In view of the problem that the current 180° turning pool of the fishway has poor flow condition and affects the fish's upward tracing, the water flow condition was improved by extending the length of the upstream and downstream of the turning section and adding the staggered guide plate. Based on the study of a certain vertical slot fishway, numerical simulation was used to research on the distribution of flow regime, velocity, turbulent kinetic energy and turbulent dissipation rate of four turning pool structures. The results indicate that extending the length of the upstream and downstream of the turning section and adding the staggered guide plate can effectively guide the mainstream to center, maintain the stability of the mainstream and avoid the formation of a large-scale recirculation zone, and it is beneficial to migratory fish. The results of this study can provide reference for the reconstruction and design of fishway.

In order to study the degradation of mica-quartz schist under the action of dry-wet cycles, which widely distributed in Shiyan, Hubei province was taken as the research object. The hydroscopicity test, wave velocity test and scanning electron microscope test were carried out on the samples under the action of dry-wet cycles, respectively, to reveal the law and mechanism of physical deterioration. The test results show that the water absorption increases greatly, the wave velocity decreases and gradually tends to be stable with the increase of the number of dry-wet cycles. Besides, the surface of the sample was gradually disseminated into reddish-brown, and the foliation was gradually cracked and connected. Finally, the flake particles became more, round and granulated, the number of cracks increased and the micro-fractures gradually expanded, so the water absorption rate increased and wave speed decreased of mica-quartz schist under the action of dry-wet cycles.

In order to qualitatively and quantitatively grasp the influence of the installation elevation of horizontal water stops at transverse joints on the structural stress of the bulb tubular power house, taking a certain engineering project as an example, a three-dimensional finite element model of the powerhouse was established to analyze the stress of the structure on the condition of the horizontal water stops changing within a certain range. The results show that the installation height of horizontal waterstops has a significant impact on the stress of structure, and an appropriate installation height of horizontal waterstops can improve stress of structure. Taking into account various factors, the optimal horizontal water stop installation height is 70% of the installable height, which can provide a reference for the design of the transverse joint water stop of the bulb tubular power house.

In order to improve the search efficiency of the NSGA-Ⅱ algorithm, this paper introduced an arithmetic crossover operator with stronger global search ability and faster convergence speed to replace the simulated binary crossover operator used in the original NSGA-Ⅱ algorithm. Based on this, an improved NSGA-Ⅱ algorithm was proposed, the G_D index was used to evaluate the convergence capability of the multi-objective Pareto solution set. The method was applied to the research of Fenhe Reservoir water supply and ecological collaborative optimal scheduling to verify its effectiveness. By comparing the Pareto solution sets generated by different algorithms and various indicators of reservoir operation, and compared with the traditional algorithm, the number of iterations to reach the convergence state after the improved algorithm was reduced by 100 generations and the convergence time is shortened by 7.76%. The water shortage rate of each department under the condition of non-optimization was decreased, of which the effect of agricultural water shortage rate is the most significant, decreasing by 13.20% to 14.52%, and the total water supply increased by 0.268 to 0.303 million cubic meters. This paper verified the effectiveness of the improved algorithm and optimized scheduling, and provides an optional new idea for multi-objective optimal scheduling of reservoirs.

The excavation of the foundation, the process of dam construction and the water level variation in foundation have significant effects on the displacement of the foundation and structure of a sluice dam on deep overburden. A finite element simulation method for the coupling of seepage and deformation during the whole process of the dam construction and operation was proposed to treat the foundation of a dam in Jinsha River. The results show that the foundation settlement caused by the dead weight of the filled concrete body of about 1 m height can be offset by 3 m height groundwater level rising in the foundation during the sluice construction. The change of groundwater level has a significant impact on the displacement increment of sluice dam during the construction period. The coupling simulation of seepage and deformation of the sluice dam in the whole construction and operation process was realized, which has supported the engineering design of the dam foundation treatment.

As a special structure connecting core wall and foundation of asphalt concrete rockfill dam, its stress state is very important to the stability of the dam. Taking the asphalt concrete core rockfill dam of Chongqing Miaotang under construction as an example, the maximum section of the dam was selected to establish a two-dimensional model for finite element calculation, and the stress distribution of the foundation under three different forms of unembedded bedrock, semi-embedded bedrock and fully embedded bedrock was discussed. The results show that there is a strong correlation between the embedment depth of the base in the bedrock and the tensile stress inside the base. During the period of water storage, the difference of tensile stress between different arrangement forms can reach up to 334%. Meanwhile, as the corridor was affected by the larger tensile stress inside the base during the period of water storage, it was easy to cause tensile damage. By changing the position of the corridor in the base, the tensile stress around the corridor can be reduced to avoid the damage of the corridor. After the location of the corridor is changed, the surrounding tensile stress can be reduced by up to 87% compared with the original.

Lakes are highly susceptible to eutrophication due to their long-term closed or semi-closed status and poor hydrodynamic conditions. This paper constructed a hydrodynamic-convective diffusion model with MIKE21 software by considering the influence of rainfall on the spatial and temporal distribution of TN concentration in the Yilong Lake. The model simulated the hydrodynamic conditions under different inlet opening and closing conditions and different flow diversion schemes. The improvement of TN concentration based on the flow velocity distribution of the lake flow field was discussed. The results show that the hydrodynamic conditions and the water quality of the lake can be effectively improved by setting up water diversion inlets and increasing water diversion flow. The overall effect of diverting water from the Chenghe alone is better than diverting water from the Chenghe and Longgang River together. Under the scheme of separate diversion from the Chenghe, when the water diversion flow was double, the overall flow rate of the lake was increased by 44.04% and the TN concentration decreased by 52.78%, with the best effect of hydrodynamic optimization and water quality improvement, but the efficiency of water quality improvement per unit of water recharge is reduced. This research could provide some references for similar projects.

To accurately evaluate the comprehensive utility tunnel under river shield tunnel construction safety, reduce the safety accidents in the construction process, based on the method of risk breakdown structure (RBS), risk evaluation index system of four first-level indicators was constructed including engineering geological risk and comprehensive utility tunnel itself risk, environment risk, construction risk management. Based on the linear combination of interval number analytic hierarchy process (AHP) and indicator correlation method (CRITIC), the comprehensive weight was determined. Based on matter element theory, the weighted average relation degree was calculated to determine the final evaluation result. This method was applied to the comprehensive pipe corridor project of Yueyang Avenue sewage treatment at the Wangjia River section. Monte Carlo method was used to analyze the sensitivity of 15 basic indexes based on matter-element theory. The research results show that the construction project of Yueyang Avenue sewage treatment comprehensive pipe corridor at Wangjia River section is medium-risk, which is consistent with the actual situation. The sensitivity analysis shows that the surrounding rock strength and the buried depth of tunnel are more sensitive. The research results can provide a basis for the safety control decision and measure making of the project.

Affected by the changes of East Asian monsoon and human activities, the hydrological processes in the southeast coastal area have been changed, and the rational development and utilization of regional water resources are facing challenges. Taking Feiyunjiang as an example, the variable parameter Budyko equation based on the moving average treatment was constructed to analyze the runoff change in the basin, and the future runoff change trend was predicted qualitatively combined with the CMIP5 model. The results show that the time-varying Budyko model is much better than the constant parameter Budyko model in the simulation of annual runoff. The hydrometeorological elements in Feiyunjiang Basin showed an upward trend after eliminating the influence of cycle. The contribution rate of climate to runoff variation in the Feiyunjiang Basin reached 85.56%, and showed a downward trend. Compared with before 2000, the contribution rate of the underlying surface to runoff change increased by 6% from 2000 to 2020. At the same time, the influence intensity of climate on runoff change changed sharply. The influence of the underlying surface on runoff reduction was weakened. In addition, under the RCP4.5 scenario, the runoff in the Feiyunjiang Basin will show a decreasing trend in the future. The research results can provide theoretical support for regional water resources planning.

In order to explore the evolution of rainfall at multiple time scales, this paper takes the Changtan Reservoir in Jiaojiang River Basin as an example and classifies independent rainfall events based on rainfall data from 1960 to 2019. The evolution of rainfall event elements is discussed from four perspectives of rainfall event scale, seasonal scale, changes in annual trends and interannual decadal change. The results show that the extreme rainfall events has strong rainfall and long rainfall duration; The rainfall duration of typhoon rainy season is shorter and the rainfall intensity is greater than that of the plum rainy season, and the variation of rainfall distribution is greater; The annual trends of rainfall event elements are similar between the two stations during the plum rainy season, but the annual trends of rainfall duration and rainfall intensity are significantly different between the two stations during the typhoon rainy season; The rainfall events of the two stations in the plum rainy season have a good response to El Nino events, while the annual rainfall of El Nino/PDO- in the typhoon rainy season is abnormally small, which is prone to drought. El Nino/PDO+ annual rainfall is abnormally high and is prone to appear flood disaster.