三峡水库香溪河库湾水华生消的数值模拟分析

Numerical Simulation of Algal Bloom in the Xiangxi River Bay at the Three Gorges Reservoir

三峡水库蓄水后,香溪河库湾成为富营养化敏感水域,水华大范围暴发,直接威胁流域生态、经济的可持续发展。应用WASP生态动力学模型对三峡水库香溪河库湾水华暴发的生物、化学和物理过程进行模拟研究,结合库湾2007年春季的监测资料,分析其水华生消机理,为水华防治提供借鉴。研究结果表明:模拟值较实测有一定滞后,且带有一定误差,一方面由于库湾水动力条件本身的影响,另一方面可能是由于硅营养的影响。从模拟结果来看,香溪河库湾发生大面积水华两次,第一次是3月下旬,第二次是4月上旬至中旬;若考虑库湾支流水华,则还有3月18日在高岚河GL、5月6-7日在XX00-XX01库段以及支流平邑口PY、高岚河GL和屈原河QY的两次小范围水华,总共暴发4次。实测结果是库湾曾发生4次较明显的水华,第一次是2月25日在平邑口PY,第二次是3月25日-4月9日库湾大面积暴发,第三次是5月6-7日至当月中旬小范围暴发。

Since the storage in Three Gorges Reservoir, Xiangxi River Bay has become the hypersensitive water area for eutrophication. Extensive outbreak of algal bloom threatens the sustainable development of ecology and economy in the basin. Based on the model of water quality analysis simulation program（WASP, 2005） developed by US Environmental Protection Agency, this paper simulates the biotic, chemical and physical process of algal bloom in Xiangxi River Bay by combining the monitoring data in Xiangxi River Bay in the spring of 2007. The authors analyze the formation and disappearance of algal bloom, hoping that it may serve as a reference for preventing algal bloom. Research results show that the average relative error of PO4 , NH4 and NO3 are small, the result of process simulation for formation and disappearance of algal bloom is satisfactory. Simulation shows that twice large area algal bloom breakout in Xiangxi River Bay, first time in late March and second time from early April to the middle of April. If the distributaries of Xiangxi River Bay take into consideration the total number of algal bloom increases to four times including March 18 in Gaolan River, May 5 and May 6 in segment XX00 to XX01, twice small range algal bloom in distributaries named Pingyikou, the Gaolan River and the Quyuan River. Measurement results show that there are three times large area algal bloom breakout in the Xiangxi River Bay, the first time is February 25 in Pingyikou, the second time from March 25 to Apirl 9 in the whole Xiangxi River Bay and the third time from May 6 and. May 7 to mid-May in small range of the Xiangxi River Bay.