摘要
水流交汇现象在河流水系中普遍存在,支渠高浓度污染物的汇入会导致干渠下游水质污染,威胁到下游各地区用水安全。建立90°等宽明渠交汇口二维水动力水质耦合模型,研究提出通过在明渠交汇口附近布置潜坝的工程措施增强污染物混合从而降低污染物浓度。对不同潜坝位置、长度、高度共14种工况进行数值模拟。研究结果表明,在交汇口附近布置潜坝可以加速污染物混合,进而降低污染物浓度极值;潜坝加速污染物混合扩散的主要机理是潜坝产生的横向流速区及回流区加剧了水体对流作用,促进了污染物的混合;在交汇口下游干渠右岸布置潜坝对污染物的混合加速效果明显;当潜坝长度为1/2河宽时,对污染物的混合最有利;潜坝越高,效果越好;在合适的潜坝布置工况下,明渠出口断面污染物浓度变异系数降低了46%,最大污染物浓度值降低了33%,效果明显。
With the rapid development of industry and agriculture,river water pollution problems are becoming more and more serious.The phenomenon of water flow confluence is common in river systems.Due to the complex hydraulic characteristics of the intersection,the influx of highly concentrated pollutants from branch channels can accumulate in the downstream of the main channel,causing river water pollution and seriously threatening the water safety of downstream regions.Aiming at the water quality pollution of the confluence caused by tributary discharge, a two-dimensional hydrodynamic and water quality coupling model of the 90° equal-width open channel confluence is establishedbased on the hydrodynamic and water quality model software Delft3D. The model parameters are calibrated through comparison and verifica⁃tion with physical model experiments in existing studies. The study proposes that the engineering measures of arranging submerged dams nearthe open channel intersection can intensify the convection of the flow, enhance the mixing of pollutants and reduce the concentration of pol⁃lutants, so as to solve the problem of water pollution near river confluences. A total of 14 arrangements of different submerged dam locations,lengths, and heights are numerically simulated. Then the pollutant distribution maps and flow field distribution maps under each working con⁃dition has been obtained, and the variation coefficient and extreme value of pollutant concentration in each section are calculated for analy⁃sis. The research findings show that the arrangement of submerged dams near the confluence can accelerate the mixing of pollutants, therebyreducing the extreme value of pollutant concentration. The main mechanism for the submerged dams to accelerate the mixing and diffusion ofpollutants is that the transverse velocity zone and recirculation zone generated by the submerged dam intensify the flow convection effect, pro⁃moting the mixing of pollutants. The arrangement of submerged dams on the right bank of the main channel downstream of the confluence hasa better effect on reducing the concentration of pollutants than the arrangement of submerged dams on the left bank. Among the simulated con⁃ditions, pollutant concentration can be most significantly reduced when the length of the submerged dam is one-half the width of the river.The higher the submerged dam , the better the effect of reducing the extreme value of pollutant concentration. The coefficient of pollutant con⁃centration variation can be reduced by 46%, and the maximum pollutant concentration value can be reduced by 33% under the appropriatesubmerged dam arrangement condition compared to the baseline condition without submerged dams. When the submerged dam is arrangedacross the river width, the generated transverse flow velocity area is located on the bank, which has limited effects on the mixing of pollut⁃ants. The research conclusions can provide a scientific basis for pollution control in converging rivers.
作者
刘洋
朱海
张召
颜培儒
王浩
徐洁如
LIU Yang;ZHU Hai;ZHANG Zhao;YAN Pei-ru;WANG Hao;XU Jie-ru(State Key Laboratory of Water Resources Engineering and Management,Wuhan University,Wuhan 430072,Hubei Province,China;College of Water Conservancy and Hydropower Engineering,Hohai University,Nanjing 210098,Jiangsu Province,China;Department of Water Resources,China Institute of Water Resources and Hydropower Research,Beijing 100038,China;College of Water Conservancy and Civil Engineering,Shandong Agricultural University,Tai’an 271018,Shandong Province,China)
出处
《中国农村水利水电》
北大核心
2023年第12期119-127,138,共10页
China Rural Water and Hydropower
基金
国家重点研发计划项目(2021YFC3200403)
黄委优秀青年人才科技项目(HQK-202320)
黄河水资源保护科学研究院科研专项项目(KYY-KYZX-2022-01)。
关键词
交汇明渠
污染物混合
数值模拟
潜坝
open channel confluence
pollutant mixing
numerical simulation
submerged dams
作者简介
刘洋(2000-),男,硕士研究生,从事水文学及水资源研究。E-mail:1752864830@qq.com;通讯作者:朱海(1986-),男,副教授,博士,从事河湖水动力与水环境数值模拟研究。E-mail:h.zhu@hhu.edu.cn。
