Effects of the 2013 Thompson Ridge Wildfire on La Jara Creek’s discharge system through stable isotope analysis

Nicole Weber, Jennifer C.McIntosh

Department of Hydrology and Atmospheric Sciences, The University of Arizona, Tucson, Arizona

Analyses of stable isotopes deuterium (δD) and oxygen-18 (δ18O) provide insight on changes in a rivers discharge sources. This study investigated the effects of the 2013 Thompson Ridge Wildfire on La Jara Creek, located in the Valles Caldera National Preserve in New Mexico’s Jemez River Basin Critical Zone Observatory (JRBCZO). This area has an array of protected biodiversity. The pre-fire data (2011 through May 2013), indicate that the creek water had been dominated by contributions from groundwater year-round. Previous studies show that the effects of wildfire on this semi-arid area may have caused the soil to become hydrophobic. This study will quantify the isotopic signature of runoff in stream samples to test the hypothesis that post wildfire infiltration had been minimized. Sample collection of precipitation, groundwater, and stream water follow United States Geological Survey (USGS) standard protocol. Pre-fire samples were analyzed with a Model DLT-100 (Version 2) Isotopic Water Analyzer by Los Gatos Research with post-fire samples waiting to be analyzed in the same manner.

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