Water Resources Research Act Program

Details for Project ID 2019NM185B

Evaluating focused aquifer recharge in arid regions using chloride profile analysis

Institute: New Mexico
Year Established: 2019 Start Date: 2019-05-15 End Date: 2020-05-15
Total Federal Funds: $21,173 Total Non-Federal Funds: $42,369

Principal Investigators: Daniel Cadol

Project Summary: Statement of Critical Water Resource Problem 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. The diminishing water levels and short forecasted aquifer lifetimes in the Ogallala Aquifer near Clovis and Portales, NM (Rawling and Rinehart, 2018) is a sobering reminder of this challenge. But where aquifers do receive sufficient recharge (e.g., Albuquerque, NM) sustainable management plans can be developed that treat the aquifer as a savings account to buffer against hard times and drought. Recent research suggests that groundwater recharge may be significant in creosote-vegetated rangelands of the Chihuahuan Dessert, which were previously thought to preclude recharge due to the high soil tensions created by the water extractive capabilities of the creosote roots (e.g., Sandvig and Phillips, 2006). Schreiner-McGraw and Vivoni (2017), using micrometeorological techniques and catchment water budgets, suggested that recharge in these areas may be as high as 20% of long-term precipitation. The challenge of accurately estimating evapotranspiration introduces a possible source of error in the water budget of Schreiner-McGraw and Vivoni (2017), hence the need to corroborate their findings with independent research. Statement of Results, Benefits Expected The scientific goal is to test the hypothesis that significant aquifer recharge occurs in very small “zerothorder†channels that drain sub-catchments within semi-arid southwestern US rangelands, as suggested by Schreiner-McGraw and Vivoni (2017). We propose to 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.