Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Ramirez Avila J.J., Achury S.O., Raju M., Chaux L.C.

Regional Curves are stream restoration practitioners' tools that relate measured stream morphology, discharge, and drainage area. These are valuable tools for geomorphic assessment to analyze departure from equilibrium conditions in disturbed ecosystems and for restoration planning to determine approximate channel dimensions and discharge. The relationship between the drainage area and the magnitude of the flow observed at bankfull stage in reference stable reaches is a fundamental key to achieve a baseline restoration design. Research on bankfull discharge in the US has resulted in general agreement that the annual series bankfull discharge recurrence intervals are approximately equal to a 1.5-year event. A study is performed to evaluate if the 1.5-year bankfull discharge recurrence interval assumption represents the flow observed at bankfull stage in reference sites assessed to estimate the Regional Curves. Datasets used to develop Regional Curves in different physiographic regions of the US have been collected and used to generate stream flow and watershed characteristics reports by using the web application USGS StreamStats. Field measured bankfull flow discharges for each individual location are correlated with the peak flow discharge frequency curves reported by StreamStats to identify a corresponding return period. Preliminary results indicate that the peak flow discharge observed at a return period of 1.5 years overestimate the magnitude of the flow observed at bankfull stage. Similarly, the determination of a return period that better represents the magnitude of the flow at bankfull stage for different locations varies among physiographic regions and more importantly, to the level of urban development of the drainage area.