水沙动态图法分析中国主要江河水沙变化

Trends analysis of the water and sediment loads of the main rivers in China using water-sediment diagram

利用《中国河流泥沙公报》数据,采用水沙动态图方法并按平衡水沙比相对应,分析中国主要河流2006年前实测水沙的变化。根据河流下游站历年水沙变化趋势,将中国主要河流大致分为4类:水量不变沙量降低、水量和沙量均降低、水量和沙量同步略降低、几近断流断沙。按地域看,中国淮河及其以南大多数河流年径流量无明显改变,而年沙量呈明显下降趋势;淮河以北地区河流水沙量均呈明显下降趋势,特别是黄河年径流量的近10年平均值仅为多年平均值的1/3,输沙量10年平均值仅为多年平均值的1/4,而海河水系的河流下游几乎是断流断沙。总体上,中国大多数河流的沙量明显下降。大多数河流入海水沙量的明显降低主要是人类活动造成的,淮河及其以南河流沙量的降低多与水库兴建、河道采砂和水土保持工程等有关;北方河流水沙量的降低主要是引水量的大幅增加、水库建设及其运行方式的改变以及水土保持工程的发挥效益等造成的。分析也表明,利用水沙动态图法分析河流的水沙长期变化具有一定的优越性。

The trends in the water and sediment loads of the main rivers in China are analyzed with the data till 2006 from the series publioation of China Gazette of River Sedimentation by using the water-sediment diagram. According to the trends in their annual runoff and sediment load entering to the sea main rivers in China can be classified into 4 groups： （1） rivers with stable water but decreased sediment loads, including Huaihe river and the rivers to its south; （2） rivers with decreased water and sediment loads, including Liaohe and the Yellow Rivers; （3） river with slightly synehronal decreased water and sediment loads, including Songhua river; and （4） rivers with greatly reduced water and zero sediment loads with example of Yongding river. Most riverste the south of the Huaihe show no evident trend in their annual runoff, but dramatically decrease for their sediment load. Both water and sediment loads of rivers north of Huaihe river have the evident decreasing tendency. The recent 10 years the average values are only 1/3 of the long term average values for the Yellow River＇s runoff and 1/4 for its sediment load, and the water and sediment loads approach zero for the rivers in Haihe river system. In general, the sediment loads of most rivers in China decrease evidently. The drops in the water and sediment loads of the rivers are mainly caused by human activities. The reduced sediment loads of the rivers in south China are more closely related to the reservoir construction, sand mining and soil conservation activities. The decreasing water and sediment loads of rivers in north China are mainly the results of rapid increased water consumption, reservoirs and their operation modes, and effects of water and soil conservation measures. It also shows that it has advantages using water-sediment diagram in analyzing the trends in water and sediment loads of rivers.