CONTRIBUTIONS OF INSAR TO CHINO BASIN HYDROGEOLOGIC ANALYSIS AND GROUNDWATER PLAN DEVELOPMENT

InSAR has been demonstrated to be an important tool in the measurement of ground surface deformation due to aquifer system compression and expansion. It can also provide important parameters for aquifer-system characterization, groundwater modeling, and infrastructure risk assessment. It has long been recognized that excessive drawdown in poorly consolidated aquifer systems has led to irreversible aquitard compaction and serious land subsidence, often with associated ground fissuring. In the historically subsiding western part of the Chino Basin that is located in southern California, InSAR has figured prominently in several aspects of aquifer system characterization and is playing an important role in the development of the groundwater management plan. A dense series of InSAR acquisitions from ERS 1/2 has provided an areally and temporally detailed record of historical inelastic aquifer system compaction as well as a component of seasonal elastic compression and expansion. For part of this period, and subsequently, the available InSAR data are reinforced by periodic resurveys of a network of horizontal and vertical control benchmarks. A major contribution of InSAR to the work in this geographic area is its use in characterizing basin hydrogeology. The close correspondence of InSAR surface measurements to the distribution and thickness of stressed aquitards, as inferred from well logs, together with the InSAR detection of a major north-south groundwater barrier, have provided important inputs to the structure of the groundwater flow model. In addition, a coordinated program of ongoing InSAR monitoring is being performed. These results, and their integration with other data and geophysical measurements, will guide future management of the basin as well as help identify areas of potential risk under proposed conditions of controlled overdraft. As a result, InSAR plays key roles in both the historical and ongoing effort to characterize, model, and manage the Chino groundwater basin.