七一冰川融水径流中悬移质与推移质动态输沙特征  

Dynamic Characteristics of Suspended Load and Bed Load Transport in Meltwater Runoff of Qiyi Glacier

作　　者：赵怡 王宁练 吴松柏 张泉 石晨烈 赵明杰 ZHAO Yi;WANG Ninglian;WU Songbai;ZHANG Quan;SHI Chenlie;ZHAO Mingjie(Shaanxi Key Laboratory of Earth Surface System and Environmental Carrying Capacity,Xi’an 710127,China;College of Urban and Environmental Sciences,Northwest University,Institute of Surface Systems and Hazards,QiYi Glacier Station,Xi’an 710127,China)

机构地区：[1]陕西省地表系统与环境承载力重点实验室,西安710127 [2]西北大学城市与环境学院,地表系统与灾害研究院,七一冰川观测基地,西安710127

出　　处：《水土保持学报》2024年第5期236-243,共8页Journal of Soil and Water Conservation

基　　金：国家自然科学基金项目(42130516,42007056);第二次青藏高原综合科学考察研究项目(2019QZKK020102)。

摘　　要：[目的]冰川融水输沙不仅可以反映冰川侵蚀速率,而且是下游河流泥沙的重要来源之一,因此,认识青藏高原地区冰川融水径流中悬移质和推移质动态输沙特征对于冰川地貌演化预测和下游防灾减灾工作具有十分重要的意义。[方法]基于2023年8月11-24日七一冰川下游河道的水文泥沙实测数据,分别构建流量-水位、悬移质含沙量-流量和单宽推移质输沙率-水流剪切应力之间的相关关系,进而重建整个研究时段的流量、悬移质和推移质动态输沙过程。[结果]七一冰川融水径流中悬移质含沙量和推移质输沙率受径流变化控制,日变化十分剧烈。悬移质含沙量每日最小值一般出现在10:00,最大值出现在16:00,中值粒径约为0.3 mm。推移质输沙过程与悬移质含沙量的日变化趋势基本相同,但推移质中值粒径远大于悬移质,约12 mm,而且在每日05:00-09:00时段,由于水流搬运能力的限制,没有推移质输沙。就输沙量而言,七一冰川融水输沙以悬移质泥沙为主,推移质日输沙量远小于悬移质日输沙量,约占悬移质日输沙量的1.73%~2.81%。冰面气温是影响冰川融水径流量、悬移质含沙量和推移质输沙率的关键因素,随着冰面气温的增加,径流量和悬移质含沙量均呈线性增加趋势而推移质输沙率呈指数函数增加趋势。[结论]在未来气候变化情景下冰川融水径流增加时,七一冰川融水径流中悬移质和推移质输沙均将变得更加显著,值得更加重视。[Objective]The transportation of sediment via glacial meltwater can not only reflect the glacial erosion and landform evolution,but also is one of the important sediment sources for the downstream river.Thus,understanding the suspended sediment and bedload dynamics in glacier meltwater runoff on the Tibetan Plateau is significant for predicting glacier landform evolution and conducting downstream disaster prevention and mitigation efforts.[Methods]To achieve the goal,the variations of flow discharge,sediment concentration of suspended load,and bed load transport rate per unit width were monitored at the downstream channel of Qiyi Glacier in the Qilian Mountains from August 11 to 24,2023.Based on the observed data,the relationship curves of flow discharge-water level,sediment concentration of suspended load-flow discharge,and unit bed load transport rate-flow shear stress were developed to obtain the variations of both water flow and sediment transport throughout the study period.[Results]The sediment concentration of suspended load and the bed load transport rate in the downstream channel of Qiyi Glacier are predominantly influenced by the variations in meltwater runoff,exhibiting pronounced daily fluctuations.The daily nadir of suspended sediment concentration is observed around 10:00,while the acme occurs around 16:00.The median particle size of the sediments is approximately 0.3 mm,indicating a fine-grained sediment composition.The variation trend of bed load transport rate versus time is almost the same to the suspended load,excepting at 05:00-09:00.During this period,there is no bed load in the channel since the flow shear stress is insufficient to mobilize and transport the bed load.Note that the median particle size of bed load is about 12 mm.The sediment transport in the downstream channel of Qiyi Glacier is primarily dominated by suspended sediment,and the daily sediment transport amount of bedload is much smaller than that of suspended sediment,accounting for only 1.73%~2.81%of the daily sediment transp

关 键 词：冰川融水径流 推移质 悬移质 输沙特征 气候变化 

分 类 号：P343.6[天文地球—水文科学]