Subsurface infiltrating irrigation is a kind of underground micro-irrigation method. The irrigation water is diverted to the soil at a certain depth under the ground through the buried pipe for subsurface infiltrating irrigation，and then the soil capillary action is used to achieve direct water supply to the root zone of crops. This irrigation method is essentially the same as the irrigation process of “Subsurface Drip Irrigation”. Subsurface infiltrating irrigation can effectively improve soil environmental quality and facilitate crop growth， and it is a highly efficient and water-saving irrigation technology with broad development prospects. It is of great significance to research on subsurface drip irrigation for promoting the development of efficient water-saving agriculture. In this paper， the relevant research progress and existing problems are reviewed from the aspects of soil water transport rule， irrigation technology parameters， irrigation system， influence and regulation of infiltration irrigation pipe clogging etc.， and the future research directions are proposed，which may be referred to by scholars in the field of water-saving irrigation research. It is concluded from this review that， compared with the production practice of subsurface infiltrating irrigation， the research on its mechanism is relatively lagging behind， which limits the deep popularization and application of this technology. The main manifestations are as follows： the law of soil water transport under subsurface infiltration irrigation is not clear enough， clogging is still the limiting factor that hinders the application and development of subsurface infiltration irrigation technology， the optimization design of subsurface infiltration irrigation water distribution system needs further research. This paper suggests carrying out a numerical simulation analysis of water infiltration under different irrigation conditions in the future， selecting the appropriate treatment level， studying the main factors affecting the effect of infiltration irrigation， and seeking the optimal combination of irrigation technology parameters. Research on crop irrigation system under the condition of subsurface infiltration irrigation is carried out to form a set of reasonable and perfect irrigation system and test method. Further research should be carried out on the rule of subsurface infiltration irrigation pipe outflow， clogging mechanism and the effective control threshold of key parameters of irrigation water quality when entering the subsurface infiltration irrigation system.

Green and sustainable development of irrigated agriculture and protection of agricultural biodiversity are the inevitable requirements for the construction of modern irrigated districts in China. However， in order to ensure the efficient utilization of irrigation water， the construction of irrigation channels has been dominated by hard engineering， which has caused the loss and fragmentation of amphibian habitat， and the damage for ecological environment of the irrigation districts. The construction of amphibian corridors in irrigation channels is an important way to improve the connectivity of agricultural landscape and the migration efficiency of frogs in farmland. This paper innovatively applies the hydraulic characteristics of curved channels to the research on ecological channels， builds the curved irrigation channel models， conducts numerical simulation experiment， analyzes the trajectory of frogs at the curved irrigation channels， proposes the design of engineered modifications to allow frogs to escape from field concrete ditches. To evaluate the effects of engineered modification on the effectiveness of frog-ways and the water transfer efficiency of irrigation channels， the paper compares the water flow pattern and calculates the head loss. By carrying out numerical simulation tests， the paper obtains the flow movement law of the concrete-lined irrigation channels with different bend angles， and the flow dynamic axis and velocity distribution are compared. As a result， the slow flow zone and the transverse circulation are found. The locations suitable for amphibian corridors to be built vary when the curvature of the curve changes. The numerical simulation and head loss calculation results show that the amphibian corridors in the bend has no obvious influence on flow pattern and water transfer efficiency， and the head loss in bend is about 3.83×10^-4 m， which can ensure the safe and unobstructed water flow. This study is expected to provide a scientific reference and technical support for the ecological reconstruction of end irrigation channel systems.

Based on BP neural network and higher-order moment method， combined with measured data， a time-varying reliability analysis method for the bending resistance of reinforced concrete aqueduct side walls is proposed. In order to evaluate the bending time-varying reliability of aqueduct side walls under the influence of steel corrosion， this paper considers the effective cross-sectional area loss effect of steel bars in concrete structures， and derives the bending time-varying performance function under the limit state of bearing capacity of the aqueduct side wall. Then， combined with the measured data of steel corrosion and the principle of BP neural network， the prediction model of steel corrosion rate is designed， and the calculation formula of effective cross-sectional area of steel bars in concrete structures is established through the hemispherical pitting model. On this basis， the point estimation and high-order moment reliability theory is introduced to develop the time-varying reliability analysis method of aqueduct structure， and finally the proposed method is applied to the bending time-varying reliability analysis of the side wall of an actual aqueduct. The results show that compared with the previous eight practical empirical models， the prediction model of BP neural network built in this paper can predict the corrosion rate of rebar in concrete structures more accurately， comprehensively， easily and quickly. By comparing with Monte Carlo simulation method， the time-varying reliability index of this method is efficient and accurate， which can provide an effective way for the evaluation and prediction of time-varying reliability of aqueducts.

This paper uses the Changshui Pond Irrigation System in Jiaxing City as the research object， and establishes a simulation model of water cycle process in irrigation system based on system dynamics， which can be applied to the simulation analysis of return flow and the calculation of irrigation water use from multiple scales based on the introduction of irrigation water regression coefficient. The results show that through the calibration and verification of the model， the simulated water volume of any typical pump station is basically consistent with the actual monitored water volume， with the absolute value of the relative error lower than 15%. Also， the simulated water level change process of the river network is basically consistent with the actual monitored water level process. The model can better reflect the water conversion process in irrigation system and provide support for the statistical work of irrigation water use in irrigation system.

Soil moisture content（SMC） and temperature are important parameters affecting the hydrological cycle and climate change. In order to monitor SMC and temperature timely and accurately， this paper proposes a method to detect based on hyperspectral technology. The dataset which contains a lot of noise and redundant information is obtained during five days of field measurements. After being denoised by Savitzky-Golay filter， the successive projection algorithm（SPA） is first used to extract the characteristic wavelength of hyperspectral database. Then， the hyperparametric weight and bias value of the support vector machine regression（SVR） are optimized by the genetic algorithm（GA）.At the same time， the SPA-GA-SVR hybrid algorithm model proposed in this paper is constructed to predict the soil moisture content（SMC） and temperature（T）.The prediction performance is compared with BP neural network， SPA-optimized BP neural network， SVR， SPA-optimized SVR and GA-optimized SVR.Results show that there is no significant difference in the prediction ability of each model when the soil moisture is less than 30%.However， hybrid models has obvious advantages over the single neural network or machine learning model on the whole dataset. Finally， the SPA-GA-SVR algorithm is superior to other models in all indicators， in which R ² is 0.981 and RMSE is 0.473% in soil moisture prediction and R ² is 0.963 and RMSE is 0.883℃ in soil temperature prediction. Research indicates that the SVR model optimized by SPA and GA can accurately predict soil moisture and temperature based on hyperspectral data.This method， which has certain application value and practical significance， can be applied to portable hyperspectral and unmanned aerial vehicle to realize real-time monitoring of soil moisture and temperature， and provide a theoretical reference for sowing and irrigation in the future.

In order to explore the carbon emission reduction potential of farmland ecosystems in cities （prefectures） of Yunnan Province， based on the Panel data related to farmland carbon emissions in cities （prefectures） of Yunnan Province from 2011 to 2020， this paper establishes an indicator system of farmland carbon emission reduction capacity from three aspects of energy factors， technical factors and economic factors， uses the Game theory combination weighting method to determine the comprehensive weight of indicators， introduces set pair analysis， cloud matter element coupling model and set pair analysis partial coefficient algorithm. It conducts a comprehensive evaluation and analysis of the carbon reduction capacity and development trend of farmland in Yunnan Province. The evaluation results indicate that：①The spatial layout of farmland carbon reduction capacity in Yunnan Province shows a pattern of strong in the southeast， weak in the southwest， and moderate in the east and west. Among them， the industrial development pattern and regional economic output value are the main influencing factors on farmland carbon reduction capacity. ②In the analysis of the development trend of carbon reduction capacity in farmland， it is found that Yunnan Province as a whole shows a negative development trend. By clarifying the current development status of carbon emissions from farmland ecosystems in Yunnan Province and identifying key regulatory areas， planning and formulating industry layout and cultivation management measures to reduce carbon emissions from farmland according to local conditions， this paper serves as a reference and decision-making basis for the development of low-carbon agriculture in Yunnan.

The research is intended to explore the variation of photosynthetic and water use efficiency of rice under drought-flood alternation condition， so as to predict yield scientifically and provide an optimum irrigation mode of rice under the disaster. Changes of water use efficiency WUE _leaf， stomatal conductance g_s， transpiration rate E and photosynthetic rate A are studied by orthogonal experiment on II you 898 rice. The results show that the significant changes of photosynthesis product accumulation when drought degree and flooding depth have changed. A significant linear relationship is displayed between A/g_s and leaf-air temperature difference in any case， but a relatively insensitive response after a drought-flood abrupt alternation. From the end of tillering stage to the beginning of jointing and booting stage， the relation between WUE _leaf and g_s can be described by convex parabola. The absolute photosynthetic rate controlled the biomass accumulation in the whole growth period. In the mid-late stage of jointing and booting，the relation between WUE_{l eaf} and g_s can be described by a concave parabola. The increase in WUE _leaf is unable to induce a compensation of yield due to an early senescence of leaves and the decreases in absolute transpiration rate at the stage. So we had better provide less water in late growth period of rice when it is exposed to an early drought-flood abrupt alternation， to avoid unnecessary water waste.

As an important tool for water management in irrigation areas and basic hardware support for digital irrigation area construction， measurement and control facilities can effectively help managers accurately grasp the water source and real-time water consumption of users， and can also provide a forceful guarantee for water fee collection， total water consumption control and quota management in irrigation areas. Taking the measurement and control gate in Ningxia Huanghuang irrigation area as an example， this paper systematically analyzes its application status， summarizes and condenses the main results from the aspects of improving the management level of irrigation area， consolidating the results of confirming practical water rights， and improving the transparency of water fee collection， puts forward the key problems in application from the aspects of equipment hardware level， planning and design， operation and maintenance， and it puts forward relevant opinions and suggestions on the selection and design of measurement and control facilities in the future.

Water use efficiency （WUE） is an important basis for ecological environment protection and reconstruction in irrigated areas. In this paper， nonlinear least squares， coefficient of variation， correlation coefficient， Mann-Kendall test， Morlet wavelet analysis and heuristic segmentation algorithm are used to study the characteristics of WUE in Qingtongxia Irrigation District of Ningxia from 1985 to 2015. The results are as follows： ① The average annual WUE in the irrigated area is 0.96 g/kg， and the spatial distribution of WUE show strong spatial heterogeneity， with the characteristics of high in the west and low in the east. There is an increasing trend of fluctuation year by year， and the interannual variation of WUE has an obvious negative correlation with ET， and a significant positive correlation with TMP. ② The annual variation of WUE in the irrigation area is positively correlated with ET， NPP， TMP and PRE， and the positive correlation coefficient of TMP is higher. ③ In general， due to a large number of ecological restoration and reconstruction projects in Qingtongxia Irrigated Area of Ningxia， the productivity of the ecosystem in the irrigated area has been improved， and the ecological status of the irrigated area has been improved to some extent. In the future， the WUE of the ecosystem in the irrigated area will continue to rise.

Jingdian Irrigation Area is a high-lift cross-basin irrigation area with agricultural economy as the main， drought and water shortage have become the main factors restricting the high and stable yield of crops， water-saving irrigation technology has been popularized in Jingdian Irrigation Area， reasonable water-saving irrigation can save water， improve unilateral water efficiency， it is beneficial to promote the intensive and economical utilization of water resources and the construction of water-saving irrigation area. This paper is based on the entropy method， the evaluation system of water-saving irrigation benefit is constructed from the aspects of social economic benefit and ecological environmental benefit， the benefits of different water-saving irrigation modes for the main crops in irrigated areas are analyzed. The results show that the efficiency of efficient water-saving irrigation is generally higher than other irrigation methods， drip irrigation is the best water-saving irrigation mode in this area. The evaluation results are basically consistent with the reality， it shows that this method is feasible to evaluate the benefit in irrigated areas， so it has a guiding significance to the comprehensive evaluation of irrigated areas.

The stability analysis of tunnel surrounding rock plays an important role in both engineering design and construction. Jiaoxiling Tunnel is the controlling project of water supply project of Jiaohua Reservoir in Hunan Province. It has the characteristics of complex geological conditions， passing through multiple fault zones， shallow buried sections and broken zones， and rich water layers. Based on the analysis of the engineering geology and hydrogeology of Jiaoxiling Tunnel， this case adopts the method of combining axial strain theory with practice to predict the limit height of spalling and caving of surrounding rock of the tunnel， and then determines the support design of each section of the tunnel. The results show that it is better to determine the thickness of shotcrete and the size of anchor rod according to the type of surrounding rock， and to determine the grouting measures in combination with the groundwater condition. The case results are helpful to provide scientific reference for the design and construction of similar projects.

In order to explore the blockage effect in the flow channel induced by the tip leakage of the semi-open centrifugal impeller， this paper uses the large eddy simulation to accurately calculate the flow field. Based on the blockage prediction model to investigate the blockage characteristics of three semi-open centrifugal impellers with tip clearance of 0.5， 1.0 and 1.5 mm under different flow conditions are studied.The research finds that there is a blockage peak in the impeller channel， and it is at plane 2 under the three tip clearances. After passing through plane 2， the blockage is greatly reduced， and there are small fluctuations in the back four sections. Through an analysis of the relative blockage at the trailing edge of the impeller under different tip clearances and different flow conditions， the study finds that the blockage at the trailing edge has the same change trend with the change of flow rate under different tip clearances. The relative blockage reaches the minimum at 1.0 Q _d and the peak at 0.6 Q _d. However， the relationship between blockage and tip clearance is not a single linear relationship at the same flow rate， and there is an optimal tip clearance to achieve the minimum blockage at the design point. At the same time， through the observation of the development of the leakage vortex， the study finds that the fragmentation and displacement of the leakage vortex will increase the blockage at the trailing edge of the blade. Through the analysis of the static pressure difference of the blade， the study finds that the operating flow has little effect on the blade load. However， the change of the tip clearance will greatly affect the blade load and the blockage at the trailing edge of the blade.

In our present stage， agricultural water right trading is dispersed and the scale is smaller， and the market activity of agricultural water right trading is not in full swing. With the contradiction between supply and demand of water resources becoming increasingly tense， agriculture has necessity to stimulate the decisive role of market in water resources allocation， and further create greater trading space for agricultural water rights. Agricultural water rights involve multi-level management systems， but few studies have analyzed the factors affecting the development of agricultural water rights trading from different dimensions in detail， so it is impossible to systematically promote the development of agricultural water rights trading. Therefore， this paper divides the key factors affecting the development of agricultural water rights trading into three dimensions： macro social economy， middle market players and their mutual relations， and micro trading elements. A qualitative analysis is made of the substantive attributes of each factor index in different dimensions and its impact on the development of agricultural water rights trading， and the macro-support for the development of agricultural water rights trading is found. This paper clarifies the development ideas of agricultural water rights trading market， and then focus on the role of micro-trading elements in the process of water rights trading. From three dimensions， it puts forward suggestions on how to strengthen the agricultural water rights trading policy and promote the construction of rural water system connectivity in multiple ways， clarify the role positioning of government and enterprises， and encourage the synchronous transfer of agricultural water rights trading and land to activate the agricultural water rights trading market so as to improve the agricultural water rights trading market to provide the construction foundation and ideas.

Global warming has changed the thermal and dynamic environment of climate effects， further exacerbating the uneven distribution of water in China within the year， and the threat of drought will continue to intensify. Flood control and drought resistance are equally important at present. How to reasonably utilize the flood control capacity of reservoirs and raise the flood control level is the key to alleviating the supply-demand contradiction of water resources in China. In the face of new situations， combining the existing operation regulations of the Three Gorges Reservoir and long series of historical runoff data， this paper takes the Three Gorges Reservoir as the object and formulates different flood control level schemes to analyze the benefits and risks of raising the flood control level of the Three Gorges Reservoir. The results indicate that relying on the current forecast level and the joint operation of upstream reservoirs， the flood control risk of the Three Gorges Reservoir flood control level rising to 155~157 m is controllable. It will not lower the flood control standards of Jingjiang and increase the risk of backwater flooding in the reservoir area. When the flood control level of the Three Gorges is raised to 153 m， the average annual power generation reached its maximum value of 102.9 billion kWh， an increase of 16.7% compared to the initial design value. Consistent with years of statistical law， the Three Gorges Reservoir reaches its maximum power generation capacity in both wet and normal years when the flood control level increases to 153 m. Higher flood control level in dry years， resulting in better power generation efficiency. The flood control benefits are negatively correlated with the flood control level， but the average annual flood detention volume of different schemes varies by 1.5 billion m3. It has changed little. The benefits of water resources are positively correlated with the flood control level. The starting water level of the Three Gorges Reservoir increases synchronously with the rise in the flood control level. When the flood control level rises to 147 m， the full storage rate of the Three Gorges Reservoir can reach 100% by the end of October. For every 1m increase in flood control level， the average annual outflow of water during the storage period can increase by about 500 million m3. Relying on the current forecast level and the joint operation of upstream reservoirs， the flood control risk of the Three Gorges Reservoir’s flood control water level rising to 155~157 m is controllable. Considering both benefits and risks， the flood control level of the Three Gorges Reservoir can be raised to 153 m at present.

An accurate runoff prediction is the prerequisite for the optimal allocation and efficient utilization of water resources， and the basis for making flood control and disaster reduction decisions. However， due to the influence of human activities， environment， climate and other factors， runoff series show nonlinear， unsteady and multi-scale changes， which increases the difficulty of accurate runoff prediction. In order to improve the accuracy and credibility of runoff prediction， this paper combines the Complete Ensemble Empirical Mode Decomposition with Adaptive Noise （CEEMDAN） method. Quantum Particle Swarm Optimization （QPSO）， Broad Learning System （BLS） model， a combined runoff prediction model based on CEEEDAN-QPSO-BLS is proposed. Firstly， CEEMDAN method is used to decompose the original runoff signal to obtain several relatively stationary intrinsic mode components. Secondly， the QPSO algorithm is used to optimize the number of node groups in the feature layer， the number of node groups in the enhancement layer and the number of nodes in the group of BLS model， and the optimal topology structure of the width learning network is obtained. Then， the optimal QPSO-BLS is used to predict multiple steady-state components， and the prediction components are reconstructed so as to obtain higher prediction accuracy. In this model， the daily runoff value of Xiaolangdi Reservoir in the Yellow River Basin is used as the experimental data， and EMD-QPSO-BLS and QPSO-BLS are used as the comparison model of CEEMDAN-QPSO-BLS. Nash-Sutcliffe efficiency coefficient （NSE）， Root Mean Squared Error （RMSE）， Mean Absolute Error （MAE） and Mean Absolute Percentage Error （MAPE） are used to evaluate the reliability and accuracy of the model prediction. The experimental results show that， compared with QPSO-BLS with EMD-QPSO-BLS models， the prediction accuracy of CEEMDAN-QPSO-BLS is improved by 79.87% and 19.80%， and the credibility is improved by 131.2% and 10.98%， respectively. This paper provides decision-making support for flood control and drought relief to protect people’s lives and property and sustainable development.

The prediction of urban river water level is of great significance to the risk management of urban waterlogging. Traditional numerical simulation models have low computational efficiency and are unable to perform real-time calculations. In response to the above issues， this paper proposes a channel water level prediction model based on Gaussian function improved BP neural network， which solves the problems of low prediction accuracy and slow convergence speed in error flat areas of the BP neural network model. This method utilizes the Gaussian function to improve the gradient descent algorithm of the BP neural network， sets different learning rates for different weights and threshold values of the model， and optimizes each parameter accordingly， which can effectively accelerate the training efficiency of the BP neural network model. In response to the problem of slow convergence speed of the model in error flat areas， the paper uses the Gaussian function to increase the learning rate of the gradient descent algorithm in error flat areas， and to control the learning rate of the gradient descent algorithm when the error is serious， which can effectively accelerate the convergence speed of the BP neural network model in error flat areas. This paper takes 6 river water level measurement stations in Jin’an District， Fuzhou City as the research object， constructs a GA-BP neural network river water level prediction model for urban river water level prediction， and explores the impact of different rainfall input forms on the accuracy of river water level prediction. The results show that the GA-BP neural network can effectively improve the convergence speed and model prediction accuracy of the BP neural network in error flat areas. The Nash Efficiency Coefficient （NSE） of the experimental set prediction is above 0.8， and the relative error of the predicted peak water level can be controlled within 5%. The input of rainfall in the form of hourly rainfall can increase the predicted NSE to over 0.9. Research has shown that using Gaussian function to improve the BP neural network model can effectively improve the prediction accuracy of the model， which is of great significance to improving urban river water level prediction.

As an important non-engineering measure， the optimal operation of reservoir flood control can reduce the loss caused by flood disasters with little investment and plays a key role in flood control and disaster reduction. In this paper， considering the safety of the reservoirs themselves and the safety of the downstream flood control section， a multi-objective optimal model for real-time flood control operation of reservoirs is established with the objective function of minimizing the maximum flow of the downstream flood control section and minimizing the maximum water level of each reservoir. Based on the “filter operator”， an improved multi-objective Lichtenberg algorithm （MOLA） is proposed， which is used to solve the multi-objective model， and the real-time flood control operation schemes of the reservoirs are obtained， to enhance the practicability of operation solutions. Finally， a comprehensive screening method based on hierarchical clustering and the physical meaning of Pareto front is proposed to screen the scheduling schemes on the Pareto front and select limited ones for the scheduler， to increase the focus of decision-making. Taking the Shiguanhe flood control system of the Huaihe River Basin as an example， this paper applies the multi-objective optimal model for real-time flood control operation of reservoirs. The result shows that the proposed model based on the improved multi-objective Lichtenberg algorithm has high computational efficiency and strong applicability. The gradient analysis method is used to quantitatively analyze the mutual feedback relationship between the maximum water level of Nianyushan Reservoir， the maximum water level of Meishan Reservoir， and the maximum flow of Jiangjiaji flood control section. The results show that the water level change of Meishan Reservoir has a more significant impact on the flow of Jiangjiaji section， and the Meishan Reservoir is a priority in flood risk control of Shiguanhe River Basin. The research results can provide decision-making support for real-time flood control operation of reservoirs.

The frequency of typhoon storm surge increases under climate change， resulting in rainstorm and flood， which poses a great threat to the safety of the reservoir dam. Due to the lack of measured flow data in some regions， research on coupling stochastic models based on rainfall data with hydrological models to simulate flood hydrogr-aphs urgently needs to be developed. In response to the lack of flow data in existing small watersheds， a Copula-LM-HMS coupled model based on rainfall stochastic model and hydrological model is studied to simulate inflow floods and calculate the risk rate of reservoir dam flood overtopping. This model generates multiple sets of 7-day rainfall data in the watershed through Copula function and Latin Hypercube Monte Carlo Simulation. The corresponding rainfall sequence is obtained by scaling and processing by using the zoom ratio method. The HEC-HMS hydrological model is used to simulate the flood hydrograph and combined with flood routing to obtain the highest water level in front of the dam， while the effect of wind and waves are considered to simulate the changes in reservoir water level under typhoon scenarios. The risk rate of dam flood overtopping is calculated and the impact of different combination conditions on the risk rate of flood overtopping is analyzed. The case study of Siming Lake Reservoir in Yuyao City shows that the constructed Copula-LM-HMS coupling model calculates that the barrage has no overtopping risk in the future typhoon scenario， with a minimum overtopping risk of 0.22% for self breaking dams and a maximum overtopping risk of 2.68%. The risk of flood overtopping is related to the distribution of rainfall and the starting water level， and the effect of wind and waves has a significant impact on the risk of flood overtopping. The calculation of flood overtopping risk rate in small and medium-sized watersheds based on coupled models can not only consider the correlation between rainfall series， watershed terrain characteristics， and actual flood regulation rules， but also extend the prediction period for reservoir dams in areas without flow data to cope with flood risks in typhoon scenarios， providing a reference for ensuring the operational safety of reservoir dams in response to future climate change impacts.

Optimal allocation of water resources can solve the problems of regional water resources shortage and unreasonable utilization， and in recent years optimization algorithms have become an important tool for obtaining the results of optimal allocation of water resources. To effectively alleviate the problems of slow convergence， local optimization and prematureness in existing optimal allocation algorithms， this paper introduces a new metaheuristic algorithm： the Cheetah Optimizer （CO）， with the advantages of fast convergence， robustness， and superiority-seeking ability， which is applied to the optimal allocation of water resources. Taking Taiyuan as the study area， this paper establishes a water resource optimization model with the objectives of economic， social， and ecological benefits， and CO is used to solve the model， then compares and analyzes the results with the Genetic Algorithm （GA）. The results show that the total pollutant discharge of CO is within the control target of the planning year （2030）， the regional satisfaction reaches 0.98， which can meet the demand for basic and development water； compared with the current year （2020）， the proportion of domestic water consumption decreases by 22.58%， and the proportion of water consumption in production increases by 10.53%， 25.81% and 12.5%， respectively. The water supply ratio of surface water and groundwater is reduced by 21.70% and 11.14%， respectively， the water supply ratio of reuse water and yellow diversion water is increased by 5.43% and 27.40%. It accords with the idea of water resources allocation in Taiyuan， and verifies the effectiveness of CO. Compared with GA， CO has increased regional satisfaction， integrated water value and water distribution equity by 7.10%， 3.57% and 56.52%， respectively， reduced pollutant emissions and water shortage by 3.11% and 3.85%， at the same time， it has better coordination， which verifies the superiority of the CO. The results show that CO is reasonable and feasible to solve the optimal allocation model of water resources， which can provide a new method for solving the optimal allocation model of water resources.

As a unit hydrograph method widely used in engineering practice， the synthetic unit hydrograph of Guangdong is obtained from the analysis and synthesis of rain and flood data before 1983， which reflects the production-confluence relationship before urbanization in Guangdong Province. However， there are few studies on the evaluation and modification of its applicability in urbanized areas. Taking Jingtian Watershed of Shenzhen City， Guangdong Province as an example， based on the rainstorm and flood records of Jingtian Hydrology Station from 2011 to 2019， this paper evaluates the applicability of the comprehensive unit line in Guangdong Province by using evaluation indexes such as Nash efficiency coefficient， identification index and correlation coefficient， and conducts a sensitivity analysis of important parameters by Spearman rank correlation coefficient method. Based on Latin hypercube sampling method and constrained least square method， the comprehensive unit line method of Guangdong Province is modified. The results show that the Jingtian Basin has experienced rapid urban expansion since the 1980s， and the proportion of impervious surface has exceeded 90%. The comprehensive unit line method in Guangdong Province has obvious shortcomings in describing the storm-flood process in this basin. The two schemes proposed in this paper can improve the simulation effect of the model by determining important parameters and modifying the unit line. Among them， the cross-validation parameter optimization method based on grid search and the unit line correction method based on constrained least square method proposed for small samples show a good simulation performance， and the indexes such as Nash efficiency coefficient， identification index and correlation coefficient are significantly improved， which better reflects the characteristics of production and convergence in Jingtian Basin. Compared with the recommended unit line of the integrated unit line method in Guangdong Province， the modified unit hydrograph method shows the characteristics of larger peak discharge， earlier peak time and smaller total duration， which is more in line with the law of production and confluence of urbanization.

The installation of groynes along the riverbanks is a widely adopted practice in stream corridor restoration projects， aiming to create backflow zones （also known as dead-water zones） that can effectively enhance the river geomorphological diversity.The presence of low-velocity circulation pattern in dead-water zones can promote sediment deposition and nutrient accumulation， thus creating a conductive environment for the growth of aquatic plants. Simultaneously， it can also influence material transport and diffusion processes within rivers， which holds immense importance to river ecosystems.The mean residence time relationship for the dead-water zone with emergent vegetation is investigated here by using a combination of dimensional analysis and genetic algorithm. For vegetated dead-water zones， the factors influencing the mean residence time can be classified into three categories： the hydraulic characteristics of the mixing layer， the morphology features of side-cavities， and the drag effect caused by vegetation. Firstly， the parameter 1+C_Dad_c， which represents the obstructive impact of vegetation， is introduced via π theorem with reference to previous work. It should be noted that in the absence of vegetation， i.e.， 1+C_Dad_c =1， the material exchange activities are not affected by the canopy factor 1+C_Dad_c . However， in the presence of vegetation， the equation 1+C_Dad_c >1 suggests an influence on exchange processes. Secondly， other dominant factors， including the mainstream Froude number Fr which reflects the inlet flow intensity， as well as the three-dimensional shape factor （Wd_c ）^0.5/L and the width-to-length ratioW/L，which reflect the morphological features of cavities， are identified through a comprehensive analysis and comparison. Then， the aforementioned four factors are used as independent variables to construct a general predictive model for the mean residence time in the vegetated cavity， i.e.， a product model of power functions incorporating these four factors. Finally， based on 85 groups of data gathered from previous studies， the genetic program Eureqa is employed to train this general model， and subsequently， a mean residence time relationship is developed for vegetated dead-water zones. The evaluation on the coefficient of determination R ² and the mean absolute error MAE demonstrates that the present formula possesses good predictive ability， and the analysis of the value ranges of each factor reveals that this formula exhibits a broad range of applicability. In addition， based on a comparative analysis of the impact of the four factors on the model results， the cavity aspect ratioW/L is considered as a critical parameter that significantly influences water residence characteristics in dead-water zones and should be duly taken into account when relevant engineering designs are conducted.

The reservoir sediment is formed by the combination and precipitation of clay， sand， organic nutrients and inorganic minerals in the reservoir. The reservoir sediment usually exists in the form of irregular and heterogeneous clay glue， which is in a fluid plastic state with good plasticity and relatively loose between particles. The accumulation of sediment in the reservoir will weaken the water storage and flood control capacity of the reservoir， and then reduce the capacity of the reservoir， shorten the life of the reservoir， and affect the shipping traffic. In addition， the long-term accumulation of reservoir sediment may cause pollution to the surrounding environment and reduce the water environment safety index， thus posing a potential threat to human survival. Therefore， it is urgent to make resource utilization of reservoir sediment. In order to improve the added value utilization rate of reservoir sediment in the field of building materials， this paper uses the reservoir sediment as auxiliary cementing material to prepare pervious concrete. Through the orthogonal test， the mix ratio design optimization of pervious concrete with reservoir sediment is studied， and the effects of slag powder， reservoir sediment and reinforcement agents on the performance indexes of pervious concrete with reservoir sediment， such as dry density， total porosity， effective porosity， permeability coefficient， ultrasonic pulse velocity and 28 d compressive strength are analyzed. The relationship between ultrasonic pulse velocity and porosity， permeability coefficient and 28 d compressive strength is studied， and the evolution law of the quality of the specimen and ultrasonic pulse velocity with the number of freeze-thaw cycles is explored. The results show that the dry density， compressive strength and ultrasonic pulse velocity of pervious concrete decrease continuously with the addition of reservoir sediment， and the porosity and permeability coefficient increase continuously. When slag powder is added， the dry density， compressive strength and ultrasonic pulse velocity of the specimen first increase and then decrease， and the porosity and permeability coefficient first decrease and then increase. The reinforcement agent has no obvious effect on the performance index of the specimen. The curve fitting of ultrasonic pulse velocity with porosity， permeability coefficient and 28 d compressive strength is well correlated. With the increase in the number of freeze-thaw cycles， the quality loss rate of the specimen increases gradually， the ultrasonic wave speed decreases gradually， and the slag powder and reinforcing agent can improve the freeze-thaw durability of the specimen. The research findings will promote the development and application of reservoir sediment in the preparation of building materials， and is expected to serve as a reference for the further application of reservoir sediment permeable concrete.

The sediment-carrying capacity is reduced due to the rise of water level and the reduction of velocity， which leads to sedimentation in the reservoir， especially in front of the dam. Therefore， the storage capacity， flood control ability， and power generation are reduced， which affects reservoir functions and economic efficiency owing to reservoir sedimentation. The main measures to solve the problem of reservoir sedimentation include dredging in reservoir， reducing inflow sediment realized by soil protection and vegetation， as well as reservoir operation management such as “storing clear water and discharging muddy flow”， and sediment discharging by heterogeneous flow， etc. In this paper， a normal funnel device with the smooth surface that has arbitrary order derivative is designed for discharging sediment in reservoir. The Euler two-phase flow near the normal funnel is numerically simulated with the Realizable k-ε turbulence model on rectangle and O-type grids. Numerical model is tested by data on experiment flow that carried out in flume. The flow velocities， vorticities and sediment phase concentrations are analyzed under different boundary conditions. Research shows that velocity gradient is large in normal funnel， and phase concentration contours display the V-shaped asymmetrical distribution. Three large vorticity areas appear in the front edge， the left and right rear sides of the normal funnel. The large flow velocities and small resistance appear near the wall of the normal funnel. The average sediment concentrations at the output of the normal funnel are 0.462， 0.521 and 0.558 under three boundary conditions. The average vorticity is reduced by 25.8%~27.2%， the efficiency of discharging sediment remarkably increases with 15.2%~16.5% in contrast to the cone funnel. It demonstrates that the normal funnel is more favorable than the cone to smoothing flow， reducing energy dissipation， enhancing the capacity of sediment transport and discharging sediment outwards reservoir.

Foamed mixture lightweight soil using river sludge（FMLSS）is a novel method of dredged silt reuse in the engineering field. The variation law of dynamic stress strain backbone curve of FMLSS under different confining pressures， different water contents， different cement contents and different air foam contents is analyzed by the indoor dynamic triaxial test. The results show that the dynamic stress strain backbone curve of FMLSS presents a law of linear increase at first and then gradually stabilize， which accords with the hyperbolic model. Compared with confining pressure， water content and air foam content，the influence of cement content on dynamic stress strain relationship of FMLSS is more significant. Considering the complexity of the mechanical properties of FMLSS， the original Hardin-Drnevich model is improved， the correction coefficient k and its function expression are proposed， then the coefficient k value is derived from the fitting curve and the change rule of coefficient k value is analyzed， and it is founded that the coefficient k value decreases with the increase in confining pressure， cement content and air foam content， increases with the increase in water content. According to the fitting results， the undetermined coefficients in the k value function are further optimized， and finally a modified Hardin-Drnevich model conforming to the dynamic characteristics of FMLSS is established， which provides support for the stability analysis， disaster prediction and engineering application of FMLSS.

As an important theory of water ecological protection and restoration， fish habitat health assessment has always been the focus of research， but there is a lack of in-depth research on quantitative comprehensive assessment. By taking 5 typical deep-pool habitats in the upper reaches of the Yangtze River as examples， this paper establishes a quantitative evaluation system of fish habitat health status. Based on the habitat health assessment （primary index） of the typical deep pool in the upper reaches of the Yangtze River， the study is divided into habitat environment and habitat function （secondary index）， covering 5 tertiary indexes （water quality， biological environment， hydrological environment， fish resource status， habitat quality） and 29 quaternary indexes. A mathematical model for comprehensive assessment of habitat health is built based on entropy weight method. The typical habitat health status is characterized by comprehensive health indicator （ρ）， and the health status of the habitat is evaluated comprehensively. The results show that one of typical deep pool habitatin the upper reaches of Yangtze River is in a very healthy state with a health grade of Ⅰ. The evaluation of the three places is Ⅱ level， in the health state. A site is rated as level III， in the sub-health state， and no healthy or poor tide point. On the whole， the typical habitat in the upper reaches of the Yangtze River is basically in health state， and shows strong spatial heterogeneity. The evaluation results objectively reflect the health status of the typical habitat in the upper reaches of the Yangtze River to a certain extent. Finally， according to the scoring grades， the urgent problems in the fish habitat ecosystem in the upper reaches of the Yangtze River are discussed， and the countermeasures and suggestions for habitat restoration are put forward.

With the fast growth of human population， socio-economic development and resource exploitation， significant alterations have unfolded within the Poyang Lake ecosystem， thrusting environmental concerns to the forefront. Presently， total Phosphorus levels in the Poyang Lake region surpass established standards， and this concentration continues to surge， bearing witness to the progressive deterioration of the lacustrine biosphere. Designated as a priority demonstration area for national ecological civilization construction and Yangtze River protection and restoration， phosphorus pollution in the Poyang Lake Basin has emerged as a critical and urgent challenge in Jiangxi Province’s management of its aquatic ecological environment. Based on the technological method of watershed zoning in the pollution source census， it presents the estimation of the total phosphorus pollution load and the quantitative analysis of phosphorus pollution sources entering the lake. The results show that the total phosphorus pollution load entering Poyang Lake in 2021 reached 14 900 tons， with the primary pollution originating from the land-based input， accounting for 87.73% of its contribution； in order of contributing weight， the sources of pollution within the lake primarily arose from endogenous releases （5.52%） and soil erosion （4.60%）. Our analysis ranks the pollution sources in descending order of contribution weight as follows： Livestock farming （48.63%） > Urban living （20.01%） > Cultivation （9.71%） > Aquaculture （7.37%） > Endogenous release （5.52%） > Soil erosion （4.6%） > Industrial enterprises （1.12%） > Rural domestic （0.89%） > Migratory bird droppings （0.46%） > Tourism （0.12%）.Notably， livestock farming emerges as the primary contributor to agricultural surface contamination concerning the total phosphorus indicator. Regarding spatial distribution， high-contributing watersheds of total phosphorus load are primarily concentrated in the Ganjiang River Gathering Area and the Binhu Area， with the contribution proportion of 50.67% and 25.92%， respectively， and concentrated production of total phosphorus in the catchment areas of the Fu River and Xinjiang River， with a contribution of 7.64% and 8.34%， the remaining catchment areas generated load into the lake with relatively low intensity， accounting for contributions totaling 7.39%. Moreover， a similar contributing structure of pollution sources in each sub-region is mainly presented as agricultural sources as the main source， with urban sources as a secondary source. Based on the research findings， it is evidenced that the sources of total phosphorus pollution in Poyang Lake exhibit spatial variability. However， the principal control sources for total phosphorus in the lake show similarities across different regions. To effectively address these concerns and enhance the overall ecological well-being of the Poyang Lake Basin， this paper strongly recommends prioritizing the control of high-contributing watersheds， such as the Binhu District and the Ganjiang Watershed. Mitigating phosphorus pollution effectively would require tailored prevention and reduction strategies， especially focusing on agricultural and urban living. Initiatives such as relocating livestock farming to areas with large environmental capacity， emissions reduction measures， and eco-friendly enrichment. Implementing these measures holds the promise of alleviating the issue of total phosphorus pollution and ensuring the sustainable development of Poyang Lake and the stability of its hydro-ecosystem.

To explore the impact of rainfall patterns on the waterlogging resilience of urban rainwater systems based on the MIKE FLOOD platform， this paper conducts a study by using the bridge partition in the starting area of converting the new and old kinetic energy in Jinan. The waterlogging process scenarios are derived for 7 return periods， 3 rainfall durations， and 3 rainfall peak coefficients of the design rainfall. The system’s waterlogging resilience is quantified by using the Analytic Hierarchy Process （AHP） based on the amount， area， and average depth of waterlogging. The results show that the peak water accumulation and peak water accumulation area both increase with the increase in the return period and rainfall duration， and the average water accumulation depth fluctuates greatly. The system performance mainly fluctuates twice. The first fluctuation is caused by changes in rainfall intensity and the shallow depths cause the second in most of the depressions in the study area. As the return period increases， the system’s waterlogging resilience decreases， and the difference in rainfall corresponding to the extreme value of waterlogging resilience caused by the unit rainfall peak coefficient increases. Overall， the more centered the rainfall peak and the longer the rainfall duration， the lower the system’s waterlogging resilience.

In order to investigate the dynamic stress characteristics of runner and distributor of pump-turbine， this paper establishes the solid domain models of stay vanes， guide vanes and runner， and carries out the FSI-based computation of runner and distributor. The calculation results show that the stress concentration at the “T” junction between the runner blade and crown is related to the vortex development state at the runner inlet； the dynamic and static interference between runner and guide vanes is the main source of pressure pulsation in the vaneless zone， where the main frequency is the blade passing frequency； the dynamic stress of guide vanes and runner is generally high because the pump-turbine is easily involved in the unstable area while working under smaller GVO （guide vanes opening） or low head conditions. The dynamic stress of guide vanes is greater than that of the runner owing to its constraint guidance effect on water flow， and increased flow rate is beneficial to reducing the dynamic stress of the runner. So for the purpose of improving the dynamic stress of runner， the measures could be taken， such as changing the distance between the guide vanes tail and runner inlet， i.e. changing the width of vaneless zone， or adjusting the unit operation area， i.e. avoiding working in low road or small opening conditions for long.

In view of the large number of joint power stations in the basin but the existence of disputes in the distribution of benefits， a more reasonable method of benefit distribution for cascade power stations is proposed. Based on Shapley value method and TOPSIS method， considering the contribution of power stations and the relative satisfaction of power stations with different objective allocation methods， this paper establishes a compensation benefit allocation model of cascade power stations based on TOPSIS-Shapley value method. At the same time， in order to solve the limitation of Shapley value method in solving the problem of joint scheduling gain allocation of multi-stakeholder cascade power stations， the paper introduces the idea of aggregation dimension reduction. The idea of the model is as follows： the increment of the cascade power generation benefits before and after the joint dispatching of the upstream power station is taken as the compensation benefit. Firstly， four different objective allocation methods are used to calculate the characteristic parameter indexes of the power station to form the basic decision matrix of TOPSIS. The TOPSIS principle is used to obtain the relative satisfaction of the power station to each allocation method. At the same time， the coalition game theory is used to calculate the power generation benefits of all possible coalition modes of the power station， and the compensation benefit allocation results based on Shapley value are obtained. Finally， the allocation coefficient obtained by TOPSIS principle is combined with the allocation coefficient obtained by Shapley value method to form a comprehensive allocation weight， which is applied to the compensation benefit allocation of eight-stage power station in the upper reaches of the Heihe River. The engineering application example shows that the method not only considers the marginal contribution of the union power station to the whole and the satisfaction degree of each power station， but also takes into account the difference of the characteristic index of the power station， and reasonably quantifies and distributes the power generation compensation benefit among the power stations. The allocation result is fair and reasonable and easy to be accepted by all parties， which can promote the power stations at all levels in the basin to participate in the joint dispatching so as to achieve the goal of maximizing the overall benefit. It has an important reference significance for the distribution of compensation benefits of a large number of cascade hydropower stations.

The water conservancy industry is promoting digital twins in an unprecedented situation. The basis of smart water management is urgently needed to solve the problem that three-dimensional visualization of water conservancy projects cannot meet the requirements of professional visualization software. In this paper， a three-dimensional visualization platform for water conservancy is built based on technologies such as Cesium， Vue and Springboot. This platform has realized the key application technologies of thematic three-dimensional visualization such as multi-source data fusion， flood discharge and flood evolution， and laid a foundation for later digital twin visualization.

Combined with the general layout of Yaojiaping Hydraulic Project， this paper carries out three dimensional finite element stress analysis and flow field calculation respectively for the diversion system of the main power station with symmetrical Y shape and asymmetric Y shape crescent ribbed steel bifurcation. The calculation results show that the stress distribution at the two sides of symmetrical bifurcation is relatively uniform and the size of the rib is smaller. However， the stress concentration is greater near point A on the inner surface of the main branch taper intersecting line In terms of hydraulics， the head loss of two branches of asymmetric bifurcated pipe is not equal. The straight branch pipe with the main coaxial line has the smallest head loss， and the inclined branch pipe has the largest head loss， but not more than 0.358m of symmetrical bifurcation. It shows that the asymmetric bifurcation is slightly better than the symmetrical Y-shaped bifurcation in terms of head loss and flow pattern of the bifurcation. Considering the structural and hydraulic characteristics of bifurcation as well as the engineering topography， it is suggested that the asymmetric Y-shaped bifurcation layout should be chosen for the diversion system of the main power station in Yaojiaping Hydropower Project.

To promote the development of intelligent operation and maintenance of hydropower units， this paper proposes a robust multi-order statistic pooling （SAMOSP） normalized flow conditional probability model（NFCPM） for unsupervised abnormal sound detection of hydropower units. A self-attentive multi-order statistic pooling module （SAMOSP） is proposed for the first time in the paper. The module starts with a one-dimensional compressed convolutional layer and a bottleneck compressing the weight vector of the excitation part of the self-attentive to time frame. The weight vectors are used to compute the multi-order statistical pooling vectors. Then the different weights of the self-attentive to multi-order statistical pooling quantities of the frequency bands are subdivided and information about the significant statistics of the different frequency bands is extracted by them to obtain the self-attentive statistical pooling feature vector of the time-frequency map. Test samples of different time periods are tested in this normal data probability model， and the corresponding scores are obtained. The lower score indicates the lower probability density， the greater the degree of abnormality， thus realizing the unsupervised abnormality detection of the audio signal of the hydropower units.

This paper proposes a model of flood regulation characterized by the combination of generation change process calculated in layers and dynamic reserved storage capacity based on sliding superposition combination and then formulates and verifies its parameters by taking Yanhe’s PSP as an example. The results show that： ① it is the better way of fitting stage-capacity curve to choose polynomial function， and reducing the calculation step can improve the accuracy of flood regulation. ② Combined with the process of PSP， flood regulation should always pay attention to the change of stagnant reservoir capacity， which can simultaneously ensure that the flow of power generation does not exceed the discharge and the flood does not encroach on the reservoir capacity of power generation. In that way， it can improve the power generation and flood control benefits of PSP. ③ By dividing the scenario of flood combination into two scenarios （power generation or not before encountering with flood）， the most unfavorable one of PSP can be effectively and comprehensively discerned. The model of flood regulation proposed in this paper can provide necessary experiences for similar projects.

The seepage failure caused by the change of reservoir water level is one of the main reasons for the instability of the earth-rock dam. Moreover， the landslide would become geological disasters easily， which poses a great threat to human life and property. Aiming at the influence of reservoir water level rise on the landslide of earth-rock dam， this paper uses a homogeneous earth dam as the research background. The plastic zone and horizontal displacement changes of the dam slope under the critical instability state are studied by COMSOL Multiphysics. Based on the FEM strength reduction method， the stability of the dam slope under three conditions of normal water level， design flood level and check flood level are analyzed. The results show that the phreatic line of earth-rock dam increases with the rise in reservoir water level. The maximum plastic strain and horizontal displacement increase linearly， and the maximum values of the strength reduction factor （SRF）， the deformation behavior is mainly a shear slip. The factor of safety （FOS） under three conditions are 1.894，1.855 and 1.831， respectively. The stability of the dam body decreases continuously， but it is higher than the critical minimum factor of safety.

To ensure the safety of on-site operations in hydropower plants， this paper studies a reverse learning based risk warning model for on-site operations in hydropower plants. It selects indicators from four types of risks： public risk， unit equipment system equipment risk， electrical system equipment risk， and hydraulic construction risk to construct a risk warning indicator system for on-site operation of hydropower plants. The sensor system based on reverse learning is adopted， and the Linear List composed of sensor input sample points and expected output value is used to retrieve the position of measurement points so as to obtain accurate risk early warning index data. LSTM neural network is used to construct a risk warning model， the warning indicator data is used as the input of the model， and the risk warning level is used as the output of the model. Reverse output comparison is implemented through the propagation path to optimize different weight matrices and deviations， thereby obtaining the risk warning results of on-site operations in hydropower plants. At the same time， the particle swarm optimization algorithm based on reverse learning behavior is used to optimize the parameters of the early warning model and improve the accuracy of the model’s early warning. The experimental results show that the model can accurately predict the risks of on-site operations in hydropower plants and ensure the safety of on-site operations.

To improve the safety of on-site operations in hydropower plants， this paper studies a quantitative analysis model based on human factors engineering for the safety classification of on-site operations in hydropower plants to reduce the risk level of on-site operations in hydropower plants. Taking human factors engineering as the starting point， this paper analyzes the influencing factors of on-site operation in hydropower plants， and selects three important factors： human factors， operation environment， and operation site to establish a quantitative analysis index system for the safety classification of on-site operation in hydropower plants. After quantifying the human factors engineering indicators， based on this， a BP neural network-based quantitative analysis model for the safety classification of on-site operation in hydropower plants is constructed. The quantified analysis indicators for the safety classification of on-site operations in hydropower plants as the model input is used after model training and testing， the quantitative analysis level for the safety classification of on-site operations in hydropower plants is output. The experiment shows that the quantitative analysis results of on-site operation safety classification of hydropower plants obtained by this model are highly consistent with the actual situation， and have the feasibility of risk warning. When the number of hidden layer nodes in the BP neural network model is 15， the risk warning effect of the model is the best. The greater the labor load and intensity of personnel， the higher the risk of on-site operations in hydropower plants. Reasonable setting of personnel work intensity and load can improve the safety of on-site operations in hydropower plants.

This paper takes the monitoring and evaluation project of the implementation of the late support policies for large and medium-sized reservoir resettlers in WZ City， GX Autonomous Region in 2021 as an example based on the original survey data of 200 resettlement families in 10 resettlement villages， and uses the grey clustering-multiple correlation-information sensitivity method and constructs an evaluation index system including per capita disposable income and other indicators. After the index weights are calculated by the entropy weight method and the sequential scoring method， the subjective and objective combined weights of the evaluation indices are determined by the combination weighting method based on game theory.The grading standards of indices are determined based on survey data and official statistical data. The index of productive and living standards of reservoir resettlers is calculated by the comprehensive scoring method， and the index is used to carry out an empirical evaluation of the production and living standards of the reservoir resettlers in the sample village. The results show that the index system and evaluation model constructed by the method in this paper are relatively reasonable and effective， and the evaluation results are in line with the reality， which serve as a reference for the evaluation of the late support effect of reservoir resettlers and other related evaluation work.