| 长江干流表层水体悬浮物的空间变化特征及遥感反演 |
| 摘要点击 2411 全文点击 730 投稿时间：2021-03-28 修订日期：2021-04-20 |
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| 中文关键词 悬浮物浓度 遥感反演 经验模型 长江干流 空间变化 |
| 英文关键词 suspend matter concentration remote sensing inversion empirical model Yangtze River mainstream spatial variation |
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| 中文摘要 |
| 总悬浮物（TSM）是描述水体光学特性和污染程度的一个重要参数，利用遥感技术准确获取面状水域悬浮物浓度的信息，可有效地对水体浑浊程度、污染程度等信息指标进行高效监测分析，解决观察范围小、不方便以及数据获取难等难题.以野外实测水体高光谱数据和悬浮物浓度及其组分等数据，参照MODIS （1~4波段）、Landsat 8（1~5波段）、Sentinel 2（2~6波段）和HJ-B1（1~4波段）等常用波段范围，构建长江干流（重庆-上海段）水体TSM的半经验模型，从而检验、比较常用卫星对河流水体TSM的反演潜力.结果表明：①枯水期长江干流浊度和TSM从重庆到上海整体程增加趋势，相反有机悬浮物浓度在总悬浮物浓度中所占的比例（OSM/TSM）从重庆到上海整体呈现较小趋势.②水体光谱曲线基本没用叶绿素a的光谱特征（700 nm附近的反射峰），而是展现出悬浮物浓度占主导因素的双峰型光谱特征.由于水体中悬浮物浓度较低（<114.68 mg ·L-1），第一峰值明显高于第二峰值，但反射峰位置具有明显的向波长方向移动的"红移"现象.③长江干流水体的反射率对悬浮物浓度最敏感的波段是600~710 nm和475~550 nm波段，这些波段大部分都落在MODI、Landsat 8，Sentinel 2和HJ-1B卫星绿波段和红波段内，因此目前常用卫星的波段设置在反演长江干流水体TSM上都具有一定的潜力.其中Sentinel 2卫星波段设置最合适长江干流水体悬浮物浓度的反演，其最佳的指数反演模型RMSE为10.23mg ·L-1，MAPE为23%. |
| 英文摘要 |
| Total suspended matter(TSM) is an important parameter that describes optical characteristics and water pollution level. Remote sensing was used to obtain suspended matter concentrations in the planar water body, which can monitor and analyze the reliability of turbidity and pollution levels. In this study, a semi-empirical model of suspended matter along the Yangtze River mainstream(from Chongqing to Shanghai) was constructed based on the field measured hyperspectral data and suspended matter concentration and its components, with reference to MODIS(1-4 band), Landsat 8(1-5 band), Sentinel 2(2-6 band), HJ-B1(1-4 band), and other commonly used band ranges. The results show that:① Turbidity and TSM of the Yangtze River mainstream increased from Chongqing to Shanghai during the dry season, whereas the proportion of OSM to TSM(OSM/TSM) decreased from Chongqing to Shanghai. ② The spectral properties of chlorophyll-a were not obvious; however, it showed a bimodal spectral characteristic of suspended matter concentration. Due to the low concentration of suspended matter in the water(<114.68 mg·L-1), the first peak value was significantly higher than the second peak. However, peak reflection and position had an obvious "red shift" phenomenon in the direction of the wavelength. ③ The reflectance values of the Yangtze River mainstream were most sensitive to the concentration of suspended matter in the 600-710 nm and 475-550 nm bands. Most of these fall in the green and red band of MODI, Landsat 8, Sentinel 2, and HJ-1B satellites. Therefore, the commonly used satellites have a band setting to detect the inversion of turbidity degree index of the Yangtze River main stream water body. The Sentinel 2 satellite band is most suitable for the inversion of suspended matter concentration in the Yangtze River mainstream. The mean absolute percentage error(MAPE) and root mean square error(RMSE) of the optimal exponential model were 10.23 mg·L-1 and 23%, respectively. |
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