eNews July 2019

USGS 104B Award Announced by NM WRRI

By Carolina Mijares, NM WRRI Accountant

NM WRRI announced its faculty grant award associated with the Research Grant between US Geological Survey and New Mexico State University, 104B State Water Resources Research Institute Program. The 104B program focuses on providing water quality and quantity information, understanding water availability, addressing the influence of climate on water resources, and responding to water-related emerging needs. Director Sam Fernald is the Lead PI on the program.

In response to the NM WRRI 2019 Request for Proposals, faculty receiving the new 104B award are Dr. Daniel Cadol, New Mexico Tech, and Dr. Talon Newton, New Mexico Bureau of Geology and Mineral Resources. Dr. Cadol describes the project below.

Evaluating focused aquifer recharge in arid regions using chloride profile analysis

Groundwater recharge is challenging to measure, yet it is the cornerstone of sustainable water use in semi-arid regions such as New Mexico. Aquifers that are not recharged represent economic time bombs: communities built on such finite resources have a finite lifetime. Accurately assessing recharge is fundamental to determining the stability of social-hydrological systems.

Recent work, conducted at the Jornada Experimental Range, suggests that small, essentially un-mapped channels (commonly termed ‘zeroth-order channels’) may be an important location for such focused recharge in creosote-vegetated rangelands of the Chihuahuan Desert (Schreiner-McGraw and Vivoni, 2017). Previously, creosote was thought to preclude recharge due to the high soil tensions created by the water extractive capabilities of its roots (e.g., Sandvig and Phillips, 2006).

The scientific goal of this project is to test the hypothesis that significant aquifer recharge occurs in these zeroth-order channels in the Jornada Experimental Range. We will test this hypothesis by analyzing the accumulated chloride within the soil and sediment profile underlying these small channels and their surrounding interfluves or hillslopes. A lack of chloride in the sediment profile under these small channels would suggest that downward-percolating water, focused into these channels during overland runoff, had transported the atmospherically deposited chloride below the root zone, and presumably to the aquifer below. A persistent chloride bulge would indicate the lack of water infiltrating below the root zone, meaning the vegetation community uses all infiltrated water to supply transpiration.

Should the findings of Schreiner-McGraw and Vivoni (2017) hold, this insight into aquifer recharge from precipitation onto basin piedmont geomorphic surfaces would fundamentally change our perception of water-use sustainability in these regions. This recharge would represent an untapped resource in a water-limited region.