Divya Sekhar Vaka

• Doctor of Philosophy
• Satellite Remote Sensing Analyst at Geofem

Sand accumulation on roads and railways due to sand and dust storms can disrupt transportation, cause delays, increase maintenance costs, and create significant safety hazards. Implementing advanced detection technology can significantly enhance the reliability and safety of transport infrastructure. In this study, we monitored sand accumulation on...

Landslides pose significant threats to life and property, particularly in mountainous regions. To address this, this study develops a landslide susceptibility model integrating Earth Observation (EO) data, historical data, and Multi-Temporal Interferometric Synthetic Aperture Radar (MT-InSAR) ground movement results. The model categorizes areas int...

Monitoring of Earth’s surface processes is eDciently performed by Differential SAR interferometry (DInSAR) techniques with the availability of open access Copernicus Sentinel-1A and 1B SAR data products having 6 days temporal resolution. With over 750 landslides triggered in Kodagu district, Karnataka, India, interferometric wide swath (IW) mode Se...

Monitoring land subsidence due to groundwater exploitation, natural oil and gas extraction, improper building foundations close to coastal areas, and tectonic movements are crucial in understanding the behavior of Earth's surface in urban areas. In the context of urban monitoring, uncontrolled constructions and irregular development activities are...

Sentinel-1 SAR data preprocessing is essential for several earth observation applications, including land cover classification, change detection, vegetation monitoring, urban growth, natural hazards, etc. The information can be extracted from the 2x2 covariance matrix [C2] of Sentinel-1 dual-pol (VV-VH) acquisitions. To generate the covariance matr...

The Ground-Based Synthetic Aperture Radar (GB-SAR) technique is a reliable tool for deformation measurement due it is highly sensitive to small displacements and frequent coverage property. GB-SAR data processing is not as complex as conventional SAR data processing for displacement mapping using PSInSAR method. The processing involves several step...

In this paper, the height accuracy of various DEMs such as TanDEM-X Global DEM, newly released TanDEM-X 90 m DEM, TanDEM-X ascending or descending DEM, SRTM 30 m, 90 m DEMs, provisional version of the NASADEM, and the aerial LiDAR DEM are assessed over three different Indian terrains. The test sites deal with flat terrain, flat terrain with forest...

The 2017 Mw 7.3 Iran-Iraq earthquake occurred in the seismically less active northern Zagros Mountains. In this study, DInSAR technique is used to derive the surface displacements of the earthquake using the Sentinel-1 and ALOS-2 images. One preseismic, three coseismic and a postseismic interferogram are generated. The coseismic interferograms did...

Accurate and precise topographic information from Digital Elevation Models (DEM) is of fundamental requirement for many geoscience and engineering applications. With a goal of providing accurate global topographic products, German Aerospace Centre (DLR) and Airbus Defence and Space developed X-band TanDEM-X mission. The TanDEM-X Global DEM is gener...

Earthquakes cause destruction and loss of human lives. Mapping the extent of surface displacements due to an earthquake is crucial for the damage assessment. Over the last two decades, Synthetic Aperture Radar Interferometry (InSAR) proved to be a prominent tool in precise mapping and measuring of ground displacements with millimetre-level accuracy...

Persistent Scatterer Interferometry (PSI) is an advanced technique to map ground surface displacements of an area over a period. The technique can measure deformation with a millimeter-level accuracy. It overcomes the limitations of Differential Synthetic Aperture Radar Interferometry (DInSAR) such as geometric, temporal decorrelation and atmospher...

Glaciers are melting at an alarming rate due to global warming. Two major glaciers of India viz. Gangotri and the Siachen are chosen for the velocity mapping. The line-of-sight (LOS) velocity fields are derived using X-band TerraSAR-X and C-band Sentinel-1A datasets. An intensity-based offset tracking method is used to generate LOS velocities of th...

Long-term ground surface displacements of seismically active Bhuj area in India between two time spans are derived from L-band ALOS-1 and ALOS-2 images using Persistent Scatterer Interferometry approach. The work also focuses on studying the influence of high resolution TanDEM-X Global DEM on topographic phase removal and it’s effect on deformation...

Persistent Scatterer Interferometry technique (PSI) exploits time series of interferometric data to estimate deformation over an area. The process involves analysing stable phase pixels from differential interferograms formed with respect to a single master. In this study, eight RADARSAT-2 C-band fine quad polarization images from 2014 to 2016 are...

SAR Interferometry (InSAR) is a technique by which a wide area can be mapped for surface deformation. The conventional InSAR technique has limitations due to baseline restriction, atmospheric phase delay, and temporal decorrelation. Persistent Scatterer Interferometry (PSI) technique is an advanced InSAR technique, and it mitigates the atmospheric...