Arizona Department of Water Resources Land Subsidence Monitoring Program

Abstract

Land subsidence due to groundwater overdraft has been an ongoing problem in south-central and southern Arizona since the 1940s. The first earth fissure attributed to excessive groundwater withdrawal was discovered in the early 1950s near Picacho, Arizona. In some areas of the State, groundwater level declines of more than 120 m have resulted in extensive land subsidence and earth fissuring. Land subsidence in excess of 5.7 m has been documented in both western metropolitan Phoenix and Eloy, Arizona. The Arizona Department of Water Resources (ADWR) has been monitoring land subsidence throughout Arizona since 1998 using Interferometric Synthetic Aperture Radar (InSAR) Data and Global Navigation Satellite System (GNSS) Data. The ADWR InSAR program has proven to be a critical resource for monitoring land subsidence throughout Arizona and has resulted in the identification of more than 26 individual land subsidence features that cover an area of more than 7300 km2. Using InSAR data in conjunction with groundwater level datasets, ADWR is able to monitor land subsidence areas as well as identify areas that may require additional monitoring. The declining groundwater levels in Arizona are both a challenge for future groundwater availability and for mitigating land subsidence. ADWR’s InSAR program will continue to be a critical tool for monitoring land subsidence due to excessive groundwater withdrawal.