HR: 0800h
AN: G51C-0852    [Abstracts]
TI: Monitoring Subsidence Trends in Phoenix With SAR Interferometry
AU: * Beaver, J
EM: John.Beaver@vexcel.com
AF: Vexcel Corporation, 1690 38th Street, Boulder, CO 80301 United States
AU: Tatlow, M
EM: matatlow@adwr.state.az.us
AF: Arizona Department of Water Resources, 500 N. 3rd Street, Phoenix, AZ 85004
AU: Marra, M
EM: Marty.Marra@vexcel.com
AF: Vexcel Corporation, 1690 38th Street, Boulder, CO 80301 United States
AB: Ground subsidence due to water extraction from aquifers in Phoenix has been monitored with SAR interferometry over a 13 year period using multiple C-Band SAR inputs and three processing methodologies. In addition to a conventional pair-wise analysis, multiple SAR acquisitions provide the opportunity to acquire ground motion estimates, over long time spans, using a time-series approach as well as a point trend estimation technique known as Coherent Target Monitoring (CTM). Redundant and independent SAR observations help confirm ground motion estimates obtained from many temporally coherent collections processed as multiple time series. Both the time-series analysis and Coherent Target Monitoring techniques reveal subsidence rates and locations that may not vary directly with contemporaneous, local water extraction rates in all cases. Instead deformation rates and locations are probably more complexly related to both current and historic pumping in a wider area, residual subsidence caused by the time lag between applied stress to the aquifer system and its equilibration over time, and heterogeneous distribution of lithologies that are more susceptible to compaction. The time-series and CTM processing methods are designed to isolate phase delays caused by atmospheric heterogeneities from ground displacement measurements by exploiting mutual coherence between co-registered scenes in a SAR time series. Furthermore, these methods permit measurement of displacements far exceeding the SAR wavelength from time series over decade long periods, in areas where coherence is not obtainable from a single spanning pair. SAR derived estimates greatly extend the spatial coverage and density of deformation measurements obtained from ground-based surveys. In some cases, the new SAR monitoring has revealed complexly shaped deformation features and broad areas of centimeter per year subsidence not observed by previous ground surveys. The success of this monitoring effort suggests this methodology could be employed in other areas where relative land surface subsidence impacts infrastructure or can be predictive of changes in the aquifer system.
DE: 1240 Satellite geodesy: results (6929, 7215, 7230, 7240)
DE: 1855 Remote sensing (1640)
DE: 1895 Instruments and techniques: monitoring
SC: Geodesy [G]
MN: Fall Meeting 2005