Abstract:On the basis of defining the risk connotation and requirements of shoreline development and utilization, a risk assessment index system for shoreline development and utilization was constructed, including 20 indicators in the four aspects of water pollution, ecological environment, engineering safety, and management and emergency response capabilities. The analytic hierarchy process and the entropy method were used to determine the subjective and objective weight, respectively.The combined weight was obtained through the principle of minimum relative information entropy. Based on the gray relational improved matter element analysis method, a risk assessment model for shoreline development and utilization was established, which was applied to the Nanjing section of the Yangtze River. The results show that the improved matter element analysis method can effectively evaluate the risk level of shoreline development and utilization with realistic assessment outcome.The shoreline of Nanjing section has an overall low development and utilization risk with good management, but preventing ecological environmental risks should be focused on. The risk level of shoreline development and utilization can be further reduced by optimizing the layout, implementing the cleanup and remediation, carrying out the ecological protection and restoration.

Abstract:Based on the data of MODIS-NDVI, air temperature, precipitation and atmospheric circulation index from 2000 to 2019, the dynamic evolution characteristics of vegetation in Liaoning Province under the influence of climate and human activities were discussed by using trend analysis, correlation analysis, path analysis and residual analysis. Combined with the superposition of trend coefficient and Hurst index, the future change trend of vegetation was analyzed. The results show that the average annual NDVI increased at a rate of 0.004/a in Liaoning Province, and the overall vegetation status was good. Spatially, the vegetation coverage in Liaoning Province was mainly improved, with slight degradation in Liaoyang and Shenyang citys. The response of vegetation to precipitation in Liaoning Province was higher than that of air temperature, and the impact of human activities on vegetation in Liaoning Province changed from negative to positive from 2000 to 2019. In the reverse continuous change of NDVI in Liaoning Province, the degraded area accounts for 55.24% of the total area, which shows the spatial distribution of NDVI scattered in the whole region. In the future, the efforts of vegetation conservation and returning farmland to forest should be strengthened. Keywords: human activity; vegetation variation; NDVI; hydrothermal condition; residual analysis; Hurst index; Liaoning Province 〖FL

Abstract:To understand the influence of water and sediment conditions on scouring and silting characteristics of the Dahukou River,based on a two-dimensional numerical model of water and sediment, the scouring and silting of the river reach under different water and sediment conditions in typical years of flood, normal and dry were simulated, and the changes of sediment scouring and silting and river morphology variation were analyzed. The results show that the original scouring and silting of the Dahukou River is represented by the first, second and fourth sections of silting, and the third section of scouring. The change of water and sediment conditions makes the riverbed scouring and silting of the Dahukou River generally show the trend of silting upstream and scouring downstream. The scouring and silting of the river section are characterized by silting along the left bank and scouring along the right bank with enhanced degree of scouring and silting. With the change of incoming water and sediment in the upstream, the Dahukou River gradually evolves into a single and curved channel, which may have certain impacts on the flood control. Keywords: water and sediment conditions;river morphology variation;river scouring and silting; Dahukou River 〖FL

Abstract:In order to explore the influence of log waterfall structure on temperature field of river hyporheic zone, a two-dimensional coupling model of surface water and groundwater was established by using the finite element software COMSOL Multiphysics, and the influence effects of log structure height, spacing and quantity on the temperature field was explored. The results show that the addition of log waterfall structure in the river can change the pressure distribution in the hyporheic zone, and increasing the height, spacing and the number of log structures can magnify the maximum pressure of the river bed. As the height of log waterfall structure increases, the temperature of the area below the logs is affected more widely by the surface water temperature. Thermal buffering of the hyporheic zone can be enhanced when the spacing and number of log waterfall structure increase. Variation of log structure parameters can affect the temperature field and thermal buffering in the hyporheic zone, resulting in thermal heterogeneity, which may increase the diversity of benthos and aquatic habitats. Keywords: river hyporheic zone; log structure; surface water-groundwater coupling model; temperature field; thermal heterogeneity 〖FL

Abstract:To improve the hydrodynamic simulation accuracy of river sections with weirs, a hydrodynamic model considering the complex operation of rubber dams was established. Based on Preissmann four-point finite difference implicit scheme discretization method, a rubber dam numerical simulation calculation process was constructed to make logical judgments, and the substitution method was used to handle the river channel containing rubber dams.One-dimensional hydrodynamic discretized equations of the river channel were then solved. The model was verified using the actual flood process of the rubber dam in the Pihe River Basin, and two different working conditions of dam collapsing and non-dam collapsing were simulated in view of a typical flood process in the Pihe River Basin in recent years. The results show that considering the rubber dam collapsing simulation, the measured data of the Pihe River Basin can be better fitted. The model can effectively simulate the flood evolution process under the influence of rubber dam scheduling and the simulation accuracy during the flood period can be improved. Keywords: rubber dam; hydrodynamic model; flood evolution; numerical simulation; Pihe River Basin 〖FL

Abstract:To investigate the cavitation characteristics of a novel inclined axial flow pump with a single flow rate of 50.m3/s,based on an axial flow pump test platform, the energy characteristics and internal flow characteristics of the inclined axial flow pump under different blade angles were analyzed.The occurrence law of cavitation phenomenon for this kind of pump was summarized and reasonable design parameters and operation parameters were determined.The results show that the blade angle and head are closely related to the cavitation performance of the pump, and the cavitation performance of the pump is poor when running at high head or ultra-low head, which is easy to produce cavitation. The angle of pump blades can be reduced by variable propeller technology, so as to improve the cavitation performance and obtain better operation stability. Keywords: inclined axial flow pump; cavitation characteristics; blade angle; variable propeller technology 〖FL

Abstract:To explore the dry-wet durability of solidified sludge in the application of landfill cover, solidification strength tests of soda residue-slag-lime were performed under the condition of dry-wet cycles. The results show that the hydration reaction continues with the increase of dry-wet cycles, leading to increasing amount of hydration products including ettringite, hydro aluminite and calcium silicate hydrate, decreasing pore volume, and dense microstructure. In general, the unconfined compressive strength has an increase trend with the dry-wet cycles. The strength after the seventh dry-wet cycle is 1.16 to 1.45 times of that before the cycles. From the perspective of microstructure and unconfined compressive strength, sludge solidified with soda residue-slag-lime has good durability under dry-wet cycles. Keywords: soda residue; solidified sludge; dry-wet cycle; unconfined compressive strength; dry-wet durability; microstructure 〖FL

Abstract:Aiming at the prominent problems of stability and leakage of geomembrane in plain reservoirs, a seepage finite element model was established in combination with a practical project of a plain reservoir with geomembrane in the Pearl River Delta. The damage and defects of geomembrane during construction and operation were simulated to analyze the influence of geomembrane defects on the seepage stability and leakage at the bottom of the reservoir. The results show that when there is no water in the plain reservoir, the geomembrane defects have little influence on the seepage field and the stability of the geomembrane at the bottom of the plain reservoir. When the water level inside the reservoir or in the outside river is in a high level, the pressure head under the defect membrane is the highest, but the geomembrane can still be stable. When the geomembrane defect is 30 m away from the blind drainage pipe and the diameter of the defect hole is 0.5 to 3.0 cm, the diameter variation of the defect hole has little effect on the leakage. However, the number and location of defects have a significant influence on the total leakage. Keywords: plain reservoir; geomembrane; defects; seepage field 〖FL

Abstract:To improve the reliability and accuracy of the calculation and analysis for the stress and deformation of the anti-seepage geomembrane at the excavation and filling boundary from the inlet and outlet of a pumped storage power station upper reservoir, the submodel method was adopted to establish a local submodel for the whole model near the boundary of excavation and filling based on the calculation and analysis of the whole finite element model of the reservoir basin backfill. At the same time, this method was used to analyze the effect on reducing the local large strain of geomembrane at the cut fill boundary by the combination of adding additional model area in the overall model and changing the laying modes of geomembrane in the local sub model. The results show that the above measures can reduce local strain so as to meet engineering requirements. Specific laying modes of geomembrane should be analyzed by water head and modulus of the support layer. Keywords: local deformation of geomembrane; submodel method; support layer;pumped storage power station 〖FL

Abstract:In order to study the rule of turbulence characteristics and tail vortex zone scale around a square pier, the flow structure surrounding a square pier was measured by the technique of particle image velocimetry

Abstract:To discuss the influence of ship waves on the cross-section size of a navigation tunnel, a numerical model of ship wave propagation in navigation tunnel was established based on the open source package FUNWAVE-TVD of completely nonlinear Boussinesq equation. The spatial and temporal distribution of maximum ship wave height and lateral velocity in navigation tunnel was emphatically analyzed, and the influences of ship draft, Froude number, water depth and width of navigation tunnel and ship type on the maximum ship wave height and lateral velocity in navigation tunnel were discussed. Based on the duration analysis of ship wave height, an empirical formula for calculating the vertical section size of navigable tunnel was proposed. Combined with the transverse velocity generated by ship wave breaking and the current inland navigation standards, the reference of water flow conditions for safe navigation in navigable tunnel and the construction requirements of tunnel transverse section size were given. The results show that, due to the reflection of the vertical walls on both sides of the tunnel, the coda wave is easily affected by the navigation tunnel bank wall to form a large wave height, and the closer it is to the bank wall of the tunnel, the lower the maximum transverse velocity is. When the ship reaches the design draft, the ship wave is not easy to break, and the maximum transverse velocity is low. Keywords: ship wave; navigation tunnel; cross-section size; Boussinesq equation; FUNWAVE-TVD 〖FL

Abstract:A 230.m high concrete faced rockfill dam

Abstract:In order to improve the accuracy and efficiency for the inverse of physical and mechanical parameters of high arch dams, Jaya algorithm and Gaussian process machine learning theory were introduced into the field of dam safety monitoring, and an arch dam parameter inverse analysis method based on the Jaya-Gaussian process regression surrogate model was proposed. The Gaussian process regression surrogate model was used instead of the traditional finite element calculation, and three intelligent optimization algorithms were used to optimize the parameters. The results show that compared with PSO and GWO algorithm, Jaya algorithm not only has high inversion accuracy, fast convergence speed, and good stability, but also has good stability, and the proposed inverse analysis strategy saves more than 80% time compared with the inverse analysis method that directly calls finite element calculation. This method can not only meet the requirements of calculation accuracy, but also greatly reduce the calculation time, providing an efficient method for the inverse analysis of physical and mechanical parameters for high arch dams. Keywords: high arch dam; displacement inverse analysis; Gaussian process regression; surrogate model; Jaya algorithm 〖FL

Abstract:Based on a deep foundation pit in water-rich silt stratum inside a subway station test section of Taiyuan, the numerical calculation software FLAC3D was adopted to simulate the bottom reinforcement, pit precipitation and excavation. The calculation results were compared and validated with the field measured data. It shows that the high-pressure jet grouting combined with double liquid grouting can effectively prevent groundwater from seepage into the pit, and the groundwater level around the foundation pit varies little during the whole construction process. During foundation pit excavation, the maximum settlement point nearby is located at about 5.m to 10.m away from the underground diaphragm wall, and the maximum influence range is less than twice of the excavation depth. In each excavation stage, the deformation of diaphragm wall presents a parabolic form of high in the middle and low on both ends and the maximum lateral displacement is 22.1.mm, located at 1/2 to 2/3 of the excavation depth. Increasing the elastic modulus of soil can significantly suppress the uplift deformation at the bottom of the pit, but has little influence on the surface settlement around the foundation pit and the horizontal displacement of the diaphragm wall. Therefore, it is not advisable to blindly increase the cement content to avoid waste in actual construction. Keywords: water-rich soft ground；deep foundation pit；combination grouting；groundwater seepage；FLAC3D；elasticity modulus 〖FL

Abstract:The source region of the Yellow River

Abstract:To study the influence of dam removal on river ecological environment, the impacts of dam removal on hydrological regime, sediment transport, fluvial geomorphology, river water quality, habitat quality and biodiversity were introduced. Progress on the response relationship among river physical chemical characteristics and important ecological characteristics was summarized.The impact of dam removal on ecological environment has spatiotemporal complexity and each ecological factor influences each other. Hydrological regime change is the trigger of all ecological responses and sediment transport is found to be the key factor affecting the ecological environment. Considering the long-term continuous development and utilization of rivers, the study of sediment transport and release of sediment pollutants, the prediction of the spatiotemporal variation of river water quality after dam removal, and the analysis of the response relationship between ecosystems at the watershed scale are important in the evaluation and decision-making of dam removal.

Abstract:In order to provide reference for seawall construction under the background of global warming, sea level rising and sustainable development, a comprehensive review on the research progress and development history of seawall construction in Jiangsu Province was summarized. The seawall construction history in Jiangsu includes the ancient seawall stage, the slope seawall stage, the standard seawall stage and the ecological seawall stage. The design standard, embankment line site selection, structural type and protection engineering were proposed. Ecological measures including seawall ecological transformation, construction of saltmarsh wetland ecosystem and submerged reef are the development directions of seawall engineering construction in the future. Keywords: muddy coast; selection of embankment type; embankment line layout; ecological seawall; Jiangsu Province 〖FL