Drop in western U.S. groundwater seen from space, Arizona one of - Tucson News Now

Drop in western U.S. groundwater seen from space, Arizona one of the worst hit

Drought continues to grip Arizona. Even after impressive July monsoon rain totals for parts of the state, nearly 98 percent of Arizona is experiencing some level of drought.  Moderate, Severe, and Extreme Drought cover parts of Pima County where the Tucson Metropolitan area is located. 

Arizona isn't the only state experiencing drought. According to the U.S. Bureau of Reclamation, the Colorado River basin, which covers seven states including most of Arizona, is now in the driest 14-year period in the past 100 years.  Drought is killing vegetation, raising wildfire risk, and dropping levels in rivers and lakes.  Underground water levels are also affected by the dry conditions.  Data gathered by a NASA satellite show just how bad the numbers are for areas hit hardest by drought.  

According to NASA Earth Observatory the map below "combines data from the satellites of the Gravity Recovery and Climate Experiment (GRACE) with other satellite and ground-based measurements to model the relative amount of water stored in underground aquifers in the continental United States. The wetness, or water content, is a depiction of the amount of groundwater on July 7, 2014, compared to the average from 1948 to 2009 (50-year average)."

The red areas show deficits for this time of year compared to the 50-year average.  Areas shown in blue indicate where groundwater levels are higher than the 50-year average. Note the red that covers most of the Four Corner's states, plus Nevada and California. 

GRACE measures these water levels by observing "small changes in Earth’s mass and its gravity field." says NASA Earth Observatory.  

These small changes  indicate movement of water across the globe.  Analysis of data indicate movement towards a possibly dire situation for the drought-riddled states of the Colorado River Basin.  Lake Mead, a major reservoir on the Colorado River, is down to historic lows.  In a new study published earlier this month, scientists say the loss of groundwater since 2004 is a major contributor to the drop in the reservoir levels. 

A further drop in Lake Mead levels could trigger a water shortage management plan.  If that happens Arizona is the first to see cuts from Lake Mead. A series of University of Arizona podcasts explores why this will happen and the impacts on the state.  

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