Abstract:Based on the statistical data of the comprehensive reform of agricultural water price from 2016 to 2018, the regional difference in the progress of the comprehensive reform of agricultural water price in China was analyzed from the perspective of three regional divisions, including northern and southern China, eastern-central-western China and seven regions. The reform periods for completion was forecasted, and suggestions to promote comprehensive reform of agricultural water price in China were put forward.

Abstract:An index system suitable for the evaluation of water network connection projects in the Dongting Lake area is proposed, which includes 12 key indexes in four factor layers, i. e. , structural connectivity, functional connectivity, ecological and environmental benefits, and socioeconomic benefits. This evaluation method is applied to comprehensively assess the water network connection project in the urban area of Lixian County. The results show that this project is excellent and the evaluated result is consistent with engineering practice. The structure and connectivity pattern of rivers and canals should be further optimized, and the transformation of ecological and environmental benefits to socioeconomic benefits should be promoted.

Abstract:Basic equations of normal and critical water depths for standard-type heteromorphic elliptic section are transcendental which cannot be solved directly. On the basis of summarizing the hydraulic factor calculation formulas of standard-type heteromorphic elliptic section, dimensionless parameters and the method of curve piecewise fitting optimization analysis were introduced to propose the explicit calculation formulas for solving the normal and critical water depth of standard-type heteromorphic elliptic section. The results of error analysis show that the absolute values of relative error of the normal and critical water depth formulas for a typical cross-section were less than 0. 362% and 0. 288%, respectively, which were within the common range in real engineering applications.

Abstract:Because the facts that numerical models based on Reynolds averaged Navier-Stokes equations cannot accurately simulate the 3D flow structures of compound open-channel flows and the high computational cost of traditional large eddy simulation (LES) method, a three-dimensional numerical model with wall-modelled large eddy simulation (WMLES) was developed to simulate the flow structure in a compound open-channel flow with a depth ratio of 0. 5 in the present study.The numerical model was verified against the detailed experimental data of Tominaga et al. and the existing results of LES.The results show that the model with WMLES is accurate in the simulation of mean velocities, bed shear stress, turbulence intensities, turbulent energy, Reynolds stresses and secondary currents. The model is reliable in 3D numerical simulations of compound open-channel flows. Comparing to the traditional LES method, the WMLES method is able to significantly reduce the computational cost.

Abstract:High concrete gravity dams operating perennially under the condition of high water pressure are prone to hydraulic fracturing failure. In this study, the hydraulic fracturing characteristics of the dam heel crack in a high concrete gravity dam were analyzed, the influence of water pressure inside the crack on the expansion of hydraulic fracturing crack was studied, and the stability of hydraulic fracturing crack and anti-sliding stability of dam foundation surface were discussed. The results show that if the initial crack is 3.0 m away from the dam heel and the depth of the crack is 2.0 m,the ultimate bearing capacity of the dam body under the water pressure in the crack decreases by 17.6% compared with that without considering water pressure inside the crack. If the initial horizontal crack depth is 2. 0 m and the distance from the crack to the dam heel is less than 5. 0 m, the crack of the dam body is in the tension shear fracture mode. If the initial horizontal crack is located at the dam heel position, the safety coefficient of anti-sliding stability of dam foundation surface in the joint under the action of water pressure decreases obviously, with a decreasing rate of 8 times compared to the case without considering the water pressure inside the crack. The effect of water pressure inside the crack is unfavorable to the crack stability and anti-sliding stability for gravity dam heel.

Abstract:Based on the GMO fluid-solid coupling model and the k-ε turbulence model, a three-dimensional numerical model was established to simulate the generation and propagation process of landslide-induced impulse waves, by using the VOF method to trace the free surface of the fluid on FLOW-3D platform. The numerical results are in good agreement with the existing measured data. The effects of fluid-solid interaction and the motion of the landslide body on wave generation and propagation were analyzed. The simulation results show that the first wave height and the propagation velocity of the impulse waves can be obviously increased by ignoring the effect of the water on the landslide. The fluid-solid interactions affect the features of impulse waves mainly during the phases of the landslide contacting the water surface to the complete immersion. Through adopting the fluid-solid coupling model in the phase of the landslide entering into the water, and then specifying the motion trajectory when the landslide is completely submerged, the obtained simulation results can also accurately capture the generation and propagation characteristics of the impulse waves.

Abstract:The vegetation concrete ecological base material was selected as the research object, and the samples with six levels of initial water contents of 13%, 19%, 25%, 31%, 37%, 43% were prepared. The dehumidification and humidification processes were simulated by drying method and stacking saturation method respectively. The macroscopic expansion and shrinkage of samples were measured by soil shrinkage meter, and the geometric characteristics of cracks on the surface of samples were extracted by Matlab software. The structural evolution law under the action of drying-wetting cycles was studied. The results show that the drying shrinkage process of the samples at laboratory temperature is manifested as three stages, including sharp shrinkage stage, smooth shrinkage stage and stable stage. During the drying-wetting cycles, the shrinkage and expansion of the samples are almost equal. The crack development process is mainly reflected in the increase of crack width, total length and total area with the increase of cycle times. If the initial water content is too low or too high, the wet expansion and dry shrinkage damage is easily occurred. The average crack width,crack total area, crack length and surface shrinkage of the samples with 31% initial water content are the smallest, which is the optimum water content in production practice.

Abstract:The combination of empirical model decomposition and long short-term memory network(EMD-LSTM)model was used to forecast the hydrological time series data. The median filter for data preprocessing was used first and then EMD was applied to decompose the time sequence. The LSTM model was used to prediction for each characteristic series from EMD, and each prediction sequence was superposed to obtain the final prediction result. Based on the data of the instantaneous flow, water velocity and water level per hour of a certain river in the South-to-North Water Diversion Project, the EMD-LSTM was used for modeling. The experimental results show that this method can realize accurate prediction of water level, water velocity and instantaneous flow for 12 h and 6 h continuously, has higher accuracy compared with the LSTM model and provides decision basis for the forecast of hydrological time series and the real-time dispatching of water resources.

Abstract:In order to improve the flood control and drainage efficiency of drainage pumping stations, an optimal scheduling model for a drainage pumping station in the polder area was established. Corresponding orthogonal test plan was formulated and the genetic algorithm was used to optimize and solve the testing scheme. The optimal dispatching scheme of maximum displacement under power consumption was obtained and the example shows that the orthogonal test method can effectively improve the flood control and drainage efficiency for drainage pump stations.

Abstract:In order to provide technical parameters for waterway regulation, wharf construction, flood control and lock design of the Minjiang River, in the absence of field data, numerical simulation, field observation and correlation analysis were used to calculate the lowest navigable water level in the downstream channel of Minjiang Shuikou Hydropower Station. Based on unstructured grid and finite volume method, a two-dimensional hydrodynamic numerical model was established from Shuikou Hydropower Station at the Minjiang River to the Mawei River, which was used to calculate the hourly water level at the downstream channel of the hydropower station. The hourly water level of the downstream channel was used to establish the correlation with the water level of Zhuqi, Wenshanli, Baiyantan and other long-term hydrological stations (base station). The cumulative frequency method is used to calculate the water level characteristic value of 90% of the cumulative frequency of the low tide as the design lowest navigable water level of the reference station. The calculation results show that the linear relationship of the hourly water level is well correlated between base stations and temporary stations with a correlation coefficient higher than 0.9, indicating a rational and reliable design lowest navigable water level.

Abstract:Considering the noise components in automatic monitoring data and the complex nonlinear relationship between dam deformation and environmental factors, a dam deformation monitoring model based on singular spectrum analysis(SSA) and support vector machine(SVM) optimized by particle swarm optimization(PSO) was proposed. SSA was used to decompose the measured deformation, and its intrinsic trend and periodic components were extracted and reconstructed. The complex nonlinear relationship between reconstruction deformation and environmental factors was then mined based on SVM optimized by PSO. The case validation results show that the model has good fitting and prediction accuracy and it can effectively mine the data characteristics inherent in the measured deformation, reduce the influence of noise components on the modeling accuracy, and has certain engineering application value.

Abstract:Aiming at the difficulty of visual monitoring for ships in the safety inspection of river courses, a visual measurement method for tracking the ship motion in river model tests and a UAV-based trajectory tracking method in real rivers were proposed based on the high-resolution color image recognition technology. The experimental results show that the maximum relative error between the model ship trajectory measured by visual monitoring and the real trajectory is -3.284%, meeting the requirements of river model experiments. The SURF method was applied to rectify the UAV images during the ship trajectory tracking process, effectively eliminating the effects of UAV position drifting on the tracking results, and the simultaneous visual tracking and monitoring of multiple ship targets were realized.

Abstract:Aiming at the serious damage to the Sandaojing main channel of the Shaanxi-Gansu-Ningyan Salt Ring Dingyang Yellow Project, six frost heaving observation sections are set up. Through the observation of main indicators such as air temperature, ground temperature, freezing depth, frost heave, and soil moisture content,the change process and law of each influencing factors are analyzed. It is proposed that the slope toe and bottom of the canal are the most severe parts of frost heave and deformation, and protection should be emphasized. The moisture content of the foundation soil is the decisive factor of frost heave damage. The key to reducing the frost damage of the channel is to reduce the moisture content of the foundation soil. According to the test results, it is proposed that the Sandaojing main canal adopts polystyrene board thermal insulation and anti-freeze heave measures during the renewal and reconstruction, and the 20 cm thick cast-in-place concrete curved slope foot and 5 cm thick polystyrene are used at the slope foot with the most severe frost heave damage. The full section adopts 0.3 mm thick omposite geomembrane to prevent seepage to reduce the high water content of the foundation soil caused by leakage, and the measures are implemented, and the effect is remarkable.

Abstract:The impacts of tideland reclamation on hydrodynamic environment near estuarine area were reviewed and evaluated. The hydrodynamic environment in the engineering water region can be changed by tideland reclamation, resulting in re-adjustment of the original stable river bed. Vast sediment accumulation can lead to the development of land area toward the sea, and coastlines can be altered. The effect of storage and dissipation of tidal energy by tidal flat can be lost, and the tidal range can be changed. Estuaries can be constricted and wetland orphology can be destructed by large scale reclamation, leading to possible reduction of flood discharge capacity of rivers and flood disasters impacted on surrounding towns. It is proposed that system evaluation should be performed for the impacts of tideland reclamation on hydrodynamics, estuary and coastline changes, flood and tide prevention so as to guide the efficient utilization and protection of tideland.

Abstract:In recent years, wetland evaluation has become a hot topic in environment research. With the enrichment of research content and methods for wetland environmental quality assessment, various mathematical methods and models are widely used. In this paper, evaluation methods of water environment, soil and ecosystems in wetlands were summarized at home and abroad. The uncertainty model of water quality evaluation, the biological effect method of soil risk evaluation and the index evaluation method of ecosystem were mainly concluded. Aiming at the shortcomings in the current study, it is pointed out that in the future, the real-time monitoring data should be automatically obtained by combining remote sensing technology and geographic information system, the dynamic evaluation model of water environment should be optimized, the establishment of wetland soil quality standard should be strengthened, and the coupling of multiple evaluation methods and the optimization of evaluation model should be further studied.