Increased flood risk on the lower Yellow River due to upstream water use

摘要

Analysis of hydrological data collected before & after the construction of several major projects on the upper Yellow River reveals that their impact on the fluvial processes in the Lower Yellow River channel is significant, due to increased flow regulation and runoff abstraction in the upstream area. Observations indicate that the fluvial processes in the lower reaches of the Yellow River is the most seriously affected, because of the huge annual sediment transport in the Lower Yellow River channel (1.6x10~9 tons on long-term average). The natural seasonal variation in river runoff has been reversed because of the construction of two major reservoirs in the upper reaches, and depositions in the main channel of the Lower Yellow River have been developing at an alarming rate in the past two decades. Such a development leads to substantial reduction of discharge capacity in the river channel and therefore to higher risks during flood season. Less runoff and fewer flushing floods also lead to more pollution in the river and a worsening water quality.