L-Band SAR Disaster Monitoring for Harbor Facilities Using Interferometric Analysis

Abstract

Synthetic aperture radar (SAR) has become a major tool for disaster monitoring. Its all-weather capability enables us to monitor the affected area soon after the event happens. Since the first launch of spaceborne SAR, its amplitude images have been widely used for disaster observations. Nowadays, an accurate orbit control and scheduled frequent observations enable us to perform interferometric analysis of SAR (InSAR) and the use of interferometric coherence. Especially for L-band SAR, its long-lasting temporal coherence is an advantage to perform precise interferometric coherence analysis. In addition, recent high resolution SAR images are found to be useful for observing relatively small targets, e.g., individual buildings and facilities. In this chapter, we present basic theory of SAR observation, interferometric coherence analysis for the disaster monitoring, and its examples for the harbor facilities. In the actual case, DInSAR measurement could measure the subsidence of the quay wall with 3 cm error.

Using ALOS-2 synthetic aperture radar (SAR) and interferometric SAR to detect landslides on the mountainous island of Pohnpei, Federated States of Micronesia

“…The study objectives were to assess the detectability of landslides in Pohnpei by using SAR satellite data and to evaluate operational methods that could provide a basis for systematic landslide occurrence monitoring within the Federated States of Micronesia (Burrows and others, 2020) This study was designed to use a limited number of existing ALOS-2 PALSAR-2 image collections of Pohnpei from before and after the rainfall event and to use the longer wavelength L-band to possibly decrease sensitivity to vegetation decorrelation (Natsuaki, 2018;Raucoules and others, 2020). Objectives were limited to the assessment of landslide detection and testing of operational methods that can lead to a consistent monitoring program.…”

“…InSAR coherence and SAR amplitude change detection methods are based on the landslide disruption of the surface to change the coherence or amplitude (Yun and others, 2015;Ge and others, 2019;Burrows and others, 2020). Whether the coherence or amplitude detection is based on single or multiple pre-event and post-event InSAR coherence or SAR amplitude pairs, the common expectation is that the post-event coherence or amplitude would be different from the pre-event coherence or amplitude (Natsuaki, 2018;Ge and others, 2019;Burrows and others, 2020;Ohki and others, 2020;Tzouvaras and others, 2020). While the generation of the InSAR coherence as a component of the InSAR phase generation would tend to be based on like-polarizations, SAR amplitude change production would preferentially use the cross-polarization to emphasize the pre-canopy backscatter (Le Toan and others, 2004;Mondini, 2017).…”