关键词: 清水沟河道, 河床调整, 平面形态, 断面形态, 黄河口

Abstract: Remarkable channel adjustments have occurred in the Yellow River estuary since the 1996 artificial avulsion from the Diaokouhe course to Qingshuigou course. The channel has evolved through four stages: rapid aggradation, undercutting, shrinkage, and severe degradation. Its geometrical variations indicate that (i) in the initial stage of 1976-1980, the study reach was drastically aggraded, with its length increasing from 75.1 km to 93.2 km; (ii) during 1980-1984, numerous branches near the river mouth were gradually coalescing into a single channel toward the southeast, and channel undercutting was dominant; (iii) after 1984, the channel’s bankfull area was decreased by 61% in severe shrinkage caused by the operation of Longyangxia reservoir, with its thalweg migrating frequently at a migrating intensity and width of 0.17 and 102 m respectively; (iv) during 1999-2016, its bankfull depth was increased by 41% and the migrating intensity and width decreased to 0.09 and 37 m respectively. In addition, we develop empirical relationships of reach-scale bankfull dimensions and thalweg-migrating intensity versus the average flow scour intensity over previous four years, which give satisfactory predictions of channel adjustments highly correlated with the real case.

Key words: Qingshuigou channel, channel adjustments, bankfull channel geometry, planform geometry, Yellow River estuary