Impacts of descending Tongguan elevation on fluvial process in the Weihe River

The Weihe River, the largest tributary of the Yellow River, empties itself into the Yellow River at Tongguan. The lower Weihe River is in the backwater region of the Sanmenxia Reservoir. The Tongguan's elevation is defined as the stage of a flood discharge at 1000 m 3/s at Tongguan hydrologic station, which is essentially the datum plane of the bed profile of the Weihe River. Severe sedimentation has occurred in the lower Weihe River since the impoundment of the Sanmenxia Reservoir in Sept 1960 because the Tongguan's elevation has risen by 5 meters. If Tongguan's elevation falls by 2m, strong erosion in the Huayin and Huaxian reaches will occur. The discharge capacity of the channel will increase, thus small and mid-scale flood stage will fall. The channel regime coefficients in the lower Weihe River will decrease and the channel became deep and narrow. As a meandering-wandering river, the channel will still wandering and the sinuosity will reduce. More stabilization engineering projects are still needed to maintain the river channel stable.