黄河入海水沙通量年内变化规律分析

Analysis on the Evolutionary Characteristics of Annual Runoff and Sediment Flux Distribution of the Yellow River

以黄河口利津水文站1950—2005年月均实测水沙资料为依据,采用随机水文学和数理统计方法对黄河入海水沙通量的年内变化规律进行了分析。结果显示:Fisher最优分割法检测出主汛期(7—10月)入海水沙出现1968年、1985年和1996年3个跳跃点,依据3个跳跃点可将汛期入海水沙过程分为4个阶段:即Ⅰ(1950—1968年),Ⅱ(1969—1985年),Ⅲ(1986—1996年),Ⅳ(1997—2005年),这一变化过程与全年入海水沙变化过程一致。4个阶段水沙年内下降过程经历了伏汛期减少→秋汛期减少→伏汛期减少3个主要过程,1—5月份水沙逐阶段下降;水沙年内分配不均匀性呈现不同程度的上升,水、沙集中程度变化过程不同步,水、沙集中期主要受不同年份伏汛和秋汛期水沙变化控制。汛期水沙占全年比例受大型水库利用方式影响不同时期呈上升或下降趋势。

Based on the observed （1950-2005） runoff and sediment data from the Lijin hydrographic station at the Yellow River estuary, an analysis is made on the evolutionary characteristics of runoff and sediment flux distribution in the year using stochastic hydrology and statistic methods in the past 50 years. The results show that： the Fisher Optimum Split method tested three possible hopping points（1968, 1985 and 1996） in the observed flood season runoff, flood season sediment, annual runoff and annual sediment data series; rank sum and mean value test results show that the three hopping points are marked. Based on the three hopping points, we divided observed flood season runoff, flood season sediment, annual runoff and annual sediment data series all into four phases, including Ⅰ （1950-1968 ）, Ⅱ（ 1969-1985 ）,Ⅲ（ 1986-1996 ）,Ⅳ（ 1997-2005 ） .The runoff and sediment decreases step by step along with time. Based on the four phases, the runoff and sediment undergo summer flood decreasing, autumn flood decreasing, summer flood decreasing again three main processes, runoff and sediment of spring and ice flood season decreased with time. Unevenness of annual runoff and sediment distribution in the year both show different extent of ascending trend. Concentration rate of annual runoff and sediment distribution do not show synchronous change, runoff and sediment flux concentration period of annual runoff and sediment＇s bring forward or putting off is controlled by summer flood decreasing or autumn flood decreasing at different phases; The ratio of flood season to annual runoff and sediment showing ascending or descending trend is regulated by Sanmenxia and Xiaolangdi reservoirs.