摘要
蓝藻水华与水生植被在光学遥感影像上容易混淆,传统方法将太湖划分为藻型湖区和草型湖区进行分区监测,近年来太湖梅梁湖等蓝藻水华易发区域出现了大量的水生植物,分区的方法已无法满足蓝藻水华和水生植被遥感监测要求。基于光谱特征分析,采用蓝藻水华与水生植被指数(cyanobacteria and macrophytes index,简称CMI)判别蓝藻水华与水生植被水域,采用浮游藻类指数(floating algae index,简称FAI)识别蓝藻水华、浮叶/挺水植被与沉水植被,构建同步监测决策树,基于Otsu算法自动获取阈值,将中分辨率成像光增仪(MODIS)卫星影像分成湖水、蓝藻水华、沉水植被和浮叶/挺水植被几种类型。结果表明,分类结果较好,符合太湖不同地物类型实际分布情况;与相关研究HJ卫星影像东部湖区水生植被监测结果进行交叉检验,水生植被的空间分布基本一致,一致性检验结果显示,2种分类结果一致的像元比例为70.11%。实现蓝藻水华及水生植物的同步遥感监测,有助于精确评估蓝藻水华的实际强度和水生植被区范围,为富营养化湖泊的水环境管理和决策提供重要的科技支撑。
引文
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