Estimating the contribution of tributary sand inputs to controlled flood deposits for sandbar restoration using elemental tracers, Colorado River, Grand Canyon National Park, Arizona

Controlled floods in the Grand Canyon National Park effectively redistribute tributary-derived sediment, with 69% to 84% of flood deposits originating from the Paria River during the 2013 and 2014 releases. This finding suggests that sandbar restoration through dam-release floods remains viable if Paria River sand inputs are sustained. Researchers used multivariate mixing analysis of seven elemental tracers (Fe, Ca, K, Ti, Rb, Sr, Zr) in sediment samples to quantify tributary contributions. Bayesian modeling revealed substantial variation among sites but confirmed the predominance of Paria River-derived material under decreasing storage conditions since 1963. The study highlights the importance of maintaining sand inputs for long-term ecosystem management.

Chapman, K. A., Best, R. J., Smith, M. E., Mueller, E. R., Grams, P. E., & Parnell, R. A. (2020). Estimating the contribution of tributary sand inputs to controlled flood deposits for sandbar restoration using elemental tracers, Colorado River, Grand Canyon National Park, Arizona. GSA Bulletin, 133(5-6), 1141–1156. https://doi.org/10.1130/b35642.1