青海湖水位演变及其影响因子分析

Study on Water Level Evolution of Qinghai Lake and Its Influencing Factors

青海湖不仅是我国最大的湖泊,也是国家生态安全战略格局的重要组成部分。在全球变暖的背景下,青海湖水位急剧变化,其对周边的交通设施、居民安全和畜牧业发展等影响较大,因此需要对气候变化下的青海湖水位演变特征及其水量平衡进行研究。本文基于布哈河口水文站、下社水文站的水文数据,刚察气象站、CMFD气象数据以及水量平衡方程,首先分析了青海湖1956-2020年的年际水位演变特征和年内水位变化特征,以及水量平衡分量——入湖径流(R_(s))、湖面降水(P)和湖面蒸发(E)对水位变化的影响;其次揭示了相同月份计算的水位值变化与R_(s)、P和E的变化是同步的;最后进一步通过岭回归方法定量计算了R_(s)、P和E对基于12月份计算的青海湖水位变化的贡献率。研究结果表明:青海湖年均水位在1956-2004年以0.8 m·(10a)^(-1)的速率下降,其中在1979-2004年间下降的主要原因是E大于(P+R_(s));2004-2020年以1.9 m·(10a)^(-1)的速率上升,其中在2004-2018年间上升的主要原因是P和R_(s)的增加;青海湖水位有明显的年内变化,5月水位开始上涨,9月达到最高,其与R_(s)、P和E的月变化一致;当年的P、R_(s)、E变化对9-12月相同月份年均水位变化的影响大于去年,当年的P、R_(s)、E对12月年均水位变化的贡献率分别为10%、70%和20%。

Qinghai Lake is not only the largest lake in China but also an important part of the national ecological security strategy.Under the background of global warming,the water level of Qinghai Lake changes rapidly,which has great effects on the surrounding traffic facilities,residents'safety and the development of animal husbandry,etc.Therefore,it is necessary to study the water level evolution characteristics of Qinghai Lake and its water balance under climate change.Based on the hydrological data of Buha River hydrology station and Xiashe hydrology station,meteorological data of Gangcha meteorological station and CMFD,and water balance equation,this paper first analyzes the inter-annual and intra-year water level evolution characteristics of Qinghai Lake from 1956 to 2020,and the water balance components,such as runoff into the lake(R_(s)),precipitation(P)and evaporation(E).The second reveals that the changes in water level values calculated in the same months are synchronized with the changes in R_(s),P,and E.Finally,the ridge regression method is employed to quantitatively calculate the contribution rates of R_(s),P,and E to the water level change of Qinghai Lake based on calculations made for December.The results show that the annual average water level declined at a rate of 0.8 m·(10a)^(-1) from 1956 to 2004,of which the main reason for the decrease between 1979 and 2004 was that E exceeded the sum of P and R_(s).However,from 2004 to 2020,the water level increased at a rate of 1.9 m·(10a)^(-1),of which the main reason for the increase between 2004 and 2018 was the increase of P and R_(s).Qinghai Lake exhibits evident intra-annual variations,with the water level starting to rise in May and reaching its peak in September,which aligns with the monthly variations of R_(s),P,and E.Furthermore,the impact of the current year's P,R_(s),and E changes on the annual water level change for the same months of September to December is greater than that of the previous year.Specifically,the contributions of the current year's P,R_(s),and E changes to the water level change calculated based on December data are 10%,70%,and 20%,respectively.