The Kujukuri Plain in Chiba Prefecture, Japan, is an area where water-soluble natural gas dissolved in groundwater is frequently pumped, and even in recent years, land subsidence of up to 2 cm/year has still occurred in some areas of Chiba Prefecture. In this paper, PSInSAR analysis is applied using Sentine1SAR data of descending and ascending orbits for five years from 2017 to 2022 to measure land subsidence in Chiba Prefecture, Japan. The results show that the locations where land subsidence occurs at more than 0.4 cm/year can be monitored with sufficient accuracy. The measurement accuracy of PSInSAR analysis is evaluated by comparing land subsidence based on PSInSAR analysis with leveling survey results in areas where land subsidence of up to 2 cm/year has occurred.

A method for estimating snow depth using Sentinel-1 SAR data was investigated, and its estimation accuracy was verified using observations at a snow depth station in the uppermost catchment area of the Tone River in Gunma Prefecture, Japan. A relation was observed between the snow depth and the backscatter coefficients of the VV and VH polarizations, for even slopes covered with trees, and it was confirmed that the snow depth could be estimated from the backscatter coefficients. The estimation accuracy at the observatory is about 20 to 30 cm, which could be used to determine the snow cover over a wide area of the catchment for estimating the amount of snowmelt.

A method for estimating snow depth using Sentinel-1 SAR data was investigated, and its estimation accuracy was verified using observations at a snow depth station in a heavy snowfall area in Niigata Prefecture, Japan. A relation was observed between the snow depth and the backscatter coefficients of the VV and VH polarizations, for flat fields and even slopes covered with trees, and it was confirmed that the snow depth could be estimated from the backscatter coefficients. The estimation accuracy at the observatory is about 20 cm, which could be used to determine the snow cover over a wide area of the catchment for estimating the amount of snowmelt.

A PSInSAR analysis utilizing Sentinel-1 SAR data was conducted for a rockfill dam, which is already in the stabilization phase but has been deformed by up to about 10 mm per year for the past several years and for which external deformation is continuously measured, to verify the accuracy of the displacement that can be determined from satellite SAR data by comparing the analysis results with survey data. The PSInSAR analysis provides many PS points on the entire outer surface of the rockfill dam. It verifies that the displacement of PS points can be measured accurately on the order of mm using Senttenel-1 SAR data, indicating that satellite SAR data can be used to manage the rockfill dams.

Some researchers have reported subsidence in Bali. However, the main factor and the subsidence mechanism remain unclear due to a lack of data. One possibility is due to groundwater extraction. During the Covid-19 pandemic, the number of visitors to Bali decreased significantly. Using the persistent interferometric synthetic aperture radar (PS-InSAR) and the trend model method, we found a strong relationship between the number of visitors and the subsidence velocity. The subsidence velocity decreased rapidly during the Covid-19 pandemic. It may cause a decrease in groundwater extraction. It may be proven that groundwater extraction is one factor of subsidence in Bali. However, a detailed field investigation, such as groundwater table measurement, is required to validate this new finding.