基于光谱特征的长江口细颗粒泥沙絮凝体投影表面积和沉速分析  

Analysis on the projected surface area and settling velocity of fine-grained sediment flocs based on spectral characteristics in the Changjiang Estuary

作　　者：程江[1,2] 蒋雪中[1] 

机构地区：[1]华东师范大学河口海岸学国家重点实验室,上海200062 [2]上海市城市排水有限公司,上海200233

出　　处：《水利学报》2011年第10期1135-1143,共9页Journal of Hydraulic Engineering

基　　金：国家自然科学基金项目(51009068;40801201;40601071)

摘　　要：2009年5月23日-6月2日在长江口南槽九段沙水域，利用便携式地物光谱仪和现场激光粒度仪分别测量了水体光谱反射率和细颗粒泥沙絮凝体现场特性以研究两者之间的关系，测量时同步采集了水样测量悬沙浓度（ssc）。研究显示：①水体光谱反射率随絮凝体投影表面积（PSA）的增加而增大，光谱曲线在350-950nm波段间存在两个明显反射峰，分别以690～720nm和810nm波长为中心；②絮凝过程改变细颗粒泥沙的水体反射光谱特征，导致SSC与光谱反射率的相关性低于PSA与光谱反射率的相关性。PSA与波长〉715nm波段光谱反射率的相关性r〉0．7，p〈0．01；⑧可选择常用卫星遥感可见光、近红外通道范围，且PSA与光谱反射率相关性较高的波段，建立PSA与单波段光谱反射率和多波段光谱反射率组合比值的拟合关系式，其中单波段860nm（r=-0．9227，p〈0．001）和860／670多波段组合（r=0．9373，p〈0．001）的指数方程预测效果均最优；④构建了光谱反射率与絮凝体沉速间的幂函数拟合关系式（r=0．8337，p〈0．001），为监测长江口大尺度区域絮凝体PSA和阢的空间分布和动态变化提供了一种新的方法。The in situ spectral reflectivity and physical characteristics of fine-grained suspended sediment flocs in surface water （0.Sm） at the Changjiang Estuary were measured by using spectroradiometer and a laser particle size analyzer respectively. Suspended sediment concentration （SSC） was attained simultaneously by water sample analysis. The analysis results show that ① Spectral reflectivity increased with increased projected surface area （PSA） of fine-grained suspended sediment flocs. Two spectral reflectivity peaks exist in 690-720nm and 810 nm band, respectively. ② Flocculation process changed the spectral characteristics of fine-grained suspended sediment, resulted in the correlation between PSA and spectral reflectivity larger than that between SSC and spectral reflectivity. The correlations between PSA and spectral reflectivity with band larger than 715 nm were bigger than 0.7 with a confidence level of p〈0.01. ③ The exponential relationship was the best one between single band spectral reflectivity and PSA, and also between multi-band spectral reflectivity ratio and PSA. The correlations of single band at 860nm with r=-0.9227 and p〈0.001, and multi-band spectral reflectivity ratio of 860/670 with r=-0.9373 and p〈0.001 were the best. ④ Based on the fine relationships between PSA and spectral reflectivity, as well as between PSA and settling veloci- ty （Ws） of floes, a power relationship with r=0.8337 and p〈0.001 was establish between spectral reflectiv- ity and Ws which could provide a new attemptable method to understand the distribution and changing process of PSA and Ws of fine-grained suspended sediment at a large scale in the Changjiang Estuary.

关 键 词：光谱反射率 细颗粒泥沙 絮凝 投影表面积 沉速 长江口 

分 类 号：TV141[水利工程—水力学及河流动力学]