黄河宁蒙河段河道演变过程及影响因素研究

根据下河沿、青铜峡、石嘴山、巴彦高勒、三湖河口和头道拐6个水文站不同时期水沙资料的分析,宁蒙河道的冲淤演变过程大致可分为三个阶段。1960年以前河床处于微淤状态。1961年至1986年,宁蒙河道呈冲刷状态。1986年以后宁蒙河道呈淤积状态。水力因素、水库调控和风沙入河等因素影响了河道的冲淤演变。黄河自1986年以来出现枯水系列,汛期来水少,挟沙能力降低,河道淤积严重。1987-2006年黄河上游主要控制站年平均径流量、输沙量均比多年均值分别减小8.7-25.5%和13-53.1%。水库调蓄造成宁蒙河道汛期水量、沙量占年水量、沙量的比例减小。宁蒙河段是黄河流域风成沙直接入黄的主要河段。风沙入黄使河道泥沙粗化,由于粒径大于0.1mm颗粒很少形成悬浮物质,影响了泥沙的输移和淤积状态。在维持河道健康的前提下,对宁蒙河段的治理应该坚持因地制宜,生物措施、工程措施相结合的综合治理原则。

Channel evolvement and influence factors in Ningxia-Inner Mongolia reach of the Yellow River

The scour and silting evolution regularities of the Ningxia-Inner Mongolia reach of Yellow river were obtained by analyzing the data of water and sediment of Xiaheyan,Qingtongxia,Shizuishan,Bayangaole,Sanhuhekou and Toudaoguai hydrographic stations in defferent times.There were three stages in the process of channel evolvement.Before 1960,it was natural stage,the channel was in micro-deposition state.From 1961 to 1986,because Yanguoxia,Sanshenggong,Qingtongxia and Liujiaxia reservoirs were put into operation,the channel was in scouting action stage.After 1986,because Longyangxia reservoir began to storage water,the water flowed into channel was decreased,the channel was in deposition stage.the annual average runoff,sediment discharge of this period were decreased 8.7-25.5% and 13-53.1%,respectively.The ratio of the water amounts and sediment in the flood season to the whole year was decreased.Ningxia-Inner Mongolia Reach is the main reach of wind blown sand into river.Wind blown sand make a significant contribution to the coarse fractions of the suspended load.In the initial stage of channel healthy,actions must be taken that suit local circumstances and comprehensive management of Biological and engineering measures must be used to develop towards sustainable,steady and harmonious trend.