三峡工程建设及其运行调度对秭归库首地区气象及生态环境的影响

Impact of the Construction and Operational Scheduling of the Three Gorges Project on the Meteorology and Ecological Environment in the Zigui Reservoir Region

三峡工程作为世界上最大型水利工程自2003年蓄水至今已有20年,但其对局地气候、生态等的影响仍不清楚,评估其对库区生态环境、气象及水资源动态的影响是保证三峡工程安全平稳运行的重要基础。本文通过秭归典型区水土保持监测站长期观测结果,从地面常规气象、典型径流场监测及老鹰沟小流域监测探讨三峡工程建成及其运行调度对库首地区生态环境的影响。结果表明,三峡工程三次蓄水后扩大了水域面积及库容量,导致年极端最高气温、平均气温和年平均最高气温均先下降后上升,且三次蓄水后的第二年降雨量均有所增加,提高了最低气温及地面温度,在一定程度上提高了宜居性;农业工程措施如间作白三叶草、黄花菜植物篱笆可以有效降低坡耕地径流量及径流泥沙量,降低农田有机质和氮磷等养分流失,对于减少面源污染、维持土地生产力具有积极作用;由于农业生产排放,老鹰沟小流域氮素平均含量为16.45 mg/L,氮素超标严重,应进一步强化环境管理,保护三峡库区水环境健康。综上所述,三峡工程的建设及其运行调度降低了局地年度气温波动幅度,对当地气候具有长期影响,合理农业工程措施有助于降低水土流失,仍需进一步完善环保措施,维持三峡库区生态平衡。

The Three Gorges Project,as the world’s largest hydropower project,has been impounding water since 2003,marking 20 years to date.However,its effects on local climate,ecology,and other factors remain unclear.Assessing its impacts on the reservoir’s ecological environment,meteorological conditions,and water resource dynamics is essential for ensuring the safe and stable operation of the Three Gorges Project.Using long-term observation results from the Zigui Soil and Water Conservation Monitoring Station,this study explores the impacts of the construction and operational regulation of the Three Gorges Project on the ecological environment of the reservoir’s upstream region by analyzing routine ground meteorological data,typical runoff field observations,and monitoring data from the Eagle Gully watershed.Results indicated that following the three stages of reservoir impoundment,there was an increase in water surface area and reservoir capacity.This caused yearly extreme high temperatures,average temperatures,and yearly average high temperatures to first decrease and then increase.Moreover,the rainfall volume increased in the second year after each impoundment stage,elevating minimum temperatures and ground temperatures,thereby improving the region’s habitability to some extent.Agricultural engineering measures,such as intercropping with clover and using marigold plant hedgerows,effectively reduce runoff and sediment loads on sloping farmlands,mitigate the loss of organic matter,nitrogen,and phosphorus from agricultural fields,and play a positive role in reducing non-point source pollution and maintaining soil productivity.Due to agricultural production emissions,the average nitrogen content in the Eagle Gully watershed reached 16.45 mg/L,indicating a significant exceedance in nitrogen levels.In conclusion,the construction and operational scheduling of the Three Gorges Project have reduced the amplitude of local annual temperature fluctuations,exerting a long-term impact on the regional climate.Rational agricultural engineering measures can help reduce soil erosion and maintain ecological balance in the Three Gorges Reservoir area.