Dragon project 2558: Exploitation of SAR and optical imagery for monitoring the environmental impacts of The Three Gorges dam

The monitoring of landslides using SAR interferometry (InSAR) was the original starting point for this project. InSAR using both 24 pre-fabricated and a large number of natural corner reflectors (CRs) was applied to monitor land surface slope stability with data from ERS and ENVISAT. Unfortunately, the combined effects of (a) 30m resolution coupled with very steep slopes predominantly in the range, East-West direction; (b) C-band artefacts caused by very high Precipitable Water Vapour (PWV); (c) dense vegetation outside of urban areas led to very limited results. Only 6/24 CRs installed could be reliably observed and natural CRs could only be reliably detected within urban cores and along ridges. Additional remote sensing environmental impact studies conducted included creation of a 30m DEM of the entire area using data fusion of ASTER and SRTM; mapping of resettlement areas using Landsat, ASTER and ENVISAT-ASAR; mapping of erosion using ASAR InSAR phase coherence and Landsat data in the upstream Jinsha river area; and the monitoring of land cover/use practices using ASTER and ASAR-AP time series to look at food security and sustainability issues in the Badong area. Field observations showed that landslides were becoming increasingly commonplace as urban developments, especially road-building spills, led to denudation of vegetation on the riverbanks.EI