In the last few years, ALOS/PALSAR (L-band) (HH, HV, VH, and VV) images have been widely used due to their ability to penetrate the surface in certain conditions, such as low moisture or dry friable sandy soil. Images from the ALOS-1 sensor were used to delineate subsurface structures, and optical images such as Landsat-7 ETM + data were used to discriminate between scatterings from the Earth’s surface and subsurface materials. Thus, the Farafra Desert is an optimal geological environment for L-band microwave penetration, as its geology is characterized by friable sand sheets covering limestone (Tarawan Formation). Speckle noise is found in radar images for many reasons, such as when an object strongly reflected between itself and the spacecraft causes noise. Refined LEE filter (RLF) is applied for speckle noise reduction; moreover, full polarimetric ALOS/PALSAR images (PLR) are transformed into circular polarization by changing both angles into orientation angle ψ = 0° and elliptical angle χ = 45°. The validation of ALOS/PALSAR outputs was carried out using ground penetrating radar (GPR) measurements. Three GPR long profiles using a 200 MHz antenna were scanned along with areas that were annotated according to ALOS/PALSAR results (high backscattering coefficient). The GPR system operated by a low-frequency antenna with a frequency of 200 MHz was capable of detecting the annotated geological structures beneath the sand sheets. Furthermore, statistical comparison of L-band SAR and GPR data illustrated a correlation that can reveal identical regions to delineate subsurface structures. These results prove that the integration of synthetic aperture radar SAR (L-band) and on-site low-frequency radar systems can be vital to detect soil structures down to several meters, ultimately innovating Earth observation systems for geological and hydrogeological mapping in arid regions.
There are more than 119 million mines were buried in 71 countries in the world. The number of mine victims is greater than the number of the victims of nuclear and chemical weapons together. Egypt is one of the countries that suffer from the presence of landmines in its soil. Hence, around 21 million landmines are found in several locations, especially at El-Alameen and Sinai Peninsula.Ground Penetrating Radar (GPR) is a near-surface geophysical imaging technique used for subsurface geologic, engineering and environmental investigations. It is an efficient tool for landmines detection, especially non-metal types such as PMN-2 landmine as well as its far detection capability.
Landmines represent a serious environmental problem for several countries as it causes severe injured and many victims. In this paper, the response of GPR from different parameters of the landmine targets has been shown and the data is correlated with observed field experiment made in 2012 at Miami Crandon Park test site. The ability of GPR for detecting non-metallic mines with different orientations was revealed and soil effect upon the GPR signal was examined putting into consideration the soil parameters in different locations in Egypt such as in Sinai and El Alamein. The simulation results showed that PMN-2 landmine was detected at 5 cm and 15 cm depths, even at the minimum radar cross section vertical orientation. The B-Scan (2D GPR profiles) of PMN-2 target at 15 cm depth figured out high reflectivity for Wadi deposits due to large contrast between PMN-2 landmine material and soil of sand dunes.
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