边滩对分层河岸带潜流层溶质迁移过程的影响

Influence of point bar on solute transportation in hyporheic zone within riparian zone with stratified structure

  • 摘要: 为探究边滩对分层河岸带潜流层溶质迁移过程的影响,利用双循环可控式河岸带模型,通过10组物理模型试验,定量分析了不同边滩淹没深度、河岸带基质和地表水流速条件下的溶质迁移特性。结果表明:边滩促进了滩前和边滩区域的溶质迁移,抑制了滩后区域的溶质迁移;随着边滩淹没深度的增加,溶质迁移速率和面积增加,但当边滩由部分淹没转变为完全淹没时,对溶质迁移过程的促进作用减弱;河岸带潜流层的分层结构显著抑制了溶质的微速迁移阶段,分层条件下微速迁移阶段的溶质质量仅为砾石条件下的1/3;3种因素对溶质迁移过程的影响程度依次为淹没深度>河岸带基质>地表水流速。本研究丰富了河岸带潜流交换理论,可为河岸带生态修复提供科学依据。

     

    Abstract: This study investigated the effect of point bar on solute transport in the hyporheic zone within a riparian zone (HZRZ) which had a stratified structure. Using a two-way flow riparian zone model, ten experimental groups were analysed. Quantitative analysis was performed to investigate the effect of point bar submergence depth (h), riparian zone sediment (s), and surface flow velocity (u) on solute transport. The findings showed that point bars improve solute transport in both the upper section of the point bar and the section where point bar located, while inhibiting it in the lower section of the point bar. Moreover, increasing the submergence depth of the point bar resulted in higher rates and areas of solute transport. However, once the point bar was fully submerged, its effectiveness in promoting solute transport diminished. Additionally, the hyporheic zone within the riparian zone, with its stratified structure, significantly reduced the slow-speed transportation period, resulting in only one-third of the observed solute mass compared with homogeneous gravel conditions. Among the factors influencing solute transport, the submergence depth of the point bar had the highest impact, followed by the riparian zone sediment and surface flow velocity. This study advances the understanding of hyporheic exchange within riparian zone and provides a scientific basis for ecological restoration in riparian zone.

     

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