近60年长江荆江三口水沙变化过程及对洞庭湖的影响

荆江三口的水沙变化过程是影响洞庭湖发育的重要环节,对洞庭湖的稳定扮演着重要的角色。通过对荆江三口五站1951—2014年的水沙观测数据进行系统分析,着重研究长江荆江三口近60年水沙变化过程及影响因素,并探讨水沙变化对洞庭湖的影响。结果表明:近60年荆江三口分泄长江径流量、输沙量均呈显著的减少趋势,也导致三口五站中的四站出现功能性断流,且断流天数呈明显增加的趋势;洞庭湖区降水量减少、水利枢纽工程等人类活动是影响三口水沙变异的主要驱动因素;荆江三口水沙变化对湖盆结构及洞庭湖形态起着重要的调控与制约作用,其分泄水沙能力的减小也导致了洞庭湖湖面面积萎缩、容积缩小,不过洞庭湖寿命随着水沙的衰减而增加。正确认识荆江三口水沙变化规律及其对洞庭湖的影响,可为三口地区水资源的开发利用、洞庭湖的综合管理提供理论基础和实践经验。

Variation Process of Water and Sediment Along Jingjiang River and Its Effect on the Dongting Lake over the Past Six Decades

The process change of water and sediment in Jingjiang River is an important part of the development of Dongting Lake,which plays an important role in the stability of Dongting Lake.Based on water and sediment data of three outlets in five stations in the Jingjiang River in the period 1951-2014,the variation process of water and sediment along Jingjiang River and influencing factors of the Jingjiang of Yangtze River were discussed,and the influence of water and sediment change on Dongting Lake was discussed.The results show that the runoff and sediment along Jingjinag River presented the significantly decreasing trend over the past six decades.The reduction of water and sediment resulted in the functional flow of the four stations in the five stations of the three stations,and the number of days of flow obviously increased.The main driving factors influencing the variation of water and sediment in the three outlets in Jingjiang River were the decreasing precipitation of Dongting Lake and the human activity such as hydro-junction projects.The process change of water and sediment in Jingjiang River plays an important role in regulating and restricting the structure of lake basin and the shape of Dongting River.The reduction of water and sediment resulted in the shrinking of the lake area and the reduction of the volume of Dongting Lake,but the life span of Dongting Lake increased.The correct understanding of the change regularity in the three outlets in Jingjiang River and its influence on Dongting Lake can provide theoretical basis and practical experience for the development and utilization of water resources in three districts and the comprehensive management of Dongting Lake.