Aiming at the leakage problem of urban water supply network, the traditional leakage location model is solved by single objective optimization method. Its objective function is composed of the weighted sum of optimization objectives. Improper value of weight factor will degrade the model positioning result. This paper proposed a multi-objective optimization model for leakage location of water supply network based on NSGA-Ⅱ. In this model, the number of leakage point and diffuser coefficient were taken as decision variables, and the minimum error between the actual monitoring value and the simulation value of pressure and flow monitoring point was taken as the optimization objective, and NSGA-Ⅱ algorithm was used to find the optimal solution. In order to verify the effectiveness of the model, it was applied to the actual water supply network in a residential area. Considering the common fault conditions in the actual operation of the pipe network, the leakage accidents of single node and two nodes were respectively simulated and located. Compared with the two widely used leak location models, the results show that the multi-objective optimization model based on NSGA-Ⅱ can accurately and stably locate the nearby area where the actual leak occurs.

As a large number of water conservancy projects have been put into use in recent years, water conservancy departments have accumulated a large amount of information about reservoir scheduling regulations. This paper analyzed the existing reservoir scheduling regulations, and proposed a construction method of reservoir scheduling regulations knowledge graph based on DataG. In the design of the ontology model, the top-down method of disassembling the ontology twice was adopted on the reservoir scheduling mode. The differentiated knowledge extraction was performed on the structured and unstructured data. In the knowledge reasoning, the reasoning path of preconditions, scheduling measures and scheduling objectives were analyzed and defined. Finally, the visualization of the reservoir scheduling regulation knowledge graph was introduced for the Three Gorges Reservoir. The knowledge graph of reservoir scheduling regulation meets the needs of spatiotemporal dimension, solves the problem of multi-source heterogeneous data extraction, and realizes intelligent retrieval and recommendation in the field of reservoir operation.

The performance of thrust bearing is very important to the energy conversion efficiency and stable operation of hydro-generator unit. Therefore, the thrust bearing of a hydropower station was taken as the research object. The characteristics of thrust bearing oil film under different rotating speed conditions were studied. The pressure, speed and temperature distribution inside the oil film were analyzed. The influence law of rotating speed on the performance of thrust bearing was clarified. The results show that the rotational speed cannot change the pressure distribution on the thrust pad surface, but with the increase of rotational speed, the relationship between the maximum pressure and rotational speed is almost linear; The high temperature zone on the thrust pad surface moves away from the main shaft towards the oil outlet side with the increase of the rotating speed, and the average temperature difference and the maximum temperature difference show an upward trend. At runaway speed, the thrust bearing needs to bear much higher pressure than the rated speed, and also needs to bear local high temperature. The maximum temperature difference at runaway speed is more than 40 K, which is easy to cause bearing bush burning. The research results provide theoretical support for the operation and optimal design of thrust bearings in hydropower stations.

The spatial and temporal variations of water quality in Wuxi water area of Taihu Lake are important for regional eutrophication control and water pollution control. Based on the monthly water quality data of Wuxi water area of Taihu Lake and the water quantity data of rivers entering the lake from 2010 to 2020, the spatial and temporal variation characteristics of water quality and eutrophication status of the lake were evaluated using the integrated pollution index and integrated nutrient status index. The inter-annual variation pattern and spatial pattern of major water quality indicators were analyzed, and the correlation between the water quality of the lake and the concentration and flux of pollutants in rivers entering the lake was investigated. The results show that the water quality of Wuxi water area of Taihu Lake improved significantly from 2010 to 2020, and the integrated pollution index and integrated nutrient status index of the whole lake decreased by 25% and 10%, respectively. Except for the concentration of total phosphorus concentration with no obvious change trend, the concentration of other water quality factors in the lake area all showed a downward trend. In terms of seasonal changes, permanganate index, total phosphorus, and chlorophyll-a concentrations maintained higher values in summer and autumn, while total nitrogen and ammonia nitrogen concentrations maintained higher values in winter and spring. Spatially, nutrient concentrations decreased from the northwestern and northern lakes to the southeastern and eastern lakes. The changes in water quality of rivers entering the lake from 2013 to 2020 are basically consistent with the trends of water quality in the lake area. The concentration of total nitrogen and ammonia nitrogen in the lake area are significantly positively correlated with the concentration of total nitrogen in inflow river and the flux of ammonia nitrogen into the lake, respectively. The spatial pattern response is consistent, and the exogenous input of the inflow river is an important factor affecting the spatial and temporal changes of water quality in the lake area.

Based on the runoff duration data of the basin in the past 50 years, the spatial-temporal evolution and ecological effects of hydrological variation in the Zuli River basin in arid and semi-arid region were studied by using cumulative anomaly analysis, M-K nonparametric mutation test, and runoff ecological index analysis with flow duration curve. The results show that since 1970, the surface runoff of the study basin was strongly affected by climate, and its runoff appeared sudden change in 1995. After studying the variation of runoff in the basin, the surface runoff decreased significantly, and the runoff in flood season and annual runoff decreased 36.9 million m³ and 32.12 million m³, respectively. After runoff variation, the ecological deficit in the study basin was obvious, and the annual proportion of runoff ecological indexes in non-flood season increased.

This paper aims at the complex flow response relationship in the short-term joint operation of Jindong-Guandi cascade hydropower stations in Yalong River basin. In order to predict the inflow response process of the Guandi hydropower station, the random forest (RF) model and support vector regression (SVR) model were combined to mine the nonlinear relationship, and compared with the traditional lag-time model and the Muskingum model. On this basis, two simulation dispatching models were established to test the applicability of each model in the short-term operation of cascade hydropower stations. The result shows that the RF-SVR model has a higher fitting ability for the flow response relationship between hydropower stations, which can reduce the errors in the formulation of short-term dispatching plan, and effectively reduce the deviation of daily generation and the risk of water level violation. The research results can provide a reference for making short-term dispatching schemes of cascade power stations under complex hydraulic connections.

It has great guiding significance of studying the hydrodynamic distribution strong tide for Shenzhen River estuary management. The physical model of Shenzhen River was established to analyze the hydrodynamic distribution characteristics of beach and trough and the neap tide. The spring tide in dry season and typhoon "Hato" were selected as the boundary conditions in tidal optimal estuary. The results show that the tidal power of the main trough of the Shenzhen Estuary is obviously better than that of the middle beach, the flow velocity tends to increase from the downstream to Shenzhen River for the discharge section is narrower in upstream during rising tidal, the power of spring tide and ebb tide in dry season is basically the same, the power of spring tide in dry season is stronger than that of ebb tide, the estuary flow pattern is mostly affected by riverbed morphology during the low water level with a large area of open beach which made the south trough flow only. During the storm surge, the hydrodynamic force of the estuary is strong, the flow velocity of the middle beach is significantly greater than that of the dry season, the middle beach water is not flowing back to the trough for the high water level and the mangroves in the middle beach has a great influence on the flow pattern. According to the hydrodynamic characteristics and flood discharge requirements, the countermeasures for ecological beach consolidation and main channel widening in Shenzhen Estuary were put forward.

The study of the effect of water vapour on soil heat and moisture migration patterns at different heat source temperatures is of great significance for the application of soil heat storage and ground source heat pump technology. In this paper, a numerical model of one-dimensional unsaturated soil water-vapour-thermal coupling migration was constructed by Hydrus-1D software, and the numerical simulation study of sandy soils with and without water vapour migration at different heat source temperatures was carried out. The results show that for soil heat migration, taking into account water vapour migration increases the radius of influence of the heat source from 60 cm to 78 cm, an increase of 30%; For soil moisture migration, the radius of influence of the heat source increases from 78 cm to 100 cm, an increase of 28.21%. Compared with not considering water vapor migration, considering water vapor migration can reduce the temperature loss during soil heat storage, and the decrease of temperature loss increases with the increase of heat source temperature. When the temperature of the heat source is above 70 ℃, the temperature and moisture fields of the soil change unsteadily and dryness may occur in the vicinity of the heat source.

In order to explore the water quality and pollution characteristics of the main water system in Chengde area, the monitoring data of 29 sections of Chengde surface water quality monitoring station from 2017 to 2020 were selected, and the water environment quality of the main water system in Chengde area was comprehensively evaluated by single factor evaluation, comprehensive pollution index and principal component analysis. The evaluation results show that generally speaking, the overall water quality of the main water system in Chengde is good from 2017 to 2020; From the perspective of time, the water quality of the main water system in Chengde in 2019 and 2020 was significantly improved compared with 2017 and 2018; From the perspective of space, the section pollution of Gonghou and Chenggang bridges is relatively serious. The water quality of the main water system in Chengde is mainly affected by the total phosphorus, COD and permanganate index.

Ganjiang river trail channel is affected by both upstream water and the backwater effect of Poyang Lake during the flood season. The study of the water level changes has guiding significance for river flood control and shipping. Based on the measured data from 1990 to 2019 at the hydrological station in the Ganjiang river trail channel, this paper adopted the Mann-Kendall trend test and the Pettitt test to analyze the trend of the characteristic water level during the flood season (flood season and backwater of Poyang Lake season). The results show that the water level of the Ganjiang river trail channel had a significant downward trend. The interannual variation of the water level during the flood season was relatively uniform, while it showed a fluctuating shape during the backwater of Poyang Lake season. The mutation years were all around 2002. The main reason for the decline of the water level during the flood period is the erosion of the riverbed. The downward trend of the riverbed has slowed down significantly after 2013, so water level during the flood period stabilized after 2016. The water level during the backwater of Poyang Lake season is mainly affected by the erosion of the riverbed, and the change of the downstream water level will also have a certain impact.