1951—2014年洞庭湖水沙阶段性演变特征及驱动因素分析

基于洞庭湖1951-2014年实测径流量和输沙量数据,采用Mann-Kendall检验、滑动t检验和有序聚类分析等多种统计方法分析洞庭湖水沙演变特征,并以回归曲线拟合及归-化曲线对降水量、径流量和输沙量之间的相互关系进行分析,以期确定影响洞庭湖水沙变化的驱动因素.结果表明:(1)入出湖径流量、输沙量的突变年份有差异,入湖径流量、出湖径流量为1971年,入湖输沙量为1985年,出湖输沙量为1970年;(2)洞庭湖入湖径流量具有以分段衰减为特征的演变过程,1972-1977年表现最明显;(3)入湖输沙量呈现分段衰减的阶段性演变特征,2004-2014年间多年平均输沙量减幅最大,衰减率为75.34％;(4)入湖、出湖径流量在1951-1971年和1978-1985年主要受降水量变化驱动,1972-1977年和1986-2014年主要受沙滩子自然裁弯、葛洲坝水电站、五强溪水库、三峡工程等人类活动影响;(5)1951-1971年入湖径流量的多寡对入湖输沙量产生一定影响,1972-2014年影响输沙量减少的主要因素是水利枢纽工程.因此,洞庭湖流域水沙过程的不同阶段其主导驱动因素有所差异.其中,入湖径流1972-1977,20042014年2个阶段及出湖径流1976-1985,2004-2014年2个阶段以水利枢纽工程驱动为主,其余2个以降水量变化驱动为主.

Evolution Characteristics and Driving Factors of Runoff and Sediment Changes in Dongting Lake During 1951-2014

Based on the data of runoff and sediment discharge measured from 1951 to 2014 in Dongting Lake,evolution characteristics of water and sediment were analyzed by Mann-Kendall test,sliding t-test and ordinal clustering analysis.The relationship between precipitation,runoff,and sediment was analyzed by regression curve fitting and normalization curve,so that the driving factors influencing the variation of water and sediment in Dongting Lake could be figured out.The main results were as follows:(1) There were differences in the mutation year of runoff and sediment into and out the lake.The mutation year was 1971 for runoff into and out of the lake,1985 for sediment into the lake,and 1970 for sediment out of the lake,respectively.(2) The runoff in Dongting Lake was attenuated by the stage,with the change being the most obvious during 1972 to 1977.(3) The sediment into the Lake was characterized by the stage attenuation,and the average annual sediment decreased by 75.34％ from 2004 to 2014.(4) The runoff into and out of the lake was mainly affected by precipitation change during 1951 to 1971 and 1978 to 1985,and by human activities such as beach natural bending cutting,Gezhouba hydro-power stations,Wuqiangxi reservoir and the Three Gorges Project during 1972 to 1977 and 1986 to 2014.(5) The amount of runoff had a certain impact on the amount of sediment into the lake during 1951 to 1971.The main factor affecting the reduction of sediment was the water conservancy project during 1972 to 2014.In summary,the dominant driving factors were different at different stages of the processes of water and sediment in Dongting Lake Basin.The runoff into the lake were mainly driven by water conservancy projects during 1972 to 1977 and 2004 to 2014.The runoff out of the lake were mainly driven by water conservancy projects during 1976 to 1985 and 2004 to 2014.The runoff into and out of the lake were mainly driven by precipitation change in the other two stages.