Abstract: Low conveyance capacity of Ningxia-Inner Mongolia Reach is key factors which threatened the security of Flooding and Ice Run upper Yellow River, it also a bottleneck developing regulation and control of runoff and sediment of the Ningxia-Inner Mongolia Reach. Conveyance capacity of overcurrent is determined by the relationship curve between water level and flow in this paper, and the current conveyance capacity and historical conveyance capacity are analyzed comparatively, the causes of the overcurrent capacity of the Ningxia-Inner Mongolia Reach are discussed. The results show that:the reach has a dramatic phenomenon of riverbed elevation and over-current capacity decline since establishment of stations; the present conveyance capacity of the reach decreased from 5 200-6 200 m³·s^-1 to 1 500-2 200 m³·s^-1, some sections More than 1 500 m³·s^-1 will lead to the floodplain, and reduce the conveyance capacity greatly; proposed the construction of standardization dike to improve the conveyance capacity; under the premise of the Yellow River dike standardization, access to the secure flow of traffic through, establishing foundation on developing runoff and sediment regulation and control of the Ningxia-Inner Mongolia Reach safely and successfully. Research has important practical significance to improve the Ningxia-Inner Mongolia Reach overcurrent condition and accelerate the Standardized construction process of the Yellow River each section of Ningxia-Inner Mongolia Reach dike.

Key words: the relationship between water level and flow, conveyance capacity, regulation and control of runoff and sediment, erosion-deposition variation