A B S T R A C T The concept of effective discharge, Q e , was introduced by Wolman and Miller (1960) as that stream discharge that transports the most sediment over time. Recently, the validity of Q e as an overall descriptor of sediment transport has been questioned because of its various interpretations and methods of calculation. A new discharge index-termed the "half-load discharge," Q 1/2 -was introduced as the discharge above and below which half of the total sediment load has been

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... rted over time. Existing methods along with long records of continuous daily suspended sediment and discharge data are used to clarify what a discharge index can accomplish. We also offer an objective and consistent empirical methodology for calculating Q e based on a kernel density function. Generalized graphical relationships are introduced for summarizing the frequency and magnitude of both stream discharge and sediment loads. We document how Q e and Q 1/2 are related to standard descriptors of river discharge as well as general characteristics of the sediment load-discharge relationship.