基于色度角信息的衡水湖富营养状态监测研究

Eutrophic status of hengshui lake based on chromaticity angle information monitoring research

【目的】营养状态作为评价湖库水环境变化特征的一个重要方面,实现对其准确、大范围的动态监测对于分析富营养化成因具有十分重要的作用。【方法】利用Landsat8遥感数据的色度角信息,构建了适用于衡水湖的叶绿素a浓度反演模型,并对其精度进行了检验,在此基础上,实现对衡水湖2013—2022年10 a间的营养状态监测,分析了其与气温和降水等气候因素的关系,对2018—2019年5次生态补水过程进行了遥感监测。【结果】结果表明:(1)该模型较为可靠,决定系数R^(2)为0.79,均方根误差和平均百分比误差分别为0.0018和4.5%;(2)近10 a衡水湖营养状态得到一定的改善,其空间变化呈现“北低南高”现象。其中,南关闸和南关新闸相对于其他湖体区域营养状态处于较高水平;(3)通过对5次生态补水过程的遥感监测发现,生态补水对于衡水湖营养状态改善具有一定的积极作用,尤其在进水口的王口闸附近,其对生态补水的响应最为及时。衡水湖营养状态是一个内在、外在、水动力等多因素影响的问题,对于个别区域存在些许波动,仍需进一步研究其内在关系。【结论】通过遥感手段实现对衡水湖营养状态的监测是可行的,能够较好揭示衡水湖营养状态变化整体规律,并实现对生态补水过程的有效监测,为衡水湖湿地水环境监测和营养状态治理提供重要的技术支撑。

[Objective]Nutritional status is an important aspect of evaluating the characteristics of water environment changes in lakes and reservoirs,and achieving accurate and large-scale dynamic monitoring of it plays a very important role in analyzing the causes of eutrophication.[Methods]The chromaticity angle information of Landsat 8 remote sensing data was utilized to construct a chlorophyll a concentration inversion model suitable for Hengshui Lake,and its accuracy was tested.Based on this,the nutritional status of Hengshui Lake was monitored from 2013 to 2022,and its relationship with climate factors such as temperature and precipitation was analyzed.Remote sensing monitoring was conducted on five ecological replenishment processes from 2018 to 2019.[Results]The result show that:(1)the model is relatively reliable,with a determination coefficient R^(2) of 0.79,root mean square error and average percentage error of 0.0018 and 4.5%,respectively;(2)In the past decade,the nutritional status of Hengshui Lake has improved to a certain extent,and its spatial changes show a phenomenon of low in the north and high in the south.Among them,the nutritional status of Nanguan Sluice and Nanguan New Sluice is relatively high compared to other lake areas;(3)Through remote sensing monitoring of five ecological replenishment processes,it was found that ecological replenishment has a certain positive effect on improving the nutritional status of Hengshui Lake,especially near the Wangkou Gate at the inlet,where its response to ecological replenishment is most timely.The nutritional status of Hengshui Lake is a problem influenced by multiple factors such as internal,external,and hydrodynamic factors.There are some fluctuations in certain areas,and further research is needed to investigate their internal relationships.[Conclusion]It is feasible to monitor the nutritional status of Hengshui Lake through remote sensing method,which can better reveal the overall pattern of changes in the nutritional status of Hengshui Lake and effectively monitor the ecological water replenishment process.This provides important technical support for the monitoring of the water environment and the management of nutritional status in Hengshui Lake wetlands.