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Precise landslide monitoring is crucial for understanding and mitigating their impact. The Three Gorges Dam has exacerbated landslides due to steep slopes and rising water levels. This study used ALOS-2 PALSAR-2 (2016–2017) and Sentinel-1A (2016–2018) data to monitor the Daping slope. Findings showed deformation rates of −86.3 mm/y (ALOS-2) and −62 mm/y (Sentinel-1A), confirmed by GNSS data. Analysis indicated that rainfall and water level fluctuations drive the Daping landslide, highlighting key factors influencing landslides in the Three Gorges region and their threats to life and property. [ABSTRACT FROM AUTHOR]

The Three Gorges Reservoir Area (TGRA) is an important ecological barrier in the Yangtze River Basin, China. Therefore, it is of great importance to understand the spatio-temporal variation and the driving factors of production-living-ecological spaces for sustainable and high-quality development in the TGRA. This study investigated the dynamic variation of production-living-ecological spaces in the TGRA by employing land use data in 2000, 2005, 2010, 2015, and 2018, and detected the influencing factors by using the Geographic detector (GeoDetector). Results implied that the structure and dynamic trajectories of production-living-ecological spaces in the TGRA varied in both horizontal and vertical directions, and the study area was dominated by ecological space. A spatial orientation towards the northeast was detected in the evolution of production-living-ecological spaces during 2000–2018. In terms of quantity, the transition from ecological space (grassland and woodland) to agriculture land accounted for the largest proportion from 2000 to 2018. However, the reverse transition from agriculture land to ecological space has increased since 2000 with the efforts of “Grain for Green”. In terms of temporal scale, there was a fluctuating trend in production space with the continuous expansion of living space, while ecological space showed an inverted U-shaped trend during 2000–2018. The dynamic pattern of production-living-ecological spaces in the TGRA was influenced by both physical and socio-economic variables as basic determinants and dominant driving factors, respectively. Finally, the harmonization and protection of production-living-ecological spaces still require policy-makers’ efforts. This work may have potential in advancing our understanding about land use conflicts, and provide a reference for rational layout of spatial functions and the realization of sustainable development in the TGRA. [ABSTRACT FROM AUTHOR]

The Three Gorges Reservoir Area (TGRA) is an important ecological barrier in the Yangtze River Basin, China. Therefore, it is of great importance to understand the spatio-temporal variation and the driving factors of production-living-ecological spaces for sustainable and high-quality development in the TGRA. This study investigated the dynamic variation of production-living-ecological spaces in the TGRA by employing land use data in 2000, 2005, 2010, 2015, and 2018, and detected the influencing factors by using the Geographic detector (GeoDetector). Results implied that the structure and dynamic trajectories of production-living-ecological spaces in the TGRA varied in both horizontal and vertical directions, and the study area was dominated by ecological space. A spatial orientation towards the northeast was detected in the evolution of production-living-ecological spaces during 2000–2018. In terms of quantity, the transition from ecological space (grassland and woodland) to agriculture land accounted for the largest proportion from 2000 to 2018. However, the reverse transition from agriculture land to ecological space has increased since 2000 with the efforts of “Grain for Green”. In terms of temporal scale, there was a fluctuating trend in production space with the continuous expansion of living space, while ecological space showed an inverted U-shaped trend during 2000–2018. The dynamic pattern of production-living-ecological spaces in the TGRA was influenced by both physical and socio-economic variables as basic determinants and dominant driving factors, respectively. Finally, the harmonization and protection of production-living-ecological spaces still require policy-makers’ efforts. This work may have potential in advancing our understanding about land use conflicts, and provide a reference for rational layout of spatial functions and the realization of sustainable development in the TGRA.

The Three Gorges is an important natural geographical landmark and one of the regions with the most abundant cultural heritage preservation in the Yangtze River Basin. Therefore, establishing a demonstration area for the Yangtze River National Cultural Park has become an important site selection objective. Research on the cultural landscape characteristics of the Three Gorges highlights its characteristics as a representative symbol of China and promotes the identification, protection, and valuation of its iconic cultural resources. Despite the current situation, where only a few tangible remnants of the Three Gorges heritage exist, the cultural context remains largely intact. Ancient poetry, with its classical Chinese cultural characteristics and unique geographical expression methods, enriches the natural scenery and humanistic imagery of the Three Gorges. This provides a valuable tool for interpreting and understanding the cultural resources of the Three Gorges and enhancing its value interpretation system. The Tang and Song dynasties saw a surge in the number, representativeness, and influence of poetry related to the Three Gorges. This article analyzes 440 Tang and Song poems about the Three Gorges, focusing on its geographic information and cultural landscapes. Using text mining technology, we extracted the most representative cultural landscapes in the area and visualized the types and distribution these cultural landscapes ArcGIS spatial analysis. Additionally, cluster analysis and spatial semantic analysis were conducted on poetry texts using ROST-CM6 to categorize different landscape themes. The cultural connotations and aesthetic characteristics of each theme were then analyzed by combining semantic networks with high-frequency words and characters. Our findings indicate that the Three Gorges cultural landscape during the Tang and Song dynasties was mainly composed of historical sites, temples, ancestral halls, and former residences of renowned figures. The landscape formed a string of beads along the river and primarily centered on Fengjie and Wushan. We identified six landscape themes on the semantic network, including the Xiajiang Grand View, the ancient capital of the White Emperor, the scenic spots of Xiling, and the clouds and rain of Wushan. The Three Gorges segment of the Yangtze River National Cultural Park followed the "One Belt, One Zone, Two Cores" spatial layout concept, with poetry culture as the soul, the poet's location as the pulse, and renowned mountains and scenic spots as the body. Historical scenes were reconstructed through logical and emotional methods, injecting the aesthetics, culture, and emotion of poetry and its historical background into the basic landscape.

The Three Gorges is an important natural geographical landmark and one of the regions with the most abundant cultural heritage preservation in the Yangtze River Basin. Therefore, establishing a demonstration area for the Yangtze River National Cultural Park has become an important site selection objective. Research on the cultural landscape characteristics of the Three Gorges highlights its characteristics as a representative symbol of China and promotes the identification, protection, and valuation of its iconic cultural resources. Despite the current situation, where only a few tangible remnants of the Three Gorges heritage exist, the cultural context remains largely intact. Ancient poetry, with its classical Chinese cultural characteristics and unique geographical expression methods, enriches the natural scenery and humanistic imagery of the Three Gorges. This provides a valuable tool for interpreting and understanding the cultural resources of the Three Gorges and enhancing its value interpretation system. The Tang and Song dynasties saw a surge in the number, representativeness, and influence of poetry related to the Three Gorges. This article analyzes 440 Tang and Song poems about the Three Gorges, focusing on its geographic information and cultural landscapes. Using text mining technology, we extracted the most representative cultural landscapes in the area and visualized the types and distribution these cultural landscapes ArcGIS spatial analysis. Additionally, cluster analysis and spatial semantic analysis were conducted on poetry texts using ROST-CM6 to categorize different landscape themes. The cultural connotations and aesthetic characteristics of each theme were then analyzed by combining semantic networks with highfrequency words and characters. Our findings indicate that the Three Gorges cultural landscape during the Tang and Song dynasties was mainly composed of historical sites, temples, ancestral halls, and former residences of renowned figures. The landscape formed a string of beads along the river and primarily centered on Fengjie and Wushan. We identified six landscape themes on the semantic network, including the Xiajiang Grand View, the ancient capital of the White Emperor, the scenic spots of Xiling, and the clouds and rain of Wushan. The Three Gorges segment of the Yangtze River National Cultural Park followed the "One Belt, One Zone, Two Cores" spatial layout concept, with poetry culture as the soul, the poet's location as the pulse, and renowned mountains and scenic spots as the body. Historical scenes were reconstructed through logical and emotional methods, injecting the aesthetics, culture, and emotion of poetry and its historical background into the basic landscape. [ABSTRACT FROM AUTHOR]

Cascade reservoir operation can ensure the optimal use of water and hydro-energy resources and improve the overall efficiency of hydropower stations. A large number of studies have used meta-heuristic algorithms to optimize reservoir operation, but there are still problems such as the inability to find a global optimal solution and slow convergence speed. Lightning search algorithm (LSA) is a new meta-heuristic algorithm, which has the advantages such as high convergence speed and few parameters to be adjusted. However, there is no study on the application of LSA in reservoir operation. In this paper, LSA is used to solve the problem of reservoir operation optimization to verify its feasibility. We also propose an improved LSA algorithm, the frog-leaping–particle swarm optimization–LSA (FPLSA), which was improved by using multiple strategies, and we address the shortcomings of LSA such as low solution accuracy and the tendency to fall into local optima. After preliminary verification of ten test functions, the effect is significantly enhanced. Using the lower Jinsha River–Three Gorges cascade reservoirs as an example, the calculation is carried out and compared with other algorithms. The results show that the FPLSA performed better than the other algorithms in all of the indices measured which means it has stronger optimization ability. Under the premise of satisfying the constraints of cascade reservoirs, an approximate optimal solution could be found to provide an effective output strategy for cascade reservoir scheduling. [ABSTRACT FROM AUTHOR]

This study used deep learning to evaluate the ecological vulnerability of Chongqing, China, discuss the deep learning evaluations of ecological vulnerability, and generate vulnerability maps that support local ecological environment protection and governance decisions and provide reference for future studies. The information gain ratio was used to screen the influencing factors, selecting 16 factors that influence ecological vulnerability. Deep neural network (DNN) and convolutional neural network (CNN) methods were used for modeling, and two ecological vulnerability maps of the study area were generated. The results showed that the mean absolute error and root mean square error of the DNN and CNN models were relatively small, and the fitting accuracy was high. The area under the receiver operating characteristic curve of the CNN model was 0.926, which was better than that of the DNN model (0.888). Random forest was applied to calculate the importance of the influencing factors in the two models. Because the main factor was geological features, the relative ecological vulnerability was mainly affected by karst topography. Through the analysis of the ecological vulnerability map, the areas with higher vulnerability are the karst mountains of Dabashan, Wushan, and Qiyaoshan in the northeast and southeast, as well as the valley between mountains and cities in the center and west of the study area. According to the investigation of these areas, the primary ecological problems are low forest quality, structural irregularities caused by self-geological factors, severe desertification, and soil erosion. Human activity is also an important factor that causes ecological vulnerability in the study area. In conclusion, deep learning, particularly CNN models, can be used for ecological vulnerability assessments. The ecological vulnerability maps conformed to the basic cognition of field surveys and can provide references for other deep learning vulnerability studies. While the overall vulnerability of the study area is not high, ecological problems that lead to its vulnerability should be addressed by future ecological protection and management measures. [ABSTRACT FROM AUTHOR]

Since the impoundment of the Three Gorges Reservoir area in 2003, the potential risks of geological disasters in the reservoir area have increased significantly, among which the hidden dangers of landslides are particularly prominent. To reduce casualties and damage, efficient and precise landslide susceptibility evaluation methods are important. Multiple ensemble models have been used to evaluate the susceptibility of the upper part of Badong County to landslides. In this study, EasyEnsemble technology was used to solve the imbalance between landslide and nonlandslide sample data. The extracted evaluation factors were input into three ensemble models, bagging, boosting, and stacking models, for training, and landslide susceptibility maps (LSMs) were drawn. According to the importance analysis, the important factors affecting the occurrence of landslides are altitude, terrain surface texture (TST), distance to residents, distance to rivers and land use. Comparing the influences of different grid sizes on the susceptibility results, a larger grid was found to lead to the overfitting of the prediction results. Therefore, a 30 m grid was selected as the evaluation unit. The accuracy rate, area under the curve (AUC), recall rate, test set precision, and Kappa coefficient of the multigrained cascade forest (gcForest) model under the stacking method were 0.958, 0.991, 0.965, 0.946, and 0.91, respectively, which were significantly better than the values produced by the other two models. [ABSTRACT FROM AUTHOR]

The Three Gorges region (TGR) located in the geographic center of China, is a transition zone between mountain and plain areas, and a probable migration corridor for hominins and other mammals between South and North China. Detailed chronological information of paleoanthropological evidence in this area could help us better understand the human evolution in East Asia. The OSL and U-series dating methods are two conventional dating methods generally adopted to date such sites; however, their applications were limited by the dating range—restricted to several hundred of millennia and ambiguous stratigraphic relationship between the archaeological remains and the dating target materials. Cosmogenic nuclide burial dating of quartzite stone artifacts and coupled electron spin resonance and uranium series dating (ESR/U-series) of fossil teeth have the potential to date Early–Middle Pleistocene hominin sites in Asia and were applied increasingly in China in recent years. However, the application of cosmogenic 26Al/10Be burial dating is limited in TGR because most sites are dominated by limestone, leading to the scarcity of the quartz component. In this case, the coupled ESR/U-series method plays a more important role in the establishment of the chronology of human settlement. In TGR, by using the coupled ESR/U-series method, we have dated seven important Early and Middle Pleistocene hominin settlement sites, including Longgupo, Jianshi, Yunxian, Meipu, Bailongdong, Changyang, and Yumidong sites. Based on our dating results, we propose that hominins were settled in TGR probably from the early stage of Early Pleistocene (∼2.5−2.2 Ma) at the Longgupo site to the late Middle Pleistocene to Late Pleistocene of the Yumidong site (∼274−14 ka) and very likely to spread to other parts of East Asia during this time period. In view of the potential of coupled ESR/U-series dating on fossil teeth from the hominin sites in the TGR, future work may consider the micro damage or non-destructive analysis of enamel fragment with the ESR method and laser ablation ICP-MS techniques that will make possible the direct dating of precious human fossils in China.

Ensemble learning methods can be used to evaluate landslide susceptibility when combined with remote sensing (RS) and geographic information systems (GIS). In this study, the rotation forest (ROF) and random forest (RF) ensemble learning models were applied to evaluate landslide susceptibility. The experiments selected the factors by analysing the linear relationship between the factors, explored the optimal proportions of non-landslide samples and landslide samples based on an unbalanced sample dataset, and used the factors before and after the selection to generate landslide susceptibility maps (LSMs) in the Zigui-Badong area. The results show that a suitable ratio between the sample types in the training set can achieve good results for both sensitivity and specificity. The RF models of the study area with 21 factors and 16 factors had sensitivities of 94.22% and 93.59%, respectively. The ROF models with 21 factors and 16 factors had sensitivities of 90.63% and 88.84%, respectively. Although both the RF and ROF models exhibited high accuracy, the RF model achieved a more reasonable and accurate LSM.

The establishment of the course of the modern Yangtze River is a topic of ongoing debate, with the formation of the Three Gorges, incised in the Huangling Massif, representing the key event under discussion. Downstream of the Three Gorges, the Cenozoic succession of the Jianghan Basin has been investigated to detect the moment of incision into the Three Gorges. Detrital apatite fission‐track data from Eocene to Miocene sediments drilled in the Jianghan Basin suggest that material was supplied by the Dabie, Qinling and Jiangnan Orogens during Eocene to early Oligocene times. At late Oligocene, the source of sediments switched to the Huangling Massif, implying incision of the Three Gorges. We therefore propose that the modern Yangtze River system formed at the late Oligocene. [ABSTRACT FROM AUTHOR]

Biocrusts affect soil detachment through above-ground (top crust's surface covering) and below-ground (sub-crust's binding and bonding, B&B) effects, which might vary with biocrust development or coverage. However, these effects in humid climates are still unclear. This study was conducted to apportion and quantify the surface covering and B&B effects of moss biocrusts with five coverage levels (1%–20%, 20%–40%, 40%–60%, 60%–80%, and 80%–100%) on soil detachment by overland flow in a subtropical humid climate. Two treatments with one being intact moss crusts and one removing the above-ground moss tissues were designed for each coverage level, and bare soil was used as the baseline. The results indicated that soil detachment capacity (Dc) and rill erodibility (Kr) decreased with biocrust coverage. After removing the above-ground moss tissues, the impeding effect of biocrusts on soil detachment weakened, but still increasing soil erosion resistance relative to bare soil. For intact crust, Dc was reduced by 50%–95% compared with bare soil, wherein 36%–55% and 14%–40% were attributed to the surface covering and B&B, respectively. The top crust contributed more than sub-crust to the soil detachment reduction, which were related to but not linear with biocrust coverage. When biocrust coverage reached mid-to-higher level (40%–100%), both top crust and sub-crust steadily contributed to soil detachment reduction with 60% and 40%, respectively. The findings advance a better understanding of the influencing mechanism of biocrusts on soil erosion in humid climates and highlight the importance of saving biocrusts as ecosystem functions. [ABSTRACT FROM AUTHOR]

River canyons mapping plays an important role in water conservation project construction, tourism resource development, and analysis of fluvial processes. However, the extraction of river canyons via manual interpretation or semi-automatic methods is inefficient and expensive, especially at large spatial scales. Therefore, the objective of this study is to propose a novel method for automatic extraction of river canyons. The method mainly involves (1) extracting the indegree of river segments and generating river buffers based on the indegree, (2) generating topographic profiles at the two riversides of each river segment based on a digital elevation model, (3) extracting peaks from the topographic curves with the assistance of depth curves, (4) matching the peaks from different sides of each river segment based on a distance-priority strategy and then generating peak pairs based on the results, and (5) extracting the geographic range and attributes of river canyons and mapping them into a layer. Results of cases in the Three Gorges and Yarlung Zangbo areas in China illustrate effectiveness and accuracy for the extraction of river canyons. In this case, the false alarm rate and the miss alarm rate of this approach are both no higher than 17%. [ABSTRACT FROM AUTHOR]

We reconstruct the incision history of bedrock rivers based on inverse modeling of the long profile of a river channel and the low‐temperature thermochronological data. Our approach first infers an erodibility‐dependent incision history through a linear inversion of the channel elevations of the river. Then to calibrate the reconstructed incision history in the geological timescale, we constrain the erosional efficiency by optimizing the erosion process of the river catchment using a Bayesian analysis, such that the exhumation and cooling paths of bedrocks in the catchment conform to the observed thermochronological ages. We apply this approach to estimate the incision history of the Three Gorges, Yangtze River in East Asia. We modeled the incision histories of three tributaries on the mainstem Yangtze River near the eastern end of the Three Gorges area, assuming that the gorge incision was driven by increased upstream drainage area of the Upper Yangtze (Scenario 1) or local tectonic uplift (Scenario 2). The results of both scenarios suggest an early Miocene onset of the incision of Three Gorges, that is, 18 ± 6 Ma or 21 ± 4 Ma, respectively. During the Pliocene, our models suggest a significant decrease in the gorge incision rate. By comparing the estimated gorge incision history to the late Cenozoic denudation of the eastern Tibetan Plateau and the regional climate change, we suggest that the incision of the Three Gorges has been heavily affected by the development of the Upper Yangtze River and the East Asian monsoon. Key Points: River incision history is modeled using topographic and published (U‐Th)/He dataInversion of the data suggests accelerated incision rate since the early MioceneGorge incision rate decreased during the Pliocene due to the declined monsoonal rainfall [ABSTRACT FROM AUTHOR]

Shu, Q.; Zhao, Z.; Zhao, Y.; Chen, Y., and Zhang, M., 2021. Magnetic properties of late Cenozoic sediments in the Subei Basin: Implications for the Yangtze River run-through time. Journal of Coastal Research, 37(1), 122–131. Coconut Creek (Florida), ISSN 0749-0208. The Subei Basin is situated in the lower reaches of the Yangtze and Huai Rivers. In this study, samples were selected from the XH-2 borehole near the subsidence center of the Subei Basin, and modern sediments from the lower reaches of the Yangtze and Huai Rivers. The aim of this study is to decipher the evolution of the regional river system and the formation of the Yangtze River's Three Gorges through the analyses of paleomagnetism, mass susceptibility, and magnetic minerals. The results show that the river system in the Subei Basin experienced several major upheavals. (1) During 4.76–4.2 million years before present (Ma BP), the Yangtze River flowed through the study area in the vicinity of the XH-2 location; (2) During 4.2–2.2 Ma BP, the Yangtze River had migrated from the study area, and the Huai River flowed through the area; (3) During 2.2–0.55 Ma BP, the Yangtze River flowed through the area again; (4) During 0.55–0.12 Ma BP, the Yangtze River and Huai River alternatively influenced the study area; and (5) Since 0.12 Ma BP, the Yangtze River withdrew from the Subei Basin entirely, and the Huai River flows through the XH-2 position again. The Yangtze River sediment in the bottom of the XH-2 borehole indicates that the time of formation of the Three Gorges of the Yangtze River is probably greater than or equal to 4.76 Ma BP. This estimated time is earlier than the previous conclusions of an Early Pleistocene run-through time for the Yangtze River. [ABSTRACT FROM AUTHOR]

Ensemble learning methods can be used to evaluate landslide susceptibility when combined with remote sensing (RS) and geographic information systems (GIS). In this study, the rotation forest (ROF) and random forest (RF) ensemble learning models were applied to evaluate landslide susceptibility. The experiments selected the factors by analysing the linear relationship between the factors, explored the optimal proportions of non-landslide samples and landslide samples based on an unbalanced sample dataset, and used the factors before and after the selection to generate landslide susceptibility maps (LSMs) in the Zigui-Badong area. The results show that a suitable ratio between the sample types in the training set can achieve good results for both sensitivity and specificity. The RF models of the study area with 21 factors and 16 factors had sensitivities of 94.22% and 93.59%, respectively. The ROF models with 21 factors and 16 factors had sensitivities of 90.63% and 88.84%, respectively. Although both the RF and ROF models exhibited high accuracy, the RF model achieved a more reasonable and accurate LSM. [ABSTRACT FROM AUTHOR]

Background: Modernization of Chinese adults is associated with increased atherosclerotic diseases. Over 1 million farmers have been resettled upland since 1996 in the Three Gorges dam project of the Yangtze River, with job and other lifestyle changes. We aimed to evaluate the impact of such rapid lifestyle changes on indices of cardiometabolic health. Methods: Ninety-five ex-farmers in Wu Shan (WS) (aged 49.7 ± 9 years) resettled uphill for 3–5 years and 87 age and gender-matched farmers in Da Chang (DC) (aged 48.8 ± 10 years) studied before resettlement were compared. Carotid intima-media thickness (IMT) was measured by ultrasound. Results: Ninety-nine percent WS residents adopted nonfarming jobs or were retired. WS ex-farmers had higher waist–hip ratio (P < 0.0001), low density lipoprotein-cholesterol (P = 0.001), triglycerides (P = 0.001), and prevalence of metabolic syndrome (MS) (43.2% vs. 17.2%, P = 0.01) compared with DC farmers. Smoking status, body mass index, systolic and diastolic blood pressures, high density lipoprotein-cholesterol, and fasting glucose were similar. Carotid IMT was significantly higher in WS residents (0.71 ± 0.16 mm) than in DC farmers (0.64 ± 0.11 mm) (P < 0.001). MS correlated with job changes to more sedentary nature (β = 0.453, P < 0.0001), but not to leisure exercise activities, nor any specific dietary habits. On multivariate regression, carotid IMT was associated with WS location (β = 0.196, P = 0.021) and presence of MS (β = 0.208, P = 0.021), independent of other traditional vascular risk factors (model R2 value = 0.444, F-value 12.0, P < 0.0001). Conclusion: Rapid lifestyle and job changes in ex-farmers in the Three Gorges region are associated with significantly worse cardiometabolic profiles and subclinical atherosclerosis, with potentially important implications for atherosclerosis prevention in modernizing China. [ABSTRACT FROM AUTHOR]

A landslide susceptibility assessment for the Three Gorges (TG) region (China) was performed in a Geographical Information System (GIS) environment and Persistent Scatterer (PS) InSAR derived displacements were used for validation purposes. Badong County of TG was chosen as case study field. Landslide parameters were derived from two datasets. The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Global Digital Elevation Map (GDEM) was used to calculate slope geometry parameters (slope, aspect, drainage, and lineament), while geology and vegetation cover were obtained from Landsat and ASTER data. The majority of historical landslides occurred in the sandstone-shale-claystone intercalations. It appears that slope gradients are more critical than other parameters such as aspect and drainage. The susceptibility assessment was based on a summation of assigned susceptibility scores (points) for each 30×30 m unit in a database of a Vector Grid File (VGF) composed of ‘vector pixels’. A landslide susceptibility map (LSM) was generated using VGF and classified with low, moderate and high landslide susceptibility zones. The comparison between the LSM and PS InSAR derived displacements suggests that landslides only account for parts of the observed surface movements.

The formation of the Three Gorges (TG), the most important capture point along the Yangtze River, has been debated since the last century. Most of hypotheses on its formation are based on the timing of unconformities detected in the sedimentary basins along the riverbed. These unconformities may mark periods of tectonic activity and enhanced hydrodynamic condition. Herein, we detail the Cenozoic sedimentary provenance of the Jianghan Basin through LA-ICP-MS zircon U-Pb geochronology and heavy mineral analyses. The obtained data suggest that during Palaeocene-Oligocene time, the Jianghan Basin was supplied by sediments from the nearby mountain belts. However, the occurrence of zircons with ages <32 Ma above the unconformity at ~24.6 Ma indicates a provenance from Cenozoic igneous rocks which are exposed only in the Qiangtang Block and the Songpan-Ganzi Orogen. We propose therefore that the TG formed between the late Oligocene and the early Miocene and that the ~24.6 Ma unconformity in the Jianghan Basin represents the best dating of the TG formation. [ABSTRACT FROM AUTHOR]

Brominated flame retardants (BFRs) have attracted increasing attention in recent decades because of their persistence, distribution, bioaccumulation, and biotoxicity in the environment. In the present study, the levels and distribution of polybrominated diphenyl ethers (PBDEs) and polybrominated biphenyl (PBBs) in twenty-four samples of twelve fish species collected from the Three Gorges Reservoir (TGR) were analyzed. The results indicated that SPBDE concentrations in fish muscle ranged from 22.62 pg g-1 by wet weight (ww) (yellowcheek carp) to 217.75 pg g-1 ww (yellow catfish). BDE47 and BDE209 were the most predominant congeners, with their sum accounted for 23.62-68.16% of SPBDEs. SPBB concentrations ranged from 27.83 pg g-1 ww (silver carp) to 155.75 pg g-1 ww (topmouth culter); BB49 and BB209 were detected in all samples, with concentrations ranging from 4.62 to 47.10 pg g-1 ww and 1.29 to 80.95 pg g-1 ww, respectively. There are no significant correlations between the BFRs levels and fish length (or weight) in these samples. Compared to other areas, the level of BFRs in edible fishes from TGR was low. [ABSTRACT FROM AUTHOR]

Geological hazard monitoring is essential to the prevention and control of geological hazards, yet conventional monitoring is often conducted for local geological hazards, and the relation between monitored results and geological hazards remains poorly understood. In this study, a regional load deformation field model was constructed using data from 26 Continuously Operating Reference Stations (CORS) and 8 gravity stations in the Three Gorges area. The relation between load-induced changes and geological hazards, as the regular characteristics (RCS) in this paper, is obtained by comparing the geological hazards with the impact of the total load change in the whole region of the Three Gorges area and the entire process from 2011 to the beginning of 2015. Geological hazards are more prone to occurring when there are one or more RCS, especially abnormal dynamic environment appears at the same time, such as solid high tide and heavy rainfall. The RCS included the ground geodesy height change rate increasing, the ground gravity change rate decreasing, the ground vertical deviation diverging, the ground geodesy height gradient growing larger and the ground gravity gradient growing larger. Using all of the 18 geological hazards from May to July 2013 to verify the RCS, it was found that the comprehensive observations of CORS and gravity stations can effectively monitor the RCS of the load-induced changes. The results of this study provide more insights associated with the geological hazards monitoring and analysis methods as well as effective support for geological hazard forecasting. [ABSTRACT FROM AUTHOR]

Rainfall and seismic activity have significant influence on the stability of dangerous rockmass. In this paper, the dangerous rockmasses are classified into three instability types according to the failure modes: sliding, falling, and toppling. The discrete element method (COMSOL) was carried out to investigate the stability of three different rockmass types. In the numerical simulation, three load combinations were applied to the numerical model: 1) rockmass weight, 2) rockmass weight + fissure water pressure, and 3) rockmass weight + fissure water pressure + earthquake force. The results show that rainfall and seismic activity play important roles in rockmass stability and the displacement and principal stress of the rockmass are influenced obviously. Wangxia dangerous rockmass in the Great Three Gorges area was selected as a case study, and its stability was analyzed by geological investigation, numerical simulation, and static calculation methods. The results show that there is a high risk that Wangxia dangerous rockmass would lose stability when rainfall season comes and seismic activity happens. A blast was conducted to remove this dangerous rockmass and an SNS net design was proposed to intercept distributed blocks based on rockfall trajectory simulation. The parameters needed in the rockfall simulation program were obtained by laboratory and field tests. Final application proved that the designed treatment is efficient and no damage was caused by the distributed blocks. The whole research may provide a useful reference to similar engineering projects in the future. [ABSTRACT FROM AUTHOR]

The evolutionary history of the Yangtze River plays a key role for understanding the Cenozoic landscape evolution of East Asia. The Three Gorges currently separate the Sichuan Basin from the Jianghan Basin to the east, and their formation is considered to establish an initial connection between the Upper and Middle reaches of the modern Yangtze River. However, despite their importance in the Yangtze River evolution, the age of the initial incision of the Three Gorges remains an ongoing debate. In this study, we use apatite-fission track and (U Th)/He data to model the thermal history of the crust during the gorge formation. Based on the modeled time–temperature paths of samples on vertical profiles and the 3D thermos-kinematic modeling of the gorge region, we suggest that the gorges were initially carved during the Late Oligocene–Early Miocene. This event connected the drainages to the west and east of the gorge regions, leading to the formation of the modern east-flowing Yangtze River. This is also consistent with the sediment provenance of the Yangtze Gravels in the Lower Yangtze reported in previous studies. The gorge formation could be a response to the base level drop in the Jianghan and Subei Basins, which led to an upstream propagation of high erosion rates in the Three Gorges areas. [Display omitted] • Incision of the Three Gorges is a key step in the evolution of the Yangtze River. • AFT and AHe dating used to investigate the timing of gorge incision. • Time-temperature history suggests two rapid cooling events. • 3D modeling predicts an incision onset age at ~18–27 Ma. • Subsidence of East China drives the drainage reorganization via headward erosion. [ABSTRACT FROM AUTHOR]

Extensive areas with low-relief surfaces that are almost flat surfaces high in the mountain ranges constitute the dominant geomorphic feature of the Three Gorges area. However, their origin remains a matter of debate, and has been interpreted previously as the result of fluvial erosion after peneplain uplift. Here, a new formation mechanism for these low-relief surface landscapes has been proposed, based on the analyses of low-relief surface distribution, swath profiles, χ mapping, river capture landform characteristics, and a numerical analytical model. The results showed that the low-relief surfaces in the Three Gorges area could be divided into higher elevation and lower elevation surfaces, distributed mainly in the highlands between the Yangtze River and Qingjiang River. The analyses also showed that the rivers on both sides of the drainage divide have not yet reached equilibrium, with actively migrating drainage divides and river basins in the process of reorganizing. It was concluded that the low-relief surfaces in the Three Gorges area did not share a common uplift history, and neither were they peneplain relicts, but rather that the effect of “area-loss feedback” caused by river capture has promoted the formation of upland low-relief surface landscapes. A future work aims to present the contribution of accurate dating of low-relief surface landscapes.

A major limitation for wide application of Synthetic Aperture Radar (SAR) remote sensing in mapping landslide surface displacements is the intrinsic gap between the ultimate objective of measuring three-dimensional displacements and the limited capability of detecting only one or two-dimensional displacements by repeat-pass SAR observations of identical imaging geometries. Although multi-orbit SAR observations of dissimilar viewing geometries can be jointly analyzed to inverse the three-dimensional displacements, the reliability of inversion results might be highly questionable in case of continuous motion because of the usually asynchronous acquisitions of multi-orbit SAR datasets. Aiming at this problem, we proposed an approach of retrieving time series three-dimensional displacements from multi-angular SAR datasets for step-like landslides in the Three Gorges area in this article. Firstly, time series displacements of a common ground target in the azimuth and line-of-sight (LOS) direction can be estimated using traditional methods of SAR interferometry (InSAR) and SAR pixel offset tracking (POT), respectively. Then, a spline fitting and interpolation procedure was employed to parameterize the displacement history in the sliding/dormant periods of step-like landslides and estimate displacements from multi-angular observations for identical date series. Finally, three-dimensional displacements can be inverted from these synchronized multi-angular measured displacements in traditional ways. As a case study, the proposed method was applied to retrieve the three-dimensional displacements history of the Shuping landslide in the Three Gorges area, China. Comparisons between SAR-measured displacements and measurements of global positioning system (GPS) showed good agreement. Furthermore, temporal correlation analyses suggest that reservoir water level fluctuation and rainfall are the two most important impact factors for the Shuping landslide stability. [ABSTRACT FROM AUTHOR]

With the rapid development of cascade reservoirs, the joint operation chart of cascade reservoirs and its optimization methods have been widely researched. Aimed at the defects of the conventional two-stage Progressive Optimality Algorithm (POA) in the optimization of energy storage operation chart, this paper proposed a new multi-stage POA optimization model. It took the traditional reverse calculation result as the initial solution, and expanded the two-stage optimization mode of conventional POA to three-stage mode, four-stage mode, or higher stages mode, and implemented the iterative calculation by taking the result of lower stages POA as the input of higher stages POA, until the result converged. In addition, enumeration method was used to iterate over all the possible combinations in local optimization to improve the efficiency of local search. In order to test and verify the rationality and validity of the proposed model, two cascade reservoirs had been taken as the instances of case study, compared with conventional two-stage POA, results showed that the power generation of Li Xianjiang and Three Gorges cascade reservoirs by the proposed multi-stage POA can respectively increase by 0.055% ($32000) and 0.077% ($3900000). So the economic benefits are remarkable, and the proposed model is reasonable and effective. [ABSTRACT FROM AUTHOR]

Every year, landslides pose huge threats to thousands of people in China, especially those in the Three Gorges area. It is thus necessary to establish an early warning system to help prevent property damage and save peoples’ lives. Most of the landslide displacement prediction models that have been proposed are static models. However, landslides are dynamic systems. In this paper, the total accumulative displacement of the Baijiabao landslide is divided into trend and periodic components using empirical mode decomposition. The trend component is predicted using an S-curve estimation, and the total periodic component is predicted using a long short-term memory neural network (LSTM). LSTM is a dynamic model that can remember historical information and apply it to the current output. Six triggering factors are chosen to predict the periodic term using the Pearson cross-correlation coefficient and mutual information. These factors include the cumulative precipitation during the previous month, the cumulative precipitation during a two-month period, the reservoir level during the current month, the change in the reservoir level during the previous month, the cumulative increment of the reservoir level during the current month, and the cumulative displacement during the previous month. When using one-step-ahead prediction, LSTM yields a root mean squared error (RMSE) value of 6.112 mm, while the support vector machine for regression (SVR) and the back-propagation neural network (BP) yield values of 10.686 mm and 8.237 mm, respectively. Meanwhile, the Elman network (Elman) yields an RMSE value of 6.579 mm. In addition, when using multi-step-ahead prediction, LSTM obtains an RMSE value of 8.648 mm, while SVR, BP and the Elman network obtains RSME values of 13.418 mm, 13.014 mm, and 13.370 mm. The predicted results indicate that, to some extent, the dynamic model (LSTM) achieves results that are more accurate than those of the static models (i.e., SVR and BP). LSTM even displays better performance than the Elman network, which is also a dynamic method. [ABSTRACT FROM AUTHOR]