Construction Of Hydropower Stations Research Articles

Study of Earthquake Landslide Hazard by Defining Potential Landslide Thickness Using Excess Topography: A Case Study of the 2014 Ludian Earthquake Area, China

Influenced by the combined effects of crustal uplift and river downcutting, rivers with significant potential energy are often found in high mountain and canyon areas. Due to the active tectonic movements that these areas have experienced or are currently experiencing, geological hazards frequently occur on the mountains flanking the rivers. Therefore, evaluating the susceptibility and risk of earthquake landslides in river segments of these high mountain and canyon areas is of great importance for disaster prevention and mitigation, as well as for the safe construction and operation of hydropower stations. Currently, a major challenge in the study of landslide susceptibility and hazard is determining the thickness of potential landslide bodies. The presence of excess topography reflects the instability of the disrupted slopes, which is also a fundamental cause of landslides. This study takes the example of the Ludian earthquake in 2014, focusing on the IX and VIII intensity zones, to extract the excess topography in the study area and analyze its correlation with seismic landslides. The correlation between the critical acceleration value and the excess topography was validated using the Spearman’s rank correlation coefficient, resulting in a correlation coefficient of −0.771. This indicates a strong negative correlation between the excess topography and critical acceleration, with significant relevance. The landslide susceptibility distribution obtained by setting the potential landslide thickness based on the excess topography and proportion coefficient showed an ROC curve analysis AUC value of 0.829. This is higher than the AUC value of 0.755 for the landslide susceptibility result using a uniform potential landslide thickness of 3 m, indicating the higher model evaluation accuracy of this approach. Earthquake landslide hazard predictions for rapid post-earthquake assessments and earthquake landslide hazard zoning for pre-earthquake planning were made using actual seismic ground motion and a 2% exceedance probability in 50 years, respectively. Comparing these with the 10,559 coseismic landslides triggered by the Ludian earthquake and evaluating the seismic landslide development rate, the results were found to be consistent with reality. The improved model better reflects the control of excess topography and rock mechanics properties on the development of earthquake landslide hazards on high steep slopes. Identifying high-risk seismic landslide areas through this method and taking corresponding preventive and protective measures can help plan and construct safer hydropower and other infrastructure, thereby enhancing their disaster resistance.

Soil quality enhancement by multi-treatment in the abandoned land of dry-hot river valley hydropower station construction area under karst desertification environment.

The medium-intensity karst desertification environment is typically characterized by more rocks and less soil. The abandoned land in the construction areas of the dry-hot river valley hydropower station has more infertile soil, severe land degradation, and very low land productivity. Therefore, it is urgent to improve the soil quality to curb the increasingly degrading land and reuse the construction site. Few studies have focused on the effect of soil restoration and comprehensive evaluation of soil quality with multi-treatment in abandoned land in the dry-hot valley hydropower station construction area. Here, 9 soil restoration measures and 1 control group were installed at the Guangzhao Hydropower Station construction in Guizhou Province, China, for physical and chemical property analysis. In total, 180 physical and 90 chemical soil samples were collected on three occasions in May, August, and December 2022. Soil fertility and quality were evaluated under various measures using membership functions and principal component analysis (PCA). This study showed that almost all measures could enhance soil water storage capacity (The average total soil porosity of 9 soil treatments was 57.56%, while that of the control group was 56.37%). With the increase in soil porosity, soil evaporation became stronger, and soil water content decreased. Nevertheless, no decrease in soil water content was observed in the presence of vegetation cover (soil water content: 16.46% of hairy vetch, 13.99% of clover, 13.77% of the control). They also proved that manure, synthetic fertilizer, and straw could promote total and available nutrients (Soil total nutrient content, or the total content of TN、TP、TK,was presented as: synthetic fertilizer (11.039g kg-2)>fowl manure (10.953g kg-2)>maize straw (10.560g kg-2)>control (9.580g kg-2);Total available nutrient content in soil, or the total content of AN,AP,A,was shown as:fowl manure (1287.670 mg kg-1)>synthetic fertilizer (925.889 mg kg-1)>sheep manure (825.979 mg kg-1)>control (445.486 mg kg-1). They could also promote soil fertility, among which the first two reached the higher comprehensive soil quality. Fertilizer was conducive to improve soil quality and fertility, yet long-term application could cause land degradation like soil non-point source pollution, compaction, and land productivity decline. Ultimately, combining fertilizer with biochar or manure is recommended to improve soil fertility. Biochar and green manure could play an apparent role in soil improvement only when there is abundant soil water. The above views provide theoretical support for curbing soil degradation, improving soil fertility and quality, enhancing land productivity, and promoting the virtuous cycle of the soil ecosystem.

Consideration on setting conditions of the upstream surge chamber in the water transmission system of pumped storage power station

Abstract Through the investigation of more than ten domestic pumped storage power stations that have been built or are under construction, the actual setting of the upstream surge chamber is obtained. The traditional upstream surge chamber setting conditions are derived from conventional hydropower station construction experience and subsequent derivations. Combined with the load shedding test and unit design parameters, the practical application of the upstream surge chamber setting conditions is evaluated, and the relevant construction experience of the pumped storage power station is summarized. The analysis and research results of the installation conditions of the upstream surge chamber are presented.

An integrated analysis of transcriptome and metabolome to reveal the effects of temperature stress on energy metabolism and physiological responses in Schizothorax wangchiachii muscles

The unique hydrological situation of Jinsha River and the construction and operation of large hydropower stations may cause resident Schizothorax wangchiachii to experience acute changes in water temperature. To reveal the response mechanisms of S. wangchiachii to high and low temperature stress, we conducted a stress experiment. Compared with the control group, the activity of antioxidant enzymes (SOD\\CAT) increased first and then decreased at high temperature, while MDA activity in the low temperature group continued to increase slowly. The activities of glycolytic enzymes were increased initially and then decreased including HK and PFK, but PK activity continued to increase throughout the stress period. Transcriptome sequencing showed that a large number of genes in muscle tissues were differentially expressed after high and low temperature stress, and the main enriched pathways included glycosaminoglycan biosynthesis, lysine degradation, glycerolipid metabolism, the PPAR signaling pathway, and the adipocytokine signaling pathway. Significant metabolic pathways were identified as enriched according to the metabolic differences,such as glycerophospholipid metabolism, qRT-PCR was used to verify gene expression. The results suggested that both high temperature and low temperature stress induced physiological responses in S. wangchiachii that maintained homeostasis by regulating glucolipid metabolism and amino acid degradation. This study revealed the response mechanisms of S. wangchiachii to high and low temperature stress, information that may serve as a reference for the study of responses in other fish to environmental changes in the upper reaches of the Yangtze River or where they are displaced by hydropower station construction.

Study on the habitat evolution after dam removal in a habitat-alternative tributary of large hydropower station

The establishment of large hydropower stations in the main stream poses a threat to fish habitats. Selecting suitable tributaries as alternative habitats is a practical measure for ecological environment protection during large hydropower station's construction. The small dams constructed on certain tributaries need to be removed in order to restore river connectivity. The removal of dams will activate hydro-sedimentary dynamics and change the original habitat in terms of topography and hydrodynamics. To explore the evolution of fish habitats following the removal of small dams, a dam-removed reach of a habitat-alternative tributary was selected as the research object, and the model of water-sediment transport and riverbed evolution in strongly disturbed dam-removed reaches and the model of fish habitat suitability evaluation were established. The key parameters calibration and model verification were completed by field monitoring results. The simulation results showed dramatic evolution in the reservoir riverbed in the initial stage after dam removal and during the high discharge period. One year after dam removal, there was a noticeable 4.0 m incision in front of the dam, along with a decrease in channel slope at the dam site from about 4.8% to approximately 1.5%. Downstream of the dam, alterations to the riverbed were mainly concentrated near the dam, and sedimentary bodies with a height of around 2.0 m have formed on the left bank following the high discharge period. The fish habitat in most areas of the dam-removed reach was suitable, except for the downstream high-velocity area. To compare the evolution process of fish habitat under two dam removal periods in wet and dry seasons, two dam removal schemes were implemented in March and June. The results showed that the riverbed evolved more gradually in the March scheme, creating a larger and continuous suitable habitat for fish. Therefore, the March scheme was recommended. By revealing the evolutionary pattern of fish habitat after dam removal, this research provides a reliable model for assessing and restoring habitats in dam-removed reaches, and enjoys significant implications for protecting river ecology in hydropower development reaches.

Influence on the surrounding vegetation’s spatiotemporal changes by Jinping II Hydropower Station

The Jinping II Hydropower Station, located near Jinping Mountain, is a strategically significant hydropower project. The construction and operation of this project have impacted the surrounding ecological environment. The Normalized Difference Vegetation Index (NDVI) is widely used in remote sensing and serves as a crucial parameter for assessing vegetation health and ecological vitality. Through quantitative analysis using Sen’s slope and the Mann-Kendall non-parametric test on NDVI, we gained a deeper understanding of the impact of hydropower station construction on the surrounding vegetation. The primary objective of this study was to systematically investigate the spatiotemporal variations in NDVI before, during, and after the construction of the Jinping II Hydropower Station. The research findings contribute to the formulation of strategies aimed at mitigating potential adverse effects on the environment while promoting the region’s sustainable development goals.

Analysis of Surrounding Rock Stability and Supporting Structure Effect Based on a Hydropower Station Underground Cavern

The surrounding rock stability is a main difficult problem in the hydropower station construction and operation. Taking one hydropower station as object, FLAC 3D numerical simulation software was used to calculate the changes in surrounding rock failure zone distribution, surrounding rock strain, and block safety factor before and after supporting. The stability of the surrounding rock after excavation was analyzed and effect of the supporting structure was also evaluated. Finding that: the supporting structure can effectively improve the stability of surrounding rock. After supporting, the failure zone range, the deformation of surrounding rock, and the internal force of the supporting structure all reduced, while the safety factor of the block improved. Due to the effect of bolt, the deformation of the surrounding rock transformed from plastic to elastic, and the rebound zone of the surrounding rock increased, while the plastic and failure zone reduced. The depth of the failure zone on the downstream side is greater than that on the upstream side, and a large number of cracking zones are distributed on the downstream side. At the same time, due to the influence of cracks and geological fracture, the failure of surrounding rock around the main powerhouse is higher than that around the tailgate chamber higher than that in the main transformer chamber. The safety factor of the key blocks distributed around the main transformer chamber and the main power house improved, the sliding form of some blocks transformed from collapse to single-surface sliding.

Quantifying the variation of Scaly-sided merganser’ population and their divergent response to changes in hydrological connectivity of rivers in a high-latitude water tower

The Scaly-sided Merganser (SSME) is a globally endangered waterbird species, primarily inhabiting rivers. In recognition of its precarious status, it was added to the International Union for Conservation of Nature’s (IUCN) Red List of Threatened Species in 2002. The SSME is highly sensitive to ecological environmental changes driven by changes in hydrological connectivity, particularly within riverine habitats. Changbai Mountain, a high-latitude water tower in the Northeast Asia, is considered one of the most optimal breeding grounds for the SSME worldwide. Its extensive water system and dense primary forest create an environment particularly well-suited for this species. Over the past 40 years, rivers within Changbai Mountain have experienced phases of hydropower development and ecological restoration. These activities have dramatically altered the hydrological connectivity of the area. However, the response of SSME to these changes in aquatic ecology, driven by shifts in hydrological connectivity, remains uncertain. We employed the AutoRegressive Integrated Moving Average (ARIMA) model to analyze changes in the population size of the SSME. Furthermore, the GeoDetector model was used to understand the impact of ecological changes on the maximum population size (MPS) and distribution of SSME in the context of alterations in hydrological connectivity. Our findings reveal that the restoration of hydrological connectivity, a method of ecological restoration, exerts a bidirectional influence on both the distribution and the MPS of SSME. Our findings can be summarized as follows. Firstly, there was a general trend of increase in both the distribution points and population size of the SSME. Secondly, the contribution of driving factors to the MPS of SSME was ranked in the following order: temperature > Connectivity Status Index (CSI) > river width > fish abundance > river depth > velocity > altitude > forest type. Thirdly, the impacts on the distribution and MPS of SSME were not due to a single factor, but rather a complex interplay of multiple factors. Finally, the construction of small hydropower stations significantly disrupted the hydrological connectivity of rivers, thereby altering the natural habitat of the SSME. The reduction in fish population, resulting from the loss of hydrological connectivity, adversely affected the MPS. Conversely, an increase in water temperature due to loss of hydrological connectivity positively impacted the MPS. However, these effects displayed heterogeneity across different rivers. Our study suggests that the construction of gravel dams may be a suitable approach in certain sections of the river, with a recommended height limit of 1.5 m. This research provides valuable insights for managers, offering a sustainable foundation for future energy planning and ecological restoration efforts.

Deformation Characteristics and Stability Prediction of Mala Landslide at Miaowei Hydropower Station under Hydrodynamic Action

In recent years, with the completion of the construction of large-scale hydropower projects in China, a series of engineering geological problems that occurred during the operation of the hydropower station have become an important issue affecting the normal operation of hydropower stations. Landslides on reservoir slopes triggered especially by water storage and other factors related to the construction of hydropower stations seriously affect the normal operation of the hydropower station and lead to other geological disasters. Research indicates that many reservoir-area landslides are triggered by hydrodynamic forces resulting from water level fluctuations in hydroelectric power stations. The Mala landslide of Miaowei Hydropower Station in the Lancang River Basin of China is taken as the engineering example to study the influence of hydrodynamic forces on the deformation characteristics and stability trends of the landslide. This paper explores the formation mechanism and influencing factors of the Mala landslide by conducting a field investigation of the Mala landslide and analyzing the monitoring data. Additionally, this paper also discusses the impacts of water storage, rainfall, and engineering construction on landslide induction. It is considered that the evolution of the Mala landslide from the initial stage of water storage to the current state mainly includes four stages: small-scale bank collapse stage, creep deformation stage, accelerated sliding stage, and uniform sliding stage. Moreover, the changes in the trend of landslide stability are analyzed using the two-dimensional finite element method. The research results provide a valuable reference for understanding the formation mechanism and predicting the deformation of reservoir landslides, which has considerable engineering practical significance.

Development of a coupled model to simulate and assess arsenic contamination and impact factors in the Jinsha River Basin, China

With the increasing severity of arsenic (As) pollution, quantifying the environmental behavior of pollutant based on numerical model has become an important approach to determine the potential impacts and finalize the precise control strategies. Taking the industrial-intensive Jinsha River Basin as typical area, a two-dimensional hydrodynamic water quality model coupled with Soil and Water Assessment Tool (SWAT) model was developed to accurately simulate the watershed-scale distribution and transport of As in the terrestrial and aquatic environment at high spatial and temporal resolution. The effects of hydro-climate change, hydropower station construction and non-point source emissions on As were quantified based on the coupled model. The result indicated that higher As concentration areas mainly centralized in urban districts and concentration slowly decreased from upstream to downstream. Due to the enhanced rainfall, the As concentration was significantly higher during the rainy season than the dry season. Hydro-climate change and the construction of hydropower station not only affected the dissolved As concentration, but also affected the adsorption and desorption of As in sediment. Furthermore, As concentration increased with the input of non-point source pollution, with the maximum increase about 30%, resulting that non-point sources contributed important pollutant impacts to waterways. The coupled model used in pollutant behavior analysis is general with high potential application to predict and mitigate water pollution.

Comprehensive Utilization Model of Yarlung Zangbo River Water Resources Based on Discrete Multi-objective Optimization Model

The Yarlung Zangbo River is rich in water resources, which is of great significance to the comprehensive utilization of water resources. The reasonable development of the hydropower resources of the Yarlung Zangbo River is realized, through the water diversion project and the establishment of the trapezoidal hydropower station. A comprehensive utilization model of hydropower resources optimized by discrete objectives is constructed, based on the discrete multi-objective optimization theory. It combined with the reading of geographic data by GPS and Matlab. The number and orientation of the optimal construction of hydropower stations and the proportion of the water transfer volume of the water diversion project are obtained, combining the cost of hydropower station construction and water diversion project implementation and the benefits brought by hydropower resources.

An integrated method to identify and evaluate the impact of hydropower development on terrestrial ecosystem

Hydropower development has an important impact on the growth of vegetation in the basin, identifying and assessing the impact of engineering factors on vegetation dynamics is essential for sustainable watershed ecosystem management. In the paper, a integrated method coupling with Bfast, Theil-Sen Median and Mann-Kendall methods based on remote sensing was developed to identify the time and magnitude of abrupt changes for NDVI, judge the NDVI change trend and detect their potential drivers. Results showed that times of major abrupt changes of NDVI for areas around Wudongde, Baihetan, Xiluodu and Xiangjiaba hydropower stations were consistent with the construction and operation time of hydropower stations and the abrupt climate change time in the statistical yearbook. The proportion of areas with positive abrupt changes of NDVI around two early operational hydropower stations with 42.9 and 26.1% were higher than those around two newly operational hydropower stations with 12.9 and 25.8%. Results obtained from Theil-Sen Median and Mann-Kendall methods showed that areas with improved vegetation coverage for two early operational hydropower stations accounted for 83.99 and 80.21%. And those areas were mainly distributed along river direction (both sides of Jinsha river). Only 9.66 and 11.43% of areas had degraded vegetation, which indicated that the operation of hydropower stations can contribute to the recovery of regional NDVI. Results also indicated that the climate change may be a potential factor to promote regional vegetation growth. But, the growth rate of vegetation reached 0.000018 and 0.000024 caused by hydropower station operation was far higher than that between 0.000008 and 0.000010 caused by climate change. This work provides an important theoretical and technical support for ecological impact assessment of climate change and engineering construction.

Accessing the Time-Series Two-Dimensional Displacements around a Reservoir Using Multi-Orbit SAR Datasets: A Case Study of Xiluodu Hydropower Station

The construction of large-scale hydropower stations could solve the problem of China’s power and energy shortages. However, the construction of hydropower stations requires reservoir water storage. Artificially raising the water level by several tens of meters or even hundreds of meters will undoubtedly change the hydrogeological conditions of an area, which will lead to surface deformation near the reservoir. In this paper, we first used SBAS-InSAR technology to monitor the surface deformation near the Xiluodu reservoir area for various data and analyzed the surface deformation of the Xiluodu reservoir area from 2014 to 2019. By using the 12 ALOS2 ascending data, the 100 Sentinel-1 ascending data, and the 97 Sentinel-1 descending data, the horizontal and vertical deformations of the Xiluodu reservoir area were obtained. We found that the Xiluodu reservoir area is mainly deformed along the vertical shore, with a maximum deformation rate of 250 mm/a, accompanied by vertical deformation, and the maximum deformation rate is 60 mm/a. Furthermore, by analyzing the relationship between the horizontal deformation sequence, the vertical deformation sequence, and the impoundment, we found the following: (1) Since the commencement of Xiluodu water storage, the vertical shore direction displacement has continued to increase, indicating that the deformation caused by the water storage is not due to the elastic displacement caused by the load, but by irreversible shaping displacement. According to its development trend, we speculate that the vertical shore direction displacement will continue to increase until it eventually stabilizes; (2) Vertical displacement increases rapidly in the initial stage of water storage; after two water-storage cycles, absolute settlement begins to slow down in the vertical direction, but its deformation still changes with the change in the storage period.

Attribution of climate change and human activities to streamflow variations with a posterior distribution of hydrological simulations

Abstract. Hydrological simulations are a main method of quantifying the contribution rate (CR) of climate change (CC) and human activities (HAs) to watershed streamflow changes. However, the uncertainty of hydrological simulations is rarely considered in current research. To fill this research gap, based on the Soil and Water Assessment Tool (SWAT) model, in this study, we propose a new framework to quantify the CR of CC and HAs based on the posterior histogram distribution of hydrological simulations. In our new quantitative framework, the uncertainty of hydrological simulations is first considered to quantify the impact of “equifinality for different parameters”, which is common in hydrological simulations. The Lancang River (LR) basin in China, which has been greatly affected by HAs in the past 2 decades, is then selected as the study area. The global gridded monthly sectoral water use data set (GMSWU), coupled with the dead capacity data of the large reservoirs within the LR basin and the Budyko hypothesis framework, is used to compare the calculation result of the novel framework. The results show that (1) the annual streamflow at Yunjinghong station in the Lancang River basin changed abruptly in 2005, which was mainly due to the construction of the Xiaowan hydropower station that started in October 2004. The annual streamflow and annual mean temperature time series from 1961 to 2015 in the LR basin showed significant decreasing and increasing trends at the α= 0.01 significance level, respectively. The annual precipitation showed an insignificant decreasing trend. (2) The results of quantitative analysis using the new framework showed that the reason for the decrease in the streamflow at Yunjinghong station was 42.6 % due to CC, and the remaining 57.4 % was due to HAs, such as the construction of hydropower stations within the study area. (3) The comparison with the other two methods showed that the CR of CC calculated by the Budyko framework and the GMSWU data was 37.2 % and 42.5 %, respectively, and the errors of the calculations of the new framework proposed in this study were within 5 %. Therefore, the newly proposed framework, which considers the uncertainty of hydrological simulations, can accurately quantify the CR of CC and HAs to streamflow changes. (4) The quantitative results calculated by using the simulation results with the largest Nash–Sutcliffe efficiency coefficient (NSE) indicated that CC was the dominant factor in streamflow reduction, which was in opposition to the calculation results of our new framework. In other words, our novel framework could effectively solve the calculation errors caused by the “equifinality for different parameters” of hydrological simulations. (5) The results of this case study also showed that the reduction in the streamflow in June and November was mainly caused by decreased precipitation and increased evapotranspiration, while the changes in the streamflow in other months were mainly due to HAs such as the regulation of the constructed reservoirs. In general, the novel quantitative framework that considers the uncertainty of hydrological simulations presented in this study has validated an efficient alternative for quantifying the CR of CC and HAs to streamflow changes.

A Comparison of Local- and Foreign-Funded Hydropower Station Construction in Nepal Based on Remote Sensing

International investors in large infrastructure projects face numerous risks. To explore this issue, this paper compares the development of two hydropower stations in Rasuwa District, Nepal: Upper Trishuli 3A, which is fully funded by a Chinese government bank, and Rasuwagadhi, which is fully funded by local government banks. The construction of these two plants was compared between 2012 and 2020 using a visual interpretation method to extract data on roads, buildings, dams, and vehicles from 1-m-resolution remote sensing imagery. Two methods were used to compare the environmental impacts of each plant. Landsat 7/8 30-m imagery was used to monitor changes in the normalized difference vegetation index around the Upper Trishuli 3A hydropower station from 2012 to 2020 and around the Rasuwagadhi hydropower station from 2014 to 2020. Then, 1-m-resolution imagery was used to observe land-cover differences in these areas and time periods. The results indicate that: (1) despite various challenges, such as geological disasters, the COVID-19 pandemic, and a blockade by the Indian government, there was no difference in construction progress between the two hydropower stations. (2) The Upper Trishuli 3A Hydropower Station was associated with better environmental protection work, as there were continuous declines in vegetation growth near Rasuwagadhi and increased overall vegetation growth near Upper Trishuli 3A. (3) Energy projects funded by the Belt and Road Initiative have benefited developing countries enormously. Finally, local conditions should be thoroughly investigated during the construction of foreign-funded power stations.

Transient analysis of a hydropower plant with a super-long headrace tunnel during load acceptance: Instability mechanism and measurement verification

The current development trend of China's hydropower is moving toward ultra-high heads, complex geological scenarios, ultra-large capacities, and the Tibetan region. The construction of hydropower stations with super-long headrace tunnels is conducive to overcoming the constraints of complex geological conditions and making full use of hydropower resources. However, these stations have unique technical problems that limit their commercial development, including pressure fluctuations during load rejection and the operational stability of the power-frequency regulation. In this study, a potential problem in hydropower stations with super-long headrace tunnels, the instability during load acceptance, is studied by combining prototype experiments with 1D transient numerical simulations. First, according to a test case using a prototype hydropower station, the instability phenomenon occurring during a simultaneous load acceptance of two Francis turbines in a hydropower station with a 20-km headrace tunnel is described. Next, using 1D steady-state and transient simulations, the factors leading to the instability are analyzed in detail. Finally, countermeasures for the safe operation of hydropower stations are proposed based on numerical simulations and supplementary prototype experiments. Hydropower stations with super-long headrace tunnels exhibit a characteristic where the net head decreases sharply with an increase in the flow rate. Therefore, prior to load acceptance, the maximum output achievable by the multiple units under the operating net head has to be carefully determined to avoid over-adjustment of the guide vane opening and detrimental phenomena such as operational instability and extremely low pressure in the draft tube.

Landslide Inventory in the Downstream of the Niulanjiang River with ALOS PALSAR and Sentinel-1 Datasets

Landslide inventory and deformation monitoring is an essential task for human life and property security during the exploitation process of hydroelectric power resources. Synthetic Aperture Radar Interferometry (InSAR) is recognized as an effective tool for ground displacement monitoring with the advantages of wide coverage and high accuracy. In this study, we mapped the unstable slopes in the downstream of the Niulanjiang River with 22 ALOS PALSAR SAR images acquired from 2007 to 2011, and 90 Sentinel-1 SAR images from 2015 to 2019. A total of 94 active slopes are identified using a displacement map from the two datasets based on Small BAseline Subset (SBAS) InSAR analysis. By comparing the results from ALOS PALSAR and Sentinel-1 data stacks, we find that the number of active slopes increased dramatically. Several impact factors, e.g., earthquake, concentrated rainfall, and construction of hydropower stations, are discussed through time series analysis of typical landslides. Furthermore, nonlinear displacement of natural unstable slopes are found to be correlated with rainfall. A climate-driven model is used to qualify the relationship between rainfall and landslide displacement. Our results can provide valuable information for landslide detection and prevention.

Short-Term Canyon Wind Speed Prediction Based on CNN—GRU Transfer Learning

Due to the particularity of the site selection of hydropower stations, the canyon wind with large fluctuations often occurs during the construction of the hydropower station, which will seriously affect the safety of construction personnel. Especially in the early stage of the construction of the hydropower station, the historical data and information on the canyon wind are scarce. Short-term forecasting of canyon wind speed has become extremely important. The main innovation of this paper is to propose a time series prediction method based on transfer learning. This method can achieve short-term prediction when there are few wind speed sample data, and the model is relatively simple while ensuring the accuracy of prediction. Considering the temporal and nonlinear characteristics of canyon wind speed data, a hybrid transfer learning model based on a convolutional neural network (CNN) and gated recurrent neural network (GRU) is proposed to predict short-term canyon wind speed with fewer observation data. In this method, the time sliding window is used to extract time series from historical wind speed data and temperature data of adjacent cities as the input of the neural network. Next, CNN is used to extract the feature vector from the input, and the feature vector can form time series. Then, the GRU network is used for short-term wind speed prediction by the time series. Experimental results show that the proposed method improves MAE and RMSE by nearly 20%, which will provide new ideas for the application of wind speed forecasting in canyons under complex terrain. The research contents of this paper contribute to the actual construction of hydropower stations.

A 3D Peridynamic Model to Simulate Indirect Tensile Failure in Marble

Driven by the commitment of achieving peak carbon dioxide emissions before 2030 and carbon neutrality before 2060, China is promoting the optimization of its energy and industry structures. In the electricity supply industry, a large number of different types of sophisticated large and giant hydropower stations are planned or being constructed in western China. In future decades, hydropower may take the dominant position in China’s electricity supply. Rock fracturing behavior plays a vital role in geotechnical hazard prevention and geotechnical engineering design. With the construction of hydropower stations, rock mechanics investigation will be of great concern. This study presents a hybrid model that coupled the finite element method and peridynamic theory to simulate the indirect tensile strength of marble. Sensitivity analyses of the loading rate, mesh size, and fracture energy release rate are performed. The numerical results indicate that both the loading rate and mesh size significantly affect the numerical representation of rock properties. After the calibration of the fracture energy release rate, Brazilian tensile strength modeling is successfully conducted, and the numerical results are consistent with the experimental results.

Analysis and optimization of air distribution and ventilation performance in a generator hall using an innovative attached air supply mode

The continuous development of hydropower necessitates the extensive design and construction of hydropower stations. As an underground large space building, it is difficult for the air in the hydropower station to directly exchange with the external environment. Scientifically reasonable air supply modes are indispensable for ensuring a uniform air distribution with low energy consumption. In this study, numerical simulations were carried out to analyse the air distributions and thermal environments under three air supply modes: roof air supply (RAS), sidewall air supply (SAS), and attached air supply (AAS). A set of evaluation indices, namely, the air velocity, air temperature, nonuniformity coefficient, and energy efficiency coefficient, were adopted to assess the ventilation performance of these three modes. Moreover, an orthogonal experiment was conducted to optimize the ventilation performance with four factors (air outlet height, air outlet width, air supply velocity, and heat source intensity) in the AAS mode. The average temperatures among the RAS, SAS, and AAS were 26.1 °C, 26.4 °C, and 26.0 °C, respectively. The results indicated that the attached air supply (AAS) mode is recommended for generator hall applications due to its lower nonuniformity coefficient and higher energy efficiency coefficient. Based on the range analysis and variance analysis, the air outlet height exhibited significant effects on the air distribution and ventilation performance. This research provides design references for the innovative design of air supply systems in large space buildings.