Observations of Confined Aquifer Systems

Land subsidence has been documented in a large and rapidly increasing number of locations worldwide, with consequences ranging from damage to buildings and infrastructure, to increase in flooding in coastal areas, and to degradation of the groundwater resources quality and quantities (e.g., Konikow LF, Kendy E, Hydrogeol J 13:317–320, 2005). While natural compaction of recently deposited sediments is commonly causing subsidence in deltas and coastal wetlands at a few mm/year (e.g., Teatini P, Tosi L, Strozzi T, J Geophys Res Solid Earth, https://doi.org/10.1029/2010JB008122 , 2011; Törnqvist TE, Wallace DJ, Storms JE, Wallinga J, Van Dam RL, Blaauw M, Derksen MS, Klerks CJ, Meijneken C, Snijders EM, Nat Geosci 1:173–176, 2008) (Chapter “ Natural Compaction of Sediments ”), excessive groundwater extraction from semiconfined or confined aquifers tends to lead to much larger subsidence at rates of up to tens of cm/year (e.g., Bell JW, Amelung F, Ferretti A, Bianchi M, Novali F, Water Resour Res, https://doi.org/10.1029/2007WR006152 , 2008) (Chapter “ Land Subsidence Hazards: A Case Study of Mexico City ”). Monitoring of such hydrologically induced time variable surface deformation, when integrated with other remote sensing and in situ datasets, enables mapping aquifer systems response to pumping and recharge, constraining aquifer-system properties, predicting hydraulic head changes, and much more. In this chapter, we first introduce the role of confined aquifers in the freshwater cycle. We then show how the land surface deforms in response to confined aquifer pumping and recharge. This leads to the applications of InSAR for quantifying the health of confined aquifer systems. Finally, we review recent progress in InSAR-based groundwater research and discuss how these technical advances may play an important role in sustainable groundwater management practices in the near future.