Open-File Report 2015–1086
AbstractObservations of very small changes of Earth’s gravitational field (time-lapse gravity) provide a direct, non-invasive method for measuring changes in aquifer storage change. An existing network of gravity stations in the Sierra Vista Subwatershed was revised in 2014 to better understand the spatial distribution of changes in aquifer storage, especially with relation to ephemeral channel recharge and a groundwater cone of depression associated with pumping in the greater Sierra Vista area. In addition, the network was extended to provide baseline data for possible future enhanced-recharge projects. This report (1) summarizes changes to the Sierra Vista Subwatershed regional time-lapse gravity network with respect to station locations and (2) presents 2014 and 2015 gravity measurements and gravity values at each station. A prior gravity network, established between 2000 and 2005, was revised in 2014 to cover a larger number of stations over a smaller geographic area in order to decrease measurement and interpolation uncertainty. The network currently consists of 59 gravity stations, including 14 absolute-gravity stations. Following above-average rainfall during summer 2014, gravity increased at all but one of the absolute-gravity stations that were observed in both June 2014 and January 2015. This increase in gravity indicates increased groundwater storage in the aquifer and (or) unsaturated zone as a result of rainfall and infiltration. |
First posted May 7, 2015 For additional information, contact: Part or all of this report is presented in Portable Document Format (PDF). For best results viewing and printing PDF documents, it is recommended that you download the documents to your computer and open them with Adobe Reader. PDF documents opened from your browser may not display or print as intended. Download the latest version of Adobe Reader, free of charge. More information about viewing, downloading, and printing report files can be found here. |
Kennedy, J.R., 2015, Gravity data from the Sierra Vista Subwatershed, Upper San Pedro Basin, Arizona: U.S. Geological Survey Open-File Report 2015-1086, 26 p., https://dx.doi.org/10.3133/ofr20151086.
ISSN 2331-1258 (online)
Abstract
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