人类活动影响下海南岛万泉河下游年最高水位阶段性演变研究

Study on the Phased Evolution of Annual Highest Water Level of the Wanquan River in Hainan Island under the Influence of Human Activities

为探明近年来海南岛万泉河下游年最高水位的演变趋势与演变机制,基于加积站1980—2020年最高水位序列,结合该站流量与河床断面地形等资料,梳理年最高水位的演变趋势,并进一步辨识人类活动在其中产生的影响。结果表明:万泉河下游年最高水位的演变可分为平稳波动期(1980—2002年)和快速下降期(2003—2020年)两个阶段,进入快速下降期后年最高水位下降约1.81m,降幅达23%。水库建设等人类活动是万泉河年最高水位阶段性显著下降的主要驱动力,其中,水库削减洪峰对年最高水位产生的影响约占41%,而水库拦沙引起河床下切带来的影响占比达51%。

The human intervention makes the changes of river flood level deviate from the natural evolution process,which has a profound impact on flood control and navigation in the basin.To investigate the evolution trend and mechanism of flood level in the lower Wanquan River of Hainan Island in recent years,based on the highest water level data at the Jiaji station,combined with the dataset of water discharge and cross-sectional morphology,the evolution trend of annual highest water level was elucidated,and the influence of human activities was further identified.The results show that the evolution of flood level in the lower Wanquan River can be divided into two stages:steady fluctuation period(1980—2002)and rapid decrease period(2003—2020).During the rapid decrease period,the annual highest water level decreases by about 1.81 m,or 23%.Human activities(e.g.reservoir construction)are the main driving force for the significant decrease of the annual highest water level.Among them,the impact of reducing effect of reservoirs for the flood peak on the annual highest water level accounted for 41%,and the impact of the riverbed downcutting caused by the sediment trapping effect of reservoirs accounted for 51%.