基于高光谱的潮间带表层沉积物粒度参数空间分布规律研究

Spatial distribution characteristics of surface sediment grain-size parameters on the intertidal flat using hyperspectral remote sensing data

研究发现,Hyperion高光谱影像的中心波长为1215和2133 nm的波段反射率组合与沉积物粒度参数(平均粒径、偏态和中值粒径)之间以及平均粒径和中值粒径之差与分选系数之间有显著的线性相关特征,据此构建了线性回归模型,反演并分析了江苏省射阳河口南侧潮滩沉积物粒度参数的空间分布规律。经独立样本的检验显示,粒度参数反演的总体平均相对精度和平均绝对精度分别在75.70%和72.17%以上。从粒度参数的空间分布来看,具有明显的空间变化特征,总体变化趋势为:平行于岸线走向由北向南颗粒逐渐变细,分选变差,偏态由近对称转为正偏;垂直于岸线走向从陆向海沉积物颗粒逐渐变粗,分选性变好,偏态由正偏转为近对称,但是在中潮位附近,沉积物颗粒粗细交替分布,平均粒径较大,分选性表现为大致由中潮位附近向海、向陆变差。这种变化趋势与研究区的水动力环境及沉积物物质来源吻合良好。

Among totally 242 spectral bands ranging from 400 to 2 500 nm of Hyperion hyperspectral re- mote sensing data, it was found that two bands with reflectance of 1 215 and 2 133 nm had relatively good correlation with the sediment grain-size parameters of mean diameter, skewness, medium diameter and sorting coefficient. And further more, the combination of the sum of these two bands divided by their difference had a significant linear correlation with the mean diameter, skewness and medium diameter while the sorting coefficient had a notable linear relationship with the discrepancy of the mean diameter and medi- um diameter. On the basis of these relationships, four linear regression models were established and ap- plied to getting the spatial distribution characteristics of grain-size parameters at the southern part of inter- tidal flat near the Sheyang Estuary in Jiangsu Province,China. Verification by independent samples show that the mean relative precision and the mean absolute precision exceed 75.70% and 72.17%, respectively. The spatial distribution pattern of grain-sizes indicates that in the direction from north to south that parallel to the coastal line, the grain-size diameters become finer, the sorting characteristics become worse and the distribution of skewness moves from near symmetry to positive deviation. While at the direction from land phase to sea that perpendicular to the coastal line, the grain-size diameters change coarser, the sorting characteristics become better and the distribution of the skewness moves from positive to near symmetry. But near the medium tidal level area, sediment is the mixture of fine and coarse matter and the mean diam- eter is a litter larger than nearby part. sorting characteristic becomes worse from medium to either land or sea direction. These variation trends are in accordance with hydrodynamic environments and sources of sediments well.