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On-line Access: 2022-06-22

Received: 2021-10-26

Revision Accepted: 2022-05-23

Crosschecked: 2022-09-22

Cited: 0

Clicked: 718

Citations:  Bibtex RefMan EndNote GB/T7714

 ORCID:

Jian-min ZHANG

https://orcid.org/0000-0002-9154-231X

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Journal of Zhejiang University SCIENCE A 2022 Vol.23 No.9 P.733-744

http://doi.org/10.1631/jzus.A2100540


Effects of the mixing degree upstream of the diverging area on the pollutant allocation characteristics of a braided river


Author(s):  Jun ZOU, Jian-min ZHANG, Chang-yuan LI

Affiliation(s):  College of Water Resource & Hydropower, Sichuan University, Chengdu 610065, China; more

Corresponding email(s):   zhangjianmin@scu.edu.cn

Key Words:  Mixing degree upstream, Diverging area, Longitudinal distance, Deviation of pollutant flux ratio, Standard deviation, Linear relationship


Jun ZOU, Jian-min ZHANG, Chang-yuan LI. Effects of the mixing degree upstream of the diverging area on the pollutant allocation characteristics of a braided river[J]. Journal of Zhejiang University Science A, 2022, 23(9): 733-744.

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Abstract: 
The mixing degree upstream of the diverging area is one of the important factors influencing the pollutant allocation characteristics of braided rivers, but the effect remains unclear at present. In this paper, physical model tests were designed to study the effect on the pollutant flux ratio with six branching forms and a series of longitudinal discharge distances. The results indicated that the mixing degree upstream of the diverging area, which is closely related to the longitudinal discharge distance, notably affected the pollutant flux ratio. The lower the mixing degree, the larger was the deviation of the pollutant flux ratio from the discharge ratio. Moreover, a linear relationship was attained between the dimensionless mixing degree and the dimensionless deviation of the pollutant flux ratio from the discharge ratio. Consideration of different branching angles or different water layers or different branches did not affect this trend. The experimental results further demonstrated that the intercept and slope of the aforementioned linear relationship depended on the branching angle and exhibited an opposite monotonicity with a symmetric branch angle as the dividing point. These results help towards a better understanding of the mechanism of the factors influencing pollutant transport in complicated braided rivers, and provide a new approach to predicting the pollutant flux ratio of braided rivers.

分流区前混合度对分汊河流分污特性的影响

作者:邹俊1,2,张建民1,李昌垣2
机构:1四川大学,水利水电学院,中国成都,610065;2江西省水利科学院,中国南昌,330029
目的:分汊河流支汊间的污染物分配规律具有重要意义。同时,分污特性受诸多因素影响,因此较为复杂。本文旨在探讨在具有分汊结构的河流中,分流区前污染物混合度对下游支汊分污比的影响。研究与排放位置相关的混合度的定义、量化以及与分污比的规律关系,以进一步认识分汊河流污染物扩散影响因素的作用机制。
创新点:1.建立水质物理模型,得到在排放位置影响下支汊分污比的变化情况。2.基于高斯分布,定义分流区前混合度,并得到无量纲化的混合度与分污比偏离量的线性关系。3.得出在线性关系中线性系数受分汊角的影响情况。
方法:1.建立包含6种分汊形式与多种排放位置的水质物理模型,得到排放位置与分污比的关系(图9~14);2.基于分流区前断面浓度分布的试验成果,借助高斯分布公式定义分流区前混合度(图16);3.通过无量纲化处理,得到分流区前混合度与分污比偏离量的关系(图18~29)。4.通过数据分析,构建线性关系中的系数与分汊角的关系。
结论:1.与纵向排放距离高度相关的分流区前混合度显著影响分污比;混合度越低,分污比偏离相应分流比的幅度越大。2.无量纲化的混合度与无量纲化的分污比偏离量呈现近似线性关系。3.线性关系中的截距和斜率与分汊角相关,并以对称分汊角为界呈现相反的单调性。

关键词:混合度;分流区;纵向距离;分污比偏离量;标准差;线性规律

Darkslateblue:Affiliate; Royal Blue:Author; Turquoise:Article

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