Development of Multi-Catchment Rating Curves for Streams of Appalachian Mixed-Land-Use Watersheds: Preliminary Results

Abstract

Anthropogenic activities can alter the quantity and quality of water. Traditional monitoring of streamflow involves measurements of stage (mm), or water height, and discharge (i.e., streamflow) (m3 s -1 ) above a local datum. However, while stage is relatively easily monitored, continuous streamflow measurement is often impractical and prohibitively expensive. To address this challenge, rating curve equations can be developed to convert stage to flow. To establish a series of rating curves for flow estimations in Appalachia, an investigation was conducted in a representative urbanizing, mixed-land-use watershed in north-central West Virginia consisting of 21 nested stream gauge sites. At each site, stage was continuously recorded at 5-minute intervals using a Solinst Levelogger. Streamflow was observed using the cross-section method and an Acoustic Doppler Velocimeter (ADV). Stream cross-sections were conducted over a range of low to high flow events. A preliminary rating curve was developed for each of the 21 study sites, with sample sizes ranging from 21 to 53 per site. Preliminary results generated R2 values ranging from 0.98 to 1. Three empirical streamflow models, Manning’s equation, Chezy equation, and Dingman and Sharma equation, were used to estimate streamflow for comparison to observed flow (i.e., velocity-area method) at each site. Validation of the empirical models showed a significant difference (α=0.05) between observed and modeled mean streamflow at sites 3, 4, 5, 8, 11, 15, 17, and 21. Even though only 8 sites showed significant differences between observed and modeled mean streamflow, the models inaccurately estimated streamflow during low flow events. While results from this study are preliminary, and not yet appropriate for stream flow estimates, work to date advances the understanding of stage versus discharge relationships in mixed-land-use watersheds of Appalachia. Ongoing research will result in a completed data set and regionally relevant rating curves.