里下河腹部典型区水质时空变化特征及其原因分析

江苏里下河地区河网密布、水体流动性差,水生态环境问题突出,水质时空特征分析可为水资源管理与水生态环境改善提供科学依据。基于2017年里下河泰州地区39个断面的全指标水质监测数据,综合运用单因子水质标识指数法、综合水质标识指数法和GIS空间分析方法,分析里下河腹部典型区水质时空变化特征及其原因。里下河腹部泰州地区水质呈现显著的年内变化,水质年内变化主要受丰水期降雨和逐月外引水源水量影响。1-5月,降水量少,外引水量增加,水质好转;6-9月,引水量下降,降水量上升,水质恶化;10月降水量和引水量都较少,水质为年内最差;10-12月,降水量少,引水量增加,水质好转。水质最差的7-10月主要污染因子为溶解氧、高锰酸盐指数、总磷;水质较差的1-2月主要污染因子为五日生化需氧量、高锰酸盐指数、总磷、化学需氧量;水质较好的3-6月主要污染因子为五日生化需氧量和总磷。里下河腹部泰州地区水质亦有显著的空间差异,外引水源水量大的月份,水质由西南部向东北部和东南部逐渐变差,水质空间变化与引水路线有较强的相关性;外引水源水量小的月份,水质总体上呈现南优北劣的特征,主要受到降水、地形和当地污染物积累的影响。

An Analysis of Temporal and Spatial Variation Characteristics of Water Quality in Lixiahe Abdominal Area

In Lixiahe Area of Jiangsu Province, river networks are densely dotted, river water liquidity is poor, and the water ecological environment problems are prominent. Temporal and spatial characteristics analysis of water quality can provide a scientific basis for water resources management and water ecological environment improvement. Based on the whole water quality monitoring data of 39 sections in Taizhou of Lixiahe area in 2017, this paper comprehensively uses single factor water quality identification index, comprehensive water quality identification index and GIS spatial analysis method to analyze the temporal and spatial variation characteristics and causes of water quality in typical areas of Lixiahe Abdominal Area. The water quality in Taizhou of Lixiahe Abdominal Area show prominent changes during the year. The annual change is mainly affected by rainfall in high water period and the amount of monthly external diversion of water sources. From January to May, the quantity of external diversion increases and the quality of water improves.From June to September, water diversion decreases, precipitation increases and water quality deteriorates.In October, precipitation and diversion of water are low, the water quality is the worst of the year. From October to December, precipitation is low, diversion water significantly increases, and water quality improves. From July to October, water quality is worst. The main pollution factors were DO,CODMn and TP;From January to February, water quality was poor. The main pollution factors were BOD5,CODMn,TP and CODCr;From March to June,water quality was good. The main pollution factors were BOD5 and TP. The water quality in Taizhou of Lixiahe abdominal area also had prominent spatial difference. In the months with large amount of external water sources,water quality gradually deteriorated from southwest to northeast and southeast,and the spatial change of water quality had a strong correlation with the water diversion route. In the months with a small amount of external water sources,the water quality generally showed the characteristics of being superior in the south and inferior in the north,mainly affected by precipitation,topography and local pollutant accumulation.