为了探明黄河源水电站大坝的修建与拆除对下游河道形态与水动力调整的影响，基于1986—2022年Landsat系列遥感影像，提取坝址下游河道的水域面积计算河道平面形态参数。采用TELEMAC-2D模型对黄河源水电站建坝前、电站运行期间、拆坝后3个阶段进行水动力模拟与分析。结果表明：相比建坝前，电站运行期间下游河道水域面积减少2.05 km2 (29.62%)，辫状强度降低0.72 (20.40%)，河道断面平均水深和流速分别减小0.22 m (12.51%)和0.11 m/s (11.73%)；相比电站运行期间，拆坝后下游河道水域面积增加1.55 km2 (31.83%)，辫状强度增大0.37 (13.17%)，断面平均水深和流速分别增大0.13 m (8.20%)和0.06 m/s (7.08%)；黄河源水电站拆除后，下游河道辫状和水动力特征均有所恢复，但工程活动对下游河道的长期影响依然存在，恢复过程较为缓慢。
英文摘要:
The construction and removal of the Yellow River Source Hydropower Station has affected the morphological and hydrodynamic adjustments of the downstream channel. To investigate the impact, we extracted the water surface area data of the downstream channel from Landsat images (1986 to 2022), and calculated the planar morphological parameters of the channel. The TELEMAC-2D model was applied to simulate and analyze hydrodynamic conditions in three stages (pre-dam construction, dam operation, and post-dam removal). The results show that compared with the pre-dam construction stage, water surface area in the downstream decreased by 2.05 km2(29.62%) during dam operation stage, with a decrease of 0.72 (20.40%) in braiding index, 0.22 m (12.51%) in average cross-sectional water depth, and 0.11 m/s (11.73%) in velocity. Following dam removal, the water surface area increased by 1.55 km2(31.83%), with an increase of 0.37 (13.17%) in braiding index, 0.13 m (8.20%) in average water depth, and 0.06 m/s (7.08%) in velocity, compared with the dam operation stage. These findings indicate that the removal of the Yellow River Source Hydropower Station contributed to partial recovery of downstream channel braiding and hydrodynamic conditions; however, the long-term effects of the engineering activities on downstream channel persist, and the recovery process remains slow.