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Detection of Land Subsidence in Kathmandu Valley, Nepal, Using DInSAR Technique

1
Geosystem and Biological Sciences Division, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba-shi, Chiba 263-8522, Japan
2
Center for Environmental Remote Sensing, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba-shi, Chiba 263-8522, Japan
*
Author to whom correspondence should be addressed.
Academic Editor: Paul Aplin
Received: 17 April 2017 / Revised: 25 May 2017 / Accepted: 6 June 2017 / Published: 11 June 2017
Differential Synthetic Aperture Radar Interferometry (DInSAR) is a remote sensing technique that is capable of detecting land surface deformation with centimeter accuracy. In this research, this technique was applied to two pairs of Advanced Land Observing Satellite (ALOS) Phased Array L-band SAR (PALSAR) data to detect land subsidence in the Kathmandu valley from 2007 to 2010. The result revealed several subsidence areas towards the center of the valley ranging from a maximum of 9.9 km2 to a minimum of 1 km2 coverage with a maximum velocity of 4.8 cm/year, and a minimum velocity of 1.1 cm/year, respectively. The majority of the subsidence was observed in old settlement areas with mixed use development. The subsidence depth was found to gradually increase from the periphery towards the center in almost all detected subsidence areas. The subsidence depth was found to be in a range of 1 cm to 17 cm. It was found that the concentration of deep water extraction wells was higher in areas with higher subsidence rates. It was also found that the detected subsidence area was situated over geological formations mainly consisting of unconsolidated fine-grained sediments (silica, sand, silt, clay and silty sandy gravel), which is the major factor affecting the occurrence of land subsidence due to groundwater extraction. View Full-Text
Keywords: land subsidence; ALOS PALSAR; DInSAR; Kathmandu valley; urban land subsidence; ALOS PALSAR; DInSAR; Kathmandu valley; urban
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Bhattarai, R.; Alifu, H.; Maitiniyazi, A.; Kondoh, A. Detection of Land Subsidence in Kathmandu Valley, Nepal, Using DInSAR Technique. Land 2017, 6, 39.

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