3.1 Influence of Streambed Depth on the Empirical RTD
The hyporheic zone RTDs generated by the particle tracking algorithm
(empirical RTDs, see Methods) become progressively heavy tailed as the
dimensionless depth is increased systematically from \(d_{b}^{*}\) =\(0.5\) to \(8\) (Figure \(1A\)). For dimensionless depths greater than,\(d_{b}^{*}>\ 6.2\ \), the shape of the empirical RTD converges to
that for an infinitely deep bed (see variations in RTD quantiles in
Figure \(1B\)), consistent with the depth threshold reported by Wörman
et al. (2002) of \(\ \frac{d_{b}}{\lambda}=1\) (equivalent to\(d_{b}^{*}=\ 2\pi\)).