2024 Abstracts

The QuEST Project: Integrating Catchment Expansion-Contraction Dynamics into Cross-Continental Hydro-Biogeochemical Predictions


Alex J. Webster1* (awebster2@unm.edu), Arial J. Shogren2, Joanna Blaszczak3, Mengye Chen4, Yang Hong4, Shannon L. Speir5, Adam Wymore6


1University of New Mexico, Albuquerque, NM; 2University of Alabama, Tuscaloosa, AL; 3University of Nevada–Reno, NV; 4University of Oklahoma–Norman, OK; 5University of Arkansas–Fayetteville, AR; 6University of New Hampshire, Durham, NH


The QuEST (Quantifying Ecosystem exports across Space and Time) Project seeks to expand understanding of hydrologic and biogeochemical change in headwater networks that dynamically expand and contract. Headwater stream networks comprise approximately 80% of all river miles on Earth and are important “reactors” due to their relatively large reactive streambed surface area as compared to the volume of water and materials they transport. The transformations and transport of materials in headwater streams reflect multiple upslopes and within-stream material sources and ecological processes. Climate-mediated changes in patterns of stream network expansion and contraction in response to shifting precipitation regimes have the potential to interact with material processing within headwaters and change material export to larger rivers. Researchers currently lack a predictive understanding of these complex interactions and how they may alter surface water quality, habitat sustainability, and drinking water security across the United States. The project’s approach integrates hydrologic modeling with complementary hydrologic and biogeochemical observations within five watersheds spanning the United States’ cross-continental aridity gradient. Specific activities include (1) integrating empirical data and hydrological models to evaluate surface and subsurface flow contributions to the flowing structure of the stream network, (2) using comparative ecohydrological metrics from repeated “snapshot” campaigns of catchment-wide stream chemistry to evaluate how small headwater tributaries impose variability observed at coarser spatial scales, and (3) deploying an array of high-frequency water quality sensors spatially distributed within each catchment to capture how stream network expansion and contraction dynamics change carbon, nutrient, and material exports across climatic conditions. As data collection occurs, researchers are also analyzing existing long-term datasets to address the project’s central questions and characterize the focal watersheds. The team will present the project’s structure and goals as well as preliminary results from initial field campaigns and ongoing analyses.