1950～2000年黄河入海水沙的逐日变化及其影响因素

Daily Variations of Water Discharge and Sediment Discharge Into the Sea from Yellow River from 1950 to 2000 and Relevant Influential Factors That Generate These Changes

对 195 0～ 2 0 0 0年的 5 1年黄河经利津水文站入海的逐日水沙实测资料进行统计分析 ,展示了黄河入海水沙的极端情况 ,如洪峰和沙峰等逐渐变少到消失的过程及逐日入海水沙量的变化规律 ,并对其影响因素进行了初步分析。结果显示 :在黄河年均入海水沙锐减的背景下 ,2 0世纪 90年代日均流量 <5 0 0m3 /s的天数增加到了是 2 0世纪 5 0年代的 3倍多 ;>2 0 0 0m3 /s的洪季流量由初期频发至 1997年消失 ;>40 0 0m3 /s的洪峰流量自 1989年以后消失 ;>60 0 0m3 /s的洪峰流量从 1986年就不再发生。 >5 0 0t/s的日均输沙率 (4 3 .2× 10 6t/d的沙峰 )都出现在 1989年以前 ;>70 0t/s的日均输沙率 (60 .5× 10 6t/d的沙峰 )出现在 1977年以前 ;含沙量 >80kg/m3 的历时和可能产生异重流的含沙量天数都逐步减少。进入 2 0世纪 90年代以来基本不存在大洪灾及由沙峰造成的河口河道快速堆积而使河流改道现象 ,引起这些变化的因素除降雨外主要为流域耗水量不断增加及大中型水库的建成运用等 ,黄河入海水沙的这种锐减及水沙峰的极端情况都会对河口演变和河口区的生态环境产生重要的影响。

This paper analyzes the daily variations of the water discharge and sediment discharge through Lijin Hydrologic Station from 1950 to 2000, and indicates the extreme circumstances including the processes in which the flood peak and sediment peak decreased and disappeared in the past 51 years. This paper also demonstrates the changes and laws of the water and sediment discharge flowing into the sea. The result displays that, with the sharp decrease of the yearly average volumes of water and sediment discharges, the number of days with daily discharge under 500m3/s was over three times greater in the 1990s than in the 1950s, the flood discharge surpassing 2 000m3/s frequently occurred at the earlier stages but disappeared in 1997, the flood peak discharges over 4 000m3/s have disappeared since 1989 and those exceeding 6 000m3/s have disappeared since 1986. At the same time, the daily average sediment discharges surpassing 500t/s occurred before 1989 and those exceeding 700t/s disappeared after 1977. The number of days when the daily average sediment content was over 80kg/m3 and probably generated Hyperpgenal plumes gradually decreased in the past 51 years. The water consumption increase and the large and medium-sized reservoirs built in the river mainstream have negative effects on the water and sediment discharge. Both the sharp decrease of the water and sediment discharges and the extreme circumstances such as flood peak and sediment peak have a great negative effect on the estuarine evolvement and estuarine ecological environment.