Abstract: | Replacement of water in a given hydrological component is one of the effects of the hydrological cycle. We introduce the concept of renewal time to express the rate of water replacement in a specific reach of a river. Based on stream‐flow data from the 1990s, a simple formula is used to estimate renewal times for several reaches in the middle and lower sections of the Yellow River (Huanghe) in China. These estimates reveal the following trends: (i) renewal times are shortest during the May–October period and (ii) annual renewal times tend to decrease when moving downstream from the middle to lower reaches. Copyright © 2003 John Wiley & Sons, Ltd. |