Can the discharge of a hyperconcentrated flow be estimated from paleoflood evidence

(1) Many ood events involving water and sediments have been characterized using classic hydraulics principles, assuming the existence of critical ow and many other simplications. In this paper, hyperconcentrated ow discharge was evaluated by using paleoood reconstructions (based on paleostage indicators (PSI)) combined with a detailed hydraulic analysis of the critical ow assumption. The exact location where this condition occurred was established by iteratively determining the corresponding cross section, so that specic energy is at a minimum. In addition, all of the factors and parameters involved in the process were assessed, especially those related to the momentum equation, existing shear stresses in the wetted perimeter, and nonhydrostatic and hydrostatic pressure distributions. The superelevation of the hyperconcentrated ow, due to the ow elevation curvature, was also estimated and calibrated with the PSI. The estimated peak discharge was established once the iterative process was unable to improve thet between the simulated depth and the depth observed from the PSI. The methodological approach proposed here can be applied to other higher-gradient mountainous torrents with a similar geomorphic conguration to the one studied in this paper. Likewise, results have been derived with fewer uncertainties than those obtained from standard hydraulic approaches, whose simplifying assumptions have not been considered.