水利工程群对洞庭湖城陵矶特征水位的综合影响

Comprehensive effect of group hydrological projects on characteristic water level of Chenglingji in Dongting Lake

基于1956-2020年洞庭湖城陵矶水文站的实测水文数据,运用Mann-Kendall检验法分析水利工程群影响下洞庭湖湖口城陵矶特征水位的时序演变特征。结果表明:城陵矶年特征水位呈显著上升趋势(P<0.05)。与时段1相比,时段2、3、4的年均水位分别抬升了0.68、1.04、1.61 m,年最高水位分别抬升了0.35、1.14、1.78 m,时段5的年均水位、年最高水位分别下降至24.97、30.50 m,年最低水位逐期抬升(18.09、18.84、19.32、20.26、20.87 m);城陵矶水位存在“涨-丰-退-枯”4个水文期,涨水期最高水位抬升了2 m以上,丰水期平均水位和最高水位在前4个时段抬升后,于第5时段分别回落至28.69、30.42 m,退水期平均水位和最高水位呈波动变化,最低水位在后4个时段逐期下降,枯水期平均水位和最低水位逐期抬升,时段5的特征水位抬升了2 m以上;水利工程群对城陵矶特征水位的影响在各典型年表现出不同的特征,三峡水库蓄水后,城陵矶特征水位在丰水年丰、枯水期下降,在平水年丰水期抬升、枯水期下降,而在枯水年丰水期下降、枯水期抬升。

Temporal evolution characteristics of characteristic water level of Chenglingji under the effect of group hydrological projects were analyzed based on the monitored hydrological data of Chenglingji Station in Dongting Lake from 1956 to 2020 using Mann-Kendall test.The results showed that the annual characteristic water level of Chenglingji showed a significant upward trend(P<0.05).Compared with the first stage,the annual average water level of the second,third and fourth stage increased by 0.68,1.04 and 1.61 m,respectively,the annual highest water level increased by 0.35,1.14 and 1.78 m,respectively;while the annual average water level and the annual highest water level decreased to 20.87 and 30.50 m,respectively at the fifth stage,and the annual lowest water level increased by stages(18.09,18.84,19.32,20.26,and 20.87 m).There were four hydrological seasons in Chenglingji water level,which were water-rising season,wet season,water-falling season and dry season.The highest water level in water-rising season increased by more than 2 m;the average water level and the highest water level in wet season fell back to 28.69 and 30.42 m at the fifth stage after increased at the first four stages;the average water level and the highest water level fluctuated in water-falling season,and the lowest water level gradually decreased at the last four stages;in dry season,the average water level and the lowest water level increased gradually,and the characteristic water level at the fifth stage increased by more than 2 m.The effect of group hydrological projects on the characteristic water level of Chenglingji presented different states in each typical year.After the operation of Three Gorges Reservoir,the characteristic water level of Chenglingji decreased in the wet season and dry season of the wet year,but increased in wet season and decreased in dry season of the usual year,and increased in dry season and decreased in wet season of the dry year.