Scholarlink

Purpose <p>Efforts were made to create a new method using digital image processing to analyze hyporheic flow in a pool-riffle sequence. This method was applied to assess the impact of vegetation cover on hyporheic velocity, residence time, and the reduction of pollutants such as phosphate and nitrate. Additionally, instantaneous vertical velocity profiles were developed to examine the importance of velocity components in upwelling and downwelling zones under both vegetated and non-vegetated conditions.</p> Materials and methods <p>Laboratory experiments were conducted, using edible dye to trace the flow. An image processing technique, implemented through a MATLAB code, was used to analyze and calculate instantaneous velocity. The dimensionless velocity profiles at different locations of vegetated and non-vegetated bedforms in the hyporheic zone were examined. Bed roughness and flow discharge influence these profiles differently across locations.</p> Results and discussion <p>The results indicate that in the downwelling zone, resultant velocity is equally influenced by horizontal and vertical components, while at the crest, this influence shifts with depth. In the upwelling zone, horizontal velocity predominantly influences the resultant velocity. The maximum error percentages were estimated at 7.89% for residence time and 10.83% for hyporheic velocity suggesting the reliability of the image processing technique. Additionally, the study examined the adsorption of phosphate and nitrate, highlighting the influence of hydrological dynamics, vegetation cover, and residence time on pollution removal.</p> Conclusions <p>This study explored hyporheic flow dynamics in a pool-riffle sequence, comparing vegetated and non-vegetated bedforms across various flow rates. Vegetation enhanced nutrient removal, improving phosphate and nitrate reduction, while also increasing residence times by up to 31.18%. Hyporheic velocities were reduced by vegetation, and image processing accurately predicted flow patterns. Findings highlight the complex interplay of vegetation, bedform structure, and flow discharge in nutrient cycling and water quality, offering insights for riverine ecosystem management.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Experimental monitoring of hyporheic flow behavior with the same bed structure and different covers by image processing

  • 期刊论文

  • 发表日期：

    2025年6月11日

查看全文
  • Fazeleh Kabiri,
  • Mohammad Reza Majdzadeh Tabatabai,
  • Mohammad Sharifi,
  • Mohammad Shayannejad

摘要

Purpose

Efforts were made to create a new method using digital image processing to analyze hyporheic flow in a pool-riffle sequence. This method was applied to assess the impact of vegetation cover on hyporheic velocity, residence time, and the reduction of pollutants such as phosphate and nitrate. Additionally, instantaneous vertical velocity profiles were developed to examine the importance of velocity components in upwelling and downwelling zones under both vegetated and non-vegetated conditions.

Materials and methods

Laboratory experiments were conducted, using edible dye to trace the flow. An image processing technique, implemented through a MATLAB code, was used to analyze and calculate instantaneous velocity. The dimensionless velocity profiles at different locations of vegetated and non-vegetated bedforms in the hyporheic zone were examined. Bed roughness and flow discharge influence these profiles differently across locations.

Results and discussion

The results indicate that in the downwelling zone, resultant velocity is equally influenced by horizontal and vertical components, while at the crest, this influence shifts with depth. In the upwelling zone, horizontal velocity predominantly influences the resultant velocity. The maximum error percentages were estimated at 7.89% for residence time and 10.83% for hyporheic velocity suggesting the reliability of the image processing technique. Additionally, the study examined the adsorption of phosphate and nitrate, highlighting the influence of hydrological dynamics, vegetation cover, and residence time on pollution removal.

Conclusions

This study explored hyporheic flow dynamics in a pool-riffle sequence, comparing vegetated and non-vegetated bedforms across various flow rates. Vegetation enhanced nutrient removal, improving phosphate and nitrate reduction, while also increasing residence times by up to 31.18%. Hyporheic velocities were reduced by vegetation, and image processing accurately predicted flow patterns. Findings highlight the complex interplay of vegetation, bedform structure, and flow discharge in nutrient cycling and water quality, offering insights for riverine ecosystem management.