摘要
[目的]河床物理堵塞是季节性河流的常见问题,对地下水补给和河流生态修复具有重要影响,分析季节性河流的入渗和堵塞特征,预测河床脱节后的入渗速率,为后续河流生态修复和补水方案优化提供科学依据。[方法]以永定河下游为参考河段选择5种河床质作为入渗介质,中值粒径(d50)分别为50、100、150、300、600μm,利用6 g/L的浑水开展一维土柱下渗模拟试验,分析河床堵塞特征与饱和流-非饱和流转化规律,研究建立考虑物理堵塞影响的河床入渗过程预测模型。[结果]1)中值粒径为50μm的细颗粒河床未发生明显堵塞,100~600μm河床发生堵塞的深度为0~5 cm,渗透系数较初始值分别下降86%、68%、93%、94%。2)50μm河床入渗全程为饱和渗流,100~600μm河床大约在2.6~51.2 h由饱和渗流转化为非饱和渗流,入渗速率降幅约为15%~30%。3)构建基于达西定律与粗颗粒渗流公式的考虑堵塞影响的河床入渗模型,模型验证表明,4种粗颗粒(100~600μm)河床入渗速率的相对误差分别为8.6%、14.7%、22.1%、36.6%,并随中值粒径的增大而增大。[结论]浑水中细泥沙对粗质地河床堵塞影响较大,河床质地越粗,越容易转为脱节河床。科学认识细泥沙在不同质地河床的下渗-堵塞规律,对后续优化生态补水方案具有重要意义。
[Objective]Physical clogging of riverbeds is a common problem in seasonal rivers,significantly affecting groundwater recharge and river ecological restoration.This study analyzes the infiltration and clogging characteristics of seasonal rivers,predicts the infiltration rates after riverbed disconnection,and provides scientific support for optimizing river ecological restoration and water replenishment schemes.[Methods]Taking the lower reaches of the Yongding River as a reference,five types of riverbed sediments with median particle sizes d50 of 50,100,150,300,and 600µm were selected as experimental media.One-dimensional soil column infiltration simulation tests using 6 g/L muddy water were conducted to analyze the riverbed clogging characteristics and the transformation pattern from saturated to unsaturated flow.A prediction model for riverbed infiltration,considering the influence of physical clogging,was developed.[Results]1)For fine particle riverbed with a median particle size of 50µm,no significant clogging occurred.For riverbeds with particle sizes ranging from 100 to 600µm,clogging occurred at a depth of 0 to 5 cm,and the hydraulic conductivity decreased by 86%,68%,93%,and 94%,respectively,compared to the initial values.2)The 50µm riverbed maintained saturated seepage throughout infiltration.For riverbeds with particle sizes ranging from 100 to 600µm,the flow transformed from saturated to unsaturated seepage within 2.6 to 51.2 hours,with infiltration rates decreasing by approximately 15%to 30%.3)A riverbed infiltration model considering clogging effects was constructed based on Darcy′s law and the seepage formula for coarse particles.Model validation showed that the relative errors of the infiltration rates for four coarse-particle riverbeds(100-600µm)were 8.6%,14.7%,22.1%,and 36.6%,respectively,and increased as the median particle size increased.[Conclusion]Fine sediment in muddy water has a significant impact on the clogging of coarse-textured riverbeds.The coarser the riverbed texture,the more likely it is to transform into a disconnected riverbed.A scientific understanding of the infiltration-clogging behavior of fine sediment in riverbeds of different textures is essential for optimizing ecological water replenishment schemes.
作者
苗庆远
潘成忠
刘聪敏
MIAO Qingyuan;PAN Chengzhong;LIU Congmin(College of Water Sciences,Beijing Normal University,Beijing 100875,China;State Key Laboratory of Earth Surface Processes and Resource Ecology,Faculty of Geographical Science,Beijing Normal University,Beijing 100875,China)
出处
《水土保持学报》
北大核心
2025年第5期71-79,共9页
Journal of Soil and Water Conservation
基金
国家自然科学基金项目(42077059)。
关键词
入渗
河床堵塞
渗流转化
变渗透系数
模型
infiltration
riverbed clogging
seepage transformation
variable permeability coefficient
model
