A method for advancing understanding of streamflow and geomorphological characteristics in mixed-land-use watersheds

Elliott Kellner; Jason A Hubbart

doi:10.1016/j.scitotenv.2018.12.070

A method for advancing understanding of streamflow and geomorphological characteristics in mixed-land-use watersheds

Sci Total Environ. 2019 Mar 20:657:634-643. doi: 10.1016/j.scitotenv.2018.12.070. Epub 2018 Dec 6.

Authors

Elliott Kellner¹, Jason A Hubbart²

Affiliations

¹ University of Missouri, School of Natural Resources, Columbia 65211, MO, USA; West Virginia University, Institute of Water Security and Science, 3107 Agricultural Sciences Building, Morgantown 26506, WV, USA. Electronic address: Elliott.Kellner@mail.wvu.edu.
² West Virginia University, Institute of Water Security and Science, 3107 Agricultural Sciences Building, Morgantown 26506, WV, USA; West Virginia University, Davis College, Schools of Agriculture and Food, and Natural Resources, 4121 Agricultural Sciences Building, Morgantown 26506, WV, USA.

PMID: 30677930
DOI: 10.1016/j.scitotenv.2018.12.070

Abstract

Methods are needed to quantify stream geomorphological response to land use and hydroclimatic variability. The method applied herein incorporated channel measurements from a physical habitat assessment (channel width, bankfull width, thalweg depth, and estimated cross-sectional area), and streamflow data collected via an experimental watershed study, to identify factors contributing to longitudinal variation in stream morphology in a mixed-land-use watershed of the central U.S. Channel and bankfull width ranged from 0.8 m and 1.8 m, respectively, at the headwaters, to 70 m and 74 m, respectively, mid-watershed. Minimum thalweg depth (0.2 m) was observed at the headwaters, while the maximum (8.6 m) was observed at the mouth. Mann Kendall results indicated a significant positive trend (p < 0.001) for each of the three metrics over the entire length of the stream. However, smaller sections of the creek exhibited contrasting trends consistent with channel widening and incision. Cross-sectional area significantly (p < 0.001) increased from the headwaters to the mouth. However, two reaches exhibited drastic reductions in cross-sectional area, which could indicate reduced channel capacity and localized flood hazard. The longitudinal pattern of channel width, bankfull width, and cross-sectional area showed the strongest (R² > 0.7), significant (p < 0.05) correlations with the estimated longitudinal pattern of 99th percentile flows, while thalweg depth correlated most strongly with 75th percentile flows (R² = 0.77, p < 0.001). Collectively, results emphasize the importance of high flows to channel morphology, but identify other factors (e.g. land use, geology, physiography) that variously contribute to observed stream geomorphology. Furthermore, results demonstrate the capacity of the method to provide detailed, quantitative characterizations of physical and hydrologic features, and to identify potential drivers of channel morphology in contemporary mixed-land-use watersheds.

Keywords: Experimental watershed study; Flow class analysis; Land use impacts; Physical habitat assessment; Stream geomorphology; Streamflow variability.