scholarly journals Long-Term and Emergency Monitoring of Zhongbao Landslide Using Space-Borne and Ground-Based InSAR

2021 ◽  
Vol 13 (8) ◽  
pp. 1578
Author(s):  
Ting Xiao ◽  
Wei Huang ◽  
Yunkai Deng ◽  
Weiming Tian ◽  
Yonglian Sha
Keyword(s):  
Landslide Monitoring ◽  
Early Investigation ◽  
Interferometric Synthetic Aperture Radar ◽  
Monitoring Methods ◽  
Barrier Lake ◽  
Monitoring Frequency ◽  
Emergency Measure ◽  
Cumulative Deformation ◽  
Timely Warning

This work presents the ideal combination of space-borne and ground-based (GB) Interferometric Synthetic Aperture Radar (InSAR) applications. In the absence of early investigation reporting and specialized monitoring, the Zhongbao landslide unexpectedly occurred on 25 July 2020, forming a barrier lake that caused an emergency. As an emergency measure, the GB-InSAR system was installed 1.8 km opposite the landslide to assess real-time cumulative deformation with a monitoring frequency of 3 min. A zone of strong deformation was detected, with 178 mm deformation accumulated within 15 h, and then a successful emergency warning was issued to evacuate on-site personnel. Post-event InSAR analysis of 19 images acquired by the ESA Sentinel-1 from December 2019 to August 2020 revealed that the landslide started in March 2020. However, the deformation time series obtained from satellite InSAR did not show any signs that the landslide had occurred. The results suggest that satellite InSAR is effective for mapping unstable areas but is not qualified for rapid landslide monitoring and timely warning. The GB-InSAR system performs well in monitoring and providing early warning, even with dense vegetation on the landslide. The results show the shortcomings of satellite InSAR and GB-InSAR and a clearer understanding of the necessity of combining multiple monitoring methods.

scholarly journals Data Correction Method of The Persistent Scatterer Interferometric Synthetic Aperture Radar Technique in Landslide Surface Monitoring

Mining Scince ◽  
2019 ◽  
Vol 26 ◽  
Author(s):  
Mowen Xie ◽  
Fuxia Lv ◽  
Liwei Wang
Keyword(s):  
Synthetic Aperture Radar ◽  
Single Point ◽  
Synthetic Aperture ◽  
Hydropower Station ◽  
Landslide Monitoring ◽  
Interferometric Synthetic Aperture Radar ◽  
Reservoir Area ◽  
Radar Technique ◽  
Aperture Radar

Landslides generally cause more damage than first predicted. Currently, many methods are available for monitoring landslides occurrence. Conventional methods are mainly based on single-point monitoring, which omits the aspect of variation in large-scale landslides. Due to the development of radar satellites, the differential interferometric synthetic aperture radar technique has been widely used for landslide monitoring. In this study, an experimental region in the Wudongde Hydropower Station reservoir area was studied using archived spaceborne synthetic aperture radar (SAR) data collected over many years. As the permanent scatterer interferometric SAR (PS-InSAR) technique is an advanced technology, it could be suitably used to overcome the time discontinuity in long time series. However, the accuracy of date processing obtained using the PS-InSAR technique is lower than that obtained using the single-point monitoring method. The monitoring results of the PS-InSAR technique only demonstrate the moving trend of landslides and do not present the actual displacement. The Advanced Land Observation Satellite and a high-precision total station were used for long-term landslide monitoring of the Jinpingzi landslide at the Wudongde Hydropower Station reservoir area. Based on a relationship analysis between the data obtained using the PS-InSAR technique and the total station, a revised method was proposed to reduce the errors in the PS-InSAR monitoring results. The method can not only enhance the monitoring precision of the PS-InSAR technology but also achieve long-term monitoring of landslide displacement from a bird’s-eye view.

scholarly journals EM-Based Monitoring and Probabilistic Analysis of Prestress Loss of Bonded Tendons in PSC Beams

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Zheheng Chen ◽  
Shanwen Zhang
Keyword(s):  
Probabilistic Analysis ◽  
Prestressed Concrete ◽  
Monitoring Methods ◽  
Prestress Loss ◽  
External Tendons ◽  
Material Environment ◽  
Key Factor ◽  
One Year

The prestress level is a key factor of prestressed concrete (PSC) beams, affecting their long-term serviceability and safety. Existing monitoring methods, however, are not effective in obtaining the force or stress of embedded tendons. This paper investigates the feasibility of elastomagnetic (EM) sensors, which have been used for external tendons, in monitoring the long-term prestress loss of bonded tendons. The influence of ambient temperature, water, eccentricity ratio, plastic duct, and cement grouts on the test results of EM sensors is experimentally examined. Based on the calibrated EM sensors, prestress loss of a group of PSC beams was monitored for one year. In order to further consider the high randomness in material, environment, and construction, probabilistic analysis of prestress loss is conducted. Finally, the variation range of prestress loss with a certain confidence level is obtained and is compared with the monitored data, which provides a basis for the determination of prestress level in the design of PSC beams.

scholarly journals Assessing Summer Pond and Lake Inlet Use by Gray Treefrogs (Hyla versicolor/chrysoscelis complex) Using PVC Pipe Traps in Northwest Missouri

2020 ◽  
Vol 48 (2020) ◽  
pp. 17-21
Author(s):  
J. D. McGhee
Keyword(s):  
Sex Ratio ◽  
Hyla Versicolor ◽  
Monitoring Methods ◽  
Contingency Table Analysis ◽  
Detection Rates ◽  
Sampling Locations ◽  
Table Analysis ◽  
Pvc Pipe ◽  
Gray Treefrog

Abstract The widespread decline in amphibian populations highlights the need for establishing rigorous monitoring methods for long-term population studies. In an attempt to launch a long-term monitoring study for a Gray Treefrog complex (Hyla versicolor LeConte /chrysoscelis Cope, hereafter treefrog) population in northwest Missouri, I tested the use of PVC pipe traps in a system of ponds and inlets along a lakeside habitat for three years. For each pond (3) and inlet (2), I established an array of 16 pipes so as to compare differences in use between pipe location, ponds and inlets, and sex ratio between sites. Pipes were checked twice a week during the summer for the presence of treefrogs. Treefrog usage of pipes between ponds and inlets were compared using a contingency table analysis, while an ANOVA was used to assess differences in sex ratios between sites (α = 0.05). A single inlet was used by treefrogs more heavily than the other ponds or inlet (G = 13.61, df = 3, P = 0.0035), however, I found no differences in terms of pipe location within a pond or inlet. Mean sex ratio between water bodies varied but did not significantly differ. There appears to be little effect in terms of pipe placement within our 50 m buffer from the water's edge, but unique habitat effects at sampling locations may significantly affect detection rates or usage.

Prediction of long-term disability in multiple sclerosis

2011 ◽  
Vol 18 (1) ◽  
pp. 31-38 ◽  
Author(s):  
R Schlaeger ◽  
M D’Souza ◽  
C Schindler ◽  
L Grize ◽  
S Dellas ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
Motor Evoked Potentials ◽  
Rank Correlation ◽  
Daily Practice ◽  
Z Score ◽  
Monitoring Methods ◽  
Spearman’S Rank Correlation ◽  
Mri Scans ◽  
Cranial Mri

Background: Little is known about the predictive value of neurophysiological measures for the long-term course of multiple sclerosis (MS). Objective: To prospectively investigate whether combined visual (VEP) and motor evoked potentials (MEP) allow prediction of disability over 14 years. Methods: A total of 30 patients with relapsing–remitting and secondary progressive MS were prospectively investigated with VEPs, MEPs and the Expanded Disability Status Scale (EDSS) at entry (T0) and after 6, 12 and 24 months, and with cranial MRI scans at entry (T2-weighted and gadolinium-enhanced T1-weighted images). EDSS was again assessed at year 14 (T4). The association between evoked potential (EP), magnetic resonance (MR) data and EDSS was measured using Spearman’s rank correlation. Multivariable linear regression was performed to predict EDSST4 as a function of z-transformed EP-latenciesT0. The model was validated using a jack-knife procedure and the potential for improving it by inclusion of additional baseline variables was examined. Results: EDSS valuesT4 correlated with the sum of z-transformed EP-latenciesT0 (rho = 0.68, p < 0.0001), but not with MR-parametersT0. EDSST4 as predicted by the formula EDSST4 = 4.194 + 0.088 * z-score P100T0 + 0.071 * z-score CMCTUE, T0 correlated with the observed values (rho = 0.69, p < 0.0001). Conclusion: Combined EPs allow prediction of long-term disability in small groups of patients with MS. This may have implications for the choice of monitoring methods in clinical trials and for daily practice decisions.

Ground motion and PSI density analysis from Envisat and Sentinel1a InSAR data in the context of a complex landslide monitoring strategy in Karnali river basin, Far-Western Nepal

2020 ◽  
Author(s):  
Arnulf Schiller ◽  
Filippo Vecchiotti ◽  
Anna Sara Amabile ◽  
Carlotta Guardiani ◽  
Megh Raj Dhital ◽  
...  
Keyword(s):  
Image Analysis ◽  
River Basin ◽  
Active Sites ◽  
Local Community ◽  
Water Saturation ◽  
Satellite Image ◽  
Landslide Monitoring ◽  
Mass Movements ◽  
Monitoring Methods ◽  
Integrated Monitoring

&lt;p&gt;Continuous INSAR-monitoring of slow mass movements in the surrounding of fast (m/year) or acute processes can deliver important data complementing geomorphologic information in order to understand the broader dynamic context in which a landslide is situated. In course of the Landslide-EVO project (NERC/SHEAR funded), focusing on flood and landside risk assessment and mitigation in the Karnali river basin region in Far Western Nepal by inclusion of local community, this has been evaluated within a test of integrated monitoring methods (comprising eg. ERT, UAV-photogrammetry, D-GPS/geodesy, microseismics, soil water saturation, rainfall, and other) on regional as well as local scale at two selected sites at Bajura and Sunkoda. It was possible to derive extended information about movements in a ROI covering 120 km by 120 km. The PSI/SBAS based velocity analysis exhibits density variations due to specific slope/sensor system geometry, vegetation, data gaps, atmospheric conditions, and high velocities in the most active sites, which causes decorrelation. However, in the less active surrounding of active landslides the velocity information shows generally higher density. INSAR techniques could well complement optical image analysis in the low velocity range of centimetres to several decimetres per year, generally too slow for optical satellite image analysis in this time scale. InSAR-data has the potential to be used for estimating a slow moving masses acceleration or a deep-seated gravitational slope deformations cumulative displacement leading to a partial or total reactivation before other indication appears. It has been shown that large and difficult accessible areas can be monitored with InSAR techniques, while specific sites are equipped with corner reflectors for better signal. The study represents the first of this kind in the region and proves the ability of INSAR techniques for retrieving critical information about mass movements affecting local communities in the Karnali river basin as an example of a developing region.&lt;/p&gt;

Mitigation reduces road mortality of a threatened rattlesnake

2017 ◽  
Vol 44 (1) ◽  
pp. 48 ◽  
Author(s):  
Michael Colley ◽  
Stephen C. Lougheed ◽  
Kenton Otterbein ◽  
Jacqueline D. Litzgus
Keyword(s):  
Temperature Fluctuations ◽  
Camera Traps ◽  
Road Mortality ◽  
Monitoring Methods ◽  
Sistrurus Catenatus ◽  
Eastern Massasauga Rattlesnake ◽  
High Road ◽  
Provincial Park ◽  
Term Data

Context Reducing road mortality is essential to reptile conservation in regions with dense road networks. The Georgian Bay, Ontario population of the eastern massasauga rattlesnake (Sistrurus catenatus) is designated as Threatened, in part because of high road mortality. In Killbear Provincial Park, four ecopassages and barrier fencing were constructed along three busy park roads to reduce road mortality of massasaugas. Aim Although mitigation of road mortality has been widely recommended and in some instances implemented for reptiles, effectiveness of mitigation efforts is often inadequately evaluated. The goals of our study were to use long-term data to quantify the effectiveness of ecopassages and barrier fencing in reducing massasauga fatalities on roads, and to evaluate the potential of these structures to serve as movement corridors for individual snakes. Methods We used five approaches to assess the overall efficacy of mitigation efforts: (1) comparison of pre- and post-mitigation road mortality; (2) camera traps in ecopassages to document massasauga and predator presence; (3) automated tag readers in ecopassage entrances to detect PIT-tagged individuals; (4) an experiment to assess massasauga willingness to enter and travel through ecopassages; and (5) measurement of temperature fluctuations in ecopassages to assess thermal suitability for massasaugas. Key results We found a significant decrease in road mortality of massasaugas on stretches of park roads associated with ecopassages and barrier fencing post construction. Automated tag readers and cameras detected the presence of massasaugas and other animals within the ecopassages, and experimental data showed that massasaugas willingly entered, and in some cases crossed through, ecopassages. Conclusion Our evaluation of mitigation structures determined that they successfully reduce road mortality and provide potential movement corridors between bisected habitats, provided that intense maintenance of the fencing is conducted yearly. We also demonstrated the need to utilise a combination of multiple post-monitoring methods to effectively evaluate mitigation structures. Implications This study provides a template for construction of similar mitigation in other key locations where reptile road mortality occurs.

scholarly journals Unsteady flow inferred for Thwaites Glacier, and comparison with Pine Island Glacier, West Antarctica

2002 ◽  
Vol 48 (161) ◽  
pp. 237-246 ◽  
Author(s):  
Jonathan Bamber ◽  
Eric Rignot
Keyword(s):  
Steady State ◽  
Unsteady Flow ◽  
Synthetic Aperture ◽  
Interferometric Synthetic Aperture Radar ◽  
Recent Past ◽  
West Antarctica ◽  
Steady State Flow ◽  
Dramatic Difference ◽  
Substantial Change

AbstractWe present a comparison of surface velocities in 1996, derived from interferometric synthetic aperture radar, with an estimate of the long-term, depth-averaged velocity based on the assumption of steady-state flow for both Pine Island Glacier and its neighbour, Thwaites Glacier, West Antarctica. The results show that the former was close to balance conditions in 1996 (within 9%). The ice flux and velocity of the latter is significantly different in magnitude and distribution from that required to maintain the basin in a state of mass balance over the long term. The balance flux was found to be 32 ± 19% less than the measured outgoing flux. We conclude that the mass imbalance and dramatic difference in the pattern of flow is most likely due to a substantial change in the flow regime of Thwaites Glacier in the recent past.

scholarly journals Landslide Geohazard Monitoring, Early Warning and Stabilization Control Methods

2014 ◽  
Vol 36 (1) ◽  
pp. 3-13 ◽  
Author(s):  
Zbigniew Bednarczyk
Keyword(s):  
Real Time ◽  
Early Warning ◽  
Warning System ◽  
Landslide Monitoring ◽  
High Plasticity ◽  
Monitoring Methods ◽  
Time Data ◽  
Stabilization Control ◽  
Starting Point ◽  
On Line

Abstract This paper is a presentation of landslide monitoring, early warning and remediation methods recommended for the Polish Carpathians. Instrumentation included standard and automatic on-line measurements with the real-time transfer of data to an Internet web server. The research was funded through EU Innovative Economy Programme and also by the SOPO Landslide Counteraction Project. The landslides investigated were characterized by relatively low rates of the displacements. These ranged from a few millimetres to several centimetres per year. Colluviums of clayey flysch deposits were of a soil-rock type with a very high plasticity and moisture content. The instrumentation consisted of 23 standard inclinometers set to depths of 5-21 m. The starting point of monitoring measurements was in January 2006. These were performed every 1-2 months over the period of 8 years. The measurements taken detected displacements from several millimetres to 40 cm set at a depth of 1-17 m. The modern, on-line monitoring and early warning system was installed in May 2010. The system is the first of its kind in Poland and only one of several such real-time systems in the world. The installation was working with the Local Road Authority in Gorlice. It contained three automatic field stations for investigation of landslide parameters to depths of 12-16 m and weather station. In-place tilt transducers and innovative 3D continuous inclinometer systems with sensors located every 0.5 m were used. It has the possibility of measuring a much greater range of movements compared to standard systems. The conventional and real-time data obtained provided a better recognition of the triggering parameters and the control of geohazard stabilizations. The monitoring methods chosen supplemented by numerical modelling could lead to more reliable forecasting of such landslides and could thus provide better control and landslide remediation possibilities also to stabilization works which prevent landslides.

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