[Objective] The hydrological processes in the river basins of cold regions are complicated due to the combined effects of snowmelt, rainfall infiltration, and other factors. Hydrometeorological stations in the alpine mountains of Northwest China are scarce, and the lack of data limits the simulation and analysis of cold-region runoff. Meteorological data has become the main bottleneck in studying hydrological processes in the alpine mountains of Northwest China. [Methods] To address the lack of meteorological data in studying hydrological processes in the alpine mountains of Northwest China, the Ganhezi River Basin in Xinjiang was selected as the study area. Using the China Meteorological Assimilation Driving Datasets for the SWAT model(CMADS), the applicability of CMADS+SWAT for runoff simulation in alpine mountains was explored, and the water yield of different runoff components in the river basin was analyzed. SWAT-CUP was used to perform sensitivity analysis, calibration, and validation of model parameters, and the coefficient of determination(R²) and Nash-Sutcliffe efficiency coefficient(NSE) were used to evaluate the applicability of SWAT model. [Results] The result showed that:(1) the CMADS+SWAT model could effectively simulate the runoff process of the Ganhezi River Basin at the monthly scale, and R² and NSE were 0.87 and 0.72 during the calibration period, and 0.84 and 0.64 during the validation period, respectively.(2) Among the different runoff components, interflow had the highest multi-year average water yield proportion at 43.7%, followed by surface runoff at 43.3%, and groundwater had the smallest proportion at only 13%. [Conclusion] The CMADS+SWAT model can effectively simulate the runoff process in the Ganhezi River Basin at the monthly scale. The findings can provide a basis for runoff simulation and analysis in the alpine mountains of Northwest China.

[Objective] Urban flooding disasters are becoming increasingly severe, which drives the upgrading of urban drainage and flood control systems. To assess urban disaster prevention and mitigation capacity, it is necessary to conduct a systematic assessment of the effectiveness of urban drainage and flood control systems. [Methods] An integrated assessment method coupling social, natural, and infrastructure dimensions was developed based on the Driver-Pressure-State-Impact-Response(DPSIR) framework. By jointly analyzing external environmental constraints and internal conditions of urban drainage and flood control systems, a framework for constructing effectiveness assessment indicators was established. The Analytic Hierarchy Process-Fuzzy Comprehensive Evaluation(AHP-FCE) method was employed to quantify indicator weights and membership degrees, and integrated with a coupling coordination degree model to assess effectiveness levels. Using the central urban area of Jiujiang City as a case study, the effectiveness of urban drainage and flood control systems in 2017 and 2021 was compared and analyzed. [Results] The result showed that with the completion of the first-phase urban water-related projects, the coupling coordination degree of the five DPSIR dimensions in the central urban area of Jiujiang City increased from 0.771 to 0.901, achieving high coordination and enhancing system effectiveness. Key indicators including compliance rates of drainage pumps and gates, levees, and urban stormwater drainage increased by 0.45, 0.50, and 0.42 points respectively, significantly improving deficiencies in the state and impact dimensions. However, the construction of the drainage pipe network was relatively underdeveloped, and the impervious surface ratio showed an increasing trend, which would be a key focus for future management. [Conclusion] This framework helps identify weaknesses in urban drainage and flood control systems and provides guidance for planning and implementing urban stormwater management strategies.

[Objective] During reservoir impoundment, reservoir-bank slopes are prone to deformation and instability due to hydraulic effects, which may subsequently generate surge hazards and pose serious threats to infrastructure and human safety in the reservoir area. The evolution process of instability-induced deformation of accumulation-body slopes and the characteristics of surge generation under fluctuating water levels are revealed. [Methods] A giant accumulation body in the reservoir area of a hydropower station on the Yalong River was selected as the research object. Field geological surveys were conducted to obtain fracture occurrence and deformation characteristics. The entire slope deformation evolution process was simulated using discrete element numerical modeling, while surge heights were calculated using the China Institute of Water Resources and Hydropower Research(IWHR) method and the Pan Jiazheng method. The synergistic effects of sliding velocity, volume, and terrain conditions were analyzed. [Results] The result showed that the deformation of the accumulation body exhibited a three-stage evolution characteristic of “creep, constant velocity, and acceleration.” The strength degradation of rock mass at the slope toe(cohesion decreased by 35% to 65% and internal friction angle reduced by 18% to 22%) was identified as the main cause of deformation initiation. The stability of locked segments at elevations of 2 905.65 m and 2 978.08 m served as the critical threshold controlling the transformation of deformation stages. After their failure, the sliding body acceleration increased from 0.06 m/s² to 0.418 m/s². Surge propagation showed significant nonlinear attenuation characteristics. The maximum surge heights calculated by the IWHR method and the Pan Jiazheng method at the opposite bank were 80.68 m and 53.53 m, respectively; at the tunnel entrance were 15.1 m and 15.09 m, respectively; and at the dam site were 3.63 m and 1.13 m, respectively. The differences revealed the terrain amplification effect. [Conclusion] The deformation-surge coupling mechanism is manifested as a chain response of “hydraulic degradation-locked segment failure-abrupt change in sliding velocity-surge propagation, ” with the stability of locked segments being the core for surge disaster prevention and control. A theoretical basis for early warning of similar landslide surges in reservoir areas is provided by these result.

[Objective] To investigate the historical and future spatiotemporal variation characteristics of extreme precipitation events in the Tuhai-Majia River Basin, aiming to provide theoretical references for preventing potential future climate disasters. [Methods] Based on daily precipitation data from 26 national meteorological stations in the Tuhai-Majia River Basin over a 55-year period from 1967 to 2021, eight extreme precipitation indices were calculated using the RClimDex1.1 model. The Mann-Kendall(M-K) test, ANUSPLIN spatial interpolation, and wavelet transform were applied to analyze the changes in extreme precipitation indices. The NEX-GDDP-CMIP6 dataset was used to predict future climate change trends in the river basin. [Results] The result showed that:(1) from 1967 to 2021, all indices in the Tuhai-Majia River Basin showed increasing trends, except for consecutive dry days(CDD) and consecutive wet days(CWD), which showed decreasing trends. Significant abrupt changes were observed in maximum 1-day precipitation(Rx1day), very extreme precipitation(R99P), CWD, and CDD during the study period. Other indices showed no significant abrupt changes. All extreme precipitation indices exhibited notable periodic variations during the study period, with major cycles generally ranging from 2 to 4.8 years.(2) The extreme precipitation indices in the study area showed significant spatial variation. Some indices were strongly correlated with topographic factors. Total annual precipitation(PRCPTOT), total extreme precipitation(R95P), and R99P showed higher values in the southern part of the river basin, while Rx1day and maximum 5-day precipitation(Rx5day) had higher values concentrated in the northern part of the river basin.(3) Under different emission scenarios(SSP1-2.6, SSP2-4.5, SSP5-8.5) from 2015 to 2100, extreme precipitation events in the river basin were projected to generally show an increasing trend.(4) The cross-wavelet transform between extreme precipitation indices and climate indices showed different power levels. Among them, the cross-wavelet power between extreme precipitation indices and sunspot number(SN) was the strongest, showing high oscillation coherence and mostly negative correlation. [Conclusion] Overall, the variations in precipitation indices indicate that the region is becoming increasingly humid. There are significant north-south differences in extreme precipitation in the Tuhai-Majia River Basin. Future efforts should focus on optimizing differentiated disaster prevention systems in the northern and southern parts of the river basin and enhancing the monitoring, early warning, and response capabilities for extreme precipitation events to reduce disaster risks within the river basin.

[Objective] With increasing energy demand and growing concerns about climate change, the rational utilization of marginal lands for cultivating biomass energy crops has emerged as a research focus in recent years. Previous studies have demonstrated that cultivating perennial biomass crops on marginal lands significantly impacts regional climate change and food production. However, these investigations did not fully consider the interactive feedback between plant growth and climate change, leading to slightly insufficient reliability of the result. [Methods] To address the limitations of earlier studies, the coupled model CWRF-Bio Cro was employed to comprehensively consider the interactive feedback between plant growth and climate change, and to analyze changes in regional precipitation patterns and their physical mechanisms under two scenarios in the United States: cultivation of perennial biomass crops on marginal lands and maintenance of existing vegetation cover. [Results] The result showed that after cultivating perennial biomass crops on marginal lands, the regional total average daily precipitation increased by 6. 33 mm/day(0. 01%), with most of the increase occurring during spring, summer, and autumn in the central and western regions and during autumn and winter in the eastern region. This was primarily due to the significant enhancement of water vapor transport and latent heat flux in the region. The regional maximum daily precipitation decreased by 2. 1 mm(4. 39%), mainly in the central and eastern regions, Resulting from a significant decrease in sensible heat flux in these regions. Meanwhile, the frequency of precipitation events with an average daily precipitation greater than 50 mm/d decreased in the central and eastern regions, with the most pronounced reduction of 31 days(0. 24%) observed in events in the range of 50. 0 ~ 99. 9 mm/day. [Conclusion] In summary, planting perennial biomass crops on marginal lands can increase regional precipitation and reduce extreme precipitation. These findings highlight the critical role of biophysical feedback mechanisms in regulating regional climate and provide a scientific foundation for developing climate-adaptive land management strategies.

[Objective] To meet the demand for efficient and sustainable water resource utilization and to reveal the spatiotemporal evolution patterns and driving mechanisms of agricultural water resource utilization efficiency(AWRUE) in the context of carbon neutrality. [Methods] From an input-output perspective, an evaluation indicator system for AWRUE was constructed by integrating the “water-land-labor-fertilizer-machinery” input factors, covering agricultural output value, carbon sink, carbon emissions, and agricultural non-point source pollution. By coupling the super-efficiency SBM model, Malmquist index model, and standard deviational ellipse method, the spatiotemporal evolution patterns of AWRUE in nine provinces and regions of the Yellow River Basin from 2011 to 2023 were systematically revealed. The geodetector method was employed to quantitatively analyze the driving mechanisms and clarify their degree of influence on efficiency. [Results] The result showed that:(1) from 2011 to 2023, the average AWRUE in the nine provinces and regions of the Yellow River Basin increased from 0.54 to 1.03, and its center of gravity initially expanded northeastward and then shifted back southwestward.(2) The technological progress index was higher than the technical efficiency index(TC=1.049 > EC=1.001).(3) In 2011, AWRUE was predominantly driven by per capita water resources(q=0.98). Policy interventions became the core driving factor(fiscal support for agriculture, q=0.94; environmental protection investment, q=0.94) in 2015. In 2019, efficiency was driven by multidimensional coupling of resources, environment, and production. It further converged towards a policy-ecology nexus in 2023. [Conclusion] The AWRUE in the nine provinces and regions of the Yellow River Basin exhibits a three-phase pattern of “low-efficiency clustering—regional breakthrough—coordinated optimization”, with regional disparities narrowing and significant effects achieved in coordinated development. Technological progress(TC) serves as the core driver for efficiency enhancement. Slack variable analysis precisely identifies redundant factors, providing a scientific basis for optimizing resource allocation. Under the “dual-carbon” strategy, the evolution of AWRUE in the nine provinces and regions of the Yellow River Basin highlights a trend of strengthened coordination between efficient water resource utilization and low-carbon agricultural transformation. The driving mechanism undergoes a systematic transition from being dominated solely by natural endowments to multidimensional regulation integrating resources, economy, production, policy, and ecology.

[Objective] The rapid increase in industrial water demand during the urbanization process has led to increasingly severe water scarcity, making the coordination between economic growth and sustainable water resource utilization a critical challenge. [Methods] Taking 31 provinces(municipalities and autonomous regions) in China as the research objects, the dynamic decoupling effect and driving mechanisms between industrial water consumption and urbanization were systematically revealed from the perspective of spatiotemporal heterogeneity. By integrating Sen + Mann-Kendall trend test, the Tapio decoupling model, and the Logarithmic Mean Divisia Index(LMDI) decomposition method, the limitations of existing studies in long-term dynamic analysis and quantitative evaluation of policy response at the provincial level were addressed. [Results] The results showed that:(1) during the study period, significant variations in industrial water consumption were observed in most provinces of China. Provinces with a decreasing trend in industrial water consumption far outnumbered those showing an increasing trend, mainly concentrated in the southeastern coastal areas, northeastern regions, and southwestern regions.(2) During the 11th Five-Year Plan period(2006—2010), urbanization and industrial water consumption showed an expansive negative decoupling relationship. During the 12th Five-Year Plan(2011—2015) and 13th Five-Year Plan(2016—2020) periods, a strong decoupling was observed, with an overall improvement in decoupling and further strengthened coordination. [Conclusion] The technological effect emerged as the primary driving factor promoting the decoupling between urbanization and industrial water consumption, while the output effect acted as the major factor inhibiting their decoupling. The structural and population effects exhibited relatively weaker impacts on the decoupling between the two. The findings can provide scientific reference for the coordinated and sustainable development of industrial water resource utilization and economic growth in China.

[Objective] Systematically reviewing the key issues, research status, and framework of urban geothermal energy development and utilization is crucial for promoting the transformation of urban energy structure and carbon emission reduction. [Methods] Building upon an in-depth review of the current research status of urban geothermal energy, the key issues in its development and utilization are highlighted based on the mutual feedback mechanism between urban geothermal energy and carbon emissions, and a future research framework and main directions are proposed. [Results] The main result are as follows:(1) existing research mainly focuses on geothermal fluid genesis, geothermal resource assessment, key technological breakthroughs, and development and utilization risks, while studies on geothermal energy targeting the coupling of complex urban spatial structures and human living environments remain insufficient.(2) Urban geothermal energy development and utilization face issues such as urban spatial heterogeneity and its complex structural characteristics, potential risks in geothermal well construction, lack of carbon accounting systems and incomplete assessment mechanisms, deficient management mechanisms and technological bottlenecks, and delays in the development of intelligent management platforms, all of which restrict the efficient development and utilization of geothermal resources.(3) In the future, research should follow the logical framework of “resource exploration-comprehensive evaluation-resource development-system construction-energy utilization-intelligent management”, with a focus on exploration technologies, development strategies, assessment models, utilization patterns, and monitoring and early warning. [Conclusion] In the future, the research system for geothermal energy development and utilization should be further improved. On the basis of balancing energy security and carbon reduction goals, efforts should be made to expand the applications of urban geothermal energy and enhance the efficiency of geothermal technology application, thereby increasing the contribution of urban geothermal energy development to the dual-carbon goals.

[Objective] In regions where multiple watersheds and multiple governance units intersect, the health status of river ecosystems is more complex. To identify the key factors of ecological degradation in transboundary rivers and to clarify the comprehensive influence mechanism of watershed environment and human disturbances, a health assessment of existing rivers is urgently needed. [Methods] A regional adaptive B-IBI evaluation system was established based on macroinvertebrate data from 66 transboundary rivers in Guizhou Province. From these, 26 representative rivers were selected. Two-way analysis of variance and redundancy analysis(RDA) were applied to determine the influencing factors of community structure in the transboundary rivers of Qiandongnan Prefecture. [Results] The result showed that the communities of large benthic macroinvertebrates were jointly driven by multiple environmental factors, exhibiting significant spatial differences and group dominance. A total of 108 benthic species belonging to 4 phyla, 7 classes, 21 orders, and 70 families were identified in the two major watersheds, with Arthropoda as the main dominant group. RDA revealed that COD_mn, dissolved oxygen(DO), total phosphorus(TP), and ammonia nitrogen(NH₃-N) were the main environmental factors driving differences in community structure across different governance unit combinations within the watersheds. Among them, the “Qiandongnan-Zunyi” combination exhibited the highest biodiversity, and the “Qiandongnan-Tongren” combination had the lowest. [Conclusion] The findings indicate that the structure and diversity of large benthic macroinvertebrate communities in the transboundary rivers of Qiandongnan Prefecture are jointly regulated by watershed differentiation and governance structure. It is recommended to introduce a “watershed-governance structure” coupling perspective to enhance governance adaptability, providing theoretical support and strategic suggestions for addressing ecological risks such as decreased ecological connectivity and habitat fragmentation.

[Objective] To mitigate the adverse impacts of non-point source pollution on the aquatic environment, it is crucial to accurately elucidate the dynamic formation mechanisms of such pollution and the synergistic control strategies within the precipitation-soil-crop system. [Methods] A multi-dimensional dynamic comparative precipitation simulation experiment was designed by controlling three key variables: crop type(wheat and maize), growth stage(growing and mature), and management practice(fertilized and unfertilized). Differences in runoff pollution characteristics under different scenarios were quantified through high-frequency runoff monitoring and soil physicochemical analysis. [Results] Runoff formed 2 hours after precipitation, and pollutant concentrations decreased over time. In maize fields with a plant height of 85 cm, runoff concentrations of chemical oxygen demand(COD), ammonium nitrogen(NH₄~+-N), total nitrogen(TN), nitrate nitrogen(NO₃~--N), and total phosphorus(TP) were 210.3%, 38.0%, 188.5%, 275.4%, and 128.1% higher, respectively, than those in wheat fields. For maize at 200 cm plant height, runoff fluxes of NH₄~+-N, TN, NO₃~--N, and TP decreased by 68.8%, 79.3%, 88.5%, and 62.5%, respectively, compared to those at 80 cm plant height. Fertilization during the wheat growing stage increased runoff concentrations of COD, TN, NO₃~--N, and TP by 43.9%, 15.9%, 57.5%, and 56.1%, respectively, compared to unfertilized plots. In contrast, fertilization during the maize growing stage reduced runoff concentrations of COD, NH₄~+-N, TN, and NO₃~--N by 18.2%, 68.2%, 25.6%, and 60.7%, respectively, compared with unfertilized plots. [Conclusion] Runoff pollution is triggered only when rainfall intensity exceeds a critical threshold, and pollutant fluxes show a pronounced decay over the rainfall duration, reflecting a “scouring threshold” effect in the surface soil. Compared to the 80 cm plant height stage, enhanced canopy interception and root uptake significantly reduced nitrogen and phosphorus loss fluxes during the mature maize stage.

[Objective] In order to address the challenges in the precise design of ventilation systems for biopile remediation of contaminated soil, [Methods] an innovative design framework based on microbial respiration dynamics was developed. Through pilot-scale data comparison, the theoretical model using the CO₂ production rate as an indicator(with a deviation of 10.7 times) was proved far superior to the traditional O₂ consumption model(with a deviation of 1 450 times), confirming the validity of CO₂ as a high-sensitivity dynamic monitoring indicator. [Results] The optimized “effective extraction flow rate”(406 m³·h^-1) was the core engineering parameter for maintaining an efficient degradation environment and avoiding metabolic inhibition. Throughout a two-week pilot remediation, the degradation efficiency of petroleum hydrocarbons(C₁₀-C₄₀) in the test group(area 1) using the optimized system reached 62.70%, which was significantly higher than that of 30.94% in the control group(area 2). Moreover, the effectiveness of the system was further verified at the microbial level by facilitating the enrichment of key degrading bacteria(Bacillus and Flavobacterium). [Conclusion] The established semi-empirical system of “theoretical calculation + comprehensive engineering coefficient(10.7)” realizes the direct coupling between microbial physiological characteristics and engineering parameters, offering a scientifically sound and practical approach for biopile ventilation design.

[Objective] To address the challenges of multi-objective coordination, high hydrological uncertainty, and limited adaptability of conventional static schemes in water resource scheduling of the Yarkant River Basin, a dynamic correction method for multi-reservoir joint scheduling is proposed to achieve dynamic coordinated scheduling between mountain and plain reservoirs, improve the flexibility and reliability of water resource scheduling, and provide a scientific basis for integrated management of inland river basins in arid regions. [Methods] A “planning-forecast-feedback” dynamic correction framework was established.(1) Based on a linear programming model, the multi-objective optimization problem was defined, including objective such as regional water supply guarantee rate, reservoir storage recovery rate, and ecological release volume.(2) Monthly-scale river inflow was predicted through rolling forecasts using the Prophet time-series model, and the constraints were dynamically updated by integrating actual inflow and forecast result.(3) The linear programming model was solved on a monthly rolling basis to adjust the reservoir scheduling schemes in real time. Taking the Yarkant River Basin as a case study, hydrological, meteorological, and operational data from the mountain reservoir(Artashi hydropower station) and 33 plain reservoirs were integrated. Historical simulations(1961—2020) and scenario analyses in typical years(dry and wet years) were conducted, and the impact of runoff forecast errors on the scheduling effectiveness was evaluated. [Results] The dynamic correction strategy showed robust performance in historical simulations. The optimal and baseline schemes achieved the objective of ecological release(≥330 million m³) from the Heiniyazi section to the Tarim River in 59 years and 50 years, respectively, with regional water supply guarantee rates exceeding 86% in all years. In the dry year(1963) and wet year(1977), water supply guarantee rates reached 88% and 98% respectively, and the release objective were fully met. When runoff forecast errors reached 25%, water supply guarantee rate decreased significantly to 78%, while the scheme maintained stable effectiveness with errors below 25%, indicating that the current forecast error(22%) in the mainstream of the Yarkant River could support the practical requirements of dynamic scheduling. [Conclusion] The results show that proposed dynamic correction framework effectively mitigates the conflict between hydrological uncertainty and rigid scheduling by coupling runoff forecasting with rolling optimization, significantly enhancing the adaptability of multi-objective water resource scheduling. The joint scheduling of mountain and plain reservoirs can balance the demands for power generation, irrigation, and ecological water supplementation, while the accuracy of monthly-scale runoff forecast is critical to the reliability of dynamic schemes. The method provides a technical pathway for refined scheduling of complex reservoir systems in arid regions. Future work should further integrate hydrological process-based models to improve long-term forecast accuracy.

[Objective] The construction quality of rock-filled concrete placement is closely related to the particle size and shape parameters of the rockfill inside the placement areas. However, current on-site evaluation and control of rockfill placement heavily rely on workers' subjective experience and judgment. Therefore, it is necessary to develop a rapid and effective method for segmentation, identification, and statistical evaluation of the rockfill placement used in rock-filled concrete. [Methods] Based on this, an improved rockfill segmentation and identification method was proposed within the YOLO(You Only Look Once) algorithm framework. Furthermore, a statistical calculation method for particle size and shape parameters was presented that accounted for the influence of boundary rockfill in images. A discrimination method for identifying concentration zones of undersized rockfill materials was proposed using the DBSCAN(Density-Based Spatial Clustering of Applications with Noise) algorithm. Then, based on relevant standards and engineering practices, a zoning evaluation method combining hard and soft indicators for the particle size and shape parameters of rockfill placement was developed. [Results] The result showed that the mean average precision(mAP50) for the segmentation and identification models of rockfill, reference markers, and safety helmets were 92.3%, 99.4%, and 97.5%, respectively, demonstrating high recognition accuracy. The proposed method for particle size and shape parameter estimation and the identification of concentration zones of undersized rockfill materials were validated through laboratory and field case studies, demonstrating reliable estimation and discrimination performance. The zoning statistical evaluation method was verified in typical engineering applications, with result consistent with actual engineering conditions. [Conclusion] The segmentation, identification, and statistical evaluation method proposed in this study enables effective field analysis and evaluation of rockfill placement quality, providing an essential technical solution for evaluating rockfill placement in rock-filled concrete engineering.

[Objective] The spatial dynamic response of a new desert highway subgrade structure by geocell reinforcement with aeolian sand is studied. [Methods] Based on the dynamic triaxial test, a field test via monitoring the response acceleration change is carried out. The attenuation law and dynamic response range of the response acceleration along the depth and horizontal directions of the subgrade are obtained for the geocell-reinforced subgrade structure. The mechanism of dynamic response of geocell-reinforced materials to aeolian sand subgrade is further discussed. [Results] The result show that both vehicle load and vehicle speed have a great influence on the response acceleration of the new aeolian sand subgrade. The response acceleration shows a nonlinear attenuation in the depth direction, and the attenuation rate gradually slows down with increasing depth. Meantime, the horizontal direction shows a variation of exponential decay. Therefore, an attenuation prediction model of response acceleration along the horizontal direction of aeolian sand subgrade is established. [Conclusion] Based on this field test condition, the most dominant dynamic response region of the subgrade is in a range of 1. 2 m in depth and 2. 5 m in horizontal. The reinforcement effect of geocell on aeolian sand increases the confining pressure level, and restricts the lateral displacement of soil. In addition, the generation of shear bands in the soil is inhibited by the reinforcement effect. This makes the energy dissipation of the subgrade soil more obvious.

[Objective] To address the operational demands of daily-regulated reservoirs without flood forecast conditions, and to overcome the dependence of traditional method on forecast data, an optimized “pre-discharge and refill” method based on flow prediction is proposed. [Methods] Taking the Batang Hydropower Station in Indonesia as the study object, a two-stage operation mode driven by the previous day's inflow was constructed. Based on the temporal correlation of inflow series, a method for estimating the current day's inflow was established. Taking an hour as the decision unit, the scheduling process of pre-discharge and refill was recursively generated based on the water balance equation, and the optimization effect was quantitatively evaluated based on observed runoff data. [Results] The results showed that when the flow prediction coefficient was 0.8, the proportion of effectively regulated days reached 42.6%, demonstrating the greatest potential for comprehensive scheduling optimization. On this basis, when 430.0 m was set as the pre-discharge water level, the power generation guarantee rate reached 99.4%, and the proportion of high-water-level operation time decreased to 8.95%. Compared with the scheme of pre-discharging to 427.5 m, these values increased by 0.1% and decreased by 3.45%, respectively. [Conclusion] On the basis of ensuring power generation efficiency, the proposed method can significantly reduce the duration of high-water-level operation. Under no-forecast conditions, it can effectively balance power generation with the risk of sedimentation-induced loss of storage capacity caused by high-water-level operation. It provides a novel approach for the multi-objective operation of reservoirs under no-forecast scenarios.

[Objective] The Hekoucun water conservancy project plays a vital role in flood control and water resource utilization, and its safety is of great significance to the local socioeconomic development. Therefore, timely monitoring of its deformation trend is necessary to identify and mitigate potential safety hazards. [Methods] Compared with traditional deformation monitoring method, Interferometric Synthetic Aperture Radar(InSAR) offered advantages such as all-day and all-weather operation, large-scale high-precision coverage, and high spatiotemporal resolution. SBAS-InSAR was employed to extract time-series deformation information of the Hekoucun water conservancy project area from October 2017 to December 2022. The accuracy was validated using leveling measurements and compared with PS-InSAR result. The spatiotemporal characteristics and influencing factors of deformation were analyzed in combination with geographic data. [Results] The results showed that the deformation extraction accuracy of SBAS was 5.21 mm, while that of PSI was 8.07 mm. The density of SBAS deformation points in the study area was 2.49 times that of PSI. The deformation rate in the Hekoucun reservoir area ranged from-8.6 to 3.2 mm/a. Two funnel-shaped settlement zones were identified: the dam-front square(about 45 mm settlement) and the flood-control warehouse(about 50 mm settlement), with the latter showing accelerated settlement after heavy rainfall in July 2021. The deformation rate of the Hekoucun dam ranged from-4 to 2 mm/a, with the maximum settlement of about 15 mm over five years. The central part of the dam crest showed the greatest settlement, with periodic fluctuations. The dam crest deformation was positively correlated with rainfall(correlation coefficients all above 0.5) and negatively correlated with water level(average correlation of-0.32). [Conclusion] The results indicate that SBAS is more effective than PSI in monitoring surface deformation in water conservancy project areas. The deformation of the dam front square and flood-control warehouse is mainly influenced by rainfall. The overall deformation characteristics of the dam show greater settlement at the center than at the shoulders, and greater settlement at the dam crest than at the dam base. Additionally, higher water levels lead to increased settlement at the dam crest. Dam deformation shows periodic fluctuations of relatively small magnitude and currently does not compromise dam safety. The findings provide scientific support for the safe operation of the Hekoucun water conservancy project and serve as a reference for deformation monitoring in other water conservancy projects.

[Objective] The rock mass within the slope hydro-fluctuation zone of large reservoirs often deteriorates due to dry-wet cycles. The aim is to investigate the deterioration patterns of the shear characteristics of basalt joint surfaces in the hydro-fluctuation zone under dry-wet cycles. [Methods] Basalt from the slope hydro-fluctuation zone of the Baihetan Reservoir was selected as the research object. Joint surface samples with roughness coefficients similar to those of natural joint surfaces were prepared using the splitting method. Direct shear tests and three-dimensional morphological scanning tests were performed on the basalt joint surfaces under different dry-wet cycles. The shear mechanical properties and the deterioration patterns of mesoscopic morphological parameters of the joint surfaces were analyzed, and a JRC-JCS model considering the dry-wet cycles was established. [Results] The result showed that with an increasing number of dry-wet cycles, the shear strength showed a deterioration trend of “rapid at first and then slowing down”. During the 12 dry-wet cycles, the deterioration in shear strength in the first five cycles accounted for 82.2% of the total deterioration, and the mesoscopic parameters of the joint surfaces also decreased accordingly. The shear strength calculated by the JRC-JCS model considering dry-wet cycles fitted well with the laboratory test values. [Conclusion] The findings reveal that the deterioration patterns of the mesoscopic morphological parameters and the roughness coefficient JRC of the joint surfaces are consistent with those of the macroscopic shear strength, indicating a good correlation between morphological parameters and shear strength. Based on the JRC-JCS model considering dry-wet cycles, the changes in mesoscopic morphological parameters of the joint surfaces can be used to predict the shear strength deterioration patterns of jointed rock masses.

[Objective] To investigate the effect of maximum suction history on the consolidated undrained mechanical properties of high liquid limit clay, samples with maximum suction history are prepared through saturation, complete dehumidification, and resaturation of undisturbed high liquid limit clay. [Methods] Triaxial shear tests were conducted to compare and analyze the mechanical responses of undisturbed samples and samples subjected to maximum suction history. The healing characteristics of high liquid limit clay were revealed based on failure modes, and these characteristics were verified by examining changes in microstructure. [Results] The result showed that maximum suction history altered the consolidated undrained mechanical properties of high liquid limit clay. Under a confining pressure of 50 kPa, the peak stress increased by 87.5% to 171.3%, while the peak pore water pressure decreased by 16.7% to 20%. Under confining pressures of 50 kPa and 100 kPa, the variance values representing anisotropy decreased from 47.1 and 321 to 8.2 and 94.9, respectively. The stress-strain curves of the samples changed from a hardening type to a softening type. The pore water pressure response shifted from “first increasing and then remaining constant” to “first increasing and then decreasing”. The effective stress path transformed from “hardening-shear dilation” and “hardening-shear contraction” to “softening-partial shear contraction-partial shear dilation”, and the degree of anisotropy was reduced. [Conclusion] High liquid limit clay exhibits healing characteristics, and the realization of these characteristics depends on the action of additional stress. Under consolidated undrained shear paths, micro-scale particle morphology remodeling and meso-scale fracture closure are promoted in samples subjected to maximum suction history. Ultimately, a macroscopic increase in shear strength of 1.2 times to 1.3 times is exhibited compared to undisturbed samples. A theoretical basis is provided for engineering practice in areas with high liquid limit clay.

[Objective] The durability of cement concrete is crucial for the health and service life of hydraulic engineering structures. Permeable crystalline materials can effectively densify the cement concrete and enhance its impermeability through precipitation/complexation-precipitation reactions, thereby improving concrete durability and extending its service life. [Methods] Based on the introduction to the composition and action mechanisms of permeable crystalline materials, the influence of internally incorporated permeable crystalline materials on concrete durability is summarized in terms of impermeability, chloride ion penetration resistance, sulfate erosion resistance, crack resistance, frost resistance, and self-healing performance of cracks. Current engineering application status of permeable crystalline materials is discussed, and recommendations for future research and development are proposed. [Results] The results show that permeable crystalline materials can enhance concrete impermeability and chloride ion erosion resistance by promoting the formation ofcrystalline substances and refining the pore structure of cement concrete. In sulfate environments, permeable crystalline materials compete with sulfate ions for calcium ions, reducing the formation of gypsum and ettringite and consequently mitigating concrete erosion damage. Additionally, these materials enhance crack resistance and frost resistance of concrete. Currently, the application of permeable crystalline materials in engineering is primarily external coating, while internally incorporated applications remain relatively rare. [Conclusion] Based on the current research status, studies on the influence of internally incorporated permeable crystalline materials on the volume deformation and carbonation resistance of concrete are scarce, indicating the need for systematic studies in the future. Concrete cracking is an important factor in durability deterioration. The relationships and models between cracks and durability can be established to evaluate the influence of crack self-healing on durability. Research on the durability of cement concrete requires long-term testing. In the future, data-driven method can be combined to achieve result prediction and thus improve testing efficiency.

[Objective] The aim is to address the difficulties in conducting large-scale explosion impact tests on coral reef limestone due to the small core size and strong heterogeneity, as well as the challenges in obtaining the propagation patterns of blast waves. [Methods] Based on the small-scale explosion simulation technology using the fine electromagnetic measurement method for blast waves, a combined design of the center-detonated miniature spherical explosive and the circular electromagnetic particle velocimeter was adopted to precisely measure the time-history curves of blast wave particle velocity in reef limestone at scaled distances of $20 \sim 80 \mathrm{~m} / \mathrm{kt}^{\frac{1}{3}}$ The result showed that the blast waves in reef limestone progressively degraded from strong intermittent shock waves into continuous compression waves, with gradually increasing duration and decreasing peak particle velocity. Within the test range, the attenuation indices of the peak stress and peak particle specific displacement of the blast waves in reef limestone were 1.89 and 1.39, respectively. Explosion-induced cavity formation in the reef limestone was obvious, but the natural pore and fracture systems significantly attenuated blast waves, inhibiting the development and propagation of explosion-induced fractures. After the explosion, the reef limestone was mainly characterized by deformation and compaction of the pores and the extension of natural fractures. [Conclusion] The research findings reveal the explosion-induced damage effects and the propagation attenuation patterns of peak stress and peak specific displacement in reef limestone, and propose a calculation formula for blast wave attenuation, providing experimental support for the analysis of the explosion impact effects in reef limestone.

[Objective] To address the difficulty in quantitatively characterizing the flowability degradation and interface bonding evolution of concrete during the construction of hydraulic structures such as cutoff walls, a time-dependent modeling method for concrete interface surface energy based on slump evolution is proposed. [Methods] Multi-age slump and spread tests were conducted to obtain the flowability degradation sequence of the concrete mixture. A three-dimensional particle flow model(PFC), consistent with the dimensions of the physical tests, was constructed. The Johnson-Kendall-Roberts(JKR) contact model was used in PFC to characterize the adhesive behavior between particles. Graded surface energy parameters were assigned to different contact interfaces—mortar-mortar, mortar-aggregate, and aggregate-aggregate—to reflect differences in bonding strength. Under the constraint of macroscopic slump result, a three-parameter Logistic function was employed to describe the time-dependent variation of the mortar-mortar interface surface energy with age. The function parameters were inversely calibrated using a sliced/nested orthogonal array(SOA-AR) design. The obtained γ_mm(t) function was then embedded into the PFC model to realize the time-dependent representation of interface bonding parameters. [Results] Numerical simulation result showed that introducing the time-dependent surface energy function could reproduce the observed age-related slump decline. The inflection point of the fitted curve was consistent with the concrete's initial setting time. After applying the γ_mm(t) function in the casting simulation, the height difference of the concrete top surface was approximately 0.26 m, which was below the 0.30 m limit specified in the code. The predicted normal reaction force at the mortar-trench wall interface ranged from approximately 0.02 kPa to 0.05 kPa, consistent with the order of magnitude of the slurry hydrostatic pressure specified in the code. The result indicated that the model could realistically reflect the flow and deposition process of the mixture and the mechanical characteristics of the interfaces. [Conclusion] The proposed time-dependent interface surface energy function effectively captures the evolution of concrete from a fluid to a setting state and establishes a mapping relationship between macroscopic flowability and mesoscopic bonding properties. The findings provide a feasible approach for the numerical simulation of underwater casting and cutoff wall construction processes involving complex interface behavior, offering a reference for related engineering practice and subsequent numerical analysis.