Hidden Water: Pozos of the Gran Desierto

Recently, the Arizona Daily Star published its 9th annual edition of research articles from the University of Arizona (UA) College of Science. One paper, “Hidden Water: Pozos of the Gran Desierto,” exiting Tucson Water website was co-written by Hector Zamora, a graduate student from the UA Department of Geosciences who now works for Tucson Water as a Hydrologist.

Hector describes the results of the work, which will be shown at the UA Museum of Art beginning in January 2019:

This project is an interdisciplinary, transboundary study between the University of Arizona, the National Park Service, and El Pinacate Biosphere Reserve that seeks to understand groundwater dynamics, including origin of water, flow paths, residence time (“age”), and source of solutes (salinity) in the Gran Desierto region of the Sonoran Desert. In specific, the study focuses on an array of freshwater springs, locally known as pozos, which occur in the saltflats located along the dunes of the Gran Desierto.

The springs constitute the only source of freshwater for at least 50 kilometers in any direction, and for centuries, they have been the sacred destination of old salt pilgrimages by the Tohono O’odham. At the same time, the springs have provided habitat for a diverse number of species, including coyotes, bobcats, great blue herons, migrating water fowl, and bats. As part of the study, my work was to collect water samples from different springs and wells within the Gran Desierto area. These water samples were analyzed for different isotopes that serve as a chemical signature to reveal the origin, residence time (“age”), and the processes to which groundwater has been subject to. Data revealed that water is ancient and residence times exceed 10,000 years.

I believe it is important to study water because, particularly in the West, water is a limited and precious resource that has allowed for the urban growth and progress of our society. By living in the heart of the Sonoran Desert, we have the duty and responsibility to understand the factors that might affect the availability of water in the future, and also the processes, natural or anthropogenic, that might diminish the quality of such a vital resource.