The Mekong River, which has high economic and ecological importance, has an extensive floodplain and delta plain that extends from Cambodia to Vietnam. Understanding the Holocene evolution of the fluvial system is needed in order to predict the future development of the system and develop a strategy to guide the sustainable management. This paper reconstructs the Holocene sedimentary evolution of the Mekong River floodplain, Cambodia, from 12 auger cores and 69 optically stimulated luminescence ages, and compares the reconstructed floodplain history with that of other large river systems. Rapid deposition of thick crevasse splays implies floodplain aggradation in response to sea-level rise before 6.5 ka. After 6.5 ka, when the sea-level reached a stillstand, the rapid aggradation ceased and levee and crevasse-splay deposition were localized near the anastomosing river channels. The rate of levee accretion was very low in the anastomosing river system (<1 m/kyr), which implies that the riverbed aggradation caused by sea-level rise before 6.5 ka outpaced levee accretion and led to avulsion by diversion into the floodbasin. Some distributary channels were abandoned around 4 ka, corresponding to a shift from an anastomosing to a single-channel river system. This shift might be attributed to an abrupt decrease in precipitation caused by weakening of the East Asian and Indian summer monsoons. Downstream of Phnom Penh, rapid levee deposition started on the uppermost delta plain after 1 ka while rapid lateral migration of the river channel occurred upstream. These increased fluvial activities correspond to accelerated mud accretion of the Mekong delta coast and potentially reflect an increase in sediment supply caused by human activities. The evolution of the Mekong River floodplain might be comparable with other large river systems in the EASM, ISM, and African monsoon regions, where a substantial weakening of the summer monsoon and hence a decrease in precipitation occurred in response to declining summer insolation in the middle to late Holocene.

湄公河具有很高的经济和生态重要性，其漫长的洪泛区和三角洲平原从柬埔寨延伸到越南。需要了解河流系统的全新世演化，以便预测系统的未来发展并制定策略来指导可持续管理。本文利用12个钻头岩心和69个光学激发发光年龄重建了柬埔寨湄公河洪泛区的全新世沉积演化，并将重建后的洪泛区历史与其他大型河流系统进行了比较。厚裂隙张开的快速沉积意味着洪泛平原在6.5 ka之前因海平面上升而聚集。6.5 ka之后，当海平面达到静止状态时，快速的沉积停止了，堤坝和裂隙张开的沉积物被定位在吻合河道附近。在吻合河系中堤防积聚率非常低（<1 m / kyr），这意味着在6.5 ka之前海平面上升引起的河床沉降超过了堤防积聚，并通过分流入洪泛区而导致淤积。一些分配河道在4 ka左右被废弃，这对应于从吻合河系向单河道河系的转变。这种变化可能归因于东亚和印度夏季风减弱造成的降水突然减少。在金边的下游，在1 ka之后，最上游的三角洲平原开始出现快速的堤防沉积，而上游的河道则发生了快速的横向迁移。这些增加的河流活动对应于湄公河三角洲海岸泥浆的加速增长，并可能反映出人类活动造成的沉积物供应增加。湄公河漫滩的演变可能与EASM，ISM和非洲季风地区的其他大型河流系统相媲美，这些地区的夏季风明显减弱，因此，由于中部夏季日晒量减少，降水减少到晚全新世。