各时段城陵矶水位变化特征及其成因分析

Analysis of Variation Characteristics of Water Level at Chenglingji and Reasons Discussion

为进一步了解城陵矶水位的变化规律,采用线性回归法和原始资料观测法分析了城陵矶1955~2014年的水位流量变化规律及其成因。结果表明,年际间,城陵矶流量逐时段呈减小趋势,水位呈增加趋势,且流量变幅大于水位;年内,城陵矶水位逐时段出现了汛期5~10月流量大幅减小、水位小幅升高及枯季1~3月流量变幅小、水位显著升高的现象,前者主要是因为顶托作用加强和河床淤积共同造成,后者主要因河床淤积抬高水位所致;城陵矶极干旱年份(2006年)的水位较正常年份(2007年)出现了水位枯季不落、汛期不汛的现象,四水及区间汇流的增加是造成枯季不落的主要原因,而松滋、太平和藕池分流比的减小是引起8~9月城陵矶水位降低的主导因素。

Linear regression method and raw data analysis method were adopted to check water level and discharge data of the Chenglingji from 1955 to 2014to explore the variation characteristics and its influencing factors.The results demonstrate that during different years,the discharge of Chenglingji shows decreasing trend at each period while water level shows increasing trend.The variation of discharge is greater than the water level.Within a year,water level presents the both phenomena of'the flow decreases significantly during flood season from May to October while the water level rises slightly'and'the flow slightly changes during drought season from January to March while the water level rises significantly'each period at Chenglingji.The former is mainly caused by the reinforced backwater effect and undergoing deposition while the latter mainly caused by the water level lifted by the undergoing deposition.Compared with normal year(2007),water level of Chenglingji occurred as the phenomenon of'there is no low water level in the drought season while no high water level in the flood season 'in the extreme arid year(2006).The increasing of discharge of Lishui,Yuanshui,Zishui and Xiangshui and the convergence of interval is the main reason of no low water level in the drought season and the reduction of the water which are diverted at the three outlets into the Dongting Lake is the main reason of the decreasing of water level at Chenglingji during August to September.