The discharge of a river which is just contained within the banks. This is the state of maximum velocity in the channel, and of maximum competence (V. P. Singh, ed. 1987). Timár (2003) Quat. Sci. Revs 22, 10 shows that sinuosity is a function of the channel slope and bankfull discharge; Wu et al. (2008) Geomorph. 100, 3–4 show that bankfull channel dimensions result from the accumulative effect of several consecutive years’ discharge and sediment load conditions.