H205-01
Assessing spatial patterns and drivers of intermittent flow in the contiguous U.S.

Wednesday, 16 December 2020: 08:30
Virtual
John Christopher Hammond1, Margaret A Zimmer2, Margaret Shanafield3, Sarah Godsey4, Kendra Elena Kaiser5, Meryl Mims6, Ryan Burrows7, Corey Krabbenhoft8, Samuel C Zipper9, Stephanie K Kampf10, Adam N Price2, Thibault Datry11, Daniel C Allen12, C. Nathan Jones13, Walter K Dodds14, George H. Allen15, Katie H Costigan16, Adam S Ward17, Michael Bogan18, Rebecca L Hale19, Kate S. Boersma20, Julian D Olden21 and Jacob Hosen22, (1)U.S. Geological Survey, Maryland-Delaware-D.C. Water Science Center, Catonsville, MD, United States, (2)University of California Santa Cruz, Santa Cruz, CA, United States, (3)Flinders University, Science and Engineering, Bedford Park, SA, Australia, (4)Idaho State University, Department of Geosciences, Idaho Falls, ID, United States, (5)Boise State University, Boise, ID, United States, (6)Virginia Tech University, Department of Biological Sciences, Blacksburg, VA, United States, (7)The University of Melbourne, Burnley Campus, School of Ecosystem and Forest Science, Burnley, Australia, (8)University at Buffalo, College of Arts and Sciences and RENEW Institute, Buffalo, NY, United States, (9)University of Wisconsin Madison, Madison, WI, United States, (10)Colorado State University, Department of Ecosystem Science and Sustainability, Fort Collins, CO, United States, (11)INRAE Lyon, Villeurbanne Cedex, France, (12)University of Oklahoma Norman Campus, Biology, Norman, OK, United States, (13)University of Alabama, Biological Sciences, Tuscaloosa, AL, United States, (14)Kansas State University, Manhattan, KS, United States, (15)Texas A&M University, Department of Geography, College Station, TX, United States, (16)University of Louisiana at Lafayette, Geosciences, Lafayette, LA, United States, (17)Indiana University, School of Public and Environmental Affairs, Bloomington, IN, United States, (18)University of Arizona, School of Natural Resources and the Environment, Tucson, AZ, United States, (19)Idaho State University, Biological Sciences, Pocatello, ID, United States, (20)University of San Diego, Biology, San Diego, United States, (21)University of Washington, School of Aquatic & Fishery Sciences, Seattle, WA, United States, (22)Purdue University, Forestry & Natural Resources, West Lafayette, IN, United States
Recorded Presentation
Abstract:
Understanding the distribution, causes, and variability of streamflow intermittence (no-flow) is critical, as non-perennial streams constitute over half the global stream network by length and drive important hydrologic, biogeochemical, and ecological function across scales. Here, we report on a broad spatial analysis of no-flow metrics using USGS gage data from 540 non-perennial rivers across the contiguous U.S. from 1979-2018. For each climate year (Apr. 1 - Mar. 31) at each gage, we quantified three metrics characterizing the mean annual no-flow regime: (1) fraction of days measuring no streamflow per year; (2) timing, as represented by the first day of the year with no flow; and (3) rate of drying, as represented by the average number of days from a local peak in daily flow to the first occurrence of no flow. We also extracted climatic, physiographic, land cover, and flow alteration characteristics for each watershed from the GAGES-2 and gridMET datasets. Multivariate analysis revealed significant differences in the timing, duration, and rate of drying of no flow by ecoregion and between natural and human altered watersheds. To quantify the drivers of spatial variability in no-flow characteristics, we developed random forest models relating the watershed characteristics to each no-flow metric for the entire contiguous U.S. as well as within six different ecoregions. Though aridity emerges as a primary driver of no-flow metrics at the national scale, the hydrologic regime of intermittent rivers is explained by regionally unique combinations of physioclimatic and antropogenic drivers. Of note, drying rate showed stronger associations with descriptors of human activities compared to the duration or timing of no flow. Although the gage records examined in this study shed important light on large-scale patterns and causes of streamflow intermittence, their sparse spatial distribution points to a need for high-density measurements at the reach and catchment scale to better understand non-perennial streams both today and in the future.
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