Thursday, July 27, 2017

That sinking feeling: State-of-art technology at work on Arizona subsidence finds you’re not imagining it

Satellite-based tech employed by Arizona Water Resources has found more than 3,400 square miles of land subsidence in the state
Arizona is sinking. Well, not all of Arizona, just certain groundwater basins in south-central and southern Arizona. Subsidence is a nation-wide and world-wide problem; subsidence as great as 19 feet has occurred since the 1950s in the areas near Luke Air Force Base and the Town of Eloy.

Land subsidence is the result of decades of excessive groundwater withdrawal that exceeds natural recharge, resulting in declining groundwater levels. As the groundwater declines, the pore spaces within the aquifer that were once supported by water pressure start to collapse, resulting in subsidence of the ground surface.

In Arizona, land subsidence has produced 167 miles of mapped earth fissures, according to data provided by the Arizona Geological Survey (AZGS). Fissures frequently damage infrastructure: roads, canals, pipelines, railways, buildings, and highways. Land subsidence also has changed the natural drainage slopes, causing areas to flood that hadn’t flooded in the past. It has reversed flood control canals, changed aquifer properties, and led to the permanent loss of groundwater storage due to compaction. ADWR has detected more than 3,400 square miles of land subsidence (see: subsidence areas in salmon, above).

 Image Source: Geoscience Australia