Badong County Research Articles

Design and operation of App-based intelligent landslide monitoring system: the case of Three Gorges Reservoir Region

Nowadays, mobile applications (Apps) have become a main form of mobile Internet services, and related applications in the geological disaster monitoring domain must follow this development trend. In this study, an innovative remote and intelligent landslide monitoring system was designed and developed, which can capture the in-depth sliding force state of the slope in real time. When it reaches the early warning threshold, the system immediately transmits the warning information to user terminals and warns users to initiate corresponding risk-avoidance plans. Next, using the developed system, an App of early warning information publishing program was developed to transmit the acquired sliding-force data by field monitoring devices to servers via Beidou Satellite or GPRS base station. The App can inquire background servers via WiFi or 4G for acquiring the monitoring data and curves of the side slope. Finally, the developed system was applied for the monitoring of the sliding mass in Zhoujiawan, Badong County, the Three Gorges Reservoir Region. The monitoring personnel could locate and inspect the failure characteristics of the deformation region in a timely manner using the developed App. The App data exhibited significant correlation and consistency with the monitored results, thus enhancing the inspection efficiency and allowing an effective emergency response.

Disintegration behavior of strongly weathered purple mudstone in drawdown area of three gorges reservoir, China

Disintegration behavior of purple mudstone in the drawdown area of the Three Gorges Reservoir (TGR) in China, as a result of exposure to cyclic wetting and drying (WD) conditions, promotes bank slope instability during reservoir operation. To better understand the disintegration behavior of the mudstone in the drawdown area during reservoir operation, 63 strongly weathered purple mudstone (SWPM) samples from the Triassic Badong group (T2b) in Badong County of the TGR area were collected for laboratory-based cyclic WD experiments. After each WD cycle, measurements of the grain size distribution curve, the clay minerals contents and the ion (K+, Na+, Ca2+ and Mg2+) content in the soak solution, tests of water absorption, and observations of microstructure were conducted on the SWPM samples. Grain size distribution curves show that the SWPM samples disintegrate during WD cycles. The ion contents in the soak solutions and clay mineral contents in the SWPM samples indicate that the clay minerals in the surficial zone of the samples run into the soak solution by hydration between deionised water and clay minerals when each wetting procedure is performed, which weakens the cement between the grains and promotes the disintegration of the SWPM samples. The microstructural observations and water absorption variations exhibit increases in pores and cracks in the surficial zone of the SWPM mudstone sample, resulting from clay mineral content losses during the wetting procedure and shrinking in volume of the SWPM sample under the drying procedure in each WD cycle. The decrease in clay mineral content and increases in pores and cracks in the surficial zone of the SWPM sample are the main reasons for the disintegrations of the SWPM samples undergoing WD cycles, with the disintegration proceeding in the form of a peeling onion.

The Fractal Characteristics of the Watershed in the Landslides Area Based on Variational Method

The fractal dimensions and their spatia1 Variation characteristics of 17 sub-watersheds in the study area from Badong county to Zigui county in TGP reservoir region were calcu1ated and analyzed based on the digital elevation model(DEM), the fundamental principle of Variational method and the functions of ArcGIS windows analysis. The results indicate that the topography of the sub-watersheds have obvious fractal features and that there are more landslides in the sub-watersheds with fractal dimension values ranging from 2.17 to 2.25, and there are some landslides in the sub-watersheds with fractal dimension values ranging from 2.40 to 2.53, and there are relatively few landslides in the sub-watersheds less than 2.17 and 2.25-2.40. The results show that fractal values of topography are closely related to the occurrence of the landslides.

The Fractal Characteristics of the River Network Based on Horton Law in the Landslides Area

This paper applies Horton law to study the fractal characteristics of 17 subwatersheds in the study area from Badong county to Zigui county in TGP reservoir region. The results indicate that the small watersheds have obvious fractal characteristics. There is a clear correlation between the fractal dimension of river network and spatial distribution of landslide and that the area with large fractal dimension is conducive to the formation and development of landslides. The results show that the fractal model provides powerful tools for quantitative description of the river network and the relationship between the river network and the landslides.

The Fractal Characteristics of the Landslides by Box-Counting and P-A Model

The landslide is a kind of complicated phenomenon with nonlinear inter-reaction. The traditional theories and methods are difficult to study the uncertainty characteristics of dynamic evolution of the landslides. This paper applies box-counting and P-A model to study the fractal characteristics of geometric shape and spatial distribution of the landslide hazards in the study area from Badong county to Zigui county in TGP reservoir region. The data obtained from the study area shows power-law distributions of geometric shape and spatial distribution of the landslides, and thus reveals some fractal or self-similarity properties. The fractral dimensions DAP of the spatial distribution of landslides by P-A model shows that DAP of the western landslides in the study area are smaller than those of the east, which shows that the geometry of the eastern landslide is more irregular and complicated than the western ones. The results show box-counting model and P-A model can be used to characterize the fractal characteristics of geometric shape and spatial distribution of the landslides.

Ecosystem Services Value Assessment and Uneven Development of the Qingjiang River Basin in China

As an important ecological barrier in Southwest China, the Qingjiang river basin plays a vital role in shaping the mountainous terrain. This paper analyzes the Ecosystem Services Value (ESV) using a series of methods based on the data of changes in land use from 2000 to 2015 and the statistical yearbook. The changes in land use between 2000 and 2015 were dominated by forest land, which accounted for 60.63% of the total area, followed by arable landwhich accounted for about 22.26%, while grassland and other land use contribution rates were the lowest, accounting for only about 17.11%. Environmental changes and economic development were uneven. The regional comprehensive strength of En’shi City, Changyang County, and Yidu City were among the highest, while Badong County, Hefeng County, and Wufeng County were among the lowest in the area under study. In addition, the ESV in 2035 was estimated to be 1.56 billion dollars, a decrease of 27.64% when compared with the year 2000. The ESV of Yidu City, Lichuan City, Jianshi County, and Hefeng County grew faster, at the rates of 94.76%, 65.12%, 96.96%, and 92.38%, respectively. However, the ESV of En’shi City, Badong County, Wufeng County and Xuan’en County showed a downward trend, at the rates of −32.53%, −487.80%, −368.07%, and −181.52%, respectively.

Dynamic assessment of rainfall-induced shallow landslide hazard

The assessment of rainfall-induced shallow landslide hazards is a significant issue in the Three Gorges Reservoir area in China due to the rapid development of land in the past two decades. In this study, a probabilistic analysis method that combines TRIGRS and the point-estimate method for evaluating the hazards of shallow landslides have been proposed under the condition of rainfall over a large area. TRIGRS provides the transient infiltration model to analyze the pore water pressure during a rainfall. The point-estimate method is used to analyze the uncertainty of the soil parameters, which is performed in the geographic information system (GIS). In this paper, we use this method to evaluate the hazards of shallow landslides in Badong County, Three Gorges Reservoir, under two different types of rainfall intensity, and the results are compared with the field investigation. The results showed that the distribution of the hazard map is consistent with the observed landslides. To some extent, the distribution of the hazard map reflects the spatial and temporal distribution of the shallow landslide caused by rainfall.

Landslide Susceptibility Mapping Using GIS-based Vector Grid File (VGF) Validating with InSAR Techniques: Three Gorges, Yangtze River (China)

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.

Influence of the impoundment of the Three Gorges Reservoir on the micro-seismicity and the 2013 M5.1 Badong earthquake (Yangtze, China)

On December 16, 2013, right after the Three Gorges Reservoir (TGR) reached its highest annual water level, a powerful M5.1 earthquake occurred in Badong County, China’s Hubei Province. The epicenter is 5.5km away from the upstream boundary and 100km from the dam. Was this earthquake triggered by the impoundment of the TGR, and what are its subsequences? To answer these questions, we constructed a coupled three-dimensional poroelastic finite element model to examine the ground surface deformation, the Coulomb failure stress change (ΔCFS) due to the variation of elastic stress and pore pressure, and the elastic strain energy potential accumulation in the TGR region upon the occurrence of this event. Our calculated maximum surface deformation values beneath the TGR compare well with GPS observations, which validates our numerical model. At the hypocenter of the earthquake, ΔCFS is around 8.0∼11.0kPa, revealing that it may be eventually triggered by the impoundment. We also discovered that the total elastic strain energy potential accumulation due to the impounded water load is around 1.7×1012J, merely equivalent to 0.01% of the total energy released by this event, indicating that this earthquake is predominately controlled by the typical regional tectonic settings as well as the weak fault zones, and the reservoir impoundment might only facilitate its procedure or occurrence. Furthermore, the stress level in this region remains high after this earthquake and the subsequent reservoir-triggered micro-seismicity or even bigger event are highly possible.

New data and interpretations of the shallow and deep deformation of Huangtupo No. 1 riverside sliding mass during seasonal rainfall and water level fluctuation

The original Badong County, Hubei, China, was mainly below the highest water level of the Three Gorges Reservoir, which is 175 m above sea level. The new downtown of Badong was rebuilt in the Huangtupo area between 1982 and 1991. After detailed geological investigation in the Huangtupo area, four independent landslides were identified, making it one of the largest and most harmful landslide group in the Three Gorges Reservoir area. Since 2003, abundant data have been obtained from the Huangtupo No. 1 sliding mass about rainfall, water level, earth surface deformation and deep deformation. The monitoring data indicate that the earth surface and deep deformation of this landslide is closely related to the seasonal rainfall and water level fluctuation of the reservoir. During increases in the water level, the earth surface deformation velocity decreases, and then increases obviously in the subsequent water level decreasing stage. Because the water level drawdown period overlaps with the rainy season in this area, the earth surface deformation is affected by both rainfall and water level. The deformation velocity of the earth surface caused by rainfall is about 5 mm/month, while that caused by water level decrease is 5–7 mm/month. On the contrary, the deformation velocity of the deep sliding mass accelerates 2 to 3 times faster than average during water level increase. The distinction of surface and deep deformation regulations indicates that the effects of seasonal rainfall and water level fluctuation on the stability of reservoir wading landslides are different. Based on all monitoring data, we also found that the Huangtupo No. 1 riverside sliding mass is creeping seasonally during the seasonal rainfall and periodic reservoir water level fluctuation. The deformation velocities of the east regions of the sliding body indicate acceleration, making these regions even more dangerous.

Experimental Research on Gravel Soil Shear Strength

With the rise in the water level of the Three Gorges Project, accurately measuring the shear strength parameters of the Three Gorges Project shore landslide has important implications for the safety of the Three Gorges Project’s surrounding area. Due to the material of reservoir area slope is complex, are mostly loose accumulation, these loose accumulation are mainly composed by landslide deposits, eluvia material, alluvial matter, landslides, strong weathered, and material composition is soil with gravel or fragments stone, the conventional small specimens test has been impossible. Badong County has long rainy season, abundant rainfall, mudslides, landslides and other geological disasters are frequent, so measuring reservoir landslide shear strength of Badong County is particularly important. Therefore, this paper takes the gravel soil of piled crushed landslide of the third senior middle school in Badong County as the research object, through lab large-scale direct shear test to research the gravel soil strength parameters’ variation of the soil samples with different coarse soil content under different moisture conditions.

Deformation monitoring of slow-moving landslide with L- and C-band SAR interferometry

SAR interferometry (InSAR) is an effective tool for wide-area earth surface deformation detection and mapping. In this letter, Persistent Scatterers InSAR method was employed to derive the deformation histories of Huangtupo and Zhaoshuling landslides located in Badong County of the Three Gorges area. One Environmental Satellite C-band Advanced Synthetic Aperture Radar (ASAR) data stack acquired from descending orbit and two Advanced Land Observation Satellite Phased Array type L-band Synthetic Aperture Radar (PALSAR) data stacks collected from two adjacent ascending orbits were used. Different deformation trends were observed from the descending and ascending data stacks. Disagreements were found on Huangtupo and Zhaoshuling landslides between measurements of ASAR data and PALSAR data, which might be primarily attributed to different viewing geometries. Meanwhile, due to smaller decorrelation effects for longer wavelength, L-band PALSAR data can be used to detect more point-like targets than C-band ASAR data, which makes it more suitable for monitoring landslides in vegetated areas such as the Three Gorges. Preliminary temporal correlation analyses between deformation measurements and water level fluctuation as well as rainfall were performed to explore the driving mechanism for landslide motion within the Three Gorges Reservoir area.

Quantitative risk analysis for landslides: the case of the Three Gorges area, China

The purpose of this study was the analysis of life and property risks due to landslides in the Three Gorges area, China. A landslide susceptibility map was created using rough set theory and a support vector machine model. A scenario based on the past landslide frequency and magnitude was used to convert the susceptibility into quantitative hazard maps. The vulnerability was defined quantitatively as a function of landslide intensity and the resistance of at-risk elements. The elements at risk (population, buildings, lifeline engineering, and land resources) were extracted from color aerial photographs, and detailed information regarding these elements was collected via fieldwork. Reconstruction-cost and market-cost approaches were used to estimate the value of property. Quantitative risk maps were developed by integrating the value of the at-risk elements with the vulnerability and landslide hazard datasets. The resulting maps are presented on a continuous scale in which the numerical values indicate the distribution of risk, including the probability of expected economic losses in renminbi (RMB) and loss of lives per map unit for property and residents, respectively. Based on the final risk maps, it is clear that high-risk areas are located in Badong County and other towns and with transportation networks and urbanized areas with dense populations and high property values. Areas of moderate risk were primarily distributed in rural areas and cultivated lands. In addition, the maps show the low-level probability of expected losses in areas where landslide hazard control measures are present or where human activity is sparse, such as unutilized areas and forests. The resulting risk values involve uncertainties and are not precise predictions of future losses, but they may nevertheless help in identifying areas where damage is likely to be greater and where mitigation measures are warranted.

Survey and cause analyses of ground surface deformation near a foundation pit slope: a case study in the Three Gorges area, China

It is common that the deformation of an excavation slope leads to the displacement or even destruction of the surrounding buildings. An effective way to put an end to such accidents is to have adequate knowledge on the trigger factors of the deformation and failure of excavation slopes. Herein, taking the foundation pit slope at the Cultural Square in Badong County, China as an example, we carried out a site survey, including the engineering geology condition, the terrain change process, the spatial distribution characteristics of the surface crack and the construction process of the foundation pit. A further study was performed on the trigger factors, such as geological environment, earthquake, rainfall, fluctuation of reservoir level, human engineering activities, on ground surface deformation. The results show that the complex engineering geological condition and weak geological environment are the internal factors that lead to the deformation of the foundation pit slop. Earthquakes and fluctuations of reservoir level have little effect on this deformation, while rainfall and the excavation have a significant influence on it. The excavation process destroys the original geological environment and is thus the critical external factor inducing the formation and growth of crack, and rainfall intensifies the deformation.

Analytical study on abnormal change in time-variable gravity at Yichang seismostation before the M5.1 Badong earthquake

Abstract: An M5.1 earthquake occurred in Badong County, only 66 km from the Three Gorges Dam, on December 16, 2013. The continuous gravity observation data obtained at Yichang seismostation nearest to the epicenter (96 km) were analyzed, and it was found that the continuous gravity observation data obtained in this rainy season did not exhibit a characteristic of seasonal change in gravity identical to that in the past years, and thereafter the M5.1 Badong earthquake occurred. Numerical simulation revealed that the water storage and discharge of the Three Gorges reservoir generated seasonal change in gravity, and the changes in atmospheric pressure and gravity load were not the main sources of the seasonal change of continuous gravity observation data whether in respect of magnitude or phase and did not have obvious breaking change on annual variation before the earthquake. Through analysis of the seasonal change data observed on the same site including cavern temperature, rainfall data and global terrestrial water model (CPC) simulated water load, it was thought that, in the observation room with cavern temperature change of only − 0.11 °C/a at Yichang seismostation, the seasonal change of continuous gravity observation result mainly originated from the seasonal change in rainfall. In the case that the changes in rainfall and its water load did not have evident breaking change on annual variation law before the earthquake, if the M5.1 Badong earthquake was the cause of the breaking change on annual variation law in Yichang this time, then it was believed through analysis of crust expansion ratio that similar anomaly should occur at a crust expansion and compression intersection, no more than 100 km away from the epicenter.

Landslide susceptibility mapping based on rough set theory and support vector machines: A case of the Three Gorges area, China

This paper aims to develop a novel hybrid model for assessing landslide susceptibility at the regional scale using multisource data to produce a landslide susceptibility map of the Zigui–Badong area near the Three Gorges Reservoir, China. This area is subject to anthropogenic influences because the reservoir's water level fluctuates cyclically between 145 and 175m; in addition, the area suffers from extreme rainfall events due to the local climate. The area has experienced significant and widespread landslide events in recent years. In our study, a novel hybrid model is proposed to produce landslide susceptibility maps using geographical information systems (GIS) and remote sensing. The hybrid model is based on rough set (RS) theory and a support vector machine (SVM). RS theory is employed as an attribute reduction tool to identify the significant environmental parameters of a landslide, and an SVM is used to predict landslide susceptibility. Four data domains were considered in this research: geological, geomorphological, hydrology, and land cover. The original group of 20 environmental parameters and 202 landslides were used as the inputs to produce a landslide susceptibility map. According to the map, 19.7% of the study area was identified as medium- and high-susceptibility zones encompassing 89.5% of the historical landslides. The results indicate high levels of landslide hazard in and around the main inhabited areas, such as Badong County and other towns, as well as in rural residential areas and transportation areas along the Yangtze River and its tributaries. The predicted map indicates a good correlation between the classified high hazard areas and slope failures confirmed in the field. Furthermore, the quality of the proposed model was comprehensively evaluated, including the degree of model fit, the robustness of the model, the uncertainty associated with the probabilistic estimate, and the model prediction skill. The proposed model was also compared with the general SVM, which demonstrated that the hybrid model has superior prediction skill and higher reliability and confirmed the usefulness of the proposed model for landslide susceptibility mapping at a regional scale.

An Earthquake Fault Zone Discovered in the Three Gorges Reservoir Area

The Maluxiang – Changduhe at Badong County is a newly discovered seismic active fault zone in the Three Gorges Reservoir Area, and the occurrence of fault is EW / N ∠60 °-70 °. The fault appears as a deeply linear valley on the topography and the fault breccia bandwidth is up to 200m. The fault is densely distributed with many springs and covered by luxuriant forests. The new site of Badong County is set up on the top of fault zone, and exists a lot of active landslides. The tested data of the absolute age of the landslides slip zone soil indicates that the landslide is active since the late Pleistocene. The Three Gorges Reservoir has continued seismic activity since 2003, and the fault zone suffers the greatest damage which is the most direct evidence as an indication of fault activity. Therefore, research on the fault zone is very important and significant for immigrant settlement in the Three Gorges reservoir.

Zonation of the Landslide Hazards Based on Artificial Neural Network

This paper applies RS and GIS technology to study zonation of the landslide hazards in the study area from Badong county to Zigui county in TGP reservoir region. The causative factors involves lithology, distance to faults, slope angle, slope aspect, elevation, drainage network, distance to river and distribution of plant, which are derived from geological map, Spot imagery data and Digital Elevation Model (DEM) based on RS and GIS technology. We analyze the zonation of the landslide hazards with artificial neural network. The research result is very coincident with the occurrence of the known landslides in the study area.

Study of an archeological opaque red glass bead from China by XRD, XRF, and XANES

As a kind of rare archeological founding in China, red decorative beads (300–400 ad) were discovered in Leijiaping, Badong County, Hubei, China. For the first time, this paper reports an advanced structural analysis of glass beads using micro synchrotron X‐ray near‐edge absorption spectroscopy. The results show that in spite of being opaque, the red bead is made of glass containing two forms of copper atoms, including 0+ and 1+. In combination with X‐ray diffraction results, it is advised that the mechanism of red coloration mainly comes from metallic copper. This paper indicates that micro synchrotron X‐ray near‐edge absorption spectroscopy is an outstanding and advanced technology to study ancient glass objects with nondestructive mode. Copyright © 2012 John Wiley & Sons, Ltd.

Using advanced InSAR time series techniques to monitor landslide movements in Badong of the Three Gorges region, China

The Three Gorges occupy 193km of the middle reaches of the Yangtze River between Fengjie in Chongqing and Yichang in Hubei Province, China. Due to steep valley-side slopes and long-term river incision, landslides are a major hazard in the Three Gorges region. In this study, we employ the SBAS InSAR technique to process Envisat SAR images collected between 2003 and 2010. Our time series results enable identification of two distinct landslides with deformation rates of up to 10–15mm/yr in Badong County, and field evidence is used to verify the positions of these failures. With both descending and ascending observations, two-dimensional velocity fields in north and up directions are recovered to better understand the landslide movements. Obvious correlation between seasonal landslide movements and water level changes is observed, which not only provides strong support of our InSAR time series results, but also indicates the impacts of water level changes to landslide activities.