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Riverine contamination of metals and metalloids is a growing global concern. However, our understanding of how cascade reservoirs influence the fate of these pollutants remains limited. In this study, we focused on the Jinsha River, a typical large river polluted with metal(loid)s in Southwest China, to investigate the partitioning and transport of these substances from the upper natural reaches to the lower cascade reservoirs-regulated reaches during both flood and dry seasons. Results revealed that the rapid urbanization and industrial development following the construction of reservoirs led to significant copper (Cu), nickel (Ni), lead (Pb), chromium (Cr), and cadmium (Cd) pollution. Through various analytical techniques such as correlation analysis, principal component analysis, redundancy analysis, and structural equation modeling, we determined that reservoirs had a profound impact on solid-associated parameters, including particulate organic matter (POM), suspended solid concentration (SSC), and median particle diameter (D50). These parameters, in turn, affected the fate of metal(loid)s through processes like sorption-desorption and dissolution-precipitation. High POM concentrations and low SSC and D50 values resulted in the precipitation of most particulate metal(loid)s, thereby reducing their transport across reservoirs. As river water moved downstream across the reservoirs, the percentage of particulate metal(loid)s decreased by 6.1% for arsenic (As), 38.3% for Cu, 74.9% for Ni, 36.8% for Cr, 17.8% for Cd, and 41.9% for Pb, respectively. Furthermore, the cascade reservoirs had cumulative effects on the deposition of particulate metal(loid)s, particularly concerning Cr, Cd, and Pb in the final reservoirs. Human health risk assessments indicated that dissolved As and Pb posed potential non-carcinogenic threats to residents. Despite the fact that reservoirs captured most particulate metal(loid)s, the transport of dissolved As and Pb across the reservoirs still impacted the safety of downstream drinking water. Therefore, in cascade reservoir systems, the concern regarding dissolved metal(loid) pollution remains a priority for future reservoir management. [ABSTRACT FROM AUTHOR]

ABSTRACT Sound is critical in fish behaviours, including reproduction, feeding, predator avoidance and habitat selection. To investigate the impact of underwater soundscape on the distribution of Cobitidae fishes, we surveyed the status of Cobitidae fish resources and the underwater soundscape along with related environmental factors at 12 sampling sites downstream of the Songxin Hydropower Station in the Heishui River, a major tributary of the Jinsha River in China. Generalised additive models (GAMs) were employed to identify the primary environmental factors influencing the distribution of Cobitidae fishes and we analysed the correlation between the abundance of Cobitidae fish and primary environmental factors. The study revealed that the water depth, flow velocity, water temperature and sound pressure level (SPL) all had highly significant effects on the distribution of Cobitidae fishes (p < 0.001), with SPL showing the lowest relative importance among these factors. Water depth positively correlated with Cobitidae fish abundance, whereas water temperature, SPL and flow velocity showed negative correlations. This study preliminarily explored the response relationship between the distribution of Cobitidae fish and four main environmental factors, offering a technical foundation for predicting the distribution of Cobitidae fishes in rivers and for implementing conservation measures of fish such as suitable habitat creation. [ABSTRACT FROM AUTHOR]

The giant Cuola landslide is one of the largest and highest landslide dams in the upper reaches of the Jinsha River, which brought about a substantial influence on the geomorphological evolution of the Jinsha River valley. Through field investigations, UAV photogrammetry, OSL, and 10Be dating methods, the topographic and geological characteristics of the Cuola landslide dam were examined, and the evolution features of formation and failure were investigated as well. The results indicate that the Cuola landslide, with a volume of ~ 4 × 108 m3 and an age of ~ 50.9 ka BP, was primarily due to a seismic event, and the major failure mode of the ~ 1590-m-high source area on the left bank was attributable to a wedge sliding. The landslide body slid into the valley and climbed ~ 540 m up the right bank with a long runout of 3740 m. The relict landslide deposits demonstrate a large-scale natural dam with a height of 272 m, a length of 1780 m, and a width of 1940 m, which completely blocked the river, and formed a dammed lake with an inundation length of 190 km and an impoundment volume of 10.817 km3. The longevity of the landslide dam was discussed in terms of glacial climate, dam morphology, and material characteristics, and fault dislocation was deduced to induce the overtopping dam break at ~ 4 ka BP. The overflowing water preferentially undercut the weak zone created by fault displacement within the dam until the onset of the final breach, facilitated by the warm climatic conditions of Holocene Climatic Optimum. The findings in this study illustrate the dramatic longevity of a natural dam produced by a giant landslide in one of the most deeply incised valleys in the world and provide a conceptual model for a better understanding of landslide-induced landscape evolution of high-relief river catchments. [ABSTRACT FROM AUTHOR]

In the context of rural revitalization, facing the two major challenges of ecological protection and rural revitalization faced by the downstream hydropower station reservoir area of the Jinsha River, taking Yongshan County in Yunnan Province, located in the reservoir areas of Xiluodu and Xiangjiaba hydropower stations in the lower reaches of the Jinsha River, as an example, analyzed the advantages of citrus industry development in the reservoir area, clarified the dual role of citrus industry in ecological protection and rural revitalization in the reservoir area, pointed out the problems in development, and proposed countermeasures and suggestions, in order to further expand and strengthen the citrus industry in the lower reaches of the Jinsha River reservoir area and provide reference for rural revitalization. [ABSTRACT FROM AUTHOR]

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The 2280 km long Jinsha River has been blocked at least four times in the past 30 years. A landslide damming hazard chain can endanger communities and infrastructures hundreds of kilometers downstream from the damming site in alpine gorges. Past damming events have resulted in severe consequences, demanding a thorough assessment of damming threats along the entire Jinsha River. This study digitizes the Jinsha River and visualizes its topographic, tectonic, hydrologic, and climate characteristics in detail. A two-stage full-probability method is proposed for assessing the damming threats along this river, making it possible to identify potential damming hotspots and high-priority zones for hazard mitigation. It is found that the upper reach of the Jinsha River poses the greatest damming threat, and the threat level gradually decreases downstream. Approximately 33.4%, 36.7%, 20.5%, and 9.4% of the entire length of the Jinsha River are classified as low, moderate, high, and very high threat levels, respectively. Compared with existing hydropower projects, future projects in the upper reach are more likely to be exposed to landslide damming. We highlight the value of basin-scale spatial threat analysis and envisage that our findings will promote more targeted local-scale risk assessments for potential damming hotspots. These outcomes provide the basis for managing the risks of river damming and hydropower infrastructure along the Jinsha River.

The Taoyuan paleolake is located at the main stream of the Jinsha River, on the southeastern edge of the Qinghai-Tibet Plateau, a region characterized by intense tectonic activity. This complex geological setting is highly prone to trigger a cascade of geological disasters, including earthquakes, landslides, and dammed lakes. To further analyze the causes of landslide-induced dammed lakes on the Jinsha River’s mainstream, this study utilized 30 m resolution DEM data and ArcGIS spatial analysis technology. This allowed for the extraction of tectonic geomorphological indices along the Jinsha River’s main stream at Taoyuan paleolake and its adjacent areas, including slope, relief degree of land surface, hypsometric integral, and river steepness index. These indices were compared with non-structural factors (precipitation and lithology) to discover significant differences in tectonic geomorphology between the upstream lacustrine sedimentary areas and downstream areas of the Jinsha River, with the Zhaizicun ancient landslide serving as a dividing point. In addition, combined with the analysis of previous research findings, it further confirmed that the tectonic activity of the Chenghai fault is the primary factor influencing the formation of the Zhaizicun ancient landslide and the differences in tectonic geomorphology in the surrounding areas. The blockage of the river caused by the landslide is also the main reason for the formation of Taoyuan paleolake. This indirectly reflects that regions with abnormal changes in tectonic geomorphology along rivers are prone to form landslides.

The river-blocking landslide disasters are widely distributed in the mountainous areas of southwest China, characterized by high-elevation long-runout movements with significant destructive power. The identification and monitoring of high-elevation long-runout landslides, as well as the prediction of unstable landslide movements, hold great significance for regional disaster mitigation and prevention. In this study, we used interferometric synthetic aperture radar to identify and monitor potential landslides in the Gongjue segment of the Jinsha River Basin in China. The Sela landslide was selected for rainfall infiltration simulation, predict the entire process of landslide instability, and explore its failure characteristics from a dynamic perspective. The monitoring results revealed the presence of four typical landslides in Gongjue County, situated within the Jinsha River area, with slope deformation rates exceeding 17 cm/yr. The maximum observed slope deformation rate reaches 46 cm/yr. Decomposition results of the time-series deformation characteristics of the landslide feature measurement points show that rainfall was the primary factor influencing the periodic deformations of landslides. Simulation results indicated that rainfall promotes landslide deformation. Under the influence of rainfall, the movement speed of the landslide increases rapidly, and the front sliding body slides first, followed by the instability of the upper sliding body. This is consistent with the damage mode caused by a traction-type landslide. Subsequently, the particle movement speed maintains a short period of rapid sliding, gradually decreasing and eventually reaching a stable state. The results of this study provide an important reference for carrying out remote monitoring and risk prediction for high-elevation long-runout landslides. [ABSTRACT FROM AUTHOR]

Copyright of Remote Sensing for Natural Resources is the property of Remote Sensing for Natural Resources Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To date, the knowledge of benthic macroinvertebrates in the upper reaches of the Jinsha River remains quite limited compared to other rivers in China due to the difficulty of sampling and special geographical environment. In this study, benthic macroinvertebrates in the upper reaches of the Jinsha River were investigated to address the knowledge gap. The results showed that dipterans dominated the communities, followed by amphipods and EPT taxa. The density, biomass and biodiversity were at a low level. As a high sediment-loaded river, unlike the Yellow River and the Wei River, oligochaetes are not commonly found in the upper reaches of the Jinsha River, and no mollusks were collected. The results of db-RDA showed that some natural factors influenced the spatial distribution of benthic macroinvertebrates in both dry and wet seasons, but during the flood season (summer and autumn), nitrogen and phosphorus became important factors due to severe soil erosion and high sediment loads in the water. The sections between above Batang and below Batang have obviously different substrates, resulting in the significantly different species composition and functional feeding groups. Moreover, higher habitat diversity can lead to higher benthic macroinvertebrate diversity after comparing the substrate types of the two sections. We consider that the unstable habitat conditions in the upper reaches of the Jinsha River are not conducive to completing the entire life cycle of benthic macroinvertebrates within a localized small habitat, and the communities are likely influenced more by seasonal contributions from populations in tributaries. Considering the impact of the existing cascade hydropower stations in the middle and lower reaches, and the realistic and potential impacts expected from the planned cascade hydropower stations in the upper reaches, it is imperative to prioritize the conservation of the tributaries along both banks of the upper Jinsha River. This enhanced conservation effort aims to preserve the diversity and integrity of benthic macroinvertebrates, which is of great significance in providing reliable food sources for the rare cold-water fish species and ensuring the safety of the aquatic ecosystem in the region.

The upstream Jinsha River, located in the eastern Tibetan Plateau, has been experiencing intense geological hazards characterized by a high density of ancient landslides, significant deformation and reactivation challenges. In this study, remote sensing interpretation, field investigations, and Small Baseline Subset Interferometric Synthetic Aperture Radar (SBAS-InSAR) technologies have been employed. Along a 17 km stretch of the Jinsha River, specifically in the Xiongba-Sela segment, 16 large-scale ancient landslides were identified, 9 of which are currently undergoing creeping deformation. Notably, the Sela and Xiongba ancient landslides exhibit significant deformation, with a maximum deformation rate of −192 mm/yr, indicating a high level of sliding activity. The volume of the Sela ancient landslide is estimated to be 1.8 × 108 to 4.5 × 108 m3, and characterized by extensive fissures and long-term creeping deformation. The SBAS-InSAR results revealed significant spatial variations in the deformation of the Sela ancient landslide, generally displaying two secondary zones of intense deformation, and landslide deformation exhibits nonlinear behavior with time. Between January 2016 and February 2022, Zone III1 on the southwest side of the Sela ancient landslide, experienced a maximum cumulative deformation of −857 mm, with a maximum deformation rate of −108 mm/yr. Zone III2, on the northeast side of the Sela ancient landslide, the maximum cumulative deformation was −456 mm, with a maximum deformation rate of −74 mm/yr; among these, the H2 and H4 secondary bodies on the south side of III1 are in the accelerative deformation stage and at the Warn warning level. We propose that the large-scale flood and debris flow disasters triggered by the Baige landslide-dammed lake-dam broken disaster chain in Tibetan Plateau during October and November 2018 caused severe erosion at the foot of downstream slopes. This far-field triggering effect accelerated the creep of the downstream ancient landslides. Consequently, the deformation rate of Zone III2 of the Sela ancient landslide increased by 6 to 8 times, exhibiting traction-type style reactivation. This heightened activity raises concerns about the potential for large-scale or overall reactivation of the landslide, posing a risk of damming the Jinsha River and initiating a dam-break disaster chain. Our research on the reactivation characteristics and mechanisms of large ancient landslides in high deep-cut valleys provides valuable guidance for geological hazard investigation and risk prevention. [ABSTRACT FROM AUTHOR]

The Jinsha River is located on the southeastern edge of the Qinghai-Tibet Plateau, spanning the transitional zone between the first and second geomorphic terraces in China. The basin is prone to frequent geological hazards. The Sichuan section of the Along- Jinsha Expressway is an important supporting project for “The Belt and Road Initiative” and the “Yangtze River Economic Belt”, which is of great strategic significance to the development of Liangshan Yi Autonomous Prefecture. In order to investigate the unique phenomenon of the differential distribution of geological disasters along the Pingshan-Jinyang section of the Jinsha River, the background conditions and characteristics of geological hazard development in the study area were systematically combed through remote sensing interpretation, field investigation and data analysis. The genetic mechanism of the differential distribution of geological hazards was analyzed, and corresponding prevention and control strategies for different hazard types was proposed in the study area. The findings are as follows: the geological hazards along the Pingshan-Jinyang section of the expressway mainly consist of debris flows in Pingshan County, where the proportion of their development is significantly lower compared to the lower annual rainfall areas of Leibo County and Jinyang County. Topography, geomorphology, geological structure and seismic activity are the internal influencing factors for the differential distribution. Critical rainfall and human engineering activities are the external factors contributing to the differential distribution. Both internal and external factors jointly dominate the differential distribution of geological hazards in the study area. Targeted prevention and control strategies are proposed based on different types of geological hazards. [ABSTRACT FROM AUTHOR]

Intense hydroelectric exploitation requires information on sediment flux to prevent the potential siltation of cascade reservoirs. As the main sediment source for the Yangtze River, the lower Jinsha River Basin (LJRB) lacks data on its sediment budget, which urges a thorough investigation to provide reliable estimates. This paper proposed a modelling framework to study soil erosion, sediment delivery, and sediment yield in this critical area with an emphasis on analyzing the underlying controls. Over the past 50 years, basin average erosion rates decreased from 26.5 to 23.7 t ha-1 a-1, with erosion hotspots (>50 t ha-1 a-1) comprising only 21.1% of the basin area but contributing 69.5% of the gross erosion. Local steepness and sparse landcover conditions were found to be directly responsible for high erosions, rather than precipitation or soils. With a dimensionality reduction strategy to remove redundant factors, the optimal variables for modelling sediment delivery ratio (SDR) were identified as Specific Catchment Area, Maximum Elevation, and Drainage Area. These three variables all had a positive correlation with SDR, and the established model can explain 86% of the SDR variation. Further modelling revealed regionalised SDRs ranging from 0.07 to 0.38 for 39 subbasins, about 30% of which were no less than 0.35. Regionalised specific sediment yield (SSY) ranged from 1.3 to 16.9 t ha-1 a-1 with 38% of the high SSYs (above 8 t ha-1 a-1) concentrating in the reservoir area from Wudongde to Xiluodu that poses siltation risks. This study addressed the scarcity of sediment budget knowledge in the LJRB, and the coupled model of erosion and sediment delivery has been validated with satisfactory predictions. Therefore, the modelling framework proposed may be adopted to diverse river basins for its low parameter requirements and solid modelling performance. [ABSTRACT FROM AUTHOR]

Recurrence of large-scale ancient landslides often manifests as catastrophic events, so it is important to assess their stability by monitoring the deformation process. In this study, the Da'ao ancient landslide along the Jinsha River in China was investigated and analyzed. Field investigation showed that the landslide body is being experienced deforming with many new failures. Three sliding events can be identified according to different main scarps. The Permanent Scatterer Synthetic Aperture Radar Interferometry (PS-InSAR) data further revealed that the most obvious deforming area is in the middle and toe part of the sliding body with the largest cumulative displacement of 55 mm during 2017 to 2021. Additionally, the relatively stable zone and the accelerating deforming zone are divided by displacement rate. This indicates that the Da'ao landslide is becoming unstable. At the same time, the Particle Flow Code (PFC) simulation verified that the risk of landslide recurrence is likely when subjected to strong earthquakes or heavy rainfall, and the resulting sidings could dam the Jinsha River. In addition, the analysis results suggested that the displacement rates were approximately 5 mm/year and 13.3 mm/year before and after the Ms 5.2 earthquake, respectively, which occurred on 04/21/2019. The deformation changed with seasonal variation during 2017–2021 and lagged behind precipitation, while the earthquake can increase the amount and rate of displacement. The results presented here can help us to understand how landslides recur over time and their deformation and failure mechanisms, which is useful for disaster prevention and mitigation. [ABSTRACT FROM AUTHOR]

[Objective] Exploring the impact of hydropower development on local climate is an important guarantee for preventing and mitigating the possible negative effects of hydropower development and realizing sustainable energy development and environmental protection. [Methods] Four typical hydropower stations, Longkaikou and Guanyinyan in the middle reaches of the Jinsha River and Xiluodu and Xiangjiaba in the lower reaches of the river, were selected. By applying the climatic propensity rate, the M-K trend test, and the wavelet analysis, this study quantitatively analyzed the monthly, seasonal and yearly changes of temperature and precipitation before and after the impoundment of water in the middle and lower reaches of the river, as well as the sudden changes in the development of hydropower and the cyclical characteristics. [Results] (1) After water storage, the hydropower station had an inhibitory effect on the highest temperature and an uplifting effect on the lowest temperature in the valley. In summer and autumn, the downstream hydropower station played a cooling role, and the average monthly temperature decreased significantly in February, June, July, September, October and November, while the midstream hydropower station did not have the temperature regulation effect, with only a slight decrease in average air temperature in July. (2) After water storage, precipitation in each season increased significantly, with an increase of 0.71~27.95 mm in April, August, and September. (3) Air temperature and precipitation were related to hydropower development, and the air temperature and precipitation of the mid-and downstream hydropower stations underwent abrupt changes at different times during the development and after the water storage. (4) Air temperature and precipitation showed similar characteristics in wavelet change period, and after water storage, local precipitation showed more significant periodicity and had a certain degree of stability. [Conclusion] At different time scales, hydropower development affected local temperature and precipitation varied across river reaches, and was constrained by multiple factors such as geographic location, the surrounding environment and water storage duration.

The Jinsha river valley in Yunnan Province is a typical dry and hot area in China. By introducing landscape pattern indices, we conducted a spatio-temporal evaluation of regional ecological security from 2000 to 2020 and quantitatively analyzed the influence of its driving factors. Those results showed that: (1) the indices that could characterized the landscape pattern were Division (DIVISION), Mean of Contiguity (CONTIG_MN), Patch Density (PD), and Area Weighted Mean of Shape (SHAPE_AM). (2) From 2000 to 2020, the regional ecological security resulted from cooperative effects of landscape pattern indices and normalized difference vegetation index (NDVI). In 2000, in addition, ecological security resulted from the effects of water quality indices. (3) In 2000, most areas in Yuanmou, Wuding County, and Dongchuan District were in an unsafe or relatively unsafe state. In 2020, some areas of Yuanmou, Wuding, and Yongsheng County were in an unsafe or relatively unsafe state. (4) From 2000 to 2020, the impact of human activity intensity gradually strengthened. Compared with social and economic driving factors, natural driving factors like rainfall and altitude have a greater impact. Our findings can provide theoretical basis and scientific guidance to formulate regional ecological development strategies. [ABSTRACT FROM AUTHOR]

[Objective] We explored the spatiotemporal evolution pattern and driving factors of ecosystem service coupling coordination between supply and demand in the Jinsha River cascade hydropower project reservoir area, and provided decision-making supports for ecological management of hydropower project reservoir area. [Methods] Based on the data of land uses, population, GDP, NDVI and precipitation in the Jinsha River Cascade hydropower project reservoir area, market value method, coupled coordination degree model and geographically weighted regression model were used to study ecosystem service coupling coordination degree between supply and demand and its driving factors. [Results] The value of ecosystem service in the reservoir area reached 91.7 billion yuan in 2019, and the total value of ecosystem service increased by 680 million yuan during the study period. The spatial distribution of coupling coordination degree between ecosystem service supply and demand in the reservoir area was relatively stable. The regions of extreme maladjustment and severe maladjustment mainly distributed on the north bank of Jinsha River, while the regions of grudging coordination and good coordination mainly distributed on the south bank of Jinsha River. Vegetation cover had a positive driving effect on the coupling coordination degree between ecosystem service supply and demand in the Jinsha River Reservoir Area, population and relief amplitude had the negative driving effect, precipitation had the positive driving relationship to the north of the reservoir area, while the rest of the reservoir areas showed the negative driving effect. [Conclusions] This research showed that the spatial distribution of the coupling coordination degree was high in the south and low in the north and was affected by multiple factors. In the future, it is necessary to strengthen the study of ecosystem services in the reservoir area of hydropower projects. [ABSTRACT FROM AUTHOR]

The lower reaches of the Jinsha River is the main distribution area of hot-dry valleys in China. While it suffers from frequent droughts, the spatiotemporal variation and driving forces of drought in this area under climate change are still unclear. The spatiotemporal variations of Temperature Vegetation Drought Index (TVDI) and drivers of drought were explored using MODIS land surface temperature and NDVI data from 2000 to 2020. The results are fivefold. (1) TVDI was highly correlated with soil moisture content at a depth of 0–7 cm, indicating that it can accurately reflect the drought situation in the study area. (2) The spatial variability of TVDI was highly heterogeneous, with a multi-year average of 0.59, and the drought level was mainly between normal and dry. (3) From 2000 to 2020, TVDI showed a slightly increasing trend. It increased in 63% of the study area, and significantly increased in 21% of the study area. At the same time, the area at the dry level increased by 14.5% in 2020 from the normal level in 2000. (4) Slightly different from the standard phenomenon of "dry gets drier, wet gets wetter", we found that both dry and wet areas were becoming drier. (5) TVDI was positively correlated with annual mean temperature in 86% of the region, of which 43% of the region showed a significant correlation. The increasing temperature was the main driving force for the increase in drought in the study area. Our results can provide new insights into the spatiotemporally heterogeneous response of drought to climate change in the lower reaches of the Jinsha River. [ABSTRACT FROM AUTHOR]

On October 11 and November 3, 2018, two large landslides occurred at the same location in Baige Village, eastern Tibet, China. These landslides pose a serious threat to both upstream and downstream areas, raising great concerns in China and worldwide. Currently, the influencing factors and fundamental mechanism of the Baige landslide are questioned, and further research is needed. Multiple methods, including comprehensive field investigation, satellite remote sensing, unmanned aerial vehicle (UAV) 3D imaging, and geographical information systems, are used to analyze the main characteristics, influencing factors, and fundamental mechanism of the Baige landslide. The results reveal that the occurrence of the Baige landslide is closely related to deep-seated gravitational slope deformations (DSGSDs); tectonic activity, river incision, earthquakes, and rainfall are also responsible for the formation of the event. From a long-term perspective, DSGSDs, active tectonic deformation, repetitive seismic activities, rapid river incision, and sustained rainfall infiltration all interact with each other and finally trigger catastrophic landslides. The damage deformation process of the Baige landslide can be divided into three stages: epigenetic deformation, time-dependent deformation, and failure. Some unstable rock masses still exist in the source area, and thus, successive deformation monitoring and timely mitigation measures should be implemented to reduce the residual risks. The research in this paper is meaningful for further research on such large-scale landslides along the Jinsha River. [ABSTRACT FROM AUTHOR]

The complex geological environment and strong tectonic movement have led to the development of a large number of ancient landslides along the Jinsha River. These landslides exhibit characteristics of large-scale, complex formation mechanisms, multiple sliding periods, and high potential hazards. In this study, we aim to construct an ancient landslide inventory and conduct potential landslide hazard assessment of the Wudongde hydropower station section and its surrounding areas, which is located in the downstream area of Jinsha River. We used the visual interpretation method to recognize large ancient landslides based on high-resolution remote sensing images on the Google Earth platform and analyzed the correlations between the landslide abundance and different influencing factors. Our results show that there were 3126 ancient landslides in the study area, covering a total area of 502.64 km2. The statistical analysis indicated that the landslide occurrence is closely related to the slope gradient and topographic relief, and the landslide abundance index increases with the increase in above two influencing factors. In addition, the ancient landslides gradually decreases with the increase in the elevation, indicating that ancient landslides are more likely to occur in lower elevation areas, i.e., lower portion of the hillslopes. In addition, combining with machine learning method (logistic regression), the potential landslide hazard assessment of the study area was calculated by the hypothetical earthquake scenario of 10% exceedance probability in 50 years. The predicted result shows that the extremely high-hazard area of landslides appeared around the hydropower station, and the high-hazard area was mainly distributed within a 5-km range along both banks of the Jinsha River. This study provides basic data and important reference for the distribution characteristics and potential hazard assessment of ancient landslides in the reservoir area of Wudongde hydropower station. [ABSTRACT FROM AUTHOR]

The objective of jointly optimizing the dispatching of cascade hydropower stations in the basin is to maximize economic benefits while ensuring the safe and stable operation constraints of power grids and hydropower stations. The existing joint optimization scheduling algorithms include dynamic programming algorithms and intelligent optimization algorithms. Among them, the progressive optimization algorithm (POA) as a representative of dynamic programming methods can effectively solve complex nonlinear constraint optimization problems. However, while it effectively addresses the issue of "dimensional disaster" in traditional dynamic programming, it also faces the challenge of "local convergence". Although the intelligent optimization algorithm such as the differential evolutionary algorithm (DE) and the genetic algorithm (GA) can effectively handle large-scale complex constraint optimization problems, these algorithms rely on their own group evolution mechanism and lack a search strategy tailored to the mathematical mechanism of the joint scheduling model of cascade hydropower stations. Starting with the theoretical analysis of the two-stage problem of optimizing and dispatching cascade hydropower stations, this paper deduces the monotonicity principle of the two-stage optimization problem for power generation dispatch and proposes a local search strategy based on the monotonicity principle. By using the cascade reservoir group in the lower reaches of JinSha River as an example, the local search strategy for the two-stage optimization problem of power generation dispatch in cascade hydropower stations is validated. This strategy improves the convergence rate and solution accuracy of the algorithm, thereby achieving an efficient solution to the joint optimization dispatch problem of cascade hydropower stations. [ABSTRACT FROM AUTHOR]

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Impoundment and water level fluctuations in reservoirs can induce landslides, especially during initial filling and drawdown. Since the initial impoundment in April 2021, multiple landslides have occurred within the Baihetan (BHT) reservoir, which is located at the boundary of Sichuan and Yunnan province in southeast China. However, due to the complex terrain conditions of reservoir banks, traditional landslide research methods, such as surveys, deformation monitoring, and geotechnical experiments, cannot be effectively conducted in a timely manner. In recent years, the development of remote sensing technology has addressed the shortcomings of traditional landslide research methods that may not be promptly carried out. In particular, interferometric synthetic aperture radar (InSAR) technology, capable of measuring subtle deformations, and portable small unmanned aerial vehicles (UAVs) have played a significant role. This study integrates multiple remote sensing data sources, including InSAR results, optical remote sensing images, digital elevation model (DEM), and UAV imagery, to investigate and elucidate the deformation characteristics and mechanisms of the Xiaomidi (XMD) landslide developed on the left bank of Jinsha River, about 100 km from the BHT hydropower dam site. The spatial deformation distribution of the landslide before and after impoundment and the deformation time series during filling were examined. Monitoring water level variation and analysing the deformation process of the landslide were achieved by employing continuous synthetic aperture radar (SAR) intensity images and DEM. UAV photography was utilized to assist in the verification of ground deformation. The findings suggest that the weak strength of the reversed bedding strata structure and the steep slope eroded by the Jinsha River are inherent factors that contribute to the development of the landslide. The rise in the water level leads to softening of the rock mass at the slope toe, thereby directly facilitating the acceleration of landslide deformation. The toppling deformation of the lower rock mass initiates the formation of surface cracks and localized uneven subsidence in the overlying colluvial deposits. [ABSTRACT FROM AUTHOR]

The formation of the Jinsha River drainage is a significant subject of concern in the geological and geomorphological fields. Among them, one key question is whether there was a regional paleo lake into which Lower Jinsha River drainage drained during the late Pliocene to early Pleistocene, due to massive fluvio-lacustrine sediments widely distributed in the Lower Jinsha River. Nevertheless, there has yet to be a consensus on the genesis of those fluvio-lacustrine sediments due to poor sedimentological and chronological data. In this study, to unravel the origin of those fluvio-lacustrine sediments and the formation model of the Lower Jinsha River, sedimentary characteristics, including spatial distribution, lithological composition, and stratigraphic contact relationship of those fluvio-lacustrine sediments were analyzed, and chronological determination of the fluvio-lacustrine sediments using Electron Spin Resonance and Optically stimulated luminescence method was conducted. The results show that in the Lower Jinsha River, the lacustrine sediments are mainly composed of silt and clay, with apparent horizontal bedding, stacked with fluvial cobble-gravel and sand, and are in unconformable contact with the underlying bedrock strata or paleo soil. The lacustrine sediments are spatially discontinuous and mainly distributed in the Shigu, Taoyuan, Panzhihua, and Longjie reaches. Downstream of these reaches are deeply incised gorges with an average slope >30°, and many landslide landforms and deposits can be identified here. In each reach, the lacustrine sediments were closely distributed along the trunk and tributary channels in the plane and were distributed at different altitudes, forming a sequence of lacustrine terraces. Chronological analysis shows that in different reaches, the deposition ages of lacustrine sediments are significantly different. In each reach, the deposition age of the lacustrine terraces of high altitude is older than that of low altitude. The above characteristics collectively indicate that the lacustrine sediments in the Lower Jinsha River were locally deposited by individual dammed lakes, probably induced by landslide rather than a regional paleo lake by tectonic activities. During the incision process of the river valley, landslides continuously block the river channel, forming dammed lakes, and then deposited lacustrine sediments at different elevations, forming lacustrine terraces. The lacustrine sediment of the topmost lacustrine terrace in Panzhihua reach was dated to be 1.78 Ma, combined with previous studies on the fluvial terraces, indicating the Lower Jinsha River existed and started to incise its valley before the early Pleistocene. The widespread dammed lake sediment indicates that the formation of the Jinsha River valley follows the pattern of "incision-landslide-damming-aggradation-incision". [ABSTRACT FROM AUTHOR]

An ancient, large-scale river-damming landslide, located 4 km on the upper stream of the dam site of the Batang Hydropower Station, southeastern Tibetan Plateau, China, was investigated herein. We used an unmanned aerial vehicle (UAV) survey, field investigations, geology and topography maps, borehole surveys, basic laboratory testing, and geological dating to reveal evidence of this river-damming landslide and its cause mechanism. The studied landslide had an estimated volume of 3.5 × 107 m3, blocked the valley, and formed a dam > 170 m in height. A large quantity of lacustrine sediments was discovered on both banks upstream of the residual landslide dam; this had a maximum thickness of 30 m, mainly comprised of fine sand and silt, with particle sizes of 0.01–0.25 mm, and demonstrated that the landslide blocked the Jinsha River. There was a clear geological structural dependence of the slope failure in the landslide area, dominated by a combination of sliding-toppling failure on cataclinal slopes. The slope instability mode was slip-controlled toppling failure within a thin-layered biotite quartz schist that exhibited inferior mechanical properties. The head scarp developed along a bedding plane that dipped steeply in the same direction as the slope. The upstream and downstream lateral scarps formed along the joint sets J2 and J3, respectively, which intersected with the bedding plane, forming a wedge and facilitating slope instability. Rapid river incision, intense tectonic activity, a high and steep slope, and thin-layered steeply dipping strata were the controlling factors for the occurrence of this landslide, all contributing to slope failure. On the basis of our comprehensive analysis of paleoearthquakes, paleoclimate, and geological dating of the landslide, we conclude that this ancient river-damming landslide event was likely triggered by a strong earthquake related to activity on the Xiongsong‒Suwalong fault in the Late Holocene. [ABSTRACT FROM AUTHOR]

AbstractLandslide susceptibility mapping (LSM) comprehensively evaluates the spatial probability of landslide occurrence by using different environmental factors. However, most of the evaluation methods ignore the dynamic characteristic factors of landslides, which makes it difficult to obtain reliable prediction results. Taking the upper reaches of the Jinsha River as the study area, this article introduces the deformation data into the landslide characteristic model and proposes an improved landslide susceptibility evaluation method. Four kinds of landslide susceptibility machine learning models were constructed by collecting 20 landslide related factors. The prediction accuracy of machine learning models is compared, and the performance of different models and the improvement of model performance by deformation information are evaluated. The results show that the performance of Random Forest and XGBoost model is better than SVM and logistic regression model. The prediction accuracy of Random Forest and XGBoost model is improved obviously after InSAR deformation is introduced. 96.9 and 93.19% of landslide areas were reasonably classified as high or very high risk levels. Compared with the calculation result of traditional model, the proportion of high and very high risk pixels in landslide area is increased by 2.97 and 1.13%, respectively. In addition, the percentage of high and very high risk areas in the susceptibility evaluation area increased from 15.45 to 16.23% and 18.73 to 21.89%, respectively. The accuracy of Random Forest and XGBoost models increased from 0.793 to 0.878 and 0.776 to 0.812, respectively, and the AUC increased by 0.9 and 1.7%, respectively. The SHAP and traditional feature importance analysis reveals that rainfall, aspect, temperature and NDVI are the main influencing factors of landslide in the upper reaches of the Jinsha River.

To develop clean energy hydropower, many dams were built in the Jinsha River Basin in the past thirty years and have significantly altered runoff and sediment transport processes. This study aims to evaluate the impacts of these reservoirs on runoff and sediment transport using data collected in the mainstream of the Jinsha River from the 1960s to 2020, for which the Mann–Kendall trend test method and double cumulative curve method are used to comprehensively judge the variation trends of annual runoff and suspended sediment load (SSL) and reveal the years in which there were credible sudden changes. The linear regression method is used to reveal the variation characteristics of the relationship between annual runoff and SSL before and after the years of abrupt change. The results show that the variations in runoff at Shigu and Panzhihua Stations have significant and relatively obvious increasing trends, respectively, and that 1985 was a sudden change year at Panzhihua Station. The runoff at Xiangjiaba Station increased slightly but not significantly. The variation in SSL shows temporal and spatial differentiation. The variation in sediment discharge at Shigu Station shows an increasing trend with a sudden change in the year 1997. Panzhihua Station shows a trend of increasing before 1998 but significantly decreasing after 1998. The fluctuation of sediment transport at Xiangjiaba Station was significant before 1998, but the trend is unclear. In the period between 1998 and 2020, a significant decreasing trend is observed, especially since 2013, when the mean annual SSL only accounted for 0.61% of its multi-year average. The variations in mean annual sediment concentration and coefficient of incoming sediment (CIS) at the hydrological stations are consistent with the variation trend of sediment transport. The correlation between water and sediment was strong before 2013 but extremely weak thereafter. The two sudden change points for the annual runoff and SSL in the years 1998 and 2013 are consistent with the years when large reservoirs were built in the river basin. The construction of large reservoirs and their large amount of sediment retention are the key reasons for the sudden changes in the water–sediment relationship and the sharp decrease in sediment transport in the downstream reach of the reservoir dam. The climate and underlying surface changes in the study area are not significant, and their impact on the water and sediment processes in the watershed is limited. [ABSTRACT FROM AUTHOR]

The equivalent relationships between flood prevention storage of a cascade reservoir system provide useful information for real-time operation. However, those relationships are implicitly hinted at in the optimized operation rules of downstream reservoirs, which may add difficultly in providing feasible operation strategies for engineering practice. In this study, we investigate the equivalent relationship between cascade reservoirs using a flood regional composition-based framework coupled with reservoir inflow and river flow routing techniques. We select the cascade reservoirs in the downstream Jinsha River and Three Gorges Reservoir (TGR) as the case study. Results reveal that (1) the equivalent relationship between flood prevention storage of cascade reservoirs in the downstream Jinsha River and TGR is approximately linear-related; (2) the conversion coefficient of equivalent relationship depends on the flood type, and the intercept term of equivalent relationship is mainly influenced by the design flood frequency; and (3) the TGR flood prevention storage (or water level) can be dynamically adjusted according to the corresponding reserved flood prevention storage of cascade reservoirs in the downstream Jinsha River, which can generate 3.56 billion kW·h (+8.5%) extra hydropower during flood season without increasing flood control risks. [ABSTRACT FROM AUTHOR]

Many studies quantify the impact of climate change and human activities on runoff changes on an annual scale, but few studies have examined this on multiple time scales. This paper quantifies the contribution of different factors to the variability of Jinsha River runoff at multiple time scales (annual, seasonal and monthly). First, the trend analysis of Jinsha River runoff is carried out, and the Mann–Kendall mutation test was then applied to the runoff data for mutation analysis. According to the mutation year, the research period is divided into the base period and the mutation period. By constructing an ABCD hydrological model simulation and monthly scale Budyko model, the contribution rate of human and climate factors to the multitime-scale runoff of Jinsha River is calculated. The results showed that: (1) The sudden year of change in the Jinsha River runoff is 1978, and the Nash coefficients of the ABCD hydrological model in the base period and sudden change period were 0.85 and 0.86, respectively. (2) Climate factors were the dominant factor affecting annual runoff changes (98.62%), while human factors were the secondary factor affecting annual runoff changes (1.38%). (3) The contribution rates of climate factors in spring, summer, autumn, and winter to runoff were 91.68%, 74.08%, 95.30%, and 96.15%, respectively. The contribution rates of human factors in spring, summer, autumn, and winter to runoff were 8.32%, 25.92%, 4.70%, and 3.85%, respectively. (4) The contribution rates of climate factors to runoff in May, June, and July were 95.14%, 102.15%, and 87.79%, respectively. The contribution rates of human factors to runoff in May, June, and July were 4.86%, −2.15%, and 12.21%, respectively. [ABSTRACT FROM AUTHOR]

Investigation of spatial susceptibility of debris flow is a basis for carrying out geological hazard prevention and developing ecological restoration plans. It is difficult to efficiently and accurately identify potential debris flow gullies on a large spatial scale simply by relying on field surveys combined with remote sensing observations or debris flow simulations with small watersheds as units. Taking the Jinsha River Basin of China as an example, we propose a quantitative scheme to describe the intensity of extrinsic forces by calculating the stream power gradient (ω). We extracted gullies prone to debris flow, assuming that there is no spatial heterogeneity in the provenance supply conditions based on the fundamental understanding that debris flow is a high-energy gravity flow. In the situation where the threshold (ω=1×10−4 W/m²) is the mutational site of the gradient change trend of the relation curve between the number of debris flow gullies and ω value, a total of about 32 thousand debris flow gullies with lengths of more than 200 m were found. In the middle and lower reaches of the basin, these gullies are located within a 30-kilometer buffer zone along the Jinsha and Yalong Rivers, and there is a power function relationship between the number of debris flow gullies and the width of a buffer zone. However, extreme weather events are likely to increase in the future under global warming, and these areas should be the critical prevention areas of debris flow disasters, especially the cascade reservoir area. The results of this study provide a lattice data set of spatial locations of the gullies prone to debris flow and the stream power gradients in the Jinsha River basin, which can be used to retrieve the exact location of the high-energy gullies and can also be used as the basic data for the study of related geological hazards and surface processes in general.

The Jinsha River basin, full of hydropower resources, is the largest hydropower energy base in China. From 2005 to 2018, four giant cascade hydropower stations (Wudongde, Baihetan, Xiluodu, and Xiangjiaba) were built along the Jinsha River. The reservoir area of four hydropower stations involves 26 counties (districts). The ecological environment of the reservoir area has a close relationship with hydropower projects, and ecosystem service value is an important standard to measure the quality of the ecological environment. Taking the reservoir area formed by four cascade hydropower stations in Jinsha River (Jinsha River Reservoir Area, JRRA) as the research object, the essay analyzed the spatial and temporal pattern of ecosystem service value in the reservoir area in 2005, 2010, 2015, and 2018. The results showed that (1) The ecosystem service value of JRRA reached 94 billion yuan in 2018, and the forestland took the largest proportion of ecosystem service value, accounting for 46.93%, followed by grassland, water area, cropland, and unused land. (2) From 2005 to 2018, the total ecosystem service value in JRRA increased by 3.374 billion yuan, and the spatial pattern of ecosystem service value showed a spatial distribution characteristic of high in the middle and low on both sides, and the spatial distribution had significant positive autocorrelation. (3) Because the area of water increased a lot, the ecosystem service value of JRRA showed a trend of overall increase which mainly occurred in the 3-km buffer zone along the river. The results further proved that the implementation of hydropower projects could improve the ecosystem service function in the reservoir area and provide technical support for the sustainable utilization of land resources and ecological compensation in the reservoir area. [ABSTRACT FROM AUTHOR]

Lots of large hydropower engineering projects have been built in Jinsha River, Lancang River and Yalong River basins in the southwest mountainous areas of China. But the complicated stratum, lithology, structure, hydrology and other geological conditions of these river basins cause widespread, large number and high frequency of reservoir landslide for large hydropower engineering projects. Synthetic aperture radar interferometry(InSAR)technology with the advantages of wide coverage, high monitoring accuracy, and unblocked by clouds, brings new opportunities for early identification and monitoring of reservoir landslide. Especially in recent years, great attention has been paid to the construction of hydropower engineering projects and the reservoir geohazard prevention. The application of InSAR early identification and monitoring of reservoir landslide for large hydropower engineering projects in southwest mountainous area of China was sorted out, and the overall change analysis was carried out from the perspectives of research time, research content and research object. By summarizing the research status and hotspots of InSAR early identification and monitoring of reservoir landslides in southwest mountainous area, it is revealed that Baihetan hydropower engineering project is a milestone and nowadays has entered the outbreak stage of InSAR technology application and research on reservoir landslide. Meanwhile, the different application requirements of InSAR technology and the applicability of InSAR algorithm in the whole life cycle of hydropower engineering project(including the stage before impoundment, impoundment stage and the stage after impoundment)were discussed. In future, with the improvement of SAR data quality and algorithm, InSAR technology will be routinely involved in the identification and monitoring of reservoir landslides throughout the life cycle of hydropower engineering projects. It can provide important support for the early identification, monitoring and early warning, and trigger mechanism research and geohazard prevention of reservoir landslide, so as to enhance the ability of the reservoir geohazard prevention in China. [ABSTRACT FROM AUTHOR]

Southwest China is an area where geological hazards occur frequently. To develop a basic understanding of geological hazards in this region, the Baihetan hydropower station section of the Jinsha River basin and its surrounding region are selected as the study area. We compile a detailed inventory including the information of all large-scale landslides (i.e., >104 ​m2 in area) and analyze their typical characteristics. In the study region that covers an area of 6372.9 ​km2, we identify 3757 large-scale landslides with a total area of 1033.5 ​km2 and an average area of 275,097 ​m2 for each individual landslide. Specifically, the Qiaojia mega-landslide has the largest area, reaching 7,717,000 ​m2. These landslides are clustered and unevenly distributed, and those along rivers are characterized by zonal distribution. The analysis of the influencing factors of landslide occurrence shows that elevation, river valley (valley), fault, slope angle, and slope aspect have obvious influences on landslide occurrence. This study is not only beneficial for further understanding the development characteristics of landslides in mountainous areas of southwest China, but also provides basic data for subsequent landslide susceptibility mapping in this region.

The increasing number of landslide hazards worldwide has placed greater demands on the production and updating of landslide inventory maps. As an important data source for landslide detection, interferometric synthetic aperture radar (InSAR) data processing is time-consuming and also requires specialized knowledge, which severely hinders its widespread application. At present, a new cloud-based online platform, i.e., Alaska Satellite Facility's Hybrid Pluggable Processing Pipeline (ASF HyP3) was developed for massive SAR data processing. In this study, combining the HyP3 online platform and Stacking-InSAR method, we constructed a new easy-to-use processing chain for rapidly identifying slow-moving landslides over large areas. With this processing chain, a total of 923 interferometric pairs covering an area of over 1800 km2 were processed within a few hours (about 4 to 5 h). A total of 81 slow-moving landslides were immediately detected and mapped using Stacking-InSAR method, of which 65 landslides were confirmed by previous studies and 16 landslides were newly detected. Results show that the new processing chain can greatly improve the efficiency of wide-area landslide mapping and is expected to serve as an effective tool for rapid updating the existing landslide inventories and contribute to the prevention and management of geological hazards. [ABSTRACT FROM AUTHOR]

Recent installment of cascade reservoirs in the Lower Jinsha River basin urges quantitative studies of sediment inflows from ungauged tributaries and sediment pattern in this basin. Based on existing observations from 18 gauging stations and a multi-factor dataset, the Spearman rank correlation analysis was used to examine the responses of sediment yield to potential controlling factors at the catchment scale. Dimensionality reduction and regression methods were integrated to identify different sets of factor variables for predicting specific sediment yield (SSY). The results show that proportion of slopes over 8°, temperature and catchment area together can best describe the regional mechanism of sediment yield, and the obtained model explained 92% of SSY variability. The estimated SSY of ungauged areas varied from 87 t / (km²·a) to 1 189 t / (km²·a) and has reduced by 50-300 t / (km 2·a) over the past 50 years. This research detected both high- yield and low- yield tributaries in the Baihetan and Xiluodu reservoirs, as well as the declining trend of SSY spatial heterogeneity. [ABSTRACT FROM AUTHOR]

Exploring the long-term mechanism of hazard formation and identifying prospective hazard areas is critical for human survival and the risk management of crucial engineering facilities. Detecting the relationships between tectonic uplift, stream incision, and hazards is the basis for solving these problems, but these relationships are always tricky to determine quantitatively. Using the Baihetan drainage area on the eastern margin of the Qinghai-Tibet Plateau in western China as a case study, we proposed a set of methods to establish and analyze the quantitative relationships between the intensity of tectonic uplift and river incision, as well as the spatial density of gravitational erosion hazards, based on the hypsometric integral (HI), steepness index (ksn), stream power gradient (ω), and steady-state coefficient. We discovered that the collapses, landslides, debris flows, and other hazards in the Baihetan drainage area are generally distributed along the extensive river valley with HI values of 0.3–0.5. Potential gravitational erosion hazards in the region are concentrated in areas where the competition between tectonic uplift and stream power is weak because there is a delay in or anticipation of the response of hazard generation to uplift and incision. When the channel profiles in a basin develop toward a steady or transient state, there is an increase in the number of gravitational erosion hazards, such as collapses, landslides, and debris flows. Therefore, transitional valleys present a lower hazard risk, including the Heishui, Qiaomaidi, Mahong, Mashu, and Yili Rivers. This knowledge deepens our understanding of the spatial variation in the basin’s driving forces for the long-term hazard formation process and provides essential reference values for further identifying the potentially hazardous sites. [ABSTRACT FROM AUTHOR]

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The upper reaches of the Jinsha River, with their complex terrain and active tectonic movements, are vulnerable to landslide-induced hazard chain events, which endanger the safety of residents and infrastructure construction. Based on the analysis of the development background of the hazard chain in the upstream area of the Jinsha River, five factors, including the lithology, distance to faults, distance to rivers, peak ground acceleration, and slope degree, were selected to identify the critical landslide-prone areas. Principal component and grey correlation analyses were then conducted to determine the contributions of these different factors. Based on ArcGIS, the study zone was categorized into five classes of landslide susceptibility: very high, high, moderate, low, and very low. The identification of the critical target areas for landslide hazard chain formation showed satisfactory accuracy. The very high- and high-susceptibility areas are concentrated along the Jinsha River. The dynamic process of a typical landslide in a very high-susceptibility area was numerically simulated using OpenLISEM. The high-precision Baige landslide data of the study area were used to calibrate the practicality of the input mass parameters, including cohesion, internal friction angle, D50, and D90. The movement and accumulation processes of a typical landslide were then numerically simulated with the verified data. The entire landslide accumulation covers an area of 0.45 km2, with a length of 1,600 m and a width of 270 m. Thus, the OpenLISEM model, which combines mass, topography, and landcover parameters, is feasible for the numerical simulation of landslide dynamic processes. The prediction of the dynamic processes and accumulation morphology of landslides can provide a reference for the formation processes and mechanisms of the landslide-induced hazard chain in the upper Jinsha River.

The Jinsha River, upstream of the Yangtze River, flows through the southeastern margin of the plateau, providing an opportunity to study the plateau uplift relative to the Sichuan basin through fluvial geomorphology. Eight tributaries of the Jinsha River located at the transition boundary from the plateau to the basin were analyzed for the feature of longitudinal profile and its evolution. The spatial distribution of slope-break knickpoints in the catchment was determined by slope-area analysis and integration analysis. Further, the magnitude and timing of the base level lowering (i.e., uplift of the Tibetan Plateau) were estimated by reconstructing the river longitudinal profile. The results show that there are two levels of slope-break knickpoints, with average elevations of 2865 m and 1523 m, corresponding to base levels relatively lowering of 1400 m and 1100 m, respectively. With reference to the long-term downcutting rate of the Jinsha River, the timings of these two phases base level lowering and uplifts are estimated to be ∼21–24 and ∼7–13 Ma, respectively. These are close to the timing of two uplifts revealed by inversion modeling of river longitudinal profiles. Therefore, the uplift of the studied region on the Tibetan Plateau can be divided into two stages, the early stage (∼20 Ma) uplift from 1500 to 2900 m and the late stage (∼10 Ma) uplift from 2900 to 4000 m, which further supports the staged outside uplift of the Tibetan Plateau.

The Jinsha River flows through one of the most geologically complex regions in western China with extremely high altitudes and capricious climates. Frequent landslides (e.g., the Baige landslides on 11 October and 3 November 2018) occurred along its stretch which posed severe damage to bridges, dams, and roads, and put the safety of local residents at risk. Systematic and comprehensive landslide detection has been rarely carried out in the Jinsha River corridor because it is a wide and hard-to-reach region. With 30 years of development, InSAR has become an effective way to map ground motion, which in turn makes it feasible to detect active landslides over wide regions. However, several challenges remain in applying InSAR in the Jinsha River corridor, such as low coherence due to dense vegetation and/or large gradient surface movements, and atmospheric effects due to the spatio-temporal variations of the atmosphere (especially the part due to tropospheric water vapor). In this paper, we propose a framework to overcome the limitations of conventional InSAR through the integration of GACOS-assisted InSAR, advanced SBAS InSAR, and SAR pixel offset tracking techniques. This integrated framework enables us to detect active landslides under complex topographic and climate conditions. Our results show that the detected active landslides are largely controlled by active faults, most of them are found at elevations of 2500–4000 m, their slopes fall between 25 and 45 ∘ facing southwest and northwest, and 83.3% of the active landslides have a NDVI value of less than 0.3. Furthermore, precipitation is one critical triggering factor of active landslides, evidenced by the high temporal correlation between average precipitation and surface displacement time series. [ABSTRACT FROM AUTHOR]

The upper reaches of Jinsha River are typical high mountain canyon areas with strong terrain cutting and deep valleys. Affected by the Jinsha River fault zone, the slope integrity is poor and the rock mass is fragmented, which makes the mountain landslide prone to occur on both sides of the river. According to the hue, plane shape, deformation sign and microtopography of landslide hazards in remote sensing images, we establish the remote sensing interpretation signs. A total of 87 landslide were identified in Zhimenda-Shigu section of Jinsha River, including 40 large and 47 super-large ones. Based on the characteristics of regional geography and geological environment, we analyse the basic characteristics and spatial distribution of landslide. The landslide in the study area have obvious chain characteristics, including landslide –blocking river disaster chain, collapse – landslide – blocking river disaster chain, landslide – debris flow – blocking river disaster chain. Taking Sela landslide, Wangbuding landslide and Tange landslide as examples, the deformation characteristics and chain characteristics are analyzed in detail based on optical remote sensing technology. From the geographical view, the Jinshajiang fault zone obviously controls the plane distribution of the Zhimenda-Shigu section of the Jinsha River. The neotectonic movement has strong activity, faster strain accumulation and relatively frequent seismic action in the middle and southern sections of the fault zone, which provides a favorable regional geological environment background for the occurrence of river blocking landslide in the favorable slope areas on both sides of the Jinsha River.

Many studies quantify the impact of climate change and human activities on runoff changes on an annual scale, but few studies have examined this on multiple time scales. This paper quantifies the contribution of different factors to the variability of Jinsha River runoff at multiple time scales (annual, seasonal and monthly). First, the trend analysis of Jinsha River runoff is carried out, and the Mann–Kendall mutation test was then applied to the runoff data for mutation analysis. According to the mutation year, the research period is divided into the base period and the mutation period. By constructing an ABCD hydrological model simulation and monthly scale Budyko model, the contribution rate of human and climate factors to the multitime-scale runoff of Jinsha River is calculated. The results showed that: (1) The sudden year of change in the Jinsha River runoff is 1978, and the Nash coefficients of the ABCD hydrological model in the base period and sudden change period were 0.85 and 0.86, respectively. (2) Climate factors were the dominant factor affecting annual runoff changes (98.62%), while human factors were the secondary factor affecting annual runoff changes (1.38%). (3) The contribution rates of climate factors in spring, summer, autumn, and winter to runoff were 91.68%, 74.08%, 95.30%, and 96.15%, respectively. The contribution rates of human factors in spring, summer, autumn, and winter to runoff were 8.32%, 25.92%, 4.70%, and 3.85%, respectively. (4) The contribution rates of climate factors to runoff in May, June, and July were 95.14%, 102.15%, and 87.79%, respectively. The contribution rates of human factors to runoff in May, June, and July were 4.86%, −2.15%, and 12.21%, respectively.

Abstract Nouelia insignis Franch. (Asteraceae) is a short, narrow endemic and endangered tree, growing with a natural population in the dry and hot valley of the Jinsha River in the southwest area of China. In this work, flowering phenology (time and duration), floral biology, visit frequency and behavior of pollinators, and pollination characteristics were studied based on investigation in the field and analysis in the laboratory with the help of a stereomicroscope, and the relationship between seed setting rate and reproductive traits, as well as the relationship between flowering time and rainfall before flowering, was tested using the method of general linear regression model. The results showed that natural population of N. insignis exhibited high flowering synchrony with relatively stable flowering duration, and the flowering time fluctuated greatly depending on the rainfall 5 months before flowering. The pollination of N. insignis required pollinators, and insect activities played a very important role in the pollination process. However, lack of the pollinators was not a limitation for reproductive fitness in N. insignis, although the number of pollinators was small and the frequency of visits was low. In addition, no pollen limitation was found during pollination. The average seed setting rate of N. insignis in the natural condition was only 1.52%–3.73%, and it was generally affected by changes in flowering phenology between years and had a higher seed set in early flowering year. The annual variation of seed set might be related to the annual variations of stamen and pistil functions, such as changes of pollen viability and stigma receptivity, which were closely related to flowering time. The results of this study are of value for further conservation actions on natural population of this threatened endemic plant.

River hydrogeochemistry offers necessary guidance for effective water environmental management. However, the influence of cascade reservoirs on river hydrogeochemistry remains unknown. In this study, the Jinsha River, the headwaters of the Yangtze River of China, was selected to investigate the spatiotemporal variations of hydrogeochemistry after the construction of six cascade reservoirs. Major ions, total dissolved solids, electrical conductivity, and pH values of sampled water in the upper natural reaches and lower reservoir-regulated reaches were analyzed in both flood and dry seasons. The results of Piper diagram and Gibbs plots showed that the hydrogeochemistry of the Jinsha River was naturally controlled by both evaporation-crystallization and carbonate weathering processes, but it was also artificially affected by reservoirs. The impoundment of cascade reservoirs affected the hydrodynamic condition of the river. The river flow in the flood season was reduced by approximately 24.5%, altering the proportions of water sources and leading to notable hydrogeochemical alterations in reservoir-regulated reaches. Conversely, river hydrogeochemistry generally remained unchanged in the dry season, owing to the insignificant effect of cascade reservoirs on river flow. In contrast to what has been observed in previous studies of individual reservoirs, the cumulative influence of cascade reservoirs on the Jinsha River flow regime did not cause abrupt hydrogeochemical changes between the upstream and downstream areas of each reservoir. Moreover, the water quality assessments revealed that the impoundment of cascade reservoirs improved downstream irrigational water quality, with lower Na+ ratio values in the flood season. This study provides the earliest evaluation of cascade reservoir influence on the hydrogeochemistry of the Jinsha River. The findings of this study can be used as a reference for scientific guidelines for future environmental management of cascade reservoirs in large rivers.

• Integrated Decision Model: The research introduces a decision model for optimizing the operation of cascade hydropower stations, balancing power generation and ecological considerations. • Jinsha River Case Study: The model's application in the lower Jinsha River uncovers significant conflicts between energy production and ecological preservation objectives. • Comprehensive Decision-Making: The study underscores the necessity of a holistic decision-making strategy that integrates multiple objectives and utilizes advanced algorithms to promote sustainable river management and align economic and ecological interests. The establishment and functioning of cascade hydropower stations have significantly altered the natural state of rivers, leading to increasingly severe ecological impacts downstream. To mitigate the adverse effects of cascade reservoir impoundment on river ecosystems and achieve the multi-objective goals of hydropower development and environment protection, this study presents an integrated decision model for optimizing the operation of cascade hydropower stations, utilizing the lower Jinsha River as a case illustration. The proposed model comprises three main components: ecological flow calculation, establishment of a multi-objective optimization model, and scheme evaluation. The ecological flow threshold for the river was determined using the Tennant method. The multi-objective optimization model was formulated with objectives including power generation, ecological flow shortage, and navigation disruption days. The NSGA-II algorithm was employed to resolve the optimization framework. The improved TOPSIS method was adopted for evaluating the operation schemes. The case study conducted in the downstream region of the Jinsha River revealed significant conflicts between the objectives of power generation and ecological conservation. Moreover, different typical years exerted a considerable influence on determining the optimal operation scheme. The proposed integrated decision model provides a scientific framework for guiding the water resource dispatching of cascade hydropower stations and achieving the harmonization of economic and ecological benefits. Overall, this research contributes to the academic field by addressing the complex difficulties related to optimizing the operation of cascade hydropower stations while considering ecological concerns. The findings underscore the importance of adopting a comprehensive decision-making approach that integrates multiple objectives and utilizes advanced algorithms for sustainable river management. [ABSTRACT FROM AUTHOR]

Numerous damming landslides have occurred at the southeastern margin of the Tibetan Plateau due to intense tectonic activities, strong river erosion, and extreme climate change. A Late Pleistocene paleo-landslide damming event has been detected in the Induba area in the upstream reaches of the Jinsha River, preserving various river-blocking phenomena, such as landslide dammed deposits and fluvial and paleo-dammed lacustrine sediments. Based on remote sensing and field investigations, we determined that the damming landslide originated from the inclined counter rock mass and experienced intense fragmentation, forming rock avalanches, which were possibly triggered by paleo-earthquakes or a combination of paleo-earthquakes and rainfall. To better understand the evolution of dam breaching and river valley landforms, optically stimulated luminescence (OSL) dating of lacustrine sediments was attempted. The results show that the landslide damming occurred ∼79.30 ka ago and formed a dammed lake upstream, which existed at least ∼20.86 ka before the dam breaching. The horizontal fluvial layers adhered to relict landslide deposits on the left bank, indicating that the process of dam breaching was conducted under the multiple circulations of lake water overtopping, fluvial deposition, and river undercutting. This study enriches our understanding of the formation of old dammed landslides and the evolution of river valley landforms in this region. [ABSTRACT FROM AUTHOR]

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As a result of the influence of plate movement, the upper reaches of Jinsha River have strong geological tectonic activities, large topographic fluctuations, and complex climate characteristics, which result in the frequent occurrence of landslide disasters. Hence, there is the need to carry out landslide susceptibility mapping in the upper reaches of Jinsha River to ensure the safety of local people's property and the safe exploitation of hydraulic resources. In this study, InSAR technology and a field geological survey were used to map the landslides. Then, the curvature watershed method was used to divide the slope units. A conditioning factor system was established, which can reflect the characteristics of the rapid uplift and vertical distribution of rainfall in the special geological environment of the study area. Finally, logistic regression, random forest, and artificial neural network models were used to establish the landslide susceptibility model. The results show that the random forest model is optimal for the landslide susceptibility mapping in this area. Additionally, the area percentages of the very low, low, moderate, high, and very high susceptibility classes were 40.13%, 20.06%, 13.39%, 12.55%, and 13.87%, respectively. Based on the analysis of the landslide susceptibility map, we suggest that the landslide geological hazards resulting from the rapid uplift of the Tibetan Plateau and the significant decrease in sea level during a glacial period in the upper reaches of Jinsha River are controlled by the double disaster effect of the geodynamic system. Consequently, this study can guide local prevention and mitigation. [ABSTRACT FROM AUTHOR]