Jianguo Chen / China Institute of Water Resources and Hydropower Research
The Xiaolangdi Hydro-project, another large hydro-project below the Sanmenxia was put into operation in Oct., 1999, has a dam with a height of 173m and a reservoir with a volume of 12.65×109 m3. The reservoir has been operated at high water level in non-flood season to retain the incoming runoff for the needs of both the ice-flood prevention and irrigation of the Lower Yellow River region, and at low water level in flood season for the needs of flood control.
The water stored above the flood control level of the reservoir was regulated and released from the Xiaolangdi Reservoir as a man-made flood peak to enhance the erosion of the Lower Yellow River. The nineteen man-made flood peaks were carried out in 2002~2015, the total water for these peaks amounted to 1.24×109m3~6.04×109m3 and the total sediment load were 0~0.08×109t. The amount of erosion was increased with the increasing of incoming water of flood, the amount of erosion and the efficiency of channel erosion was gradually declined from 2006.
The erosion appeared along the whole river, the total erosion for the nineteen man-made flood peaks amounted to 0.427×109t, 1 m3 of incoming water could erode averagely about 6kg of bed sediment. Moreover, all the erosion happened in the main channel, which was beneficial to the enlargement and comparatively narrower of cross-sections, dropping the water level and increases of flood conveying and sediment transporting capacities.
The incoming runoff for the nineteen man-made flood peaks accounted for 19.1% of the total runoff in 2002-2015, the erosion was 17.5% of the total correspondingly. All of these imply that the man-made flood peak resulted from the utilization of abandoned water of the reservoir is much affective to strengthen the channel erosion although it is just a part of the total erosion.