基于MODIS数据遥感反演呼伦湖水体总磷浓度及富营养化状态评价

Determination total phosphorus concentration and evaluation eutrophication of Hulun Lake with MODIS data

水体中总磷的浓度是衡量水环境的重要指标之一,对于水质和富营养化评价的研究具有重要意义。利用遥感卫星反演TP浓度并进行湖泊富营养化评价可以对湖泊TP浓度分布及富营养化程度进行全面整体监测,对水体水质实时动态监测和富营养化、洪灾等应急处理有较大的实用价值。以呼伦湖为研究区域,分别用2012年8月5日和2013年7月2日13个取样点的实测TP浓度值并结合同一天MODIS影像,进行TP浓度的特征波段选择,建立了基于MODIS遥感影像的半经验回归模型并进行验证,然后,应用模型反演呼伦湖2013年5—10月水体TP浓度值并结合舒金华修正营养状态指数模型进行富营养化评价。结果表明,在呼伦湖流域应用MODIS数据500 m分辨率中的第6、7波段可以较好地模拟水体中的TP浓度,呼伦湖2013年5—10月TP浓度分布较均匀,水体呈富营养化水平,与日常观测和其他学者得到的结果一致。研究表明,模型具有一定的预测能力,利用MODIS影像可以较好地对湖泊水体TP浓度进行反演并评价富营养化水平。

The total phosphorus( TP) concentration is an important indicator in the evaluation of water environment. The distribution of TP concentration of lake can be retrieved with satellite data,then,the eutrophication of the lake can be evaluated with the satellite retrieval TP concentration. The TP concentration and eutrophication of lake can be holistically evaluated and monitored,which is of great practical value in real time dynanic monitoring of the water quality,eutrophication and emergency processing of floods. The typical bands of TP concentrations were selected with the measuring data of TP concentration of Hulun Lake on July 2,2012 and August5,2012 as well as the MODIS images on the same days. The semi-empirical regression model were determined and validated,and the TP concentration was derived with the model,and then the eutrophication of the lake was evaluated combined with the index model corrected with nutrition state by Shujinhua. The results show that the No. 6,No. 7 bands of MODIS images with 500 m resolution ratio can be used in simulating the TP concentration. The TP concentration distribution of Hulun Lake is relatively uniform in the period of May to October,2013. The lake is in eutrophication state which is consistent with the daily observation and the results from other scholars. The study shows that the developed model can be used in prediction TP concentration retrieval with MODIS images to evaluate the eutrophication of lake.