, (5): 1-4.
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    To study the purification effect of artificial ecological pool on rice field drainage, this paper analyzes the purification effects of TN, NH4 +-N for paddy field drainage by two years’ rice field drainage artificial ecological pool purification test for emergent plants, floating plants and submerged plants. The artificial ecological pond has an obvious purification effect on TN and NH4 +-N in paddy field drainage. Different aquatic plants can reduce the pollutant concentration to the level before unsewage in the 6th to 7th day after purification. Among them, the removal of TN and NH4 +-N from Hydrilla verticillata is the best, and the removal effect is more than 90% after 4 days of purification. Artificial ecological pool can effectively purify rice field sewage and reduce agricultural non-point source pollution. Black algae have the best purification effect and are suitable for popularization in artificial ecological pools.

  • CHANG Li-wei, CHENG Lei, CHEN Jin, HAN Dong-yang, ZHANG Lu, LIU Pan, CHANG Jian-bo
    China Rural Water and Hydropower. 2023, (6): 1-11.
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    Uneven spatial and temporal distribution of water resources is widely existed. Building reservoirs is one of the most effective means to regulate water resources. In China, more than 90 000 reservoirs of various kinds have been built. In order to maximizing the engineering benefits and water security capability of reservoirs, comprehensive, accurate and georeferenced attribute datasets of reservoirs and dams at national and global scales are urgently needed including location, boundary, height, storage capacity and function. During the past decade, several reservoir and dam data sets have been published and significantly advanced the large-scale researches on the environmental impacts of reservoirs and dams. However, there are significant discrepancies in the numbers and values of attributes amongst data sets. Therefore, it is urgent to carry out comparative assessment and to identify the future direction of these data sets. In this study, main contents of the present publicly available reservoir and dam data sets were introduced, data sources of reservoir and dam information and the production procedures were summarized, and basic georeferenced attributes were compared amongst different data sets including location, classification, boundary, etc. More importantly, the spatial distribution characteristics and statistical differences of each data set in China are compared comprehensively. Problems such as timeliness of data set, repeated definition of reservoir and lake, and difference of reservoir area are also explored. Moreover, urgent and important research issues related to such data are reviewed, such as flood control, power generation and irrigation benefit of reservoirs, hydrological, carbon and interception effects of reservoirs and dams, and river habitat fragmentation, etc. Finally, the future production and application of dam and reservoir data sets are discussed. It is found that present data sets contain more large reservoirs and less mall reservoirs, and large reservoirs have comprehensive attributes, while small reservoirs have insufficient attributes. There are also many other differences between different data sets. In the future, it is necessary to further improve the data records of reservoirs and dams and coordinate the differences of data sets to achieve complete simulation of reservoirs and dams.

  • FAN Yi-jing, LIU Zhen, YUAN Jia, LIU Xin
    China Rural Water and Hydropower. 2023, (9): 35-45.
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    Urban water resources planning and management is a key link to ensure sustainable urban development and satisfy the basic needs of residents. Short-term water demand forecasting is the basis of urban water resources planning and management. As temperature, precipitation and evaporation vary significantly with the seasons, they directly affect the peak of water consumption in different seasons. As a result, the traditional fixed time slot prediction based on time series algorithm cannot adapt to the change of time slot, so the prediction accuracy cannot be guaranteed. Aiming at the problem of low accuracy of fixed time slot prediction, this paper studies a dual-time scale urban short-term water demand prediction model based on 24 h time resolution in four seasons and 15 min time resolution in summer. This model uses Anomaly-Transformer model to detect outliers and calibrate outliers by piecewise curve fitting. Principal component analysis is used to analyze and extract the main components of urban short-term water demand factors. In the standard model analysis of AutoML, three models with the best effects are selected as the base learner of the stacking model combined with the long-term and short-term memory network (LSTM, long-term and short-term memory) and the neural prophet model (NP) after hyperparametric optimization of Optune framework predict the short-term water demand of the city on both time scales, and add the safety net mechanism to ensure the accuracy of the LSTM-NeuralProphet model. Compared with other models (LSTM model, Neural Prophet model, BP neural network model), the average absolute error of LSTM-Neural Prophet model is reduced by 0.18%~1.96% on the data set with 24 h time resolution of four seasons. In the summer 15 min time resolution data set, the reduction is 0.45%~11.90%. The experimental results show that the LSTM-Neural Prophet model has a better fitting effect and higher prediction accuracy, and can accurately predict the urban water demand at both time scales, and can be applied to the short-term urban water demand prediction research.

  • HE Li, CHU Meng-xi, ZHANG Jin-chao, DU Yu
    China Rural Water and Hydropower. 2023, (8): 1-6.
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    In order to study the dynamics of the water resources system and to solve the problems existing in traditional TOPSIS evaluation of water resources carrying capacity, for example, when the evaluation values are close to the interval classification boundary,the grade differentiation is not high, thus it is difficult to form an objective and effective evaluation. In this paper, due to the advantage that D-S evidence theory can effectively reduce loss caused by data variability and fuse the results objectively and accurately, it is used to improve TOPSIS method for water resources carrying capacity evaluation. By fusing the distance between the indicator vectors in TOPSIS method and the positive and negative ideal solutions, the synthetic confidence of each grade of water resources carrying capacity is obtained, and the grade of water resources carrying capacity is judged based on the synthetic confidence value with greater differentiation. On this basis, the indicator increment is introduced to calculate the changes in the water resources carrying capacity over the years, and the time power vector is used to combine the changes over the years to analyze the trend of water resources carrying capacity. The results show that: the discriminations between the evaluation value and the interval boundary are improved from 0.000 3, 0.001 1 in 2018 and 2020 to 0.019 and 0.336 7 respectively by improved the TOPSIS. Meanwhile, the error between the predicted trend using the proposed trend analysis method and the actual result is 0.001 9 in 2020. Finally, it is predicted that the water resources carrying capacity will have a negative trend in 2021. The main impact indicators are annual precipitation and per capita water resources by the obstacle factor model. The suggestions are put forward to strengthen the construction of the ecological environment and optimize the rational allocation of water resources. The method in this paper has higher grade distinction, and the evaluation results are reasonable and objective, in line with the actual situation. And it can also make comprehensive use of the dynamic data of the past years so that it can accurately describe the changes in water resources carrying capacity, which can provide a scientific basis for the development and protection of water resources.

  • ZHU Bin-hao, ZHOU Jian-zhong, FANG Wei, ZHANG Yong-chuan
    China Rural Water and Hydropower. 2023, (5): 119-123.
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    In order to flexibly use the prediction features of each independent model to perform high-precision coupled runoff forecasting in the study basin under the premise of considering the applicable conditions of each hydrological model, this paper constructs a multi-model runoff forecasting method library covering Xinanjiang model, Tank model and TOPMODEL model, and introduces least squares, ridge regression and extreme gradient boosting tree methods to couple each independent model for hydrological forecasting. A multi-evaluation metric system is proposed to analyze the prediction performance of each coupled method. The conclusions show that the extreme gradient boosting tree method has stable prediction performance and strong generalization ability compared with the other two methods in the runoff forecasting of the Yajiang-Jiju interval in the Yalong River Basin, which provides a new idea for the runoff forecasting of other areas in the basin.

  • XI Bin, CHEN Qian-qian, CHEN Wei, XI Wang, ZOU Yan, HUANG Hai-tao, CHEN Zhi-gang, SHEN Shi-xuan, CHEN Ye-xin, KONG Qing-hao
    China Rural Water and Hydropower. 2023, (5): 5-11.
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    When the boat enters the drinking water source river from the waterway, it will pull the sewage into the drinking water source river. In order to improve the water quality of the drinking water source river and reduce the pollution of a certain drinking water source river, this paper optimizes the boundary of the drinking water source river branch. By using the Mike21FM hydrodynamic module, the two-dimensional hydrodynamic mathematical model of the drinking water source channel after the optimization of the current channel and the boundary of the branch stream is established. The mathematical model parameters are calibrated and verified through the physical model test, and the drinking water source under the current situation and the optimized scheme are simulated. The flow field of the river channel and the amount of sewage pulled into the drinking water source river channel by different boat speeds are calculated. The results show that optimizing the boundary of the drinking water source river branch can effectively improve the estuary of the drinking water source river branch flow field, the optimized scheme can greatly reduce the amount of sewage towed into the drinking water source river when the ship sails into the upper reaches of the drinking water source river at the same boat speed, and when the speed of the boat is 6 knots, the amount of sewage drawn into the optimized drinking water source river by the boat passing through the drinking water source river is the least. It is recommended that combined with the total benefit of project investment selection, optimizing the boundary of the drinking water source river branch to reduce the amount of sewage towed into the drinking water source river; boats slow down before entering the upper reaches of the drinking water source river, which can effectively reduce the amount of sewage pulled by the boat into the drinking water source river.

  • ZUO Xiang, ZHAO Xing-xing, YE Rui-lu, CONG Xiao-fei, LIU Xiu-heng
    China Rural Water and Hydropower. 2023, (11): 10-18.
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    Model parameter calibration is an important way to improve the simulation effect of hydrological models. In order to solve the problems of low initial population quality, prematurity and poor local search ability of traditional genetic algorithm, this paper proposes an improved adaptive genetic algorithm (IAGA) to optimize the parameters of Xin?anjiang model. The Ergodic characteristics of chaos variables are used to randomly generate the initial population and select the best, so as to improve the individual quality of the initial population. Aiming at the evolutionary process of crossover and mutation, this paper designs the discrete coefficient of population objective function to reflect the degree of population dispersion. By using this coefficient, the adaptive adjustment crossover and mutation probability operators are constructed to prevent premature convergence of genetic algorithm. Based on the ring crossover operator, the global search ability of the algorithm is improved. The adaptive non-uniform mutation operator is used to optimize the local search ability of the algorithm in real time and avoid falling into local optimum. The IAGA algorithm, traditional genetic algorithm (GA) and adaptive genetic algorithm (AGA) are applied to the parameter calibration of the Xin′anjiang model in the Qinhuai River Basin, and the performances are compared from the aspects of convergence, time-consuming, stability and effect. The results show that the IAGA algorithm has more excellent optimization ability, better convergence results, higher stability and accuracy. The flood simulation results are better than the GA algorithm and the AGA algorithm. During the calibration period and the verification period, the deterministic coefficients are higher than 0.85, and Nash-Sutcliffe efficiency coefficient are higher than 0.8, which generally meets the second-level standard of hydrological forecasting. The results show that it is feasible to improve the traditional genetic algorithm by using the above comprehensive means, and the improved IAGA algorithm has a good application prospect, which provides an effective way for the automatic calibration of Xin′anjiang model.

  • WANG Jun, WANG Wen-chuan, QIU Lin, HU Xiao-xue
    China Rural Water and Hydropower. 2024, (2): 1-7.
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    A multi-strategy fusion improved Golden Jackal Optimization Algorithm (MGJO) is proposed to address the shortcomings of the Golden Jackal Optimization Algorithm in solving complex or high-dimensional optimization problems, such as being prone to local optima, slow convergence speed, and low computational accuracy. Firstly, by introducing a chaotic mapping strategy to initialize the population instead of random parameters, the algorithm can generate initial solutions with good diversity in the search space and avoid the initial population distribution deviating from the optimal value. Secondly, a nonlinear dynamic inertia weight is proposed to make the search process more realistic, effectively balancing the algorithm′s global and local search capabilities. Finally, the position update strategy of Cauchy mutation is introduced to fully utilize the guiding role of the optimal individual to improve population diversity, effectively exploring unknown regions and avoiding the algorithm falling into local optima. In order to verify the optimization accuracy, convergence performance, and stability of the improved Golden Jackal Optimization Algorithm, eight benchmark test functions with different features are selected for experiments. The results show that among the 8 benchmark test functions, the improved Golden Jackal Optimization Algorithm has achieved optimal results in terms of mean, standard deviation, and optimal value. In addition, the results of Wilcoxon’s sign rank test indicate that the improved Golden Jackal Optimization Algorithm is significantly superior in statistics. Through practical applications, it shows that the Golden Jackal Optimization Algorithm based on multi-strategy fusion improvement can effectively estimate the parameters of the Muskingum Model, and the optimization effect is significantly better than the particle swarm optimization algorithm, the sine cosine optimization algorithm, and the Golden Jackal Optimization Algorithm. This further verifies the effectiveness of multi-strategy fusion improvement and the superiority of the improved algorithm in parameter optimization. This provides an effective new method for more accurate estimation of the parameters of the nonlinear Muskingum Model.

  • ZHANG Xiao-lei, ZHU Yu, CUI Zhen-hua
    China Rural Water and Hydropower. 2023, (9): 146-152.
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    In order to study the river regime evolution of the braided reach in Lower Yellow River after the operation of the Xiaolangdi Reservoir, the Landsat satellite remote sensing images of the braided reach in Lower Yellow River during the past 20 years from 2001 to 2020 are selected, and the edge extraction algorithm is used based on ARCGIS and ENVI software to extract water edge and correct the normalized differences. The water body index method (MNDWI) is used to extract the water body and analyze the characteristic indicators such as the water surface width of the river channel during the flood season, the position of the mainstream after the flood season, and the number of central banks after the flood season. The results show that: ①After the operation of Xiaolangdi Reservoir, after 20 years of dredging adjustment, the river conditions in the braided reach in Lower Yellow River have been significantly improved during the flood season, and the mainstream has basically returned.②There is no obvious change in the river shape of this reach, and the width of the water surface increases and decreases with the amount of water during the flood season, and generally widens year by year. However, the width of the water surface of the Jiahetan-Gaocun section is relatively stable due to the control of the river channel improvement project. ③Using the MNDWI method to intelligently extract the water body, it is found that the swing of the mainstream presents three rules: ①The position of the mainstream is basically unchanged. ②Mainstream position moves in the same direction. ③ Mainstream locations are migratory. ④The number of the mid-channel beaches is negatively correlated with the water volume, generally decreasing year by year from 2001 to 2007, reaching a minimum of 13 in 2007, increasing year by year from 2007 to 2015, reaching a maximum of 58 in 2015, and decreasing year by year from 2015 to 2020, and at the same time, the location of the river-shaped abrupt change in the channel will also change. The adjustment of river regime will change the effectiveness of the river improvement project, and will also affect the production and life of the people in the beach area. Therefore, it is necessary to strengthen the monitoring of the river regime in the wandering section of the Lower Yellow River and pay enough attention to the changes of the heart beach to enhance the understanding of the law of river situation adjustment and the evolution of the heart beach in the Lower Yellow River.

  • WANG Xin, HU Tie-song, ZENG Xiang, LI Xiang
    China Rural Water and Hydropower. 2023, (12): 1-6.
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    Within the hierarchical decision structure of reservoir pre-impoundment operations, the parameter equifinality of hydropower generation leads to non-uniqueness of optimal solutions, i.e., the “ill-posedness” of solving reservoir operation optimization problems. Under such circumstances, the realization of operation benefits is affected by whether the reservoir operator selects the refill plan in favor of flood safety, implying that not only competitive relationship but also cooperative potential exists between flood control and water conservation. In light of this, a cooperation incentive (CI) model based on the lower-level satisfaction is developed to provide a mechanism to promote the water conservation department’s cooperation with the flood control department and enhance the reservoir operation benefit. Based on the framework of ill-posed bilevel programming, regarding the actual decision characteristics, the model described the nonlinear correlation between the cooperation willingness and the expected benefit of the water conservation department given certain flood control rule, so that the probability of selecting the refill plan in favor of flood safety can be derived. The CI model is solved by using multi-swarm evolutionary particle swarm optimization algorithms. Quantitative indicators are proposed to evaluate the Pareto efficiency loss and overall goal achievement of the reservoir operation optimization under cooperation. In the Three Gorges Reservoir pre-impoundment case study, the results are compared with those of the optimistic, pessimistic, and partial cooperation models. Results show that the CI mechanism motivates the benefit concession of the flood control department to increase hydropower generation and encourage the water conservation department’s choice in favor of flood safety. Further, the efficiency loss in operation decisions due to competitive gaming process can be more prominently reduced. Findings also indicate that nonlinear satisfaction-expected benefit relationship can better describe the practical decision making in reservoir operation.

  • WANG Han-hui, DING Gang, WANG Ji-liang, YANG You-kui
    China Rural Water and Hydropower. 2023, (5): 199-205.
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    Southwest China is rich in hydropower resources, but the extremely high and steep environmental slope in the dam site area has a height of hundreds of meters or even kilometers, and the slope is more than 50°~60°. The above hazard sources seriously threaten the construction and operation safety of hydropower projects, and are the key technical problems restricting the construction of hydropower projects. Focusing on the difficulties of investigation, prevention and control of ultra-high and steep environmental slopes, this paper carries out a systematic and in-depth research. Key technologies such as rapid and accurate investigation, systematic and efficient prevention and control and efficient integrated control have been developed and successfully applied in the prevention and control of ultra-high and steep environmental slopes of Wudongde Hydropower Station.

  • LI Wen-zhong, LIU Cheng-shuai, WU Qiang, HU Cai-hong, Xie Tian-ning, TIAN Lu
    China Rural Water and Hydropower. 2023, (11): 35-44.
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    Flood forecasting is one of the important non-engineering measures for flood control and disaster reduction in the middle reaches of the Yellow River. In this study, a GRU-Transformer flood forecasting model is constructed by coupling gated recurrent units (GRU) with Transformer machine learning models, and rainfall-runoff simulations are conducted to predict flood events in typical sub-basins of the middle reaches of the Yellow River. The predictive results are compared and analyzed with those of the ANN(Artificial Neural Network) and WOA-GRU(Whale Optimization Algorithm Gate Recurrent Unit) neural network flood forecasting models, with a focus on exploring how to better apply the Transformer model to the field of flood forecasting in order to improve the accuracy of flood forecasting in the middle reaches of the Yellow River. The model is established by using historical observed flood data from 1990 to 2016 in the Gu County Reservoir Controlled Basin. The input data includes rainfall data measured at 24 stations and discharge data at the outlet cross-section, while the output data includes flood events under different lead times. The model is calibrated by using 39 flood cases and validated using 10 flood cases. The results of the study show that the GRU-Transformer model has good applicability in flood forecasting, exhibiting higher predictive accuracy in the 1~6 hour lead time flood forecasting, with NSE values of greater than 0.85 in both calibration and validation periods. Its predictive accuracy is better than the WOA-GRU and ANN models under the same lead time, but decreases to a certain extent with increasing lead times. The GRU-Transformer model is more stable and better at predicting flood peaks, showing excellent performance in predicting small flow flood processes and simulating the recession phase of floods. However, it tendes to underestimate flood peaks with longer lead times. Compared with the WOA-GRU and ANN models, the GRU-Transformer model has better robustness, and its predictive accuracy decreases slowly as lead times increases. Hence, the GRU-Transformer model can be used as one of the better flood forecasting methods, providing new forecasting methods and scientific decision-making basis for flood prevention and control in the river basin.

  • MA Meng-yang, ZHAO Yong, WANG Qing-ming, LIU Rong, LI En-chong
    China Rural Water and Hydropower. 2023, (7): 55-62.
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    Influenced by climate change, human activities, and other factors, the Haihe River Basin (HRB) is one of the regions with the most severe water resources decline in China. To study the influencing factors of the evolution of water resources in the HRB, taking into account the changes in precipitation intensity levels within the year, based on meteorological observation data, the third water resources assessment and water resources bulletin in the HRB, this paper uses the linear slope, M-K trend test, and t-test to analyze the variation in the total amount of water resources, different levels of precipitation, and potential evapotranspiration in the HRB from 1956 to 2019. The M-K mutation test is used to analyze the abrupt change time of the total water resources in the HRB, and the partial least squares regression is used to analyze the quantitative contributions of meteorological factors and underlying surface changes on the variations in the total water resources before and after the abrupt change. The results show that: ① The total amount of water resources in the HRB decreased significantly at a rate of 3.048 billion m3/10 a, and an abrupt change occurred in 1980. Before and after the abrupt change, the total water resources decreased from 41.09 billion m3 to 29.90 billion m3. ② Before and after the mutation, light rain, moderate rain, heavy rain, torrential rain, and potential evapotranspiration decreased by 8.34, 6.69, 12.96, 21.17, and 19.1 mm, respectively. Among them, light rain, moderate rain, heavy rain, and potential evapotranspiration decreased non-significantly, but torrential rain decreased significantly. ③ Among the 11.19 billion m3 of the decline in total water resources, the contributions of light rain, moderate rain, heavy rain, heavy rain, potential evapotranspiration, and underlying surface were -800 million m3 (7%), -520 million m3 (5%), -1.60 billion m3 (14%), -3.47 billion m3 (30%), 120 million m3 (1%) and -4.91 billion m3 (43%), respectively. The reduction of torrential rainfall and the underlying surface changes were the main factors for the decrease in water resources in the HRB. The study serves as a scientific basis for formulating sustainable water resources development and utilization plan in the HRB.

  • GUO Jia-li, GUO Dong-hao, DING Guang-xu, LI Ying, LI Ying-hai, YANG Xu, ZHANG Hai-rong
    China Rural Water and Hydropower. 2023, (5): 72-78.
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    High-quality hydrometeorological observation data is the basic support for meteorological and hydrological disaster monitoring, forecasting and warning, and long-term climate change trend analysis. To solve the problem of low spatial resolution of existing integrated precipitation data at the watershed scale, this paper uses ensemble Kalman Filter (EnKF) fusion algorithm to merge precipitation data from 33 ground stations and TRMM and CMORPH satellite products at the daily scale in Qingjiang River Basin, yielding the 0.05°×0.05° fusion precipitation production of Qingjiang River Basin i.e., MSAP. The Leave-One-Out Cross-Validation method is used to quantitatively analyze the satellite precipitation data, ground interpolation data and MSAP fused precipitation data. It is proved that the EnKF fusion algorithm can improve the precision of precipitation in Qingjiang River Basin from three aspects: correlation coefficient R, mean absolute error MAE and root mean square error RMSE. In addition, the fusion algorithm overcame the shortcomings of low accuracy of satellite data and ground data in part of the watershed boundary area, which shows that the EnKF fusion algorithm has application potential in precipitation data fusion. Furthermore, MSAP is compared with CMFD, ERA5 and MSWEP reanalysis data, and the spatial distribution of heavy precipitation events corresponding to the two largest flood peaks in Qingjiang River Basin and Yangtze River during the flood season in 1998 is analyzed. The results also show that the MSAP data has the highest R and the smallest MAERMSE in terms of the time scale. In terms of the spatial distribution of errors, the spatial difference of accuracy evaluation index of MSAP data in each site is the smallest, and the order of accuracy of the four kinds of reanalysis data from high to low is MSAP > CMFD > MSWEP > ERA5. CMFD, MSWEP and MSAP can reflect the center of rainstorm to some extent in the process of 5-day and 2-day heavy precipitation events. In terms of spatial distribution and precipitation amount, MSAP and CMFD are basically consistent.

  • CAI Mu-liang, ZHI Huan-le, LI Wen-huan, HUANG He, LIU Xian, JIANG Shui-hua, ZHANG Xiu-ping
    China Rural Water and Hydropower. 2023, (7): 35-40.
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    At present, the flood inundation process analysis in a watershed under real-time rainfall cannot meet the needs of practical engineering application because of its complicated implementation procedure. Although the non-source inundation analysis method is highly popularized and is easy to implement, its actual physical significance is not strong. To this end, this paper aims at establishing a cellular automata-based flood inundation analysis model with the aid of real-time rainfall forecast and GIS technologies, in which the GIS technology is used to generate the raster data for digital elevation model. Then, the flood inundation area and water depth can be obtained according to the underlying surface conditions of the watershed. Finally, the Yuanzhou watershed in Yichun City, Jiangxi Province, is taken as a typical case for investigation, two kinds of rainfall losses, including vegetation interception and soil infiltration, are considered. The runoff coefficient is used to represent runoff loss process generated by rainfall. Then, the flood inundation data of Yuanzhou watershed at four different moments (10 minutes, 30 minutes, 1 hour and 2 hours) are evaluated by using the established cellular automata-based flood inundation analysis model. The results of the non-source inundation analysis method and MIKE SHE based-overland flow model are employed to validate the effectiveness of the established cellular automata-based flood inundation analysis model. The results indicate that the established model in this paper can well consider the influences of the underlying surface condition of the watershed and the rainfall production and confluence processes, and thus can simulate the flood inundation more reasonably and output the flood inundation data in real time, as compared with the non-source inundation analysis method and MIKE SHE based-overland flow model. The established cellular automata flood inundation analysis model has strong popularization and application prospects, clear practical physical meaning and simplified calculation process, and can accurately output the flood inundation process under a real-time rainfall event. The research outcomes can provide theoretical references for the risk assessment of flood disaster and the formulation of flood control and rescue decision plan under a heavy rainfall event.

  • BAI Meng-ting, LI Fa-wen, YANG Suo-lin, BAI Rui-zheng
    China Rural Water and Hydropower. 2023, (9): 1-8.
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    In the 1990s, the discipline of eco-hydrology was gradually derived. Eco-hydrology mainly studies the coupling mechanism and development law of ecological process and hydrological process. In recent years, water resources shortage, uneven spatial and temporal distribution of water resources, water waste, water pollution and other problems are prominent. It has become an urgent need for the rational allocation of water resources to master the distribution law of water resources with temporal and spatial changes, formulate ecological protection strategies suitable for sustainable development of local ecological environment, and establish watershed management and control mode and water resources development strategy based on water resources carrying capacity. To achieve the above requirements and objectives, eco-hydrological regionalization is the basis, and the objective of eco-hydrological regionalization is to provide a minimum management unit for analysis and evaluation under different ecological systems and hydrological characteristics. Eco-hydrological regionalization is mainly used to study the regional differentiation of eco-hydrological phenomena and reveal the regional distribution law of eco-hydrological phenomena. This paper focuses on the development of ecological regionalization, hydrological regionalization and eco-hydrological regionalization, the construction of ecohydrological regionalization index system, and the methods of eco-hydrological regionalization. The problems existing in the current research are discussed: foreign researches mainly focus on ecological regionalization or hydrological regionalization, but the regionalization considering the coupling relationship between ecology and hydrology is scarce. Although domestic researches on eco-hydrological regionalization have been carried out, they focus on traditional methods such as principal component analysis and clustering method, fixed time period analysis and large and medium spatial scale research. The future research direction and development trend are put forward: optimizing the evaluation index system, integrating multi-source data, improving the accuracy of regionalization method and monitoring the dynamic change of regionalization.

  • ZHENG Hao, HE Hua-xiang, LI Hai-ming, NIU Cun-wen, WANG Jia-hao, LI Xin-yang
    China Rural Water and Hydropower. 2023, (11): 69-78.
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    In order to dynamically analyze the impact of future land use change on the non-point source pollution load in the watershed,this study couples the PLUS land use prediction model with the SWAT non-point source pollution load model,so as to reveal the distribution of non-point source pollution in the watershed under different land use change scenarios.By taking the Dongjiang Lake Basin as the research area,this paper simulates and predicts the temporal and spatial evolution of non-point source pollution under different land use patterns in the historical series of the study area and in the following 2035 by building the SWAT non-point source pollution model and the PLUS land use model.The results show that the SWAT model has good applicability to the Dongjiang Lake Basin.The Nash–Sutcliffe efficiency index of the river runoff in regular and verification periods are 0.80 and 0.71. Meanwhile,the ammonia nitrogen and total phosphorus rates are higher than 0.5 in both periods.The temporal and spatial evolution characteristics,as well as changing trends,of non-point source pollution in the Dongjiang Lake Basin are studied by using long series simulation results.Non-point source pollution in the Dongjiang Lake Basin is affected by natural processes such as precipitation and runoff and land use patterns. From a time perspective,the pollution output load is concentrated during the high-water period with heavy precipitation. The inter-regional change reveals a trend of non-point source pollution first increasing and then decreasing; from the perspective of spatial scale,higher loads of ammonia nitrogen and total phosphorus are concentrated in the northwestern and central sub-basins with larger runoff and scattered farmland. The impact of different types of land use on non-point source pollution is studied in conjunction with the distribution pattern of land use and non-point source pollution.The contribution degree of total phosphorus load is cultivated land > construction land > grassland > forest land >unused. The land use pattern in 2035 is set by using the PLUS land use model under the historical trend scenario and territorial spatial planning, and the simulation and analysis of the response to non-point source pollution are completed on this basis.Under two different land use pattern scenarios,the territorial spatial planning scenario reduces ammonia nitrogen by 2.12 t and total phosphorus by 54.6 t compared with the historical trend scenario.The former scenario is more beneficial to control the non-point source pollution loads in the Dongjiang Lake Basin.The increase in pollution load is caused by the pollution of farmland, the rapid expansion of construction land and the reduction of forest land,and the restricted conversion of forest land and cultivated land plays an important role in reducing the pollution load of the watershed.

  • YANG Yan-mei, GAO Da-ming, ZHAO Jian, JI Yao, SU Jing
    China Rural Water and Hydropower. 2023, (5): 18-25.
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    Agricultural non-point source pollution has become one of the principle source of surface water pollution in China, and abundance of pollution control technologies spring up, aiming at prevention and control of agricultural non-point source pollution. Thus, how to select the technology with the highest comprehensive evaluation of environment, economy and society, is a decision problem. In this paper, an intuitionistic fuzzy-entropy weight-TOPSIS method is proposed by integrating intuitionistic fuzzy set theory and entropy weight method into Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS) framework, and applied to an evaluation case of agricultural non-point source pollution control technology. The method has the advantages on transforming qualitative evaluation language into quantitative intuitionistic fuzzy number and obtain objective weights for index, simultaneously. The practical technology assessment case is carried out as validation, based on the typical agricultural non-point source pollution control technologies developed by Major Science and Technology Program for Water Pollution Control and Treatment Ministry of Ecology and Environment. According to the characteristics of the technologies, an index system is established, including the indices that can represent environmental benefit, economic benefit and technical performance of the technologies, in order to provide an evaluation basis for the method. The result shows that, technologies with high comprehensive evaluation can be selected by the proposed method from the source reduction technologies, the process interception technologies, the end treatment technologies and the whole process control technologies, respectively. Among 12 technologies in the source reduction category, Rotation Farmland and Citrus Orchard in Reservoir D 4 gets the highest comprehensive evaluation, closely followed by Nitrogen and Phosphorus Reduction Technology Based on Slow and Controlled Release Fertilizer for Rice D 7 and Integrated Technology of Rice Fertilization and Transplanting D 8; Among 9 technologies in the process interception category, Compound Hedgerow Control Technology for Soil Nitrogen and Phosphorus Interception and Loss Control in Sloping Farmland D 21 gets the highest comprehensive evaluation, closely followed by Pollution Control Technology of Farmland Receding Water D 16 and Regulation Technology of Planting Structure and Fertilizer Structure on Sloping Land D 19; Among 4 technologies in the end treatment category, the Ditch-canal-pond system purification technology D 23 gets the highest comprehensive evaluation, closely followed by Collection and Re-reduction Technology of Non-point Source Pollution in Phosphorus-Rich Areas D 22 and Low-cost comprehensive disposal technology of farmland waste D 24; Among 9 technologies in the whole process control technologies category, the 4R Technology System of “Reduce-Retain-Reuse-Restore” D 29 gets the highest comprehensive evaluation, closely followed by Agricultural Pollution Control Technology Based on Soil Nutrient Reservoir Expansion D 32 and Large-area Contiguous and Multi-type Planting Mosaic of Farmland Non-point Source Pollution Control Technology D 28. Further, analysis on advantages and disadvantages of the technologies are carried out from aspects of environment, economy and technical performance, thus some improvement recommendation technologies are proposed. This study is a new attempt to apply the intuitionistic fuzzy-entropy weight-TOPSIS method to agricultural non-point source pollution technology evaluation, which demonstrates that the method can also be applied to a wide scope of technology evaluation in other fields.

  • AHATI•Ke-li-mu, ZENG Yu-jie, LIU De-di
    China Rural Water and Hydropower. 2023, (6): 21-26.
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    Water is the vital factor constraining the sustainable development in arid area. To alleviate water shortage due to increasing socioeconomic water demand in arid area, Yizhou District in Hami is taken as a case study to evaluate the balance between water demand and supply in the future. Water demand in 2021, 2030, and 2040 are selected as baseline, short-term planning, and long-term planning years, respectively, based on which rational water resources allocation is conducted. Results indicate that water demand in Yizhou District will increase remarkably due to rapid socioeconomic expansion, from 375.02 million m3 in 2021, to 397.17 and 487.56 million m3 in 2030 and 2040, respectively. Water resources allocation can effectively alleviate the water shortage led by the uneven temporal-spatial distribution of water availability. Water supply for socioeconomic users is thus ensured (the total water shortage rate in 2021 and 2030 are 2.78% and 4.2%, respectively), which is of significance for the local sustainability. However, as the over-increased water demand will exceed the regulating capacity of local water system in 2040, the total water shortage rate will considerably increase to 15.56%, among which the shortage rates of ecological, industrial, and agricultural users will be 8.37%, 9.98%, and 22.15%, respectively. The stability of the local ecosystem, and economy will be altered, which will further challenge the sustainable development goals of Yizhou District. This paper cannot only help the rational water resources allocation and water use structure improving in Yizhou District, but also contribute to the water resources management in arid areas.

  • GUO Shi-hao, YIN Shu-hua, JIANG Tong, LIU Lai-sheng
    China Rural Water and Hydropower. 2023, (6): 57-65.
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    Taking the Ningxia Yinchuan metropolitan area urban-rural east water supply project and its water supply range as the research object, this paper establishes a multi-objective mathematical optimal allocation model of water resources, economy and environment and solves the multi-objective problem by the non-dominated sorting genetic algorithm-II(NSGA-II). The hypervolume (HV) index is used to evaluate the convergence and distribution of the Pareto solution set obtained at different iterations. Considering the computing time, convergence and distribution, the Pareto solution set obtained at 700 iterations is determined as the basis for subsequent data analysis and calculation. By calculating the fuzzy membership degree of each target value in the scheme set and analyzing the pairwise relationship between each target, it is found that there is a negative correlation between water resources objectives and economic objectives, as well as economic objectives and environmental objectives, and a positive correlation between water resources objectives and environmental objectives. Then, the weight of each objective is determined as (0.48, 0.32, 0.2) by using the method of two elements contrasting. The multi-objective fuzzy optimization model is used to screen the Pareto solution set, and the scheme with the largest superior genus degree (ui =0.757) is determined as the optimal scheme. Under the optimal scheme, the groundwater consumption is 9 932.9 thousand m3, the surface water consumption is 64 569.0 thousand m3, the economic target is 40.745 billion yuan, and the environmental target is 1 040.9 thousand kg. This scheme can realize the optimal allocation of water resources and provide a reference for regional decision makers in water resources allocation.

  • WANG Xue-chun, SONG Lan-lan, ZHANG Qi-cheng, LI Shi-jun
    China Rural Water and Hydropower. 2023, (11): 105-111.
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    Ponds are essential elements of both natural landscapes and urban environments, serving as green infrastructures and playing a vital role in contemporary water conservation planning. They provide a wide range of ecosystem services that contribute to the overall health and sustainability of the environment. These services include flood regulation, nutrient retention, mitigation of the urban heat island effect, as well as supporting fish production and aquaculture. Evaluating the significance of ponds by examining their characteristics, determining their priority level for governance and protection, and proposing utilization strategies based on their importance levels are crucial steps in understanding and optimizing their ecological service functions. These efforts form the foundation for effective governance and protection of ponds and ensure their continued contribution to the land ecosystem’s service function and overall effectiveness. By analyzing the land use status of Liaocheng City, an assessment is conducted to understand the characteristics and spatial distribution of pits and ponds. Subsequently, an evaluation index system is developed to determine the importance of these pits and ponds in the region. This comprehensive analysis provides valuable insights into the significance of these water bodies and their role in the local ecosystem. It is found that the distance from the main rivers/lakes and reservoirs is conducive to the migration of Amphibian. The number and area of ponds around cultivated land are much larger than other types of land use. The number of ponds in each district and county decreases according to cultivated land, forest land, rural residential land, and urban residential land. The density of pits and ponds is 3~10 /km2, and the main gathering centers are in the northeast of Dongchangfu District, the middle of Dong’e County and the northeast of Gaotang County.The density and importance of ponds show a trend of high in the north and low in the south, and high in the east and low in the west. To make the most of ponds with high importance scores, this paper recommends strategically utilizing them based on their specific morphology and spatial distribution. This may involve implementing measures such as maintaining their natural features, protecting the surrounding vegetation, and ensuring proper water management practices. On the other hand, for ponds with low importance scores, an ecological reclamation approach can be pursued in conjunction with local land comprehensive improvement plans. By implementing these strategies, Liaocheng City can effectively utilize and protect its pit and pond resources. This will contribute to the preservation of the land ecosystem’s service functions and enhance the overall ecological well-being of the region.

  • HU Zhi-dan, ZHU Chun-zi, TIAN Dan, TAO Si-ming
    China Rural Water and Hydropower. 2023, (8): 41-45.
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    In 2022, the Pearl River Basin underwent extensive, severe and protracted rainstorms and floods. This study investigates the causes of this event, compares it with historical floods, and exemplifies the patterns of rainstorms and floods in the Pearl River Basin. To this end this study first presents the meteorological context and precipitation events leading to the flood. It then examines the flooding process, flood composition, the impact of water conservancy projects and comparisons with past rainstorms and floods. The results reveal that cumulative rainfall in the Pearl River Basin from late May to early July in 2022 was 50% higher than a normal year, with the Beijiang and Hanjiang River Basins experiencing the highest levels since 1961. The Pearl River Basin endured two major floods and eight numbered floods due to persistent heavy rainfall, with the Beijiang River encountering the largest flood since 1915. Flood composition analysis using national flood forecasting system of China shows that the primary inflow for the Xijiang River originates from the Hongshui River, Liujiang River, Yujiang River and Guijiang Rivers, with different flood volume proportions for each flood. The Beijiang River’s primary flood comes from the Lianjiang River, followed by the interval flow, while the Hanjiang River’s main flood arises from the Meijiang and Ting Rivers. In comparison with the 2005 and 2008 rainstorms and floods, the 2022 rainstorm duration was longer and had more floods. Moreover, the flood magnitude of the Beijiang River in 2022 was a heavy flood, which was more severe than that in 2005 and 2008, while the flood magnitude of the Xijiang River was less severe. The coordinated operation of flood control projects in the basin achieved significant flood control benefits, during this flooding process, preventing the simultaneous occurrence of severe floods in the Xijiang and Beijiang Rivers, and effectively ensuring the flood control safety in crucial areas.

  • DUAN Wen-hua, LYU Yan-chun, ZHENG Yang, LV Yi-jing, CHEN Qi-juan, YAO Chen
    China Rural Water and Hydropower. 2023, (5): 206-211.
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    To improve the dynamic quality of hydropower units during the startup process, this paper proposes a multi-objective optimization method based on nonlinear model of hydropower turbine governing system ( HTGS). A nonlinear model of the governing system is established in order to accurately describe the hydraulic and mechanical dynamic characteristics of the system. When the optimization targets are selected, the suppression of hydraulic pressure fluctuation and mechanical vibration is also considered comprehensively in addition to the requirement of fast and stable speed rise, so three objectives are selected: absolute value integral of relative error of speed, absolute value integral of relative error of water pressure at the inlet of voluteand relative value of maximum axial water thrust. Then the multi-objective particle swarm optimization (MOPSO) algorithm is used to optimize the opening law of the guide vane, and Pareto optimal solution sets are obtained, four solutions are selected in a weighted way for simulation experiment. The results show that the multi-objective optimization method can effectively suppress hydraulic pressure fluctuation and mechanical vibration while ensuring the steady rise of rotational speed, and achieve good control quality, it can provide decision-making support for the safe and stable operation of hydropower units.

  • CHEN Meng, CHEN Hua, HUANG Gui-ping, WANG Heng-sheng, WANG Xiao-sheng, GAO Ya-fen, XIANG Wu-lin, LIU Bing-yi, WANG Jun
    China Rural Water and Hydropower. 2023, (5): 106-110.
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    The construction of intelligent water conservancy in the new era puts forward higher requirements for the simplicity, accuracy and continuity of flow measurement, and the traditional contact flow measurement method is gradually unable to meet the needs. In order to make full use of the advantages of modern video image recognition and artificial intelligence technology, so as to provide a new solution to river flow measurement, this paper takes the video non-contact flow measurement method as the research object, studies and establishes a video flow measurement calculation method based on space-time image velocimetry (STIV), selects Qilijie Hydrological Station in Jianxi Basin of Minjiang River in Fujian Province as a demonstration application station for flow comparison test, and evaluates the accuracy and error analysis of the test results. The results show that the effect of establishing the velocity and discharge correlation of Qilijie Hydrological Station by means of the univariate linear alignment of water level segmentation is good. The actual effective comparison water level range is 89.41~100.43 m, the flow range is 69.31~9 122.57 m3/s, the maximum systematic error of the correlation line is 0.11%, the maximum uncertainty of the random machine is 7.80%, and the relative error is within ± 8%. Compared with the comparison results, the accuracy of various indicators meets the specification requirements, The water level discharge relation curve thus obtained can be used as the flow pushing scheme of Qilijie Hydrological Station. As a new non-contact instrument method, video flow measurement method has the advantages of fast measurement, safety and efficiency, full range monitoring, less affected by extreme conditions, low cost, high accuracy of flow measurement results, good safety, wide range of flow measurement, feasibility and strong potential for practical testing work, which can effectively improve the efficiency of flow measurement, reduce the intensity of field labor, and save human and material resources. The in-depth research, development and application of it can further promote the modernization and intelligent construction of hydrometry in China.

  • SHAO Xin-xin, LEI Guo-qing, ZENG Wen-zhi, HUANG Jie-sheng
    China Rural Water and Hydropower. 2023, (6): 168-174.
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    Stomatal conductance is an important indicator of plant transpiration, and accurate quantification of stomatal conductance is significant for the study of the surface hydrological cycle. To improve the accuracy of stomatal conductance simulations, this paper uses two machine learning models, CatBoost (CAT) and Artificial Neural Network (ANN), and a dataset consisting of Pinus edulis and Juniperus monosperma, to simulate stomatal conductance, and the simulation results are compared with the Ball-Berry model and Medlyn model. The input variables of net photosynthetic rate (An ), leaf surface carbon dioxide concentration (Cs ), relative humidity (RH), saturated vapor pressure difference (VPD), leaf temperature (TL), and predawn leaf water potential (LWP) are designed as three modeling strategies in machine learning models. The input variables in strategy ①are An, Cs and RH; in Strategy ②are An, Cs, and VPD; in Strategy ③are An, Cs, RH, VPD, TL, and LWP. The results show that ① Ball-Berry model and Medlyn model have similar simulation effects, with RMSE of 0.013 8 and 0.013 9 mol/(m2·s), respectively. ② Compared with the Ball-Berry model and Medlyn model, the RMSE of the CAT model and ANN model under different input strategies decrease by 19.35%~45.65% and 26.90%~55.07%, respectively. ③ In the machine learning models, the simulation effect of strategy ③ is better than strategy ① and ②, and ANN is better than CAT. In strategy ③, the RMSE of the ANN model is 36.70% and 38.54% higher than that of strategy ① and ②, respectively.④ Stomatal conductance simulations for the entire dataset consisting of both plants under each model and strategy are consistent with the simulated patterns of stomatal conductance for Pinus edulis and Juniperus monosperma, respectively, with better results for Pinus edulis and then for Juniperus monosperma. These results indicate that the machine learning model (ANN model in particular) is more suitable for accurate simulation of the stomatal conductance of plants, and can provide a practical tool for estimating plant transpiration capacity and simulating agricultural hydrology.

  • LI Ning-ning, ZHAO Bi-kui, CHENG Tao, LIU Xia, TAN Chao, LIAO Hua-ming, LIN Hao-wei
    China Rural Water and Hydropower. 2023, (11): 19-26.
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    In recent years, uncommonly severe droughts have attacked many places in Guangdong Province, with long duration, wide impact and serious consequences, which is contrary to people’s general understanding of the water-rich areas in the south. In order to find out the causes, influencing factors and characteristics of drought in Guangdong Province, and effectively identify the weaknesses in drought disaster prevention and control, taking the typical drought-prone counties in Guangdong Province-Chaonan District in eastern Guangdong and Xuwen County in western Guangdong Province as examples, based on the natural disaster risk theory, this paper establishes a drought disaster risk assessment zoning model, which couples the three elements of hazard, vulnerability and defense, and the evaluation index system and calculation method of comprehensive risk index are put forward. The index weight is determined by analytic hierarchy process. The natural breakpoint method is used to scientifically divide the regionalization, and the risk matrix method is introduced to aggregate the drought risk and drought defense and disaster reduction ability to represent the level of drought disaster prevention and control, and the risk influencing factors and risk levels of drought disaster are qualitatively and quantitatively evaluated. The results show that, under the main influence of less natural rainfall and large demand for economic and social water, the comprehensive risk of drought disaster in Chaonan increase from west to east, most towns and streets have moderate drought risks, while the whole area of Xuwen has medium-high and above drought risks, the comprehensive risk of drought disaster in western and central areas is high. If the water supply engineering capacity, river system density and drought-defense investment level are not high, it can be determined that most towns and streets in Chaonan are medium prevention areas, and most towns and villages in Xuwen are key prevention areas. The rationality of the results is verified by typical historical drought events, and some measures and suggestions are put forward for the weaknesses of drought defense in drought-prone counties. The research results can provide technical support for improving the drought-defense and disaster reduction system in typical drought-prone counties in Guangdong Province.

  • SUN Xue-lan, ZHANG Chao-yu, BAI Yu-chun, DUAN Jing-jing, JI Zi-qing
    China Rural Water and Hydropower. 2023, (6): 95-100.
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    In order to explore the effect of vegetation on the hydraulic characteristics of naturally curved rivers, this paper designs two layout forms of uniform and cluster to simulate artificial regular planting and natural cluster vegetation groups respectively. Through continuous bending flume experiment, the paper comparatively analyzes the influence of different layouts on flow field, hydrodynamic axis and turbulent kinetic energy distribution. The results show that: ①There are obvious velocity zones in the flow field of the continuous curved channel : the high velocity zone is close to the convex bank, and the low velocity zone is distributed near the concave bank. Compared with the surface flow, the distribution range of the high velocity zone of the bottom flow is expanded, and the low velocity zone is reduced. The distribution range of high velocity area increases and that of low velocity area decreases greatly after vegetation distribution, and the influence of cluster layout is obviously greater than that of uniform layout. ②The hydrodynamic axis of the continuous curved channel flow deviates from the normal position, which shows the dynamic change process of closing to the convex bank firstly and then leaving the convex bank. Vegetation layout greatly delays the process, and the delay degree of cluster layout is greater than that of uniform layout. ③The turbulent kinetic energy distribution along the continuous curved channel flow is uneven, and the maximum value appears near the top of the bend. From the numerical changes of turbulent kinetic energy, it can be seen that the vegetation layout makes the turbulent kinetic energy of the water flow generally increase, and the influence of cluster layout is greater than that of uniform layout.

  • BAI Jia-qi, ZHANG Zhao, CHEN Ming-rui, XUE Ping, LEI Xiao-hui, SANG Guo-qing
    China Rural Water and Hydropower. 2023, (7): 153-159.
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    In large-scale inter-basin open channel water transfer projects, all kinds of water conveyance elements are connected with each other, and their flow characteristics are different, an analysis of the hydraulic response characteristics of the ditch basin is of great significance for the safe and stable operation of the project. By constructing one-dimensional hydrodynamic model and taking safety regulation as guidance, the feasible time domain of safety regulation is analyzed. In order to avoid the occurrence of water level exceeding the limit, the earliest and the latest regulating time of the buildings that do not exceed the upper and lower limits of the water level of the canal pool are calculated, taking the upper and lower reaches of the pumping station in the river mouth of the Yangtze-Huaihe River Diversion Project as an example, the study is carried out. During the study, due to the selection of channel segment, the earliest regulation time was 0 h, so the latest regulation time is analyzed. The results show that: ① when the initial upstream flow and downstream water level remain unchanged, the latest regulation time decreases with the increase in the target flow and flow variation in a power function relationship ② When the initial upstream flow is the same and the flow variation is different, the latest regulation time gradually decreases with the increase in the downstream water level, and the decrease trend of the latest regulation time becomes gentler with the increase in flow variation; ③ The latest regulation time has the strongest correlation with the flow variation, but has a poor correlation with the upstream initial flow. Finally, based on the calculation results of feasible region of safety regulation time, a fast generation formula of the latest regulation time is constructed.

  • YE Chang-liang, YAN Hong-ye-yu, AN Dong-sen, LI Huai-cheng, ZHENG Yuan
    China Rural Water and Hydropower. 2023, (11): 196-201.
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    In order to explore the influence of the staggered impeller on the pressure fluctuation characteristics of the double entry two-stage double suction centrifugal pump, this paper uses the method of combining experiment and numerical simulation to carry out a research on the same pump with symmetrical impeller and staggered impeller as the contrast scheme, and quantifies the pressure pulsation characteristics of the suction chamber, inter-stage flow channel and volute under three typical working conditions of 0.6Q, 1.0Q and 1.2Q. The results show that: ① in terms of external characteristics, the head and efficiency of the pump with staggered impeller are higher than those with symmetrical impeller at all working conditions, and they can be 2% and 3% higher than those at 1.0Q working condition. ② In terms of pressure pulsation characteristics, for the suction chamber, the influence of staggered impellers on pressure pulsation is small at all working conditions, and the difference of dominant frequency amplitude is less than 2%. For the inter-stage flow channel, the staggered impeller can restrain the pressure fluctuation at all working conditions. For example, the dominant frequency amplitude at the tongue of the inter-stage flow channel can be reduced by 13.5% compared with that of the symmetrical impeller. For the volute, the staggered impeller can improve the pressure fluctuation under all working conditions. For example, the dominant frequency amplitude at the tongue of the volute can be reduced by 31.9% at most. This finding can provide a reference for the application of staggered impeller in double inlet two-stage double suction centrifugal pump.

  • LIN Xing-yu, CAI Tun, YANG Ke-jun
    China Rural Water and Hydropower. 2023, (10): 1-8.
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    Riverbed roughness is an important aspect of river dynamics research, and its quantitative measurement has always been challenging. In this experiment, regardless of the macroscopic undulation of the riverbed, we laid the initial bed surface in a straight channel with non-uniform natural sand and thickened it by gradually increasing the flow rate of water. Laser scanning technology was used to obtain high-resolution bed elevation data after each bed roughening. Statistical theory and variogram function were used to investigate the surface roughness characteristics of riverbeds with varying degrees of coarseness, and to deepen the understanding of their statistical characteristics. The study's main finding is that artificially laid non-uniform sand presents an elevation frequency distribution that approximates a normal distribution. On the contrary, the frequency distribution of the stable rough bed surface formed by the continuous cumulative erosion of different flow intensities shows a slight positive deviation trend. The study found evidence that the increase of flow intensity leads strictly to an associated elevation standard deviation increase. This finding indicates that elevation standard deviation can be used as a reliable indicator to measure the characteristics of riverbed roughness in future studies. The study revealed that the kurtosis of the bed elevation data precisely decreased monotonically with the flow intensity, and that skewness and kurtosis showed a monotonic trend, indicating that they can be used to measure bed roughness. Additionally, the study found that the flow forming the bed surface is anisotropic, and as flow intensity increases, the rough layer breaks and becomes rougher again. This leads to an increase in the base value of the two-dimensional bed elevation variogram. Therefore, the study suggests that the base value of the two-dimensional variogram could serve as another reliable index for evaluating bed surface roughness. In addition, due to the influence of water flow, although the change trend of the characteristic parameters of the average variogram along the flow direction, vertical flow direction and radial profile elevation is consistent, the average variogram base value and golden point value of the transverse section are slightly larger than those of the transverse and longitudinal sections. Conversely, in the radial section, the abutment value and nugget value are considerably smaller than the values in transverse and longitudinal sections. In conclusion, this study enhances our understanding of the characteristics of bed roughness and provides crucial insights into statistical expressions for quantifying it.

  • GE Xin-feng, MENG Han, SUN Jie, HE Tao, HUANG Jin-wei, WANG Jian-ming
    China Rural Water and Hydropower. 2023, (7): 229-235.
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    The existence of cavitation is very unfavorable to the operation of the turbine, which will not only reduce the output and efficiency of the turbine, destroy the overcurrent parts of the turbine, but also lead to the unsafe and unstable operation in serious cases. Accurate identification of the cavitation position helps to prevent cavitation damage. This paper uses the VOF multiphase flow model and SST k- ωturbulence model to simulate the Schnerr-Sauer cavitation model. Through an analysis of the distribution rules of the velocity field and pressure field of the gas phase are obtained. The main conclusions are as follows: When the fluid flows through the contraction pipe section, the speed increases rapidly, and the absolute pressure at the outlet of the nozzle drops rapidly to the saturated steam pressure needed to form cavitation, which creates conditions for cavitation. There is a speed attenuation in the center of the injection needle, and a low pressure zone in the nozzle exit and the tip area of the injection needle. The gas phase is mainly distributed at the outlet position of the nozzle. Under the opening of 20% and 80%, the gas phase is symmetrically distributed in the injection outlet torus, but not fully covered, the gasification area corresponds to the position of the anterior fluid diversion area, and the opening of 40% and 60% evenly covers the nozzle outlet. The maximum gas phase generation rate and gas distribution along the axial direction under different injection needle opening degrees first increase and then decrease with the opening degrees. The water vapor content at 40% opening degree is the most, and the cavitation range at 40% opening degree is the largest

  • MA Qin-zhen, SONG Hui, ZHU Jin-rui, ZHANG Huan, LI Zhan-yong, LI Qi-fei
    China Rural Water and Hydropower. 2023, (11): 174-181.
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    With the guide vane of the pump-turbine as the main research object, the guide vane opening of 11, 33 and 41 mm is selected to analyze the influence of different guide vane airfoils on runaway characteristics of pump-turbine, so as to provide methods and theoretical guidance for the design and optimization of guide vane airfoil of pump-turbine. The results show that the improved guide vane airfoil has a better improvement effect on the "S" characteristics of the unit under three kinds of guide vane openings. After the improvement of the guide vane airfoil, the internal flow state of the unit is improved on runaway characteristics. The velocity streamlines in the guide vane and runner area are evenly distributed, and the concentrated distribution area of vortex core is reduced. After the improvement of guide vane airfoil, the relative value of pressure pulsation amplitude of monitoring points in vaneless area at different openings decreases in different degrees, and the velocity pulsation curve is gentle and the velocity peak value is smaller than before the improvement. The concentrated distribution area of vortex core in the draft tube of the improved guide vane airfoil is reduced, and the unit can operate in a relatively stable state.

  • WANG Zhao, ZHANG Run-run, ZHANG Yang
    China Rural Water and Hydropower. 2023, (11): 52-63.
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    Evapotranspiration is a key factor in hydrological and energy cycles, and its spatio-temporal evolution is influenced by various complex factors such as watershed climate, energy, and underlying surface. The influencing factors of evapotranspiration in different climate regions have spatio-temporal differences and different sensitivity characteristics. Studying the spatio-temporal changes in evapotranspiration is beneficial for revealing the response characteristics of hydrological cycles in complex environments, further deepening people’s understanding of water balance in watersheds, and providing theoretical reference for the rational planning and utilization of water resources in watersheds. Based on the SWH dual source evapotranspiration model, the evapotranspiration and its components of the Poyang Lake Basin from 2001 to 2017 are simulated. On the basis of multi-temporal and spatial scale validation, the spatial-temporal evolution characteristics of the total evapotranspiration (ET), soil evaporation (Es), plant transpiration (Ec) and evaporation ratio (Es/ET) of the basin are analyzed. Based on the SOBOL sensitivity analysis method, the sensitive influencing factors and actual change causes of the evapotranspiration components of the basin are explored. The results show that the correlation coefficients between the simulated and measured values of the SWH model at the 8-day scale are 0.92 and 0.89 at the station and watershed, respectively, indicating good simulation results. At the 0.05 significance level, the annual ET in the Poyang Lake Basin does not decrease significantly at the rate of 1.0 mm/a, Es decreases significantly at the rate of 2.6 mm/a, Ec does not increase significantly at the rate of 1.7 mm/a, and Es/ET decreases significantly at the rate of 0.28%/a. The spatial distribution characteristics of Es/ET in the basin are high in the middle and low around, with Es/ET in winter>spring>autumn>summer. Except for summer, Es/ET shows a significant downward trend, mainly concentrated in the southern plain of the lake area and the Xinjiang River basin, accounting for 33.86% of the total basin area. Temperature and wind speed are the main sensitive factors affecting changes in ET and Es in the watershed, followed by precipitation and net radiation. Es is also more sensitive to NDVI. The main sensitive factor for Ec and Es/ET at both annual and seasonal scales is the NDVI, and the significant increase in NDVI is the main reason for the changes in Ec and Es/ET in the watershed.

  • YAN Xin, CHEN Hua, SHANG Zhi-hong, WANG Jin-xing
    China Rural Water and Hydropower. 2023, (6): 36-46.
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    Precipitation is the basic component of the earth water cycle. As a water flux, it connects the atmospheric process with the surface process, and has important significance in meteorology, climatology and hydrology. Due to the strong temporal and spatial variability of precipitation, it is one of the most difficult hydrological variables to measure accurately at present. Accurate precipitation data with high temporal and spatial resolution is very important for many applications such as hydrological and meteorological analysis. This paper takes Hanjiang River Basin as the research area and puts forward a two-step downscaling-merging method. By using the complementary characteristics of data availability and accuracy of precipitation observed by rainfall gauges and retrieved by satellites, a high-quality daily precipitation product with a spatial resolution of 0.01 can be generated by fusing gauge observations and GPM satellite precipitation products. The obtained fused precipitation product is driven by semi-distributed hydrological model WASMOD-D to simulate the rainfall-runoff process, and its runoff simulation effect is verified. The results show that: ① The downscaling algorithm based on random forest model not only significantly improves the spatial resolution of GPM precipitation, but also maintains good accuracy. ②The linear fusion model of precipitation data based on the co-Kriging method, the fusion scheme greatly improves the estimation accuracy of GPM precipitation, with the average absolute error and root mean square error reduced by 32.38% and 21.38% respectively, and the bias dropped below 1%; ③ Considering the simulation results of daily runoff under two different scenarios, the overall simulation effect of integrating precipitation data is the best because of combining the advantages of satellite precipitation data and gauge observations, and the overall improvement effect is obvious. This paper provides a new idea for the data fusion method based on Satellite-Gauge(S-G),and the research results can be used as a reference for obtaining high-resolution and high-precision precipitation data.

  • HE Cheng-ming, ZHANG Gen-guang, XU Xiao-yang
    China Rural Water and Hydropower. 2023, (7): 82-86.
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    Flow resistance is of great significance to the study of flow structure, bedload movement and transport rate. The factors affecting the flow resistance include bed sediment gradation, flow condition, bed surface structure and bedload transport rate. Considering a synthesis of bed surface sediment condition, flow condition and bedload transport, the flow resistance of flat and non-uniform bed surface is divided into grain resistance and bedload transport resistance. Based on the variation of the bedload transport rate on the process of bed surface coarsening, the degree coefficient of bed surface coarsening is expressed as a function of the relative transport rate. Combined with resistance formula of uniform bed surface and non-uniform bed surface which has coarsened completely, this paper establishes the grain resistance formula of bed surface including the structural parameters. Based on the difference of mechanical characteristics of rolling and saltation bedload, the forces of rolling bedload on the bed surface are analyzed, and the energy consumption of rolling bedload carried by water is obtained, and compared with the calculation formula which is established by bagnold. The bedload transport resistance formula is established by combining the proportion of rolling and saltation bedload under different flow strengths. The coarsening coefficient of bed surface is determined from the measured coarsening surface data, and finally the calculating formula for flow resistance of the flat and non-uniform bed surface with bedload transportation is established. Verified by the measured data and compared with other scholars’ resistance calculation formulae, the root mean square relative error (RMSRE) of the formula is only 0.094, which is less than that of other scholars, indicating that the resistance calculation formula is highly accurate.

  • XU Zhong-wu, CAI Wei, ZHOU Jian-fang
    China Rural Water and Hydropower. 2023, (8): 222-228.
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    To improve the scientificity and normalization of structural linear analysis of plane steel gate via ANSYS software, some problems are deeply discussed from grid division and leakage hole simplification on the basis of the intake emergency gate of a hydropower station. The results show that: ① the element type shell281 is preferred for spatial thin-walled structures, such as plane steel gates, due to its higher accuracy of stress; ② the size of the mesh has little effect on the deflection, but a reasonable mesh size can make the finite element calculation results of stress independent of the mesh size and reduce the calculation amount; ③ compared with free partition, mapping partition will provide higher grid quality, but it also brings in a large amount of work without obviously improving of calculation accuracy of stress and deflection; ④ leakage hole can be simplified and ignored in establishing the plane steel gate model if the ratio between hole diameter and beam height of plane steel gate is less than or equal to 0.15 and vice versa.

  • LIN Guang-hong, ZHU Bi-ying, CHEN Jie, QIU Yuan-lin, LIU Jian-hua, CHEN Hua
    China Rural Water and Hydropower. 2023, (6): 47-56.
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    Monthly precipitation prediction is crucial for water resources allocation, planning and management. However, the prediction is influenced by various factors, thus it is extreamly difficult and uncertain. To investigate the performance of monthly precipitation predictions based on climate models in China and the influence of bias correction methods, this paper selects China’s mainland as the research area, adopts 1981 to 2014 as the research period, and evaluates the predictive capability of nine climate models (CFSv2, SEAS5, CanSips, GEMNEMO, CCSM4, GFDL, CanCM3, CanCM4, GEOSS2S) for monthly precipitation prediction in different forecasting periods. Clustering analysis is adopted to analyze the patterns of prediction ability of climate models with forecasting period. The linear scaling (LS) and quantile mapping (QM) bias correction methods are used for the post-processing of the predicted precipitation, and the effects of the two methods are compared in validation (2008 to 2014). The results show that the accuracy of precipitation prediction varies among climate models, and the capability to summer precipitation prediction depends on the forecasting periods and forecast regions. The SEAS5 climate model performs optimal in different regions and forecasting periods, and its forecasting capability stabilized with the extension of forecasting period. In terms of bias correction, the bias correction methods can significantly improve the prediction ability of precipitation for all of the climate models and the two methods exhibited similar performs, however, the mean absolute relative error of LS method is less than 50%, which indicates that the LS method is generally slightly outperforms QM method. In addition, the SEAS5 climate model still performs best after bias corrections. This paper reveals the superiority of the SEAS5 climate model for monthly precipitation prediction in China’s mainland and the enhancement of the prediction capability of climate models by the bias correction methods. This study provides a reference for the application of precipitation predictions based on climate models.