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动床条件下植被盖度对坡面流水动力特性的影响
唐科明1, 张光辉2, 曹 颖3
1.四川农业大学 水利水电学院;2.北京师范大学 地理科学部;3.北京市地质研究所
摘要:
【目的】探讨动床条件下植被盖度对坡面流水动力参数的影响。【方法】采用变坡水槽,在2°~10°坡度、0.25~2.0 L/s流量、0%~25%盖度条件下,系统研究动床条件下植被盖度对坡面流流速、流型、流态、阻力系数等水动力参数的影响。【结果】流速为0.09~1.13 m/s时,盖度显著影响坡面流流速,且随着盖度增加,坡面流流速呈幂函数式降低;流量越大,相同盖度增幅引起的流速降幅越大。统计分析显示,相同试验条件下,动床坡面与定床坡面的流速无显著差异。试验条件下雷诺数为557~5 560,弗劳德数为0.22~5.52,盖度对坡面流流型、流态影响显著,随着盖度增加,雷诺数及弗劳德数减小,坡面流流态由急流向缓流区域延伸。阻力系数为0.03~2.09,且随着盖度增加而增大。【结论】植被盖度显著影响坡面流流速、流型、流态及阻力系数。
关键词:  动床条件  植被盖度  坡面流  水动力特性  阻力系数
DOI:
分类号:
基金项目:国家自然科学基金项目(41601288)
Influences of vegetation coverage on hydraulic characteristics of overland flow on an eroding bed
TANG Keming,ZHANG Guanghui,CAO Ying
Abstract:
【Objective】Influences of vegetation coverage on hydrodynamic characteristics of overland flow on an eroding bed were investigated.【Method】Influences of simulated vegetation cover on hydraulic parameters including flow velocity,flow pattern,flow regime,and resistance coefficient of overland flow were investigated systematically under 2°-10° slope,0.25-2.0 L/s flow discharge, and 0%-25% vegetation coverage using an experimental flume with varying slope.【Result】When flow velocity fluctuated from 0.09 to 1.13 m/s,vegetation cover significantly impact flow velocity and flow velocity declined in a power function as the increase of vegetation coverage.Greater flow discharge had larger decrease in flow velocity with same increase of coverage.Statistical analysis showed that there was no significant difference in flow velocity between the eroding bed and the fixed bed under same experimental conditions.Reynolds number ranged from 557 to 5 560,and Froude number ranged from 0.22 to 5.52.Vegetation coverage had significant impact on overland flow pattern and flow regime.Reynolds number and Froude number decreased as vegetation coverage increased,and overland flow developed from supercritical flow to subcritical flow with increasing vegetation coverage.Flow resistance coefficient fluctuated from 0.03 to 2.09,and resistance coefficient increased as vegetation coverage increased.【Conclusion】Vegetation coverage significantly affected overland flow velocity,flow pattern,flow regime,and flow resistance coefficient.
Key words:  eroding bed  vegetation coverage  overland flow  hydraulic characteristics  resistance coefficient

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