中文摘要：

基于宁蒙河段的水沙和河道断面资料,分析了该河段主要水文站年内的冲淤过程、规律和近期变化情况.结果表明：①宁蒙河段河道在年内经历两次冲淤平衡,一次是冬季的冲淤平衡,一次是春、夏、秋季的冲淤平衡,后者水量较为丰沛且对河道冲淤起主要作用;②宁蒙河段淤积主要发生在内蒙古河段,石嘴山和头道拐水文站的断面冲淤变化不大,其余水文站断面均发生了明显淤积;③近期河道淤积的主要原因是径流量较少和大流量洪峰日数显著减少.

英文摘要：

Based on the detailed data on runoff,sediment and cross-section,process,pattern and recent changes of scour and silting within the reach of Ningxia-Inner Mongolia had been analyzed. The result indicates that 1)Ningxia-Inner Mongolia reach has twice balances of erosion and deposition,one occurs in winter and another one is in spring-summer-autumn respectively. The latter one has more runoff,so it is vital effect on balance of reach;2)the deposition mainly occurs in the Inner Mongolia section. River sections almost kept balance in scour and siltation at Shizuishan and Toudaoguai hydrometric stations. The others have significant deposition;3)recent siltation of channel is mainly due to significantly reduction of volume of runoff and number of days of flood peaks.