黄河宁蒙河段冲淤时空分布特征与淤积原因

在补充完善水沙、观测断面等资料的基础上,采用沙量平衡法和断面法分析计算了1960年以来宁蒙河段的泥沙冲淤量,两种方法计算结果接近、各有特点,可互为补充使用。分析冲淤量时间分布特征表明,不同时期年内的冲淤分配特征不同,1987年以来宁蒙河段泥沙淤积加重,且淤积加重主要集中在汛期和小于0.1 mm的各粒径组泥沙,大于0.1 mm的粗泥沙淤积量有所减少。分析冲淤量空间分布结果表明,宁蒙河段淤积主要发生在内蒙古三湖河口至头道拐河段和巴彦高勒至三湖河口河段,1987年以来以河槽淤积为主,横断面萎缩。根据宁蒙河段水沙来源情况,从多个方面分析宁蒙河段淤积变化原因表明,干流水沙条件变化尤其是龙刘水库联合运用对干流水沙条件的显著改变,包括减少了汛期水量以及大流量过程,是导致宁蒙河段淤积加重的主要原因。

Spatial-temporal distribution characteristic and course of sedimentation in the Ningxia-Inner Mongolia reaches of the Yellow River

With water-sediment and section-observation data,the sediment erosion and deposition of Ningxia-Inner Mongolia reaches of the Yellow River since 1960 were calculated by the sediment balance method and the section method. The results from two methods were close and complementary. The erosion and deposition varies in different periods that the sedimentation in the Ningxia-Inner Mongolia reaches has been aggravating since 1987, which mainly concentrated in the flood season and the sediment volume of particle size less than 0.1mm, while particle size more than 0.1mm has decreased. That sedimentation mainly occurred at Sanhuhekou-Toudaoguai reach and Bayangaole-Sanhuhekou reach that river channel sedimentation predominated and cross sectionh has atrophied since 1987. According to the source of water and sediment, the mainstream water and sediment conditions change, especially that from the combination of Longyangxia and Liujiaxia reservoirs, including the decrease of water amount and the flow process during the flood season,is the main cause of the increased deposition in Ningxia-Inner Mongolia reaches of the Yellow River.