CAREER: How hydroclimate variability is transmitted through the critical zone

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Some of Earth’s most productive and biodiverse forests experience prolonged drought. Moisture stores found below ground are central to the resilience of these ecosystems, however, it remains unclear how root-zone moisture will respond to changes in climate, such as decreased snowpack or increased severity and frequency of drought. This is largely because forest root-zones commonly extend into rock beyond depths of conventional sensing and sampling. Consequently, root-zone moisture storage is one of the most poorly constrained and sparsely observed variables in the water cycle. This research will generate new measurements of root-zone water storage to support improved forecasting of water supply to forest vegetation and streams under climate change. This project will also prepare the next generation of hydrologists and geoscientists to tackle water resource challenges in a changing climate through an educational plan focused on experiential undergraduate training as well as undergraduate and graduate student research training. The compounding and interacting changes to climate projected for the next century are expected to disproportionately impact upland forests, which play an important role in recharging groundwater aquifers and supplying water to river networks. There are open questions about how moisture stored in the root-zone of these forests may dampen or amplify their sensitivity to hydroclimate variability. This proposal will intensively document root-zone moisture storage across a network of hydrologic monitoring sites in Texas, California and Colorado to evaluate how root-zone moisture responds to climate variability. Importantly, measurements of moisture storage will extend beneath soils into the weathered bedrock. These on-the-ground measurements will then be used to advance satellite-based methods for measuring root-zone zone moisture at larger scales. The resulting datasets will inform an ecohydrologic model to evaluate how patterns of root-zone moisture storage respond to drought, changes in snowpack, and land use disturbance. Field work and student training will leverage partnerships with the USDA (Forest Service), local water agencies, and NSF-supported research, including the Critical Zone Collaborative Network. Educational activities will increase access and equity in experiential geoscience education through a targeted summer research program and mentorship network for graduates of the University of Texas at Austin’s GeoFORCE outreach program and the integration of a local case-study into the University of Texas undergraduate geoscience curriculum.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.