Seasonality and evaporation of water resources in Reynolds Creek Experimental Watershed and Critical Zone Observatory, Southwestern Idaho, USA

• Published in: Vadose zone journal Vol. 22; no. 6
• Main Authors: Schlegel, Melissa E., Souza, Jennifer, Warix, Sara R., MacNeille, Ruth, Murray, Erin, Radke, Anna, Godsey, Sarah E., Seyfried, Mark S., Finney, Bruce, Flerchinger, Gerald, Lohse, Kathleen A.
• Format: Journal Article
• Language: English
• Published: Wiley 01.11.2023
• DOI: 10.1002/vzj2.20278
• ISSN: 1539-1663

The Reynolds Creek Experimental Watershed (RCEW) and Critical Zone Observatory (CZO), located south of the western Snake River Plain in the Intermountain West of the United States, is the site of over 60 years of research aimed at understanding integrated earth processes in a semi‐arid climate to aid sustainable use of environmental resources. Meteoric water lines (MWLs) are used to interpret hydrologic processes, though equilibrium and nonequilibrium processes affect the linear function and can reveal seasonal and climatological effects, necessitating the development of local meteoric water lines (LMWLs). At RCEW‐CZO, an RCEW LMWL was developed using non‐volume‐weighted, orthogonal regression with assumed error in both predictor and response variables from several years of precipitation (2015, 2017, 2019, 2020, and 2021) primarily at three different elevations (1203, 1585, and 2043 m). As most precipitation is evaporated or intercepted by vegetation in the driest months, an RCEW LMWL for groundwater recharge (RCEW LMWL‐GWR) was also developed using precipitation from the wettest months (November through April). The RCEW LMWL (δ2H = 7.41 × δ18O – 3.09) is different from the RCEW LMWL‐GWR (δ2H = 8.21 × δ18O + 9.95) and compares favorably to other LMWLs developed for the region and climate. Comparative surface, spring, and subsurface water datasets within the RCEW‐CZO are more similar to precipitation during the wettest months than dry months, illustrating that some semi‐arid hydrologic systems may most appropriately be compared to MWLs developed from precipitation only from the wettest season. Core Ideas Reynolds Creek Experimental Watershed has years of research on integrated earth systems in a semi‐arid climate. Local meteoric water lines (LMWLs) are used to reveal seasonal and climatological effects on hydrologic processes. LMWLs were developed for full year and wettest months, as dry month evapotranspiration uses most precipitation. Comparative surface, spring, and subsurface water datasets are more like precipitation from wet months than full year. Semi‐arid hydrologic systems may more appropriately be compared to precipitation from wettest months. Core Ideas Reynolds Creek Experimental Watershed has years of research on integrated earth systems in a semi‐arid climate. Local meteoric water lines (LMWLs) are used to reveal seasonal and climatological effects on hydrologic processes. LMWLs were developed for full year and wettest months, as dry month evapotranspiration uses most precipitation. Comparative surface, spring, and subsurface water datasets are more like precipitation from wet months than full year. Semi‐arid hydrologic systems may more appropriately be compared to precipitation from wettest months.