A study of changes in the relationship between discharge and water levels in the Red River in the Hanoi area

Abstract

Nowadays, our understanding of hydrological processes has made significant advances. The relationship between discharge (Q) and water level (H) changes when the riverbed erodes. Currently, the construction of hydraulic and transportation infrastructures for water resource exploitation has influenced most natural rivers and streams to varying degrees. The impacts of climate change and riverbed sand and gravel mining are also among the causes of changes in the Q~H relationship. Water levels along the Red river in the Hanoi area are currently declining, despite no significant change in discharge, while the river channel continues to deform and degrade. Variations in river water levels present significant challenges to scientists, as the channel is in a state of continuous change due to multiple factors, including sediment imbalance. These variations partly explain riverbank erosion incidents, which have a serious impact on infrastructure and socio-economic activities along both riverbanks. This study analysed changes in the Q~H relationship at the Son Tay and Ha Noi hydrological stations using a numericcal modelling approach. The results show that the Q~H relationship in 1971 was less scattered than in 1996, when it was more sensitive to discharge fluctuations. Water levels increased more rapidly as Q increased. A more pronounced looped relationship was observed, reflecting the dynamic impact of flood flows on channel morphology.