Science Service System

Summary of Proposal MTH0251

TitleDetermination of TerraSAR-X InSAR performance near an injection/pumping well, and performance versus Radarsat and Envisat for ground motion monitoring and validation versus GPS measurements
Investigator Cohen, David - Neva Ridge Technologies, Engineering
Team Members
Carande, Richard - Neva Ridge Technologies, N/A
Conway, Brian - Arizona Department of Water Resources, Hydrology
Tatlow, Maurice - Arizona Department of Water Resources, Hydrology
SummaryDuring the past century, one portion of our proposed study area has subsided by approximately 18 feet. This led to the imperceptible reversal of the drainage direction of a recently constructed flood control structure that caused several million dollars of damage after heavy rains in 1993. In a second area, earth fissures caused by differential land subsidence have impacted a critical portion of an earthen dam, forcing the flood control district responsible for the structure to spend millions constructing a second dam behind the compromised section. ADWR has significant in using InSAR data to understand issues of importance to the water resource community. Through a three-year NASA project, together with team member David Cohen, ADWR has acquired significant data and information regarding the InSAR performance in the Phoenix Valley. It is our hope to extend this knowledge with the benefit of the TerraSAR-X capabilities. We propose to use two modes of TerraSAR-X for three activities. First, we plan to validate TerraSAR-X derived InSAR displacements against ground truth - a dedicated network of survey stations that run through the major and minor axes of the deformation feature. The particular deformation feature will be identified based on measurements obtained once we are closer to the TerraSAR-X data acquisition. The deformation rate will determine whether static GPS, RTK GPS, or differential leveling survey techniques are required. Quarterly surveys will be performed to determine if a seasonal deformation signature is definable. ADWR and our local cooperators will perform these surveys. The second activity will be a comparison of the TerraSAR-X InSAR results with those obtained by Radarsat and Envisat. We are obtaining data from these systems as part of the ongoing mandated activities at ADWR. The comparison will consider general performance, coherence obtained, and measurement noise over similar periods. The third activity will be an investigation into the ability to measure small-scale surface deformation produced radially away from a well performing a pump test of the aquifer, or conversely, a well performing an injection test into the aquifer. These types of tests are performed to determine specific aquifer parameters. The depth-to-water is monitored real-time while water is being either extracted from the aquifer (pump test) or injected into the aquifer (injection test). If we can determine the shape, extent, and magnitude of the surface deformation caused by such a test, we will gain new insight about the aquifer system, which in turn will improve the accuracy of our groundwater models and our use of our water resources. There are no significant issues associated with planning such a test and coordinating it with scheduled data acquisitions. Support for this activity: Based on the results of our NASA grant ADWR was able to include a line item in our annual budget to support SAR data purchases. In addition, the local county flood control district has recently signed an intergovernmental agreement (IGA) with ADWR to supply additional data monies for on-going SAR research. Required data: For the evaluation of TerraSAR-X versus other sensors, and the validation with GPS data, we will require one or two single-polarization, stripmap frames acquired approximately every cycle for an 1 to 1.5 year period. Note that the specific area of interest in the Scottsdale region will fit within a 30km frame, but without a swath plan we cannot say whether a single TerraSAR-X stripmap collect will frame our area. For the injection/pump well test, we will require a single frame of high-resolution, single-polarization data acquired over 4 cycles. The location of the well will be in the vicinity of the stripmap mode data to be acquired. We can provide a specific coordinate when required. We will deliver a report of the results of these activities.

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