“7.20”暴雨对黄河干流河南段水文水质影响及应对措施分析

Title Influence of July 20’s Rainstorm on Hydrology and Water Quality in the Mainstream of Yellow River,Henan Province and Analysis of Countermeasures

气候变化背景下极端天气事件对人类和自然生态系统造成的影响越来越受到关注。通过对河南2021年“7.20”暴雨后黄河干流河南段水质进行跟踪监测以及对暴雨前后各代表站流量含沙量等水文要素分析,揭示“7.20”暴雨引发的黄河干流水文要素变化状况以及对应污染物输移规律,探究此次暴雨对黄河干流河南段水文以及水质的影响。研究结果表明,各水文站点含沙量变化趋势与流量变化趋势保持一致,呈显著正相关性,均为先上升后下降趋势,同时受降雨汇流状况影响,峰值出现时间有所差别。暴雨给黄河干流河南段水质带来一定不良影响,其中,主要超标污染物为TP与TN。TP可快速恢复至正常水平,TN浓度达到峰值后持续下降,其余指标略有波动,但可较快恢复至暴雨前水准。总体而言,暴雨引发了严重的总氮超标现象,持续时间较TP等指标长,且氮磷具有异源性。但暴雨引发的水质污染是短期、动态可恢复的,入河污染负荷未长时段超出黄河干流环境容量。建议采用LID措施、耕作方式调整、调蓄池、农村坑塘体系、滨水缓冲带、生态沟渠等手段,降低暴雨期氮磷等污染物入河风险,保护黄河健康。

The impact on human and natural ecological systems caused by extreme weather events under climate change conditions has re⁃ceived widespread attention.A continuous water quality monitoring is taken in the mainstream of Yellow River after July 20’s rainstorm in Henan Province to reveal the contaminant transportation rule during this flood event and study the influence on water quality in mainstream of Yellow River.The results show that the variation trend of sediment concentration keeps consistent with that of discharge,it has significant positive correlation with discharge,the concentration increases first and then decreases,and it is affected by rainfall confluence,peak value appears differently.The peak value of flow emerges one day behind that of rainfall.As for the water quality,the rainstorm brings a bad influ⁃ence on water quality in mainstream of Yellow River,Henan Province,and the major excessive pollutants are total phosphorus and total ni⁃trogen.The concentration of total phosphorus exceeds the standard in July 21th,and then turns normal in a short-term,while the concentra⁃tion of total nitrogen increases firstly,and then decreases after the peak value.The concentration of other water quality indices fluctuate at first during rainfall period and the concentration can turn normal in a few days after the rain.Overall,this rainstorm causes a serious excess of total nitrogen,and its duration of pollution is longer than TP and other indicators.The source of nitrogen and phosphorus are different.What is more,the water pollution caused by rainstorm is dynamic and retrieval,the total pollution load has not exceeded the environmental capacity of Yellow River mainstream for a long time.To protect the healthy life of Yellow River,the measures of LID measures,tillage mode adjustment,storage pool,ponds,riparian buffers and other measures should be taken to reduce the risk of pollution during rainstorm period.