Using California's Drought to Analyze Groundwater Inputs from Fractured Bedrock to Alpine Meadows

Quantifying the contribution from groundwater is critical for understanding alpine water supply during both drought and future climate change. Past hydrologic studies in high-elevation mountain meadows have focused on water derived from snowmelt, streams, and adjacent hillslopes to support alpine vegetation. Given California's multi-year drought, one can better identify previously unrecognized groundwater contributions to high-elevation meadows from underlying bedrock. This project will sample and better define the deep groundwater component of the Sierra system through chemical and isotopic means. The project will develop connections to scientists at national labs; and two graduate students will gain field experience, learn new field methods, and participate in laboratory analysis. The Sierra Nevada National Parks and Forests represent an important outdoor classroom for education of the general public in the natural sciences. All project results will be given to the National Park Service for incorporation into their outdoor education programs.

This investigation will take advantage of the current drought when contributions from flowpaths in deep fractured bedrock will yield a high-fidelity geochemical signal that will enable quantification of the location and volume of groundwater entering meadows from bedrock sources. This project will demonstrate a computational methodology for geochemical deconvolution of deep bedrock groundwater and shallow groundwater geochemical signals that can be transferred to other high-elevation meadows where groundwater input has generally been unrecognized. This project will investigate a suite of naturally occurring geochemical tracers in Yosemite groundwater wells to identify the locations of groundwater discharge from fractured bedrock contributing to meadows in the Sierra Nevada Mountains of California. New methods of groundwater sampling for noble gas and isotopic tracers will be developed. Samples of groundwater and stream water will be analyzed for multiple chemical constituents through collaboration with the scientists at Lawrence Livermore National Lab.

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