Affected by the recent anomalous global climate and frequent typhoons as well as storms during the flood seasons, Taiwan's rainfall is one of the highest in the world. Extreme rainfall events with long duration and high intensity, which cause sediment hazards such as landslides, debris flows, and river siltation are very common. These affect the safety of irrigation facilities and threaten the lives and property of nearby residents besides causing immediate economic loss.

Relevant data collection after major natural disasters is often very urgent due to the necessarily for disaster relief; therefore, remote sensing technology is often used internationally to conduct post-disaster data collection and wide-scope data surveys. Currently, the most widely used satellite-based remote sensing methods in Taiwan are optical in nature. However, after typhoons or storms, clouds often appear and mask the target for several days, which affects the availability of optical satellite images for analysis. This all-weather imaging capability can accomplish the objective of post-disaster real-time data collection better than optical satellite.

This study attempted to collect radar monitoring system specifications and operational data as well as to establish satellite SAR image pre-processing, satellite SAR image detecting technology, and radar imaging detecting technology at hillslope disaster variation point and radar technology to detect hillslope disaster elevation variation. These have been successfully applied on actual cases. This study concludes that SAR can be utilized as:

1. Satellite radar image pre-processing technology: which targets repeatedly observed pre- and post-disaster radar images and searches for large quantities of conjugate points that are evenly distributed and highly reliable to conduct automated matching process. At the same time, it also targeted Taiwan’s terrains to create localized radar pre-processing operation workflow to produce accurate ortho-rectified image and digital terrain model information, aiding environmental variation detection and increase the overall efficiency.
2. Satellite radar imaging in hillslope disaster change point detecting technology: After radiometric correction, image ortho-rectification, and filtering processing, ortho-rectified SAR image can be complemented with automated image identification technology to establish hazard change point detecting technology to quantify and assess hillslope disaster change’s area.
3. Satellite radar technology observing hillslope disaster elevation change: establish hillslope disaster elevation change technology such as phase comparison method and digital terrain subtraction method to observe and then generate digital terrain models, landslide earth volumes, elevation change volume, and stream-way change suitable for Taiwan to obtain the quantified post-disaster data.