Erosion and deposition evolution of the abandoned Diaokou course of the Yellow River and influential factors

From 1964 to 1976, the Yellow River flowed through the Diaokou course into the Bohai Sea. In 1976, the Diaokou course was abandoned and replaced by an artificial diversion to the Qingshuigou course. Based on the measured elevation data of the abandoned Diaokou course in years of 1976, 2000, and 2016, we calculated the volume of erosion and deposition along the Diaokou course at different stages, described the spatial distribution of erosion and deposition of the Diaokou course, and discussed the potential impact factors on the Diaokou course evolution over the last 40 years after its abandonment. The results indicate that during 1976-2000, the Diaokou course experienced erosion at rate of ～1.92×10⁶ t/a, and during 2000-2016, the Diaokou course was silted at deposition rate of ～7.99×10⁶ t/a. The erosion and deposition along the Diaokou course present significant spatial difference during 2000-2016. Taking section D20 as the boundary, the seaward river section was in scouring state, and the storage capacity of river channel increased; while the landward section was in siltation state, and the storage capacity of the river channel decrease. The evolution of erosion and sedimentation in the Diaokou course was not only affected by the ecological water diversion and marine dynamic erosion, but also by the development of nearby oil fields, farming, and forestation. Therefore, to maintain the water flow capacity of the Diaokou course, cleaning up the Diaokou course is urgent to ensure good condition of the Diaokou course as a backup waterway of the Yellow River seaward empting.