松花江流域极端降雨变化对流域输沙量的影响

Effects of Precipitation Extremes Change on Sediment Load in Songhua River Basin

基于松花江流域及其周边共43个气象站点1960—2014年逐日降雨数据及佳木斯水文站输沙量数据,采用Mann-Kendall非参数趋势分析方法、小波周期性分析和双累积曲线法,分析了流域内7个极端降雨指数和输沙量的动态变化趋势,在此基础上定量评估了流域极端降雨变化对输沙量的影响。结果表明:1960—2014年间,松花江流域7个极端降雨指数(最大1 d降雨量(RX1day)、连续5 d最大降雨量(RX5day)、降雨强度指数(SDII)、大于95%分位值强降雨量(P95pTOT)、大雨量(HP)、暴雨量(RSP)和汛期降雨量(FSPTOT))皆呈阶段性波动变化,存在16~20 a的大周期和5~6 a的小周期变化特征,但近55 a各极端降雨指数整体上呈不显著的变化趋势;期间佳木斯水文站输沙量的变化趋势与7个极端降雨指数的变化趋势类似。松花江流域各极端降雨指数与输沙量均存在极显著相关性(p<0.01),其中RX5day、P95pTOT与输沙量的相关性最显著。双累积曲线分析显示,流域输沙量与各极端降雨指数关系的突变点均发生在1977年。与基准期(1960—1977年)相比,1978—2014年松花江流域各极端降雨指数对输沙量变化的影响在3.09%~15.24%之间,其中SDII变化对输沙量的影响最大(15.24%),其次是FSPTOT(14.81%)和RX5day(14.34%)。

Study on the effects of extreme precipitation events on runoff and sediment load not only can reveal the mechanism of runoff and sediment,but also provide important scientific support for basin disaster warning. Currently,there is limited information on the effects of extremes precipitation events on river sediment load. Thus,Songhua River Basin（ SRB）,located in the northeast of China was selected as study area,and daily precipitation data from 43 meteorological stations within and surrounding the SRB and sediment load from Kiamusze hydrologic station during 1960—2014 were collected. Seven extreme precipitation indices,including maximum 1-day precipitation（ RX1day）,maximum 5-day precipitation（ RX5day）, simple daily intensity index（ SDII）, strong rainfall more than 95% points value（ P95 pTOT）,heavy precipitation（ HP）,rainstorm precipitation（ RSP） and flood season precipitation（ FSPTOT）） were chosen to quantify precipitation extremes. The Mann-Kendall＇s non-parametric trend analysis method and wavelet periodic analysis method were used to analyze the dynamic change of precipitation extremes and sediment load. Double mass curve method was used to assess the effect of extreme precipitation events on sediment load change. The results showed as follows： there was no significant change trend of the seven precipitation extreme indices during 1960—2014; while thereexisted 16 ~ 20 a main period and 5 ~ 6 a minor period. Meanwhile,the change trend of sediment load in Kiamusze hydrologic station was similar with the precipitation extremes. The precipitation extreme indices had highly significant correlation with sediment load（ P〈0. 01） in the SRB,among which correction between sediment load and RX5 day and P95 pTOT was the most significant. The abrupt change by double mass curve method indicated that the abrupt change point between sediment load and each extreme precipitation index occurred in 1977. Compared with the baseline period in 1960—1977,the effects of precipitation extreme indices on the sediment load were ranged from 3. 09% to 15. 24% in 1978—2014,in which the effect of SDII was the highest with 15. 24%,followed by FSPTOT with 14. 81% and RX5 day with 14. 34%. These findings would provide useful information for forecasting sediment disaster and taking measures in conserving soil and water in the SRB.