Abstract: The Central Line Project of South-to-North Water Transfer is a large-scale linear water conveyance building in China. To guarantee the safe operation of main canals is an important measure to promote people's livelihood and economic development in water-receiving areas. In this paper, the improved SBAS InSAR technology was used to process the 90-view Sentinel-1A data covering the main canal of Huixian segment of the Central Line of South-to-North Water Transfer from April 11, 2015 to March 09, 2019. The deformation information of the Huixian segment and its surroundings in the aforementioned time period was obtained. The settlement of Huixian segment mainly distributed in the southwestern area of the city center of Huixian and the northern area of Luohe Town, while the main canals were basically stable with no large-scale settlement funnel and only a few small settlement areas along the line. The expansive soil segment of Huixian County canal was further investigated comprehensively in consideration of expansive soil characteristics, rainfall, and soil moisture. Result demonstrated a periodic settlement trend, and the settlement was highly correlated with rainfall and soil moisture.

Key words: Central Line Project of South-to-North Water Transfer, time series InSAR, small baseline, deformation monitoring, expansive soil canal section