Monitoring Groundwater-Storage Change and Land Subsidence in the Tucson Active Management Area, Arizona
Abstract
The U.S. Geological Survey monitors groundwater-storage change and land subsidence caused by groundwater withdrawal in the Tucson Basin and Avra Valley—the two most populated alluvial basins within the Tucson Active Management Area. The primary management goal of the Tucson Active Management Area is safe-yield by the year 2025. A number of hydrogeologic investigations are ongoing including 1) monitoring groundwater-storage change and land subsidence at a network of stations in the Tucson Basin and Avra Valley, 2) maintaining a network of vertical extensometers for continuous monitoring aquifer compaction and water level, and 3) microgravity and GPS surveys every 1-3 years from 1997 to the present, with the addition of annual InSAR data beginning in 2000. Temporal microgravity surveys are used to detect local changes in the gravitational field of the Earth through time. The gravity changes are used to infer groundwater-storage change in Tucson Basin and Avra Valley where significant variations in pore-space (water mass) storage occur—this results from groundwater mining, artificial recharge, and periodic natural recharge events. Groundwater-storage change is an important, but typically poorly quantified component of the groundwater budget in alluvial basins, including Tucson Basin and Avra Valley. In areas where water-level elevation data are available, estimates of aquifer-storage properties also are estimated by dividing the volume of aquifer-storage change (measured with gravity methods) by the water-level elevation change in the aquifer. Results of the monitoring show that while increases in gravity and water-level rise occur following large natural recharge events and near areas where artificial recharge is occurring, overall declining gravity reflects general overdraft conditions. However, the rate of overdraft has decreased from 25,000-50,000 acre-feet per year from 2000 to 2006, to less than 25,000 acre- feet per year from 2006 to the present. Groundwater storage in Avra Valley has increased about 25,000 acre-feet per year during the past ten years, largely as a result of artificial recharge of Colorado River water in the monitored region.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFM.H42D..03K
- Keywords:
-
- 1804 Catchment;
- HYDROLOGYDE: 1846 Model calibration;
- HYDROLOGYDE: 1855 Remote sensing;
- HYDROLOGY