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High-frequency temperature and conductivity loggers as a method to classify perennial, intermittent and ephemeral flow classes in the Great Plains
Citation:
Kelso, J., K. Fritz, Tracie-Lynn Nadeau, W. Beck, R. Harrington, R. Mazor, AND B. Topping. High-frequency temperature and conductivity loggers as a method to classify perennial, intermittent and ephemeral flow classes in the Great Plains. 2021 Society of Freshwater Science Annual Meeting, Virtual, May 23 - 27, 2021.
Impact/Purpose:
The presence of surface flow is a fundamental basis for stream classification used in the management of water resources. However, because direct measurement of flow duration is too resource intensive there is a need for rapid approaches for accurately characterize flow duration class. Streamflow duration assessment methods (SDAMs) are rapid, indicator-based tools for classifying streamflow duration at the reach scale (40 - 200 m). Direct hydrologic data are fundamental the identifying SDAM indicators that can accurately classify reaches that have year-round flow (perennial), dries for some period during the year (intermittent), and flows only during and immediately after precipitation (ephemeral). This study evaluates the utility of data loggers to characterize flow duration at study sites used to develop an SDAM for the U.S. Great Plains. More information on SDAMs and how they are being developed by USEPA's Office of Water and Office of Research and Development can be found here: https://www.epa.gov/streamflow-duration-assessment
Description:
High-frequency hydrological data in non-perennial streams are needed to inform watershed management decisions based on flow duration. Stream Temperature Intermittency and Conductivity (STIC) loggers are an inexpensive method to infer flow duration. We identified reaches across the Great Plains with hydrologic data from USGS gages and previous field observations. Based on these previous data, study reaches were assigned an initial classification of perennial (n= 45), intermittent (n=74), or ephemeral (n=56), and STIC loggers were deployed. Sites were visited three times during water year 2020 to download loggers and record hydrologic condition (e.g., flowing, dry, isolated pools). Twelve percent of all loggers had >10% of data missing due to battery failure (9%), premature full memory (2%), or user error (1%). Initial flow classes were compared to new classifications based on 2020 hydrologic conditions. Initial classifications based on previous field observations were less consistent with new classifications than initial USGS gage classifications for ephemeral reaches (14% vs 100%), intermittent reaches (49% vs 66%), and perennial reaches (29% vs 77%). Results indicate high-frequency data can improve characterization of flow duration at the reach scale in streams of the Great Plains.
