1954—2015年东江流域水沙演变规律

Changes in runoff and sediment patterns in the Dongjiang River basin from 1954 to 2015

流域水沙过程在区域水土资源形成、河流海岸地貌重塑及生态环境演变中起着关键作用,在气候变化和人类活动双重影响下其演变规律一直以来备受关注。基于多元时序聚类与侵蚀性降雨分析,以博罗水文站为例,探讨东江流域水沙演变规律及潜在驱动因素。结果表明:①大规模的植树造林活动使得1980—2015年研究区域的森林覆盖率增长了超过30%;②博罗水文站的水沙关系在1987年后发生明显变异,主要原因可归结为由水库修建运行及植树造林所造成;③2005—2006年出现与1954—1987年相似的水沙关系,原因是极端天气带来降雨侵蚀力的异常增强,超过了产沙阈值。相关研究结果可为东江流域水沙关系及其对全球变化的响应研究提供科学依据,支撑东江流域气候变化应对和水土资源开发。

Runoff and sediment processes at a basin scale,are an important research focus because of their role in providing regional water and soil resources,reshaping rivers and coastal landforms,and altering ecosystems.Using multivariate time series clustering and erosive rainfall analysis,this study presents a case study of Boluo hydrometric gauge in the Dongjiang River basin to explore variations of flow discharge and sediment load and their potential driving factors.The results indicated that:①Forest coverage increased by more than 30%in the study area during 1980—2015 owing to large-scale afforestation activities.②The flow discharge-sediment load relationship at the Boluo hydrometric gauge showed significant changes after 1987,primarily attributed to reservoir construction and operation,as well as afforestation activities.③Extreme weather events intensified rainfall erosivity beyond the sediment-yielding threshold,leading to a flow discharge-sediment load relationship that was similar in 2005—2006 to that in 1954—1987.These findings provide a scientific basis for studying the runoff-sediment relationship in the Dongjiang River basin and its response to global changes.They support climate change adaptation and the development of water and soil resources in the basin.