Thursday, September 29, 2011, 4:30AM - 5:30AM
Many of the world's largest river deltas are sinking. Despite decades of research, it is still unclear whether the sinking is natural (caused by sediment compaction and regional tectonics) or man-made (caused by oil extraction and choked sediment supplies). Current techniques for mapping and understanding delta subsidence are not conclusive, because they rely on arrays of devices (GPS or tide gauges) to obtain a few measurements across huge areas. In the last fifteen years, however, Interferometric Synthetic Aperture Radar (InSAR) has emerged as a technique that can produce subsidence maps with much higher spatial resolution than any array-based method. InSAR uses satellite radar data to measure height changes of the earth’s surface. It has a spatial resolution of 20 meters in the horizontal, and up to 5 mm in the vertical, allowing it to map subsidence across deltas in great detail. InSAR can also be used to create topographic maps that penetrate vegetation canopies, so that low-lying topography of vegetated coastlines can be resolved and evaluated for flood risk. This talk will discuss the principles of InSAR, and evaluate InSAR's potential for improving our understanding of delta topography and subsidence.