流域总量控制下赣江流域控制单元划分技术

作为“控制单元的总量控制技术”的关键环节,控制单元的概念、内涵及划分方法一直存在较大分歧,其重要性没有得到应有的体现. 在分析欧美控制单元的基础上,提出了控制单元的概念(基于“控制单元的总量控制技术”的理念,为实现水环境容量总量的计算、分配和管理等目标,综合考虑水文、水环境、水生态和水体使用功能等因素而人为划分的水质目标管理单元),并阐述了其内涵. 基于GIS技术,采用多指标空间叠加分析和专家判断方法,提出了不同尺度流域的控制单元的划分原则、指标体系及技术路线,并以赣江和锦江流域为例进行了控制单元的划分,赣江流域划分为17个1级控制单元、57个2级控制单元；锦江流域划分为4个控制单元. 对锦江流域开展了非点源参与下动态水环境容量计算及控制单元总量动态分配,丰水期COD_Mn和NH₄+-N水环境容量分别占研究区年总容量的63.4%和60.6%. 假设总量利用率为70%,将控制单元的分配结果作为SWAT(soil and water assessment tool)模型的点源输入,验证控制单元划分方案的可行性,模拟结果显示,良田和均车断面的ρ(NH₄+-N)均满足GB 3838—2002《地表水环境质量标准》Ⅲ类水质标准的要求,说明划分方案可行. 

Study on Control Unit Division Technology for Total Amount Control in Gangjiang Basin

Control units are a critical part of “Total Amount Control by Control Unit Technology.” However, their definition, content and division are debated, and their importance has not received enough attention. The control unit in the present study was selected as water quality target management unit based on the concept of “Total Amount Control by Control Unit Technology”. It was artificially divided for realizing the purposes of computing, allocation and management of water environment capacity by considering hydrology, water environment, water ecology and water use function and other factors. Moreover, using GIS (geographic information system) techniques, the spatial superposition analysis with multiple criteria and the expert decision-making methods, we described the principles, the criteria system and the technical route of the control unit division at different basin levels. Ganjiang Basin can be divided into 17 control units at Grade 1 and 57 control units at Grade 2, while Jinjiang Basin contains 4 control units. Furthermore, with the involvement of non-point source pollution, the dynamic water environment capacity was calculated, and the total dynamic allocation was performed. The results showed that the water environment capacity of COD_Mn and ammonia nitrogen in the rainy season accounted for 63.4% and 60.6%, respectively. Finally, to evaluate the feasibility of the control unit divisions, the SWAT (soil water and assessment tool) with the point pollution source inputs from the allocated control units was applied under the assumption of the utilization ratio for 70% of the total amount. The results showed that the concentration of NH₄+-N at the sampling sites of Liangtian and Junche met the water quality of Standard-Ⅲ (GB 3838-2002), suggesting that the division scheme was reliable.