|Bieger, Katrin - Texas Agrilife Research|
|Rathjens, Hendrik - Purdue University|
|Allen, Peter - Baylor University|
Submitted to: Journal of the American Water Resources Association
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/3/2016
Publication Date: 12/1/2016
Citation: Bieger, K., Rathjens, H., Allen, P.M., Arnold, J.G. 2016. Development and comparison of multiple regression models to predict bankfull channel dimensions for use in hydrologic models. Journal of the American Water Resources Association. 52(6):1385-1400. doi:10.1111/1752-1688.
Interpretive Summary: River dimensions (width, depth, and cross-sectional area) are critical input data for watershed models used for regional and national conservation and environmental assessment. River dimension data is used in modeling sediment and nutrient transport and flood plain and riparian processes. In this study, regional regression equations predicting bankfull width, depth, and cross-sectional area as a function of drainage area are developed for the Physiographic Divisions and Provinces of the U.S. and compared to a nationwide equation. Results show that the regional curves at division level are more reliable than the nationwide curve. The results provide input data for local watershed studies and for the USDA Conservation Effects Assessment Project (CEAP) in national conservation assessment.
Technical Abstract: Bankfull hydraulic geometry relationships are used to estimate channel dimensions for streamflow simulation models, which require channel geometry data as input parameters. Often, one nationwide curve is used across the entire United States (U.S.) (e.g., in Soil and Water Assessment Tool), even though studies have shown that the use of regional curves can improve the reliability of predictions considerably. In this study, regional regression equations predicting bankfull width, depth, and cross-sectional area as a function of drainage area are developed for the Physiographic Divisions and Provinces of the U.S. and compared to a nationwide equation. Results show that the regional curves at division level are more reliable than the nationwide curve. Reliability of the curves depends largely on the number of observations per region and how well the sample represents the population. Regional regression equations at province level yield even better results than the division-level models, but because of small sample sizes, the development of meaningful regression models is not possible in some provinces. Results also show that drainage area is a less reliable predictor of bankfull channel dimensions than bankfull discharge. It is likely that the regional curves can be improved using multiple regression models to incorporate additional explanatory variables.