Citation:

Mazor, R., B. Topping, Tracie-Lynn Nadeau, K. Fritz, J. Kelso, R. Harrington, W. Beck, K. McCune, A. Allen, R. Leidy, J. Robb, AND G. David. Implementing an Operational Framework to Develop a Streamflow Duration Assessment Method: A Case Study from the Arid West United States. WATER. MDPI, Basel, Switzerland, 13(22):3310, (2021). https://doi.org/10.3390/w13223310

Impact/Purpose:

Flow duration classification is used to implement several federal, state and local stream management programs. Because the flow duration of streams via existing maps, remote sensing, and gauging is constrained, field-based tools are often needed by practitioners. Here we document the development of a beta method to rapidly classify stream reaches in the Arid West, evaluate its performance compared with other methods, and identify the successes and challenges in developing such a tool.

Description:

Streamflow duration information underpins many management decisions. However, hydrologic data are rarely available where needed. Rapid streamflow duration assessment methods (SDAMs) classify reaches based on indicators that are measured in a single brief visit. We evaluated a proposed framework for developing SDAMs to develop an SDAM for the Arid West United States that can classify reaches as perennial, intermittent, or ephemeral. We identified 41 candidate biological, geomorphological, and hydrological indicators of streamflow duration in a literature review, evaluated them for a number of desirable criteria (e.g., defensibility and consistency), and measured 21 of them at 89 reaches with known flow durations. We selected metrics for the SDAM based on their ability to discriminate among flow duration classes in analyses of variance, as well as their importance in a random forest model to predict streamflow duration. This approach resulted in a “beta” SDAM that uses five biological indicators. It could discriminate between ephemeral and non-ephemeral reaches with 81% accuracy, but only 56% accuracy when distinguishing 3 classes. A final method will be developed following expanded data collection. This Arid West study demonstrates the effectiveness of our approach and paves the way for more efficient development of scientifically informed SDAMs.

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