scholarly journals Monitoring and Mapping of Shallow Landslides in a Tropical Environment Using Persistent Scatterer Interferometry: A Case Study from the Western Ghats, India

Geomatics ◽  
2020 ◽  
Vol 1 (1) ◽  
pp. 3-17
Author(s):  
Ambujendran Rajaneesh ◽  
Natarajan Logesh ◽  
Chakrapani Lekha Vishnu ◽  
El Hachemi Bouali ◽  
Thomas Oommen ◽  
...  

Persistent Scatterer Interferometry (PSI) techniques are now well established and accepted for monitoring ground displacements. The presence of shallow-seated landslides, ubiquitous phenomena in the tropics, offers an opportunity to monitor and map these hazards using PSI at the regional scale. Thus, the Western Ghats of India, experiencing a tropical climate and in a topographically complex region of the world, provides an ideal study site to test the efficacy of landslide detection with PSI. The biggest challenge in using the PSI technique in tropical regions is the additional noise in data due to vegetation. In this study, we filtered these noises by utilizing the 95-percentile of the highest coherence data, which also reduced the redundancy of the PSI points. The study examined 12 landslides that occurred within one of the three temporal categories grouped as Group 1, Group 2, and Group 3, categorized in relation to PSI monitoring periods, which was also further classified into east- and west-facing landslides. The Synthetic Aperture Radar (SAR) data is in descending mode, and, therefore, the east-facing landslides are characterized by positive deformation velocity values, whereas the west-facing landslides have negative deformation values. Further, the landslide-prone areas, delineated using the conventional factor of safety (FS), were refined and mapped using PSI velocity values. The combination of PSI with the conventional FS approach helped to identify exclusive zones prone to landslides. The main aim of such an attempt is to identify critical areas in the unstable category in the map prepared using FS and prioritizing the mitigation measures, and to develop a road map for any developmental activities. The approach also helps to increase confidence in the susceptibility mapping and reduce false alarms.

2020 ◽  
Vol 1 (1) ◽  
pp. 33-41
Author(s):  
S. A. Saldaña-Mendoza ◽  
J. A. Ascacio-Valdés ◽  
A. S. Palacios-Ponce ◽  
J. C. Contreras-Esquivel ◽  
R. Rodríguez-Herrera ◽  
...  

2019 ◽  
Vol 11 (14) ◽  
pp. 1675 ◽  
Author(s):  
Tomás ◽  
Pagán ◽  
Navarro ◽  
Cano ◽  
Pastor ◽  
...  

This work describes a new procedure aimed to semi-automatically identify clusters of active persistent scatterers and preliminarily associate them with different potential types of deformational processes over wide areas. This procedure consists of three main modules: (i) ADAfinder, aimed at the detection of Active Deformation Areas (ADA) using Persistent Scatterer Interferometry (PSI) data; (ii) LOS2HV, focused on the decomposition of Line Of Sight (LOS) displacements from ascending and descending PSI datasets into vertical and east-west components; iii) ADAclassifier, that semi-automatically categorizes each ADA into potential deformational processes using the outputs derived from (i) and (ii), as well as ancillary external information. The proposed procedure enables infrastructures management authorities to identify, classify, monitor and categorize the most critical deformations measured by PSI techniques in order to provide the capacity for implementing prevention and mitigation actions over wide areas against geological threats. Zeri, Campiglia Marittima–Suvereto and Abbadia San Salvatore (Tuscany, central Italy) are used as case studies for illustrating the developed methodology. Three PSI datasets derived from the Sentinel-1 constellation have been used, jointly with the geological map of Italy (scale 1:50,000), the updated Italian landslide and land subsidence maps (scale 1:25,000), a 25 m grid Digital Elevation Model, and a cadastral vector map (scale 1:5,000). The application to these cases of the proposed workflow demonstrates its capability to quickly process wide areas in very short times and a high compatibility with Geographical Information System (GIS) environments for data visualization and representation. The derived products are of key interest for infrastructures and land management as well as decision-making at a regional scale.


Landslides ◽  
2021 ◽  
Author(s):  
Sansar Raj Meena ◽  
Omid Ghorbanzadeh ◽  
Cees J. van Westen ◽  
Thimmaiah Gudiyangada Nachappa ◽  
Thomas Blaschke ◽  
...  

AbstractRainfall-induced landslide inventories can be compiled using remote sensing and topographical data, gathered using either traditional or semi-automatic supervised methods. In this study, we used the PlanetScope imagery and deep learning convolution neural networks (CNNs) to map the 2018 rainfall-induced landslides in the Kodagu district of Karnataka state in the Western Ghats of India. We used a fourfold cross-validation (CV) to select the training and testing data to remove any random results of the model. Topographic slope data was used as auxiliary information to increase the performance of the model. The resulting landslide inventory map, created using the slope data with the spectral information, reduces the false positives, which helps to distinguish the landslide areas from other similar features such as barren lands and riverbeds. However, while including the slope data did not increase the true positives, the overall accuracy was higher compared to using only spectral information to train the model. The mean accuracies of correctly classified landslide values were 65.5% when using only optical data, which increased to 78% with the use of slope data. The methodology presented in this research can be applied in other landslide-prone regions, and the results can be used to support hazard mitigation in landslide-prone regions.


2018 ◽  
Vol 265 ◽  
pp. 461-469 ◽  
Author(s):  
Joannès Guillemot ◽  
Guerric le Maire ◽  
Manjunatha Munishamappa ◽  
Fabien Charbonnier ◽  
Philippe Vaast

2018 ◽  
Vol 17 (1) ◽  
pp. 21
Author(s):  
Arun Kanagavel ◽  
Sethu Parvathy ◽  
Abhiijth P. Chundakatil ◽  
Neelesh Dahanukar ◽  
Benjamin Tapley

Distribution and habitat associations of the Critically Endangered frog Walkerana phrynoderma (Anura: Ranixalidae), with an assessment of potential threats, abundance, and morphology. Little is known about Walkerana phrynoderma, a frog endemic to the Anamalai Hills of the Western Ghats of India. Baseline information (i.e., distribution, threats, habitat characteristics, activity patterns, and relative abundance) is provided for this species, with the aim of improving our understanding of the status of the species in the wild. Visual-encounter, transect, and time-activity budget surveys were conducted in and around the Anamalai Hills of the Western Ghats. The frog skin was swabbed to determine the presence/absence of Batrachochytrium dendrobatidis, and habitat and environmental characteristics were recorded at sites where W. phrynoderma was found. These data were compared with those of sites apparently lacking this species that had suitable habitat. Walkerana phrynoderma is restricted to evergreen forests between 1300 and 1700 m a.s.l. in the Anamalai Tiger Reserve and at Munnar; thus, its range was extended from the state of Tamil Nadu to the adjoining state of Kerala. Pesticide runoff and human disturbance are the most severe threats to the species; B. dendrobatidis was not detected. This nocturnal anuran prefers forest edges and is associated with well-shaded forest foors in cool areas near freshwater streams. Walkerana phrynoderma is rarely encountered whereas its congener, W. leptodactyla, is more common. The impact of anthropogenic disturbances, especially waste disposal and development of tourism infrastructure, should be evaluated. The land that is owned by the Forest Department peripheral to the protected areas could be designated as eco-sensitive sites to prevent changes in land use that could have an adverse effect on W. phrynoderma.


Zootaxa ◽  
2018 ◽  
Vol 4415 (1) ◽  
pp. 76
Author(s):  
M. B. MALIPATIL ◽  
G. G. E. SCUDDER

Paraindopamphantus gen. nov., containing one species, I. bruneiensis sp. nov., is reported from Brunei, as the first member of the subfamily Pamphantinae from South East Asia and the second from the Oriental Region. The strikingly myrmecomorphic P. bruneiensis, collected only from Bukit Sulang, nr Lamunin in Brunei in the canopy of Shorea johorensis Foxw. (Dipterocarpaceae) tree by insecticide fogging is described and illustrated. The genus is placed in tribe Indopamphantini, that at present contains only other genus Indopamphantus Malipatil recorded from the Western Ghats of India. The significance of the habitus and myrmecomorphy of this species, in relation to Indopamphantus makutaensis Malipatil, is discussed. A key to the two genera of Indopamphantini is provided. 


2018 ◽  
Vol 228 ◽  
pp. 110-119
Author(s):  
Priya Davidar ◽  
François Munoz ◽  
Jean-Philippe Puyravaud ◽  
D. Mohandass ◽  
V.S. Ramachandran

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