Tributary sand input data, Colorado River, Grand Canyon National Park, Arizona

These data were compiled from sampling pre-dam flood terraces and sand bar deposits of the Colorado River in Glen Canyon between Glen Canyon Dam and the Paria River confluence. This includes sand deposits from the 2008, 2012, 2013 and 2014 high flow experiments (HFE) in Marble Canyon. Sand sources from these locations were sampled in September/October of 2013 and 2014. Also, samples of suspended sediment from a selection of Paria River flash floods that preceded the 2013 and 2014 high flow experiments were collected. The suspended sediment samples were wet sieved to separate the <63-micron fraction at the Grand Canyon Monitoring and Research Center. A Niton XL3-t 955 portable XRF was used to measure the elemental concentration of half-phi grain size fractions from every sand sample. Samples were tested 3 times, for 90 seconds each, measuring the concentration of seven elements (Fe, Ca, K, Ti, Rb, Sr, and Zr). The average concentration for each element over the three tests is used in all subsequent analyses. MixSIAR Bayesian mixing model using JAGS for Markov Chain Monte Carlo simulation was used to calculate the relative contribution of Paria River- versus Glen Canyon-derived sand in Marble Canyon HFE deposits.