不同级别降雨对北运河水系汛期污染强度影响分析

Analysis of impact of different rainfall levels on pollution intensity of North Canal River during flood season

为探究不同降雨级别对北运河水系汛期污染强度的影响,选取2023年夏季3场不同级别的典型降雨开展北运河水系汛期污染强度监测,根据汛期污染强度统计方法,分析北运河干流及4条支流出口断面化学需氧量汛期污染强度变化,以及化学需氧量浓度峰值出现时间和恢复时间,研究各水系化学需氧量汛期污染强度和降雨级别的关系。结果表明:北运河干流及4条支流出口断面化学需氧量汛期污染强度随降雨次数的增加而有所下降;首场降雨化学需氧量汛期污染强度随降雨级别增加而变大。化学需氧量浓度随降雨级别增加在逐渐上升,大暴雨级别污染物累积导致流域出口断面水质恶化。相同降雨级别各流域污染物达到最大浓度时间和恢复时间存在差异,可能与各流域路面硬化程度有关。研究成果为研究降雨对城市河道水质的影响提供依据。

To investigate the impact of different rainfall levels on pollution intensity in the Beiyun River system during the flood season,three typical rainfall events of varying levels in the summer of 2023were selected to monitor pollution intensity.Using statistical methods,changes in the chemical oxygen demand CODcr pollution intensity of the main stream and four tributary outlets of the Beiyun River were analyzed,along with the peak and recovery times of CODcr concentration.The relationship between CODcr pollution intensity and rainfall levels in different parts of the river system during the flood season was also examined.The results showed that CODcr pollution intensity at the outlet sections of the main stream and four tributaries decreased as rainfall frequency increased during the flood season.During the first flood season rainfall,CODcr pollution intensity increased with rising rainfall levels.CODcr concentration also increased with higher rainfall with pollutant accumulation during extremely heavy rainstorms,which led to a deterioration in water quality at basin outlet sections.Differences were observed in the peak concentration and recovery times of pollutants across different watersheds under the same rainfall conditions,which might relate to the extent of road hardening in each watershed.The effectiveness of sponge city construction in the study area was analyzed to provide insights into the impact of rainfall on urban river water quality.