长江流域资源与环境 >> 2014, Vol. 23 >> Issue (s): 103-.doi: 10.11870/cjlyzyyhj2014Z1015

• 生态环境 • 上一篇    下一篇

基于CE-QUAL-W2模型的龙川江支库富营养化预测

梁 俐,邓 云 ,郑美芳,魏 希   

  1. (四川大学水力学与山区河流开发保护国家重点实验室,四川 成都 610065)
  • 出版日期:2014-11-26

PREDICTING OF EUTROPHICATION IN THE LONGCHUAN RIVER BASED ON CEQUALW2 MODEL

LIANG Li, DENG Yun, ZHENG Meifang, WEI Xi   

  1. (State Key Lab of Hydraulics and Mountain River Enginerring, Sichuan University, Chengdu 610065, China)
  • Online:2014-11-26

摘要:

支库水体由于流速缓慢、水温高且营养物质易于富集,较主库更易发生富营养化。通过立面二维水动力学和水质模型(CEQUALW2)对金沙江乌东德水库蓄水(2020年)后龙川江支库的富营养状况进行了预测。结果表明:在水位较高的春季4月和汛末蓄水期8~9月,大于60%河段的表层水体中Chla浓度均超过64 mg/m3,该时期富营养化风险较大;而在水位快速下降的泄水期5~7月及水温较低的冬季12~2月库区Chla值均未达到26 mg/m3,富营养化风险相对较小。在此基础上,对影响支库藻类生长的主要因素进行了分析,在库区营养盐浓度均较充足的4月和8月,由于靠近河口段表层水域存在较为明显的水温分层及缓慢的流速,藻类在此区域大量聚集,且汇口处Chla浓度较上游库尾处来流分别提高了近70倍和100倍;干流对支流的倒灌影响有时会为支库提供有利于藻类生长的水动力和水温条件,并其也是龙川江支库营养盐的一个主要来源。通过对乌东德单独运行时的调度情景和削减入流营养盐的数值模拟表明,采用降低水库运行水位或“双重营养盐削减”的措施,均能够有效的达到制约支库库区富营养化的目的 

Abstract:

After impounding, water environment of reservoirs has been significantly changed due to dramatically increased water level, lower flow velocity, poorer diffusion ability and longer retention time in the tributaries. This change can lead to eutrophication which is more likely to occur in tributary than in main stream. Longchuan River, one of the branches of Wudongde Reservoir in Jinsha River, is the major water source to supply drinking and irrigating for Chuxiong City. The change of water dynamic condition in Longchuan River could result in eutrophication after Wudongde Reservoir impounding. A twodimensional, laterally averaged hydrodynamic and waterquality model, CEQUALW2 was taken to perform simulations and predictions of eutrophication in Longchuan Rivers backwater area. The simulation parameters included water temperature, total nitrogen (TN), total phosphorus (TP), flow velocity and chlorophylla (Chla). The simulation results were as follows: firstly, when the operation water levels were high in April, August and September, the Chla concentrations were high and reached 64mg/m3 over 60% distance along the river, so higher risk of eutrophication existed. The lowest risk happened from May to July because of higher flow velocity, and December to February because of lower water temperature. The second, main factors that limited the algae growth were flow velocity and water temperature when the nutrient saline levels were high. For instance, there were obvious stratification and slow velocity in the surface of section near estuary in April and August, so Chla concentrations in the rivers mouth were 70 times and 140 times higher than the sub reservoir tail. The third, there were significant intrusions from Wudongde Reservoir to Longchuan Bay with three forms of intrusion to the surface, middle and bottom respectively.The unique flow characteristic provided a hydrodynamic background of nutrient distributions of Longchuan Bay. Moreover, the densitystratified flow in different direction along depth could decrease the flow velocity of surface water and enhance the capacity of heat storage at certain time, which provided favorable hydrodynamics and temperature for the algae growth in tributary. In addition, the model was also used to evaluate the effects of change of reservoir operation and reduction of nutrient load on algae biomass of branch reach. The modeling results of the four conditions (decreasing water level to 950m in April, cutting TP and TN concentrations of branch into two different nutrient levels, cutting nutrient of branch and main stream synchronously) indicated that decreasing water level and cutting nutrient could improve the water quality of branch and restrict the eutrophication of branch effectively. However, only cutting nutrient concentration of branch was not enough, cutting nutrient of branch and main stream synchronously was more effective. Therefore decreasing water level and “double cutting nutrient” can be taken to restrict the eutrophication in reservoir when great risk for eutrophication existed, and can be used to control algae bloom in the branch of similar ChannelType reservoirs

No related articles found!
Viewed
Full text


Abstract

Cited

  Shared   
  Discussed   
[1] 任雪梅,徐永辉,周 彬,杨达源. 宜宾—重庆段川江高阶地物质来源的定量分析——判别分析在重矿物分析中的应用[J]. 长江流域资源与环境, 2006, 15(3): 330 -334 .
[2] 徐天宝, 彭静, 李翀. 葛洲坝水利工程对长江中游生态水文特征的影响[J]. 长江流域资源与环境, 2007, 16(1): 72 -75 .
[3] 王红娟,姜加虎,黄 群. 东洞庭湖湿地景观变化研究[J]. 长江流域资源与环境, 2007, 16(6): 732 .
[4] 罗小龙, 陈雯, 金志丰. 南京城郊结合部拓展的机制、问题与对策[J]. 长江流域资源与环境, 2008, 17(2): 175 .
[5] 蒲志仲. 水资源所有权问题研究[J]. 长江流域资源与环境, 2008, 17(4): 561 .
[6] 游文荪| 丁惠君*| 许新发. 鄱阳湖水生态安全现状评价与趋势研究[J]. 长江流域资源与环境, 2009, 18(12): 1173 .
[7] 王立辉, 黄进良, 孙俊英. 湖北省农情遥感速报系统的设计与实现[J]. 长江流域资源与环境, 2010, 19(z1): 190 .
[8] 姜苹红, 崔永德, 王海军, 王洪铸. 汉阳湖群底栖动物群落及其对环境质量的指示[J]. 长江流域资源与环境, 2011, 20(05): 525 .
[9] 叶殿秀, 赵珊珊, 孙家民. 近50多年青海玉树冻土变化特征分析[J]. 长江流域资源与环境, 2011, 20(09): 1080 .
[10] 宗 玮 |林文鹏 |周云轩 |芮建勋. 基于遥感的上海崇明东滩湿地典型植被净初级生产力估算[J]. 长江流域资源与环境, 2011, 20(11): 1355 .