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This paper analyzed the water and sediment characteristics and eroding effect on river of flood in 2018. The result shows that this flood has the characteristics including large volume of water, long duration and high flood peak, the dis-charge of the flood peak coming into and routing through the Ningxia and Inner Mongolia reach of the Upper Yellow River varies from 2 880 m³/s to 3 600 m³/s, among which wick flood plains in the reach from Sanhuhekou to Toudaoguai arc overflowcxL The flood effects the Ningxia-Inner Mongolia reach evidently, it has an obvious effect of " depositing on floodplain and eroding channel" in Bayangaole to Sanhuhekou reach. The scour efficiency of overbank flood is higher than that of non-overbank floord. After the flood, the same discharge water level of Bayangaole and Simhuhekon stations in Inner Mongolia reach drops 0.71 m and 0.47 m respectively and the bankfull discharge increases 500 m³/s and 320 m³/s respectively. [ABSTRACT FROM AUTHOR]

Based on the analysis of the measured data, the source of grouped sediment and the law of erosion and deposition in the NingxiaInncr Mongolia reach of the Yellow River arc showed that the fine sediment(d≤0.025 mm) is the main part of the sediment and comes from the upstream of Xiaheyan and the tributaries in Ningxia. The erosion and deposition efficiency of the fine and medium sediment (0.025 mm< d≤0.05 mm) are decreased significantly with the increase of discharge. The coarse sediment(0.05 mm0.1 mm) account for a small part of the sediment. The extra coarse sediment mainly comes from desert acolian sand, which often deposits and is difficult to improve the transportation capacity with the increase of discharge. Therefore, the comprehensive control scheme of " intercepting the coarse sediment and discharging the fine" for reducing sedimentation in Ningxia-Inner Mongolia reach is put forward, which the reservoirs arc regulated recovering flood process to transport fine and medium sediment and water conservation and desert control arc implemented to intercept coarse sediment and extra coarse sediment. The hydrodynamic model was used to calculate the effect of deposition reduction schemes. It shows that the deposition reduction effect of various single measures is limited and the river channel continues to deposit. Only use the control scheme of "intercepting the coarse sediment and discharging the fine" can make the river channel slightly scoured and the schemes including reservoir regulation in the Inner Mongolia reach has a good effect on the flood restoration process. [ABSTRACT FROM AUTHOR]