基于水质管理目标的博斯腾湖生态水位研究

人类开发活动导致湖泊生态功能严重退化,研究湖泊生态水位对于维持湖泊生态系统健康意义重大。针对博斯腾湖化学需氧量(COD)浓度较高的水环境现状,分析博斯腾湖水位和COD浓度关系,研究提出基于水质管理目标的生态水位,以期为博斯腾湖水资源、水环境管理提供参考。结果表明,博斯腾湖水位与水体COD浓度显著负相关,但由于COD浓度空间差异较大以及影响因素不唯一,水位与COD浓度两者之间曲线估计结果不理想。为实现博斯腾湖COD浓度小于20 mg/L的水质管理目标,引入累计水位概念进行统计分析得到两个特征水位:所有COD浓度大于等于20 mg/L的数据对应水位的平均值为1046.02 m,该水位在历史丰水期水位的频率为60.83%,可作为最小生态水位;所有COD`浓度小于等于20 mg/L的数据对应水位的平均值为1046.4 m,该水位在历史丰水期水位的频率为44.70%,可作为适宜生态水位。适宜生态水位1046.4 m与已有研究成果基本相符,博斯腾湖在1046.4 m时既有利于水质管理,也可保障湖泊整体生态系统健康。

Study of ecological water levels of Bosten Lake for water quality management

Human activities have led to serious degradation of lakes in terms of their ecological functions, making the study of the ecological water level of lakes exceedingly important. Based on the current water environment in Bosten Lake, where there is a high concentration of chemical oxygen demand (COD), a study of the ecological water level of Bosten Lake was conducted for water quality management, by analyzing the relationship between COD concentration and water level. Results showed a significant negative correlation between the water level and COD concentration. However, because of the large spatial variation in the COD concentration and multiple influencing factors, the curve estimation between COD concentration and water level was unsatisfactory. To realize water quality management objectives of Bosten Lake with a COD concentration of less than 20 mg/L, the concept of cumulative water level was introduced for statistical analysis to obtain two characteristic water levels:1046.02 m was the average water level for all COD concentrations greater than or equal to 20 mg/L, and it can be used as the minimum ecological water level based on a 60.83% cumulative frequency in the flood season; 1046.4 m was the average water level for all COD concentrations less than or equal to 20 mg/L, and it can be used as the optimal ecological water level based on a 44.70% cumulative frequency in the flood season. The optimal ecological water level of 1046.4 m is consistent with previous studies, which means that it is conducive to both water quality management and overall ecosystem health of Bosten Lake.