This study analyzed the mechanism of groundwater gushing from Quaternary boreholes at Aishan section of the lower reaches of the Yellow River in autumn floods. Groundwater level analysis, meteorological analysis, runoff analysis of the Yellow River, combined with isotopic analysis of groundwater and surface water samples were used. The results show that the average groundwater level was increased more than 3 m, which reduced the groundwater runoff. The increase of groundwater level was the basic factor of groundwater gusher. Continuous high water level of the Yellow River and the intensive water replenishment of the Yellow River to groundwater directly led to the groundwater gushing. The warning groundwater level of wells near Aishan section of the lower reaches of the Yellow River was 39.5 m within the 500 m outside the dike. This paper provides a basic understanding for preventing groundwater gushing from wells outside the levee of the Yellow River, and it is helpful for the protection of the levee of the Yellow River.

For the intersection problem of the outlet pipe shared by adjacent units of pumping station, three schemes for the intersection of the outlet pipe of the adjacent units was proposed based on the original scheme of the pump station. The influence of different intersection forms of the outlet pipe on the hydraulic performance of the pump station pipe was investigated with numerical simulation. The results show that the hydraulic losses of plan 2 and 3 were reduced by about 50% compared to the original plan. The flow field distribution before the junction point of the outlet pipes was improved obviously by the three optimization schemes. In the middle flow surface, the pressure and streamline distribution characteristics of plan 3 were better. Compared with the original scheme, plan 1 and plan 2 can improve the flow field of unit 2 and the vortex and secondary flow were reduced before the intersection point. After the intersection point, the flow field distribution of plan 2 was smoother and the hydraulic performance was better. Both the hydraulic performance of each scheme and construction were considered, plan 3 was finally determined as the optimal scheme.

Aiming at the low natural moisture content of natural wide graded gravel anti-seepage soil material in 300 m level high core wall rockfill dam, field contrast test between the process of “belt conveyor filling water + stacker heap + bin stuffy material” and the process of “layered paving + pipe network water + bin stuffy material” was carried out to verify the rationality and feasibility of the relevant filling water process. The test results show that the combination process of belt conveyor with water is superior to the pipe network stratified water process, mainly manifested that the belt conveyor automatic water system can achieve real-time, efficient and accurate automatic water filling soil; After water replenishment, the soil material is transported by the belt and piled by the stacker, which can realize automatic and uniform piling. After adding water to soil material, the moisture content inside the soil material is basically stable during 3-4 days of smother, and the time required for smother is short. This paper also put forward the improvement measures of water filling process of belt conveyor. The improved process of "water filling of belt conveyor + stoker + silo boring" can provide reference for soil water content adjustment of similar earth-rock dam.

The evaluation of carrying capacity of water resources in the middle reaches of the Heihe River is important to promote the efficient use of water resources and sustainable economic development of the region. This paper quantitatively analyzed the dynamic changes of the water resources carrying capacity of the middle reaches of the Heihe River from 2000 to 2020 by selecting 10 evaluation indexes and using the fuzzy comprehensive evaluation model. The results show that the water resources carrying capacity of the region is between 0.3 and 0.5, with the highest value reaching 0.471 in 2020, and the water resources carrying capacities are in a bearable state. In order to improve the rational and efficient use of water resources, the middle reaches of the Heihe River should adjust the water use structure and strengthen the development of water-saving economy and ecological environmental protection.

The rise and fall of reservoir water level will make the water storage environment of bank slope rocks different at different heights and water levels, and the types of water rock interaction are also different. Based on this, the deterioration test of rock mechanical properties of bank slope in water rock interaction zoning was carried out. The results show that the compressive and tensile strength of rock samples decrease with the increase of test cycle, showing a deterioration trend from fast to slow. With the advance of water rock interaction cycle, the shear failure characteristics become more and more obvious in the compressive and tensile tests of rock samples; The microstructure of rock sample gradually transits from dense to loose, porous and multi crack structure. Under different water rock interaction, the mechanical properties and microstructure deterioration degree of rock samples ranks thermal wet cycle > dry wet cycle > long-term immersion. The results can provide ideas for the long-term stability analysis of bank slope based on water rock interaction zoning.

Water environment safety has always been an important issue that plagues the healthy development of country's social economy. Low-impact development technologies have good resilience in dealing with water environment safety issues. Taking Cangzhou China-Europe Green Industrial Park as the research object, the rainstorm flood model and the rainwater resource utilization benefit model were established. The study found that green roofs have an obvious control effect on ground runoff. The reduction rate and control rate of the total runoff are 56.31% and 68.32%, respectively, and the peak flow reduction rate is 48.58%. The control rate for pollutants of TP, TN, SS and COD is 72.92%, 74.82%, 74.44% and 73.89%, respectively. However, with the increase of rainfall intensity, the runoff control rate and the pollutant concentration control rate decreased, showing a significant negative correlation between the fourth and fifth power functions. After calculation, green roof can produce better economic and environmental benefits.

In order to reveal the pollution characteristics of heavy metals in surface sediments in the upper reaches of the Zhanghe River, the chemical fractions and contents of Cr, As, Cd and Pb in 32 samples were determined. The potential ecological risks were assessed by rations of secondary phase and primary phase, and risk assessment code method. The correlation analysis was used to analyze the sources of heavy metals. The results show that the average contents of heavy metals Cr, As, Cd and Pb are 91.51±24.30, 9.81±3.05, 0.12±0.05, 18.30±5.43 mg/kg, respectively, and only the average contents of Cd do not exceed the background value. Only the content of Cd does not exceed the background value. The exchangeable fraction of Cd is larger than Cr, As, and Pb, and its biochemical activity is relatively high. The potential risks of heavy metals are sorted as Cd>Pb>As>Cr, and the risks are mainly concentrated in the source of Zhuozhang River and the west headwater of Qingzhang River. These four heavy metals mainly come from mineral exploitation, and mining activities contribute to the content and potential risks of heavy metals.

Investigating the effect of spacing on the effect of staggered-slip permeable spur dike on flow mitigation can provide a theoretical basis for the design of modern shore protection projects. The CCHE2D software was used to conduct a two-dimensional numerical simulation study of the solid flume model in the Xinqiman section of the Tarim River. And then the effect of different spacing on the water surface line, flow velocity and bed shear stress distribution in the upstream permeable spur dike area under the action of staggered-slab permeable spur dike was analyzed. When the relative dam length ratio is 0.21, and the inflow and dam length remain unchanged, the larger the spacing, the better the uniformity of flow and velocity behind the upstream permeable spur dike, and the lower the value of water level and shear stress in the riverbed. When the spacing is 5 times the effective dam length, the flow velocity, water level and riverbed shear stress behind the upstream permeable spur dike tend to be stable. The results of the study can improve the theory of flow mitigation effect in the action area of inserted permeable spur dike.

In recent years, rainstorm and flood disasters occur frequently in the basin. Accurate and reliable flood forecasting is an important measure to effectively prevent and resist mountain torrents. Taking Lushui basin as the research area, this paper constructed the HSPF semi-distributed model. Choosing the representative floods in the flood data of the basin from 2013 to 2020, the calibration and verification of the model parameters were carried out. The accuracy of flood simulation was evaluated by using indexes of certainty coefficient and relative error. The results show that the model has a good performance in the field flood simulation of Lushui basin. The qualified rates of peak time and peak discharge of 15 flood simulations are 100.0% and 80.0%, respectively, the qualified rates of flood volume and runoff depth are 93.3%, and the average value of certainty coefficient is 0.80. The overall prediction accuracy reaches class B, indicating that the HSPF flood prediction model has good applicability in Lushui basin. The research results can provide basis for flood forecasting in this area.

Aiming at the problem of failure path analysis of high arch dams, the current numerical simulation methods still do not take into account the tensile and compressive damage characteristics of dam concrete. Therefore, the concrete damaged plasticity (CDP) constitutive model was used to analyze the damage and failure characteristics of the Laxiwa arch dam under the conditions of static overload, sudden temperature drop and maximum credible earthquake. The results show that the dam body mainly suffers from the tensile failure of concrete at the dam heel and bank slope dam foundation under overload conditions, and loses its bearing capacity after the damage penetration zone is formed; Under the condition of sudden temperature drop, the concrete of the dam body may cause tensile damage in the surface hole and the 1/4 arch dam crest, arch end and dam heel area; While under the earthquake condition, the surface hole near the crown beam of the dam crest downstream surface is mainly used for tensile damage. Tensile failure is dominant, and a horizontal band-shaped failure area is gradually formed and the bearing capacity is lost. The research results clarified the possible damage characteristics and failure paths of the Laxiwa arch dam, and provided a reference for determining the key parts of the Laxiwa arch dam structural safety monitoring analysis.