Cumulative hyporheic discharge to the channel (log scale) by water age (log scale) for a representative unit (RU) of water stored in a hyporheic zone.

Each curve is associated with a different value of α, the negative power-law exponent used to describe the hyporheic water age distribution of hyporheic discharge. Units of hyporheic exchange (y-axis) can be interpreted in terms of length (e.g., m day⁻¹), area (e.g., m² day⁻¹), or volume (e.g., m³ day⁻¹) depending on whether the RU is one dimensional (e.g., 1 m of hyporheic water thickness), two dimensional (e.g., 1 m² of hyporheic water cross-sectional area), or three dimensional (e.g., 1 m³ of hyporheic water). Hash marks on each curve demarcate the maximum water age (τ_i) for each of 50 transient storage zones (TSZs) in the RU; each TSZ contains 2% (0.02 m^x) of water stored in the RU.