Analysis of morphodynamic evolution in a meandering estuarine channel in the context of climate change

在长期基础上，根据人类活动和灾害发生的时间将整个研究期间分为三个阶段：(1)人类活动时期(1953-1998年)；(2)无人类活动和无灾害时期(1998-2003年)；(3)灾害时期(2003-2022年)。在第一阶段，由于大量的人类活动，如疏浚(防洪)、填海造地、采砂等，河床下降；第二阶段，河床高程上升了0.5-1m，这是由于潮汐引起的陆上输沙和沉积过程。在-3期间，由于极端洪水灾害侵蚀了河口上游沉积的泥沙，河床高程下降。虽然极端的洪水和山体滑坡灾害为奇库戈河提供了大量的泥沙，但灾害提供的泥沙似乎被困在了河流的上游，不足以到达河口。3期间，现有沉积物的侵蚀和上游泥沙供应不足导致河口河床高程下降。

On a long-term basis, the whole study period was divided into three based on the time of human activities and disasters occurrence; (1) the period of human activities (1953-1998), (2) the period of no human activities and no disasters (1998-2003), and (3) the period of disasters (2003-2022). During period-1, the riverbed was lowered due to extensive human activities such as dredging (flood control), land reclamation, sand mining, etc. During period-2, the bed elevation increased by 0.5-1 m, which was due to the tide-induced landward sediment transport and deposition process. During period-3, the bed elevation decreased as extreme flood disasters eroded the sediment deposited upstream of the estuary. Although the extreme floods and landslide disasters supplied massive sediments into the Chikugo River, it seemed that sediments supplied by disasters were trapped upstream of the river and were not enough to reach the estuary. The erosion of existing deposits and lack of sediment supply from the upstream caused the decrease in estuarine bed elevation during period-3.