洞庭湖入出湖径流泥沙年内变化规律及成因分析

根据洞庭湖入出湖水文站实测月径流泥沙长序列观测资料,运用不均匀系数、集中度和集中期、MannKendall趋势检验法等方法,分析了洞庭湖入出湖径流泥沙年内变化规律及其成因。结果表明:四水入湖径流量年内分配不均,集中于5-7月;输沙量年内分配极为不均并呈现出越来越不均匀的趋势,集中于6-7月;荆江三口各站历年径流量年内分配整体趋势上变化不大,三口径流集中期均为每年的7月份,输沙量年内分配越来越不均匀;城陵矶径流量和输沙量不同年代之间的C_(V_y)值差异较大,输沙量C_(V_y)值呈较为明显的波动增大趋势,径流量C_(V_y)值无明显趋势性变化;径流集中在7月,输沙在水沙交互影响下集中于4月;水利工程和水土保持工作的实施使得洞庭湖水沙年内分配更加均匀。四水、三口和出湖集中期呈逐渐推迟的规律,泥沙的集中度均高于径流。

Analysis on annual variation law and its causes of runoff and sediment flowing in and out of the Dongting Lakes

According to the long time series observation data of monthly runoff and sediment, annual variation law and its causes of runoff and sediment flowing in and out of the Dongting Lake were analyzed by means of non-uniformity coefficient, concentration degree and concentration period, and the Mann-Kendall trend test methods. The results showed that: Annual runoff distribution of the four Rivers (i.e., the Xiang River, Zi River, Yuan River and Li River) into the Dongting Lake were uneven, the concentration period was from May to July. Annual sediment distribution were very uneven and had a trend of being more and more uneven, the concentration period was from June to July; Annual runoff distribution of three oulets of Jingjiang into the Dongting Lake changed little in general trend, but the annual distribution of sediment were more and more uneven, the concentration period of runoff and sediment were both July; The C_Vy values of annual runoff and sediment in Chenglingji differed for different years, C_Vy values of annual sediment fluctuated and had increase trend, but there was no trend for C_Vy of annual runoff; the concentration period of runoff was in July, but the concentration period of sediment was in April due to the interaction of runoff and sediment; Annual distribution of runoff and sediment became more uniform because of the application of the hydraulic engineering construction and conservation of water and soil. The concentration period of runoff and sediment for the four rivers, three outlet and the lake delayed gradually, the concentration degree of sediment was higher than runoff.