摘要
潜流驻留时间是反映潜流交换、溶质迁移转化、生物组成、生态过程的重要特征变量。应用双循环可控式河岸带模型,以NaCl为示踪剂,深入研究了河岸带蜿蜒性与植被密度对潜流驻留时间的复合效应;应用量纲分析和主成分分析法,探析了潜流驻留时间的关键影响因子及其作用程度和敏感性。结果表明:①河岸带植被密度对潜流驻留时间具有促进作用,但存在一定的阈值。②潜流驻留时间分布与河岸蜿蜒形态呈类镜像效应;潜流驻留时间在河岸带蜿蜒波不同位置差异明显,迎水面平均驻留时间约为背水面的1/2。③河岸带蜿蜒性与植被密度是影响潜流驻留时间的关键因子,总作用程度达91.07%。潜流驻留时间对蜿蜒性最敏感,对植被密度敏感性较弱,对复合因子的敏感性介于两者之间;迎水面内组合因子对潜流驻留时间具有共同促进效应,背水面内组合因子对潜流驻留时间具有抑制和促进双重效应。
Hyporheic linkages between riparian zones and stream channels are a key component to riparian and stream system,which greatly influence the solutes transportation and transformation that are fundamental to sustaining biogeochemical cycling,biological community,ecological processes and habitat. The extent to which transportation and transformation processes occur is greatly dependent on the hyporheic residence time(HRT). However,our understanding of how this HRT mechanisms is still poorly understood. To explore the mechanism of HRT in riparian zones,we designed an experimental installment,a two-way flow riparian zone model,to evaluate the rate at which an active hyporheic flow developed. Using sodium chloride(NaCl) as conservative solute tracer,tracer experiment was conducted to explore compounding effects of meandering degree and vegetation density on HRT in riparian zone. As vegetation in riparian zones has the potential to fast the hyporheic exchange,it had resulted in the decreasing of the HRT with vegetation density increasing. But vegetation density had a critical value. When the vegetation density was larger than the critical value,the HRT no longer reduced. Over the entire riparian zone,the influence of morphology had apparent mirror-like effect on the distribution of HRT which depended on the position of meandering topography of riparian zone. The mean HRT of the upstream face was about 1/2 of that of downstream face. What’s more,hydraulic,vegetation,morphology and soil features had been identified as the key influencing factors of HRT by using dimensional analysis and their sensitivities had been valued with the method of principal components analysis(PCA). Together,the meandering amplitude of topography and the vegetation space were the most sensitive parameters because their total contribution rate reached 91.07%. Under the action of the both factors,it appeared promotional effects on the HRT of the upstream face of meandering wave while there existed not only the promotional effects but also inhibition effects on the HRT of the downstream face of meandering wave.
作者
夏继红
窦传彬
蔡旺炜
曾灼
余根听
XIA Jihong;DOU Chuanbin;CAI Wangwei;ZENG Zhuo;YU Genting(College of Agricultural Science and Engineering,Hohai University,Nanjing 210098,China;Zhejiang Institute of Hydraulics&Estuary,Hangzhou 310009,China)
出处
《水科学进展》
EI
CAS
CSCD
北大核心
2020年第3期433-440,共8页
Advances in Water Science
基金
国家重点研发计划资助项目(2018YFD0900805)
国家自然科学基金资助项目(41471069)。
关键词
蜿蜒河岸带
植被密度
潜流驻留时间
复合效应
敏感性
meandering riparian zone
vegetation density
hyporheic residence time
compounding effect
sensitivity
